YALE UNIVERSITY
                        MRS. HEPSA ELY SILLIMAN
                           MEMORIAL LECTURES


In the year 1883 a legacy of eighty thousand dollars was left to the
President and Fellows of Yale College in the city of New Haven, to be
held in trust, as a gift from her children, in memory of their beloved
and honored mother, Mrs. Hepsa Ely Silliman.

On this foundation Yale College was requested and directed to establish
an annual course of lectures designed to illustrate the presence and
providence, the wisdom and goodness of God, as manifested in the natural
and moral world. These were to be designated as the Mrs. Hepsa Ely
Silliman Memorial Lectures. It was the belief of the testator that any
orderly presentation of the facts of nature or history contributed to
the end of this foundation more effectively than any attempt to
emphasize the elements of doctrine or of creed; and he therefore
provided that lectures on dogmatic or polemical theology should be
excluded from the scope of this foundation, and that the subjects should
be selected rather from the domains of natural science and history,
giving special prominence to astronomy, chemistry, geology, and anatomy.

It was further directed that each annual course should be made the basis
of a volume to form part of a series constituting a memorial to Mrs.
Silliman. The memorial fund came into the possession of the Corporation
of Yale University in the year 1901; and the present volume constitutes
the fourteenth of the series of memorial lectures.




                       SILLIMAN MEMORIAL LECTURES

                   PUBLISHED BY YALE UNIVERSITY PRESS


  ELECTRICITY AND MATTER. _By_ JOSEPH JOHN THOMSON, D.S.C., L.L.D,
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  THE INTEGRATIVE ACTION OF THE NERVOUS SYSTEM. _By_ CHARLES S.
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                          A CENTURY OF SCIENCE
                               IN AMERICA


[Illustration: B. Silliman]




                                   A
                           CENTURY OF SCIENCE
                               IN AMERICA
  WITH SPECIAL REFERENCE TO THE AMERICAN JOURNAL OF SCIENCE 1818–1918


                                   BY

               EDWARD SALISBURY DANA · CHARLES SCHUCHERT
        HERBERT E. GREGORY · JOSEPH BARRELL · GEORGE OTIS SMITH
                 RICHARD SWANN LULL · LOUIS V. PIRSSON
            WILLIAM E. FORD · R. B. SOSMAN · HORACE L. WELLS
              HARRY W. FOOTE · LEIGH PAGE · WESLEY R. COE
                         AND GEORGE L. GOODALE

[Illustration: [Logo]]

                               NEW HAVEN
                         YALE UNIVERSITY PRESS
          LONDON · HUMPHREY MILFORD · OXFORD UNIVERSITY PRESS
                              MDCCCCXVIII




                          COPYRIGHT, 1918, BY
                         YALE UNIVERSITY PRESS




                             PREFATORY NOTE


The present book commemorates the one-hundredth anniversary of the
founding of the American Journal of Science by Benjamin Silliman in
July, 1818. The opening chapter gives a somewhat detailed account of the
early days of the Journal, with a sketch of its subsequent history. The
remaining chapters are devoted to the principal branches of science
which have been prominent in the pages of the Journal. They have been
written with a view to showing in each case the position of the science
in 1818 and the general progress made during the century; special
prominence is given to American science and particularly to the
contributions to it to be found in the Journal’s pages. References to
specific papers in the Journal are in most cases included in the text
and give simply volume, page, and date, as (=24=, 105, 1833); when these
and other references are in considerable number they have been brought
together as a Bibliography at the end of the chapter.

The entire cost of the present book is defrayed from the income of the
Mrs. Hepsa Ely Silliman Memorial Fund, established under the will of
Augustus Ely Silliman, a nephew of Benjamin Silliman, who died in 1884.
Certain of the chapters here printed have been made the basis of a
series of seven Silliman Lectures in accordance with the terms of that
gift. The selection of these lectures has been determined by the
convenience of the gentlemen concerned and in part also by the nature of
the subject.




                           TABLE OF CONTENTS


                                                                    Page

 Prefatory Note                                                      vii

    I. The American Journal of Science from 1818 to 1918. Edward
         Salisbury Dana                                               13

   II. A Century of Geology: The Progress of Historical Geology in
         North America. Charles Schuchert                             60

  III. A Century of Geology: Steps of Progress in the
         Interpretation of Land Forms. Herbert E. Gregory            122

   IV. A Century of Geology (continued): The Growth of Knowledge of
         Earth Structure. Joseph Barrell                             153

    V. A Century of Government Geological Surveys. George Otis
         Smith                                                       193

   VI. On the Development of Vertebrate Paleontology. Richard Swann
         Lull                                                        217

  VII. The Rise of Petrology as a Science. Louis V. Pirsson          248

 VIII. The Growth of Mineralogy from 1818 to 1918. William E. Ford   268

   IX. The Work of the Geophysical Laboratory of the Carnegie
         Institution of Washington. R. B. Sosman                     284

    X. The Progress of Chemistry during the Past One Hundred Years.
         Horace L. Wells and Harry W. Foote                          288

   XI. A Century’s Progress in Physics. Leigh Page                   335

  XII. A Century of Zoology in America. Wesley R. Coe                391

 XIII. The Development of Botany since 1818. George L. Goodale       439




                               PORTRAITS


 Benjamin Silliman                                        _Frontispiece_
 From a painting by G. S. Hubbard, Esq., in possession of Miss Henrietta
                               W. Hubbard
 Benjamin Silliman, Jr.                                opposite page  28
 James D. Dana                                           „      „     36
 Edward S. Dana                                          „      „     48
 Wolcott Gibbs                                           „      „     52
 James Hall                                              „      „     84
 G. K. Gilbert                                           „      „    140
 Edward Hitchcock                                        „      „    156
 O. C. Marsh                                             „      „    232
 F. V. Hayden                                            „      „    196
 J. W. Powell                                            „      „    204
 Clarence King                                           „      „    208
 George J. Brush                                         „      „    276
 J. Willard Gibbs                                        „      „    324
 H. A. Newton                                            „      „    336
 James Clerk Maxwell                                     „      „    348
 Louis Agassiz                                           „      „    404
 Thomas H. Huxley                                        „      „    410
 A. E. Verrill                                           „      „    412
 Asa Gray                                                „      „    444
 Charles Darwin                                          „      „    452




                          A CENTURY OF SCIENCE
                               IN AMERICA




                                   I
           THE AMERICAN JOURNAL OF SCIENCE FROM 1818 TO 1918

                           By EDWARD S. DANA


                            _Introduction._

In July, 1818, one hundred years ago, the first number of the American
Journal of Science and Arts was given to the public. This is the only
scientific periodical in this country to maintain an uninterrupted
existence since that early date, and this honor is shared with hardly
more than half a dozen other independent scientific periodicals in the
world at large. Similar publications of learned societies for the same
period are also very few in number.

It is interesting, on the occasion of this centenary, to glance back at
the position of science and scientific literature in the world’s
intellectual life in the early part of the nineteenth century, and to
consider briefly the marvelous record of combined scientific and
industrial progress of the hundred years following—subjects to be
handled in detail in the succeeding chapters. It is fitting also that we
should recall the man who founded the Journal, the conditions under
which he worked, and the difficulties he encountered. Finally, we must
review, but more briefly, the subsequent history of what has so often
been called after its founder, “Silliman’s Journal.”

The nineteenth century, and particularly the hundred years in which we
are now interested, must always stand out in the history of the world as
the period which has combined the greatest development in all
departments of science with the most extraordinary industrial progress.
It was not until this century that scientific investigation used to
their full extent the twin methods of observation and experiment. In
cases too numerous to mention they have given us first, a tentative
hypothesis; then, through the testing and correcting of the hypothesis
by newly acquired data, an accepted theory has been arrived at; finally,
by the same means carried further has been established one of nature’s
laws.

_Early Science._—Looking far back into the past, it seems surprising
that science should have had so late a growth, but the wonderful record
of man’s genius in the monuments he erected and in architectural remains
shows that the working of the human mind found expression first in art
and further man also turned to literature. So far as man’s thought was
constructive, the early results were systems of philosophy, and
explanations of the order of things as seen from within, not as shown by
nature herself. We date the real beginning of science with the Greeks,
but it was the century that preceded Aristotle that saw the building of
the Parthenon and the sculptures of Phidias. Even the great Aristotle
himself (384–322 B. C.) though he is sometimes called the “founder of
natural history,” was justly accused by Lord Bacon many centuries later
of having formed his theories first and then to have forced the facts to
agree with them.

The bringing together of facts through observation alone began, to be
sure, very early, for it was the motion of the sun, moon, and stars and
the relation of the earth to them that first excited interest, and,
especially in the countries of the East, led to the accumulation of data
as to the motion of the planets, of comets and the occurrence of
eclipses. But there was no coördination of these facts and they were so
involved in man’s superstition as to be of little value. In passing,
however, it is worthy of mention that the Chinese astronomical data
accumulated more than two thousand years before the Christian era have
in trained hands yielded results of no small significance.

Doubtless were full knowledge available as to the science existing in
the early civilizations, we should rate it higher than we can at
present, but it would probably prove even then to have been developed
from within, like the philosophies of the Greeks, and with but minor
influence from nature herself. It is indeed remarkable that down to the
time with which we are immediately concerned, it was the branches of
mathematics, as arithmetic and geometry and later their applications,
that were first and most fully developed: in other words those lines of
science least closely connected with nature.

Of the importance to science of the Greek school at Alexandria in the
second and third centuries B. C., there can be no question. The geometry
of Euclid (about 300 B. C.) was marvelous in its completeness as in
clearness of logical method. Hipparchus (about 160–125 B. C.) gave the
world the elements of trigonometry and developed astronomy so that
Ptolemy 260 years later was able to construct a system that was well
developed, though in error in the fundamental idea as to the relative
position of the earth. It is interesting to note that the Almagest of
Ptolemy was thought worthy of republication by the Carnegie Institution
only a year or two since. This great astronomical work, by the way, had
no successor till that of the Arab Ulugh Bey in the fifteenth century,
which within a few months has also been made available by the same
Institution.

To the Alexandrian school also belongs Archimedes (287–212 B. C.), who,
as every school boy knows, was the founder of mechanics and in fact
almost a modern physical experimenter. He invented the water screw for
raising water; he discovered the principle of the lever, which appealed
so keenly to his imagination that he called for a ποῦ στῶ, or fulcrum,
on which to place it so as to move the earth itself. He was still nearer
to modern physics in his reputed plan of burning up a hostile fleet by
converging the sun’s rays by a system of great mirrors.

To the Romans, science owes little beyond what is implied in their vast
architectural monuments, buildings and aqueducts which were erected at
home and in the countries of their conquests. The elder Pliny (23–79 A.
D.) most nearly deserved to be called a man of science, but his work on
natural history, comprised in thirty-seven volumes, is hardly more than
a compilation of fable, fact, and fancy, and is sometimes termed a
collection of anecdotes. He lost his life in the “grandest geological
event of antiquity,” the eruption of Vesuvius, which is vividly
described by his nephew, the younger Pliny, in “one of the most
remarkable literary productions in the domain of geology” (Zittel).

With the fall of Rome and the decline of Roman civilization came a
period of intellectual darkness, from which the world did not emerge
until the revival of learning in the fifteenth and sixteenth centuries.
Then the extension of geographical knowledge went hand in hand with the
development of art, literature, and the birth of a new science.
Copernicus (1473–1543) gave the world at last a sun-controlled solar
system; Kepler (1571–1630) formulated the laws governing the motion of
the planets; Galileo (1564–1642) with his telescope opened up new vistas
of astronomical knowledge and laid the foundations of mechanics; while
Leonardo da Vinci (1452–1519), painter, sculptor, architect, engineer,
musician and true scientist, studied the laws of falling bodies and
solved the riddle of the fossils in the rocks. Still later Newton
(1642–1727) established the law of gravitation, developed the calculus,
put mechanics upon a solid basis and also worked out the properties of
lenses and prisms so that his Optics (1704) will always have a prominent
place in the history of science.

From the time of the Renaissance on science grew steadily, but it was
not till the latter half of the eighteenth century that the foundations
in most of the lines recognized to-day were fully laid. Much of what was
accomplished then is, at least, outlined in the chapters following.

Our standpoint in the early years of the nineteenth century, just before
the American Journal had its beginning, may be briefly summarized as
follows: A desire for knowledge was almost universal and, therefore,
also a general interest in the development of science. Mathematics was
firmly established and the mathematical side of astronomy and natural
philosophy—as physics was then called—was well developed. Many of the
phenomena of heat and their applications, as in the steam engine of
Watt, were known and even the true nature of heat had been almost
established by our countryman, Count Rumford; but of electricity there
were only a few sparks of knowledge. Chemistry had had its foundation
firmly laid by Priestley, Lavoisier, and Dalton, while Berzelius was
pushing rapidly forward. Geology had also its roots down, chiefly
through the work of Hutton and William Smith, though the earth was as
yet essentially an unexplored field. Systematic zoology and botany had
been firmly grounded by Buffon, Lamarck and Cuvier, on the one hand, and
Linnæus on the other; but of all that is embraced under the biology of
the latter half of the nineteenth century the world knew nothing. The
statements of Silliman in his Introductory Remarks in the first number,
quoted in part on a following page, put the matter still more fully, but
they are influenced by the enthusiasm of the time and he could have had
little comprehension of what was to be the record of the next one
hundred years.

Now, leaving this hasty and incomplete retrospect and coming down to
1918, we find the contrast between to-day and 1818 perhaps most
strikingly brought out, on the material side, if we consider the ability
of man, in the early part of the nineteenth century, to meet the demands
upon him in the matter of transportation of himself and his property. In
1800, he had hardly advanced beyond his ancestor of the earliest
civilization; on the contrary, he was still dependent for transportation
on land upon the muscular efforts of himself and domesticated animals,
while at sea he had only the use of sails in addition. The first
application of the steam engine with commercial success was made by
Fulton when, in 1807, the steamboat “Clermont” made its famous trip on
the Hudson River. Since then, step by step, transportation has been made
more and more rapid, economical and convenient, both on land and water.
This has come first through the perfection of the steam engine; later
through the agency of electricity, and still further and more
universally by the use of gasolene motors. Finally, in these early years
of the twentieth century, what seemed once a wild dream of the
imagination has been realized, and man has gained the conquest of the
air; while the perfection of the submarine is as wonderful as its work
can be deadly.

Hardly less marvelous is the practical annihilation of space and time in
the electric transmission of human thought and speech by wire and by
ether waves. While, still further, the same electrical current now gives
man his artificial illumination and serves him in a thousand ways
besides.

But the limitations of space have also been conquered, during the same
period, by the spectroscope which brings a knowledge of the material
nature of the sun and the fixed stars and of their motion in the line of
sight; while spectrum analysis has revealed the existence of many new
elements and opened up vistas as to the nature of matter.

The chemist and the physicist, often working together in the
investigation of the problems lying between their two departments, have
accumulated a staggering array of new facts from which the principles of
their sciences have been deduced. Many new elements have been
discovered, in fact nearly all called for by the periodic law; the
so-called fixed gases have been liquefied, and now air in liquid form is
almost a plaything; the absolute zero has been nearly reached in the
boiling point of helium; physical measurements in great precision have
been carried out in both directions for temperatures far beyond any
scale that was early conceived possible; the atom, once supposed to be
indivisible, has been shown to be made up of the much smaller electrons,
while its disintegration in radium and its derivatives has been traced
out and with consequences only as yet partly understood but certainly
having far-reaching consequences; at one point we seem to be brought
near to the transmutation of the elements which was so long the dream of
the alchemist. Still again photography has been discovered and perfected
and with the use of X-rays it gives a picture of the structure of bodies
totally opaque to the eye; the same X-rays seem likely to locate and
determine the atoms in the crystal.

Here and at many other points we are reaching out to a knowledge of the
ultimate nature of matter.

In geology, vast progress has been made in the knowledge of the earth,
not only as to its features now exhibited at or near the surface, but
also as to its history in past ages, of the development of its
structure, the minute history of its life, the phenomena of its
earthquakes, volcanoes, etc. Geological surveys in all civilized
countries have been carried to a high degree of perfection.

In biology, itself a word which though used by Lamarck did not come into
use till taken up by Huxley, and then by Herbert Spencer in the middle
of the century, the progress is no less remarkable as is well developed
in a later chapter of this volume.

Although not falling within our sphere, it would be wrong, too, not to
recognize also the growth of medicine, especially through the knowledge
of bacteria and their functions, and of disease germs and the methods of
combating them. The world can never forget the debt it owes to Pasteur
and Lister and many later investigators in this field.

To follow out this subject further would be to encroach upon the field
of the chapters following, but, more important and fundamental still
than all the facts discovered and the phenomena investigated has been
the establishment of certain broad scientific principles which have
revolutionized modern thought and shown the relation between sciences
seemingly independent. The law of conservation of energy in the physical
world and the principle of material and organic evolution may well be
said to be the greatest generalizations of the human mind. Although
suggestions in regard to them, particularly the latter, are to be found
in the writings of early authors, the establishment and general
acceptance of these principles belong properly to the middle of the
nineteenth century. They stand as the crowning achievement of the
scientific thought of the period in which we are interested.

Any mere enumeration of the vast fund of knowledge accumulated by the
efforts of man through observation and experiment in the period in which
we are interested would be a dry summary, and yet would give some
measure of what this marvelous period has accomplished. As in geography,
man’s energy has in recent years removed the reproach of a “Dark
Continent,” of “unexplored” central Asia and the once “inaccessible
polar regions,” so in the different departments of science, he has
opened up many unknown fields and accumulated vast stores of knowledge.
It might even seem as if the limit of the unknown were being approached.
There remains, however, this difference in the analogy, that in science
the fundamental relations—as, for example, the nature of gravitation, of
matter, of energy, of electricity; the actual nature and source of
life—the solution of these and other similar problems still lies in the
future. What the result of continued research may be no one can predict,
but even with these possibilities before us, it is hardly rash to say
that so great a combined progress of pure and applied science as that of
the past hundred years is not likely to be again realized.


              _Scientific Periodical Literature in 1818._

The contrast in scientific activity between 1818 and 1918 is nowhere
more strikingly shown than in the amount of scientific periodical
literature of the two periods. Of the thousands of scientific journals
and regular publications by scientific societies and academies to-day,
but a very small number have carried on a continuous and practically
unbroken existence since 1818. This small amount of periodical
scientific literature in the early part of the last century is
significant as giving a fair indication of the very limited extent to
which scientific investigation appealed to the intellectual life of the
time. Some definite facts in regard to the scientific publications of
those early days seem to be called for.

Learned societies and academies, devoted to literature and science, were
formed very early but at first for occasional meetings only and regular
publications were in most cases not begun till a very much later date.
Some of the earliest—not to go back of the Renaissance—are the
following:


  1560. Naples, Academia Secretorum Naturæ.

  1603. Rome, Accademia dei Lincei.

  1651. Leipzig, Academia Naturæ Curiosum.

  1657. Florence, Accademia del Cimento.

  1662. London, Royal Society.

  1666. Paris, Académie des Sciences.

  1690. Bologna, Accademia delle Scienze.

  1700. Berlin, Societas Regia Scientiarum. This was the forerunner of
  the K. preuss. Akad. d. Wissenschaften.


The Royal Society of London, whose existence dates from 1645, though not
definitely chartered until 1662, began the publication of its
“Philosophical Transactions” in 1665 and has continued it practically
unbroken to the present time; this is a unique record. Following this,
other early—but in most cases not continuous—publications were those of
Paris (1699); Berlin (1710); Upsala (1720); Petrograd, 1728; Stockholm
(1739); and Copenhagen (1743).

For the latter half of the eighteenth century, when the foundations of
our modern science were being rapidly laid, a considerable list might be
given of early publications of similar scientific bodies. Some of the
prominent ones are: Göttingen (1750), Munich (1759), Brussels (1769),
Prague (1775), Turin (1784), Dublin (1788), etc. The early years of the
nineteenth century saw the beginnings of many others, particularly in
northern Italy. It is to be noted that, as stated, only rarely were the
publications of these learned societies even approximately continuous.
In the majority of cases the issue of transactions or proceedings was
highly irregular and often interrupted.

In this country the earliest scientific bodies are the following:


  Philadelphia. American Philosophical Society, founded in 1743.
  Transactions were published 1771–1809; then interrupted until 1818 _et
  seq._

  Boston. American Academy of Arts and Sciences, founded in 1780.
  Memoirs, 1785–1821; and then 1833 _et seq._

  New Haven. Connecticut Academy of Arts and Sciences, begun in 1799.
  Memoirs, vol. 1, 1810–16; Transactions, 1866 _et seq._

  Philadelphia. Academy of Natural Sciences, begun in 1812. Journal,
  1817–1842; and from 1847 _et seq._

  New York. Lyceum of Natural History, 1817; later (1876) became the New
  York Academy of Sciences. Annals from 1823; Proceedings from 1870.


The situation is somewhat similar as to independent scientific journals.
A list of the names of those started only to find an early death would
be a very long one, but interesting only historically and as showing a
spasmodic but unsustained striving after scientific growth.

It seems worth while, however, to give here the names of the periodicals
embracing one or more of the subjects of the American Journal, which
began at a very early date and most of which have maintained an
uninterrupted existence down to 1915. It should be added that certain
medical journals, not listed here, have also had a long and continued
existence.[1]


                      _Early Scientific Journals._


  1771–1823. Journal de Physique, Paris; title changed several times.

  1787–. Botanical Magazine. (For a time known as Curtis’s Journal).

  1789–1816. Annales de Chimie, Paris. Continued from 1817 on as the
  Annales de Chimie et de Physique.

  1790. Journal der Physik, Halle (by Gren); from 1799 on became the
  Annalen der Physik (und Chemie), Halle, Leipzig. The title has been
  somewhat changed from time to time though publication has been
  continuous. Often referred to by the name of the editor-in-chief, as
  Gren, Gilbert, Poggendorff, Wiedemann, etc.

  1795–1815. Journal des Mines, Paris, continued from 1816 as the
  Annales des Mines.

  1796–1815. Bibliothèque Britannique, Geneva. From 1816–1840,
  Bibliothèque Universelle, etc. 1846–1857, Archives des Sci. phys. nat.
  Since 1858 generally known as the Bibliothèque Universelle.

  1797. Journal of Natural Philosophy, Chemistry and the Arts
  (Nicholson’s Journal) London; united in 1814 with the Philosophical
  Magazine (Tilloch’s Journal).

  1798–. The Philosophical Magazine (originally by Tilloch). This
  absorbed Nicholson’s Journal (above) in 1814; also the Annals of
  Philosophy (Thomson, Phillips) in 1827 and Brewsters’ Edinburgh
  Journal of Science in 1832.

  1798–1803. Allgemeines Journal der Chemie (Scherer’s Journal).
  1803–1806; continued as Neues Allg. J. etc. (Gehlen’s Journal). Later
  title repeatedly changed and finally (1834 _et seq._) Journal für
  praktische Chemie.

  1816–18. Journal of Science and the Arts, London. 181930, Quarterly J.
  etc. 1830–31, Journal of the Royal Institution of Great Britain.

  1818. American Journal of Science and Arts until 1880, when “the Arts”
  was dropped, New Haven, Conn. First Series, =1–50=, 1818–1845; Second
  Series, =1–50=, 1846–1870; Third Series, =1–50=, 1871–1895; Fourth
  Series, =1–45=, 1896–June, 1918.

  1818. Flora, or Allgemeine botanische Zeitung. Regensburg, Munich.

  1820–1867. London Journal of Arts and Sciences (after 1855, Newton’s
  Journal).

  1824–. Annales des sciences naturelles. Paris.

  1826–. Linnæa, Berlin, Halle; from 1882 united with Jahrb. d. K.
  botan. Gartens.

  1828–1840. Magazine of Natural History, London; united 1838 with the
  Annals of Natural History, and known since 1841 as the Annals and
  Magazine of Natural History.

  1828–. Journal of the Franklin Institute, Philadelphia, from 1826;
  earlier (1825) the American Mechanics Magazine.

  1832–. Annalen der Chemie (und Pharmacie) often known as Liebig’s
  Annalen. Leipzig, Lemgo.


           _The Founder of the American Journal of Science._

The establishment of a scientific journal in this country in 1818 was a
pioneer undertaking, requiring of its founder a rare degree of energy,
courage, and confidence in the future. It was necessary, not only to
obtain the material to fill its pages and the money to carry on the
enterprise, but, before the latter end could be accomplished, an
audience must be found among those who had hitherto felt little or no
interest in the sciences. This great work was accomplished by Benjamin
Silliman, “the guardian of American Science,” whose influence was second
to none in the early development of science in this country. Before
speaking in some detail of the early years of this Journal and of its
subsequent history, it is proper that some words should be given to its
founder.

Benjamin Silliman, son of a general prominent in the Revolutionary War,
was born in Trumbull, Connecticut, on August 8, 1779. He was a graduate
of Yale College of the class of 1796. Though at first a student of law
and accepted for the bar in Connecticut, he was called in 1802 by
President Timothy Dwight—a man of rare breadth of mind—to occupy the
newly made chair of chemistry, mineralogy (and later geology) in Yale
College at New Haven. To fit himself for the work before him he carried
on extensive studies at home and in Philadelphia and spent the year 1805
in travels and study at London and Edinburgh, and also on the Continent.
His active duties began in 1806 and from this time on he was in the
service of Yale College until his resignation in 1853. From the first,
Silliman met with remarkable success as a teacher and public lecturer in
arousing an interest in science. His breadth of knowledge, his
enthusiasm for his chosen subjects and power of clear presentation,
combined with his fine presence and attractive personality, made him a
great leader in the science of the country and gave him a unique
position in the history of its development.

Much might be said of the man and his work, but, the best tribute is
that of James Dwight Dana, given in his inaugural address upon the
occasion of his beginning his duties as Silliman professor of geology in
Yale College. This was delivered on February 18, 1856, in what was then
known as the “Cabinet Building.” Dana says in part:


  “In entering upon the duties of this place, my thoughts turn rather to
  the past than to the subject of the present hour. I feel that it is an
  honored place, honored by the labors of one who has been the guardian
  of American Science from its childhood; who here first opened to the
  country the wonderful records of geology; whose words of eloquence and
  earnest truth were but the overflow of a soul full of noble sentiments
  and warm sympathies, the whole throwing a peculiar charm over his
  learning, and rendering his name beloved as well as illustrious. Just
  fifty years since, Professor Silliman took his station at the head of
  chemical and geological science in this college. Geology was then
  hardly known by name in the land, out of these walls. Two years
  before, previous to his tour in Europe, the whole cabinet of Yale was
  a half-bushel of unlabelled stones. On visiting England he found even
  in London no school public or private, for geological instruction, and
  the science was not named in the English universities. To the mines,
  quarries, and cliffs of England, the crags of Scotland, and the
  meadows of Holland he looked for knowledge, and from these and the
  teachings of Murray, Jameson, Hall, Hope, and Playfair, at Edinburgh,
  Professor Silliman returned, equipped for duty,—albeit a great
  duty,—that of laying the foundation, and creating almost out of
  nothing a department not before recognized in any institution in
  America.

  He began his work in 1806. The science was without books—and, too,
  without system, except such as its few cultivators had each for
  himself in his conceptions. It was the age of the first beginnings of
  geology, when Wernerians and Huttonians were arrayed in a contest....
  Professor Silliman when at Edinburgh witnessed the strife, and while,
  as he says, his earliest predilections were for the more peaceful mode
  of rock-making, these soon yielded to the accumulating evidence, and
  both views became combined in his mind in one harmonious whole. The
  science, thus evolved, grew with him and by him; for his own labors
  contributed to its extension. Every year was a year of expansion and
  onward development, and the grandeur of the opening views found in him
  a ready and appreciative response....

  And while the sciences and truth have thus made progress here, through
  these labors of fifty years, the means of study in the institution
  have no less increased. Instead of that half-bushel of stones, which
  once went to Philadelphia for names, in a candle-box, you see above
  the largest mineral cabinet in the country, which but for Professor
  Silliman, his attractions and his personal exertions together, would
  never have been one of the glories of old Yale....

  Moreover, the American Journal of Science,—now in its thirty-seventh
  year and seventieth volume [1856],—projected and long-sustained solely
  by Professor Silliman, while ever distributing truth, has also been
  ever gathering honors, and is one of the laurels of Yale.

  We rejoice that in laying aside his studies, after so many years of
  labor, there is still no abated vigor.... He retires as one whose
  right it is to throw the burden on others. Long may he be with us, to
  enjoy the good he has done, and cheer us by his noble and benign
  presence.”


In addition to these words of Dana, much of vital interest in regard to
Silliman and his work will be gathered from what is given in the pages
immediately following, quoted from his personal statements in the early
volumes of the Journal.


                   _The Early Years of the Journal._

In no direction did Silliman’s enthusiastic activities in science
produce a more enduring result than in the founding and carrying on of
the Journal. The first suggestion in regard to the enterprise was made
to Silliman by his friend, Colonel George Gibbs, from whom the famous
Gibbs collection of minerals was bought by Yale College in 1825.
Silliman says (=25=, 215, 1834):

[Illustration: THE AMERICAN JOURNAL OF SCIENCE, MORE ESPECIALLY OF
_MINERALOGY_, _GEOLOGY_, AND THE OTHER BRANCHES OF NATURAL HISTORY;
INCLUDING ALSO _AGRICULTURE_ AND THE ORNAMENTAL AS WELL AS USEFUL ARTS.
CONDUCTED BY _BENJAMIN SILLIMAN_, PROFESSOR OF CHEMISTRY, MINERALOGY,
ETC. IN YALE COLLEGE, AUTHOR OF TRAVELS IN ENGLAND, SCOTLAND, AND
HOLLAND, ETC. VOL. I. ... NO. I. ENGRAVING IN THE PRESENT NO. New
apparatus for the combustion of TAR, &c. by the vapour of water. New
York: PUBLISHED BY J. EASTBURN AND CO. LITERARY ROOMS, BROADWAY, AND BY
HOWE AND SPALDING, NEW-HAVEN Abraham Paul, printer. 1818.]


  “Col. Gibbs was the person who first suggested to the Editor the
  project of this Journal, and he urged the topic with so much zeal and
  with such cogent arguments, as prevailed to induce the effort in a
  case then viewed as of very dubious success. The subject was thus
  started in November, 1817; proposals for the Journal were issued in
  January, 1818, and the first number appeared in July of that year.”


He adds further (=50=, p. iii, 1847) that the conversation here recorded
took place “on an accidental meeting on board the steamboat Fulton in
Long Island Sound.” This was some ten years after Robert Fulton’s
steamboat, the Clermont, made its pioneer trip on the Hudson river,
already alluded to. The incident is not without significance in this
connection. The deck of the “Fulton” was not an inappropriate place for
the inauguration of an enterprise also great in its results for the
country.

In the preface to the concluding volume of the First Series (loc. cit.)
Silliman adds the following remarks which show his natural modesty at
the thought of undertaking so serious a work. He says:


  Although a different selection of an editor would have been much
  preferred, and many reasons, public and personal, concurred to produce
  diffidence of success, the arguments of Col. Gibbs, whose views on
  subjects of science were entitled to the most respectful
  consideration, and had justly great weight, being pressed with zeal
  and ability, induced a reluctant assent; and accordingly, after due
  consultation with many competent judges, the proposals were issued
  early in 1818, embracing the whole range of physical science and its
  applications. The Editor in entering on the duty, regarded it as an
  affair for life, and the thirty years of experience which he has now
  had, have proved that his views of the exigencies of the service were
  not erroneous.


The plan with which the editor began his work and the lines laid down by
him at the outset can only be made clear by quoting entire the “Plan of
the Work” which opens the first number. It seems desirable also to give
this in its original form as to paragraphs and typography. The first
page of the cover of the opening number has also been reproduced here.
It will be seen that the plan of the young editor was as wide as the
entire range of science and its applications and extended out to music
and the fine arts. This seems strange to-day, but it must be remembered
how few were the organs of publication open to contributors at the time.
If the plan was unreasonably extended, that fact is to be taken not only
as an expression of the enthusiasm of the editor, as yet inexperienced
in his work, but also of the time when the sciences were still in their
infancy.

He says (=1=, pp. v, vi):


                           “PLAN OF THE WORK.


  This Journal is intended to embrace the circle of THE PHYSICAL
  SCIENCES, with their application to THE ARTS, and to every useful
  purpose.

  It is designed as a deposit for _original American communications_;
  but will contain also occasional selections from Foreign Journals, and
  notices of the progress of science in other countries. Within its plan
  are embraced

  NATURAL HISTORY, in its three great departments of MINERALOGY, BOTANY,
  and ZOOLOGY;

  CHEMISTRY and NATURAL PHILOSOPHY, in their various branches: and
  MATHEMATICS, pure and mixed.

  It will be a leading object to illustrate AMERICAN NATURAL HISTORY,
  and especially our MINERALOGY and GEOLOGY.

  The APPLICATIONS of these sciences are obviously as numerous as
  _physical arts_, and _physical wants_; for no one of these arts or
  wants can be named which is not connected with them.

  While SCIENCE will be cherished _for its own sake_, and with a due
  respect for its own _inherent_ dignity; it will also be employed as
  the _handmaid to the Arts_. Its numerous applications to AGRICULTURE,
  the earliest and most important of them; to our MANUFACTURES, both
  mechanical and chemical; and to our DOMESTIC ECONOMY, will be
  carefully sought out, and faithfully made.

  It is also within the design of this Journal to receive communications
  on MUSIC, SCULPTURE, ENGRAVING, PAINTING, and generally on the fine
  and liberal, as well as useful arts;

  On Military and Civil Engineering, and the art of Navigation.

[Illustration: Very truly Yours, B. Silliman]

  Notices, Reviews, and Analyses of new scientific works, and of new
  Inventions, and Specifications of Patents;

  Biographical and Obituary Notices of scientific men; essays on
  COMPARATIVE ANATOMY and PHYSIOLOGY, and generally on such other
  branches of medicine as depend on scientific principles;

  Meteorological Registers, and Reports of Agricultural Experiments: and
  we would leave room also for interesting miscellaneous things, not
  perhaps exactly included under either of the above heads.

  Communications are respectfully solicited from men of science, and
  _from men versed in the practical arts_.

  Learned Societies are invited to make this Journal, occasionally, the
  vehicle of their communications to the Public.

  The editor will not hold himself responsible for the sentiments and
  opinions advanced by his correspondents; but he will consider it as an
  allowed liberty to make slight _verbal alterations_, where errors may
  be presumed to have arisen from inadvertency.”


In the “Advertisement” which precedes the above statement in the first
number, the editor remarks somewhat naïvely that he “does not pledge
himself that all the subjects shall be touched upon in every number.
This is plainly impossible unless every article should be very short and
imperfect....”

The whole subject is discussed in all its relations in the “Introductory
Remarks” which open the first volume. No apology is needed for quoting
at considerable length, for only in this way can the situation be made
clear, as seen by the editor in 1818. Further we gain here a picture of
the intellectual life of the times and, not less interesting, of the
mind and personality of the writer. With a frank kindliness, eminently
characteristic of the man, as will be seen, he takes the public fully
into his confidence. In the remarks made in subsequent volumes,—also
extensively quoted—the vicissitudes in the conduct of the enterprise are
brought out and when success was no longer doubtful, there is a tone of
quiet satisfaction which was also characteristic and which the
circumstances fully justified.

The INTRODUCTORY REMARKS begin as follows:


  The age in which we live is not less distinguished by a vigorous and
  successful cultivation of physical science, than by its numerous and
  important applications to the practical arts, and to the common
  purposes of life.

  In every enlightened country, men illustrious for talent, worth and
  knowledge, are ardently engaged in enlarging the boundaries of natural
  science; and the history of their labors and discoveries is
  communicated to the world chiefly through the medium of scientific
  journals. The utility of such journals has thus become generally
  evident; they are the heralds of science; they proclaim its toils and
  its achievements; they demonstrate its intimate connection as well
  with the comfort, as with the intellectual and moral improvement of
  our species; and they often procure for it enviable honors and
  substantial rewards.


Mention is then made of the journals existing in England and France in
1818 “which have long enjoyed a high and deserved reputation.” He then
continues:


  From these sources our country reaps and will long continue to reap,
  an abundant harvest of information: and if the light of science, as
  well as of day, springs from the East, we will welcome the rays of
  both; nor should national pride induce us to reject so rich an
  offering.

  But can we do nothing in return?

  In a general diffusion of useful information through the various
  classes of society, in activity of intellect and fertility of resource
  and invention, producing a highly intelligent population, we have no
  reason to shrink from a comparison with any country. But the devoted
  cultivators of science in the United States are comparatively few:
  they are, however, rapidly increasing in number. Among them are
  persons distinguished for their capacity and attainments, and,
  notwithstanding the local feelings nourished by our state
  sovereignties, and the rival claims of several of our larger cities,
  there is evidently a predisposition towards a concentration of effort,
  from which we may hope for the happiest results, with regard to the
  advancement of both the science and reputation of our country.

  Is it not, therefore, desirable to furnish some rallying point, some
  object sufficiently interesting to be nurtured by common efforts, and
  thus to become the basis of an enduring, common interest? To produce
  these efforts, and to excite this interest, nothing, perhaps, bids
  fairer than a SCIENTIFIC JOURNAL.


The valuable work already accomplished by various medical journals is
then spoken of and particularly that of the first scientific periodical
in the United States, Bruce’s Mineralogical Journal. This, as Silliman
says (=1=, p. 3, 1818), although “both in this country and in Europe
received in a very flattering manner,” did not survive the death of its
founder, and only a single volume of 270 pages appeared (1810–1813).

Silliman continues:


  No one, it is presumed, will doubt that a journal devoted to science,
  and embracing a sphere sufficiently extensive to allure to its support
  the principal scientific men of our country, is greatly needed; if
  cordially supported, it will be successful, and if successful, it will
  be a great public benefit.

  Even a failure, in so good a cause, (unless it should arise from
  incapacity or unfaithfulness,) cannot be regarded as dishonourable. It
  may prove only that the attempt was premature, and that our country is
  not yet ripe for such an undertaking; for without the efficient
  support of talent, knowledge, and money, it cannot long proceed. No
  editor can hope to carry forward such a work without the active aid of
  scientific and practical men; but, at the same time, the public have a
  right to expect that he will not be sparing of his own labour, and
  that his work shall be generally marked by the impress of his own
  hand. To this extent the editor cheerfully acknowledges his
  obligations to the public; and it will be his endeavour faithfully to
  redeem his pledge.

  Most of the periodical works of our country have been short-lived.
  This, also, may perish in its infancy; and if any degree of confidence
  is cherished that it will attain a maturer age, it is derived from the
  obvious and intrinsic importance of the undertaking; from its being
  built upon permanent and momentous national interests; from the
  evidence of a decided approbation of the design, on the part of
  gentlemen of the first eminence, obtained in the progress of an
  extensive correspondence; from assurance of support, in the way of
  contributions, from men of ability in many sections of the union; and
  from the existence of such a crisis in the affairs of this country and
  of the world, as appears peculiarly auspicious to the success of every
  wise and good undertaking.


An interesting discussion follows (pp. 5–8) as to the claims of the
different branches of science, and the extent to which they and their
applications had been already developed, also the spheres still open to
discovery.

The Introductory Remarks close, as follows:


  In a word, the whole circle of physical science is directly applicable
  to human wants and constantly holds out a light to the practical arts;
  it thus polishes and benefits society and everywhere demonstrates both
  supreme intelligence and harmony and beneficence of design in the
  Creator.

  The science of mathematics, both pure and mixed, can never cease to be
  interesting and important to man, as long as the relations of quantity
  shall exist, as long as ships shall traverse the ocean, as long as man
  shall measure the surface or heights of the earth on which he lives,
  or calculate the distances and examine the relations of the planets
  and stars; and as long as the _iron reign of war_ shall demand the
  discharge of projectiles, or the construction of complicated defences.


The closing part of the paragraph shows the influence exerted upon the
mind of the editor by the serious wars of the years preceding 1818, a
subject alluded to again at the close of this chapter.


In February, 1822, with the completion of the fourth volume, the editor
reviews the situation which, though encouraging is by no means fully
assuring. He says (preface to vol. =4=, dated Feb. 15, 1822):


  Two years and a half have elapsed, since the publication of the first
  volume of this Journal, and one year and ten months since the Editor
  assumed the pecuniary responsibility....

  The work has not, even yet, reimbursed its expenses, (we speak not of
  editorial or of business compensation,) we intend, that it has not
  paid for the paper, printing and engraving; the proprietors of the
  first volume being in advance, on those accounts, and the Editor on
  the same score, with respect to the aggregate expense of the three
  last volumes. This deficit is, however, no longer increasing, as the
  receipts, at present, just about cover the expense of the physical
  materials, and of the manual labour. A reiterated disclosure of this
  kind is not grateful, and would scarcely be manly, were it not that
  the public, who alone have the power to remove the difficulty, have a
  right to a frank exposition of the state of the case. As the patronage
  is, however, growing gradually more extensive, it is believed that the
  work will be eventually sustained, although it may be long before it
  will command any thing but gratuitous intellectual labour....

  These facts, with the obvious one,—that its pages are supplied with
  contributions from all parts of the Union, and occasionally from
  Europe, evince that the work is received as a national and not as a
  local undertaking, and that the community consider it as having no
  sectional character. Encouraged by this view of the subject, and by
  the favour of many distinguished men, both at home and abroad, and
  supported by able contributors, to whom the Editor again tenders his
  grateful acknowledgments, he will still persevere, in the hope of
  contributing something to the advancement of our science and arts, and
  towards the elevation of our national character.


In the autumn of the same year, the editor closes the fifth volume with
a more confident tone (Sept. 25, 1822):


  A trial of four years has decided the point, that the American Public
  will support this Journal. Its pecuniary patronage is now such, that
  although not a lucrative, it is no longer a hazardous enterprise. It
  is now also decided, that the intellectual resources of the country
  are sufficient to afford an unfailing supply of valuable original
  communications and that nothing but perseverance and effort are
  necessary to give perpetuity to the undertaking.

  The decided and uniform expression of public favour which the Journal
  has received both at home and abroad, affords the Editor such
  encouragement, that he cannot hesitate to persevere—and he now renews
  the expression of his thanks to the friends and correspondents of the
  work, both in Europe and the United States, requesting at the same
  time a continuance of their friendly influence and efforts.


Still again in the preface to the sixth volume (1823) he takes the
reader more fully into his confidence and shows that he regards the
enterprise as no longer of doubtful success. He says:


  The conclusion of a new volume of a work, involving so much care,
  labour and responsibility, as are necessarily attached, at the present
  day, to a Journal of Science and the Arts, naturally produces in the
  mind, a state of not ungrateful calmness, and a disposition, partaking
  of social feeling, to say something to those who honour such a
  production, by giving to it a small share of their money, and of their
  time. The Editor’s first impression was, that the sixth volume should
  be sent into the world without an introductory note, but he yields to
  the impulse already expressed, and to the established usages of
  respectful courtesy to the public, which a short preface seems to
  imply. He has now persevered almost five years, in an undertaking,
  regarded by many of the friends whom he originally consulted, as
  hazardous, and to which not a few of them prophetically alloted only
  an ephemeral existence. It has been his fortune to prosecute this work
  without, (till a very recent period,) returns, adequate to its
  indispensable responsibilities;—under a heavy pressure of professional
  and private duty; with trying fluctuations of health, and amidst
  severe and reiterated domestic afflictions. The world are usually
  indulgent to allusions of this nature, when they have any relation to
  the discharge of public duty; and in this view, it is with
  satisfaction, that the Editor adds, that he has now to look on
  formidable difficulties, only in retrospect, and with something of the
  feeling of him, who sees a powerful and vanquished foe, slowly
  retiring, and leaving a field no longer contested.

  This Journal which, from the first, was fully supplied with original
  communications, is now sustained by actual payment, to such an extent,
  that it may fairly be considered as an established work; its patronage
  is regularly increasing, and we trust it will no longer justify such
  remarks as some of the following, from the pen of one of the most
  eminent scientific men in Europe. “Nothing surprises me more, than the
  little encouragement which your Journal,” (“which I always read with
  very great interest, and of which I make great use,”) “experiences in
  America—this must surely arise from the present depressed condition of
  trade, and cannot long continue.”


Six years more of uninterrupted editorial work passed by, the sixteenth
volume was completed, and the editor was now in a position to review the
whole situation up to 1829. This preface (dated July 1, 1829), which is
quoted nearly in full, cannot fail to be found particularly interesting
and from several standpoints, not the least for the insight it gives
into the writer’s mind. It is also noteworthy that at this early date it
was found possible to pay for original contributions, a privilege far
beyond the means of the editor of to-day.


  When this Journal was first projected, very few believed that it would
  succeed.

  Among others, Dr. Dorsey wrote to the editor; “I predict a short life
  for you, although I wish, as the Spaniards say, that you may live a
  thousand years.” The work has not lived a thousand years, but as it
  has survived more than the hundredth part of that period, no reason is
  apparent why it may not continue to exist. To the contributors,
  disinterested and arduous as have been their exertions, the editor’s
  warmest thanks are due; and they are equally rendered to numerous
  personal friends for their unwavering support: nor ought those
  subscribers to be forgotten who, occupied in the common pursuits of
  life, have aided, by their money, in sustaining the hazardous novelty
  of an American Journal of Science. A general approbation, sufficiently
  decided to encourage effort, where there was no other reward, has
  supported the editor; but he has not been inattentive to the voice of
  criticism, whether it has reached him in the tones of candor and
  kindness, or in those of severity. We must not look to our friends for
  the full picture of our faults. He is unwise who neglects the maxim—

                        —fas est ab hoste doceri,

  and we may be sure, that those are quite in earnest, whose pleasure it
  is, to place faults in a strong light and bold relief; and to throw
  excellencies into the shadow of total eclipse. Minds at once
  enlightened and amiable, viewing both in their proper proportions,
  will however render the equitable verdict;

                    Non ego paucis offendar maculis,—

  It is not pretended that this Journal has been faultless; there may be
  communications in it which had been better omitted, and it is not
  doubted that the power to command intellectual effort, by suitable
  pecuniary reward, would add to its purity, as a record of science, and
  to its richness, as a repository of discoveries in the arts.

  But the editor, even now, offers payment, at the rate adopted by the
  literary Journals, for able original communications, containing
  especially important facts, investigations and discoveries in science,
  and practical inventions in the useful and ornamental Arts.

  As however his means are insufficient to pay for all the copy, it is
  earnestly requested, that those gentlemen, who, from other motives,
  are still willing to write for this Journal, should continue to favor
  it with their communications. That the period when satisfactory
  compensation can be made to all writers whose pieces are inserted, and
  to whom payment will be acceptable, is not distant, may perhaps be
  hoped, from the spontaneous expression of the following opinion, by
  the distinguished editor of one of our principal literary journals,
  whose letter is now before me. “The character of the American Journal
  is strictly national, and it is the only vehicle of communication in
  which an inquirer may be sure to find what is most interesting in the
  wide range of topics, which its design embraces. It has become in
  short, not more identified with the science than the literature of the
  country.” It is believed that a strict examination of its contents
  will prove that its character has been decidedly scientific; and the
  opinion is often expressed to the editor, that in common with the
  journals of our Academies, it is a work of reference, indispensable to
  him who would examine the progress of American science during the
  period which it covers. That it might not be too repulsive to the
  general reader, some miscellaneous pieces have occasionally occupied
  its pages; but in smaller proportion, than is common with several of
  the most distinguished British Journals of Science.

  Still, the editor has been frequently solicited, both in public and
  private, to make it more miscellaneous, that it might be more
  acceptable to the intelligent and well educated man, who does not
  cultivate science; but he has never lost sight of his great object,
  which was to produce and concentrate original American effort in
  science, and thus he has foregone pecuniary returns, which by pursuing
  the other course, might have been rendered important. Others would not
  have him admit any thing that is not strictly and technically
  scientific; and would make this journal for mere professors and
  amateurs; especially in regard to those numerous details in natural
  history, which although important to be registered, (and which, when
  presented, have always been recorded in the American Journal,) can
  never exclusively occupy the pages of any such work without repelling
  the majority of readers.

  If this is true even in Great Britain it is still more so in this
  country; and our savants, unless they would be, not only the exclusive
  admirers, but the sole purchasers of their own works, must permit a
  little of the graceful drapery of general literature to flow around
  the cold statues of science. The editor of this Journal, strongly
  inclined, both from opinion and habit, to gratify the cultivators of
  science, will still do everything in his power to promote its high
  interests, and as he hopes in a better manner than heretofore; but
  these respectable gentlemen will have the courtesy, to yield something
  to the reading literary, as well as scientific public, and will not,
  we trust, be disgusted, if now and then an _Oasis_ relieves the eye,
  and a living stream refreshes the traveller. Not being inclined to
  renew the abortive experiment, to please every body, which has been so
  long renowned in fable; the editor will endeavor to pursue, the even
  tenor of his way; altogther inclined to be courteous and useful to his
  fellow travellers, and hoping for their kindness and services in
  return.


                    _The Close of the First Series._

The “First Series,” as it was henceforth to be known, closed with the
fiftieth volume (1847, pp. xx + 347). This final volume is devoted to an
exhaustive index to the forty-nine volumes preceding. In the preface
(dated April 19, 1847) the elder Silliman, now the senior editor,
reviews the work that had been accomplished with a frank expression of
his feeling of satisfaction in the victory won against great obstacles;
with this every reader must sympathize. He quotes here at length (but in
slightly altered form) the matter from the first volume (1818), which
has been already reproduced almost entire, and then goes on as follows
(pp. xi _et seq._):

[Illustration: James D. Dana]


  Such was the pledge which, on entering upon our editorial labors in
  1818, we gave to the public, and such were the views which we then
  entertained, regarding science and the arts as connected with the
  interests and honor of our country and of mankind. In the retrospect,
  we realize a sober but grateful feeling of satisfaction, in having, to
  the extent of our power, discharged these self-imposed obligations;
  this feeling is chastened also by a deep sense of gratitude, first to
  God for life and power continued for so high a purpose; and next, to
  our noble band of contributors, whose labors are recorded in half a
  century of volumes, and in more than a quarter of a century of years.
  We need not conceal our conviction, that the views expressed in these
  “Introductory Remarks,” have been fully sustained by our fellow
  laborers.

  Should we appear to take higher ground than becomes us, we find our
  vindication in the fact, that we have heralded chiefly the doings and
  the fame of others. The work has indeed borne throughout “the impress”
  of editorial unity of design, and much that has flowed from one pen,
  and not a little from the pens of others, has been without a name. The
  materials for the pile, have however been selected and brought in,
  chiefly by other hands, and if the monument which has been reared
  should prove to be “_aere perennius_,” the honor is not the sole
  property of the architect; those who have quarried, hewn and polished
  the granite and the marble, are fully entitled to the enduring record
  of their names already deeply cut into the massy blocks, which
  themselves have furnished.

  If a retrospective survey of the labors of thirty years on this
  occasion has rekindled a degree of enthusiasm, it is a natural result
  of an examination of all our volumes from the contents of which we
  have endeavored to make out a summary both of the laborers and their
  works....

  The series of volumes must ever form a work of permanent interest on
  account of its exhibiting the progress of American science during the
  long period which it covers. Comparing 1817 with 1847, we mark on this
  subject a very gratifying change. The cultivators of science in the
  United States were then few—now they are numerous. Societies and
  associations of various names, for the cultivation of natural history,
  have been instituted in very many of our cities and towns, and several
  of them have been active and efficient in making original observations
  and forming collections.


A summary follows presenting some facts as to the growth of scientific
societies and scientific collections in this country during the period
involved: Then the striking contrast between 1818 and 1847 in the matter
of organized effort toward scientific exploration is discussed, as
follows (pp. xvi _et seq._):


  When we began our Journal, not one of the States had been surveyed in
  relation to its geology and natural history; now those that have not
  been explored are few in number. State collections and a United States
  Museum hold forth many allurements to the young naturalist, as well as
  to the archaeologist and the student of his own race. The late
  Exploring Expedition [Wilkes] with the National Institute, has
  enriched the capital with treasures rarely equalled in any country,
  and the Smithsonian Institution recently organized at Washington, is
  about to begin its labors for the increase and diffusion of knowledge
  among men.

  It must not be forgotten that the American Association of Geologists
  and Naturalists—composed of individuals assembled from widely separate
  portions of the Union—by the seven sessions which it has held, and by
  its rich volume of reports, has produced a concentration and harmony
  of effort which promise happy results, especially as, like the British
  Association, it visits different towns and cities in its annual
  progress.

  Astronomy now lifts its exploring tubes from the observatories of many
  of our institutions. Even the Ohio, which within the memory of the
  oldest living men, rolled along its dark waters through interminable
  forests, or received the stains of blood from deadly Indian warfare,
  now beholds on one of its most beautiful hills, and near its splendid
  city, a permanent observatory with a noble telescope sweeping the
  heavens, by the hand of a zealous and gifted observer. At Washington
  also, under the powerful patronage of the general government, an
  excellent observatory has been established, and is furnished with
  superior instruments, under the direction of a vigilant and well
  instructed astronomer—seconded by able and zealous assistants.

  Here also (in Yale College) successful observations have been made
  with good instruments, although no permanent building has been erected
  for an Observatory.

  We only give single examples by way of illustration, for the history
  of the progress of science in the United States, and of institutions
  for its promotion, during the present generation, would demand a
  volume. It is enough for our purpose that science is understood and
  valued, and the right methods of prosecuting it are known, and the
  time is at hand when its moral and intellectual use will be as obvious
  as its physical applications. Nor is it to be forgotten that we have
  awakened an European interest in our researches: general science has
  been illustrated by treasures of facts drawn from this country, and
  our discoveries are eagerly sought for and published abroad.

  While with our co-workers in many parts of our broad land, we rejoice
  in this auspicious change, we are far from arrogating it to ourselves.
  Multiplied labors of many hands have produced the great results. In
  the place which we have occupied, we have persevered despite of all
  discouragements, and may, with our numerous coadjutors, claim some
  share in the honors of the day. We do not say that our work might not
  have been better done—but we may declare with truth that we have done
  all in our power, and it is something to have excited many others to
  effort and to have chronicled their deeds in our annals. Let those
  that follow us labor with like zeal and perseverance, and the good
  cause will continue to advance and prosper. It is the cause of
  truth—science is only embodied and sympathized truth and in the
  beautiful conception of our noble Agassiz—“it tells the thought of
  God.”


The preface closes with some personal remarks:


  In tracing back the associations of many gone-by years, a host of
  thoughts rush in, and pensive remembrance of the dead who have labored
  with us casts deep shadows into the vista through which we view the
  past.

  Anticipation of the hour of discharge, when our summons shall arrive,
  gives sobriety to thought and checks the confidence which health and
  continued power to act might naturally inspire, were we not reproved,
  almost every day, by the death of some co-eval, co-worker, companion,
  friend or patron. This very hour is saddened by such an event,—but we
  will continue to labor on, and strive to be found at our post of duty,
  until there is nothing more for us to do; trusting our hopes for a
  future life in the hands of Him who placed us in the midst of the
  splendid garniture of this lower world, and who has made not less
  ample provision for another and a better.


_Editorial and financial._—The editorial labors on the Journal were
carried by the elder Silliman alone for twenty years from 1818 to 1838.
As has been clearly shown in his statements, already quoted, he was,
after the first beginning, personally responsible also for the financial
side of the enterprise. With volume =34= (1838) the name of Benjamin
Silliman, Jr., is added as co-editor on the title page. He was graduated
from Yale College the year preceding and at this date was only
twenty-one years old. His aid was unquestionably of much service from
the beginning and increased rapidly with years and experience. The elder
Silliman introduces him in the preface to vol. =34= (1838) and comes
back to the subject again in the preface to vol. =50= (1847). The whole
editorial situation is here presented as follows:


  “During twenty years from the inception of this Journal, the editor
  labored alone, although overtures for editorial cooperation had been
  made to him by gentlemen commanding his confidence and esteem, and who
  would personally have been very acceptable. It was, however, his
  opinion that the unity of purpose and action so essential to the
  success of such a work were best secured by individuality; but he made
  every effort, and not without success, to conciliate the good will and
  to secure the assistance of gentlemen eminent in particular
  departments of knowledge. On the title page of No. 1, vol. =34=,
  published in July, 1838, a new name is introduced: the individual to
  whom it belongs having been for several years more or less concerned
  in the management of the Journal, and from his education, position,
  pursuits and taste, as well as from affinity, being almost identified
  with the editor, he seemed to be quite a natural ally, and his
  adoption into the editorship was scarcely a violation of individual
  unity. His assistance has proved to be very important:—his near
  relation to the senior editor prevents him from saying more, while
  justice does not permit him to say less.”


As is distinctly intimated in the preceding paragraph the elder Silliman
was fortunate in obtaining the assistance in his editorial labors of
numerous gentlemen interested in the enterprise. Their cooperation
provided many of the scientific notices, book reviews and the like
contained in the Miscellany with which each number closed. It is
impossible, at this date, to render the credit due to Silliman’s helpers
or even to mention them by name. Very early Asa Gray was one of these as
occasional notes are signed by his initials. Dr. Levi Ives of New Haven
was another. Prof. J. Griscom of Paris also sent numerous contributions
even as early as 1825 (see =9=, 154, 1825; =22=, 192, 1832; =24=, 342,
1833, and others).

Some statements have already been quoted from the early volumes as to
the business part of Silliman’s enterprise. The subject is taken up more
fully in the preface to volume =50= (1847). No one can fail to marvel at
the energy and optimism required to push the Journal forward when
conditions must have been so difficult and encouragement so scanty. He
says (pp. iii, iv):


  This Journal first appeared in July, 1818, and in June, 1819, the
  first volume of four numbers and 448 pages was completed. This scale
  of publication, originally deemed sufficient, was found inadequate to
  receive all the communications, and as the receipts proved
  insufficient to sustain the expenses, the work, having but three
  hundred and fifty subscribers, was, at the end of the year, abandoned
  by the publishers.

  An unprofitable enterprise not being attractive to the trade, ten
  months elapsed before another arrangement could be carried into
  effect, and, therefore, No. 1 of vol. =2= was not published until
  April, 1820. The new arrangement was one of mutual responsibility for
  the expenses, but the Editor was constrained nevertheless to pledge
  his own personal credit to obtain from a bank the funds necessary to
  begin again, and from this responsibility he was, for a series of
  years, seldom released. The single volume per annum being found
  insufficient for the communications, two volumes a year were afterward
  published, commencing with the second volume.


The publishers whose names appear on the title page of the four numbers
of the first volume are “J. Eastburn & Co., Literary Rooms, Broadway,
New York” and “Howe & Spalding, New Haven.” For the second volume and
those immediately following the corresponding statement “printed and
published by S. Converse [New Haven] for the Editor.”

Silliman adds (p. iv):


  At the conclusion of vol. =10=, in February, 1826, the work was again
  left upon the hands of its Editor; all its receipts had been absorbed
  by the expenses, and it became necessary now to pay a heavy sum to the
  retiring publisher, as an equivalent for his copies of previous
  volumes, as it was deemed necessary either to control the work
  entirely or to abandon it. The Editor was not willing to think of the
  latter, especially as he was encouraged by public approbation, and was
  cheered onward in his labors by eminent men both at home and abroad,
  and he saw distinctly that the Journal was rendering service not only
  to science and the arts, but to the reputation of his country. He
  reflected, moreover, that in almost every valuable enterprise
  perseverance in effort is necessary to success. He being now sole
  proprietor, a new arrangement was made for a single year, the
  publishers being at liberty, at the end of that time, to retire, and
  the Editor to resume the Journal should he prefer that course.

  The latter alternative he adopted, taking upon himself the entire
  concern, including both the business and the editorial duties, and of
  course, all the correspondence and accounts. From that time the work
  has proceeded without interruption, two volumes per annum having been
  published for the last twenty years; and its pecuniary claims ceased
  to be onerous, although its means have never been large....


Later in the same preface he adds (p. xiv):


  It may be interesting to our readers to know something of the
  patronage of the Journal. It has never reached one thousand paying
  subscribers, and has rarely exceeded seven or eight hundred—for many
  years it fluctuated between six and seven hundred.

  It has been far from paying a reasonable editorial compensation; often
  it has paid nothing, and at present it does little more than pay its
  bills. The number of engravings and the extra labor in printer’s
  composition, cause it to be an expensive work, while its patronage is
  limited.


It is difficult at this date to give any adequate statement of the
amount of encouragement and active assistance given to Silliman by his
scientific colleagues in New Haven and elsewhere—a subject earlier
alluded to. It is fortunately possible, however, to acknowledge the
generous aid received by the Journal in the early days from a source
near at hand. It has already been noted in another place that the
dawning activity of science at New Haven was recognized by the founding
of the “Connecticut Academy of Arts and Sciences,” formally established
at New Haven in 1799 and the third scientific body to be organized in
this country. From the beginning of the Journal in 1818, the Connecticut
Academy freely gave its support both in papers for publication and at
least on one occasion later it gave important financial aid. Upon the
occasion of the celebration of the centennial anniversary of the Academy
on October 11, 1899, Professor, later Governor, Baldwin, the president
of the Academy, discusses this subject in some detail. He says in part:


  To support his [Silliman’s] undertaking, a vote had been passed in
  February [1818], “that the Committee of Publication may allow such of
  the Academy’s papers as they think proper, to be published in Mr.
  Silliman’s Scientific Journal.”

  Free use was made of this authority, and a large part of the contents
  of the Journal was for many years drawn from this source. In some
  cases this fact was noted in publication;[2] but in most it was
  not....

  In 1826, when the Journal was in great need of financial support, the
  Academy further voted to pay for a year the cost of printing such of
  its papers as might be published in it. In Baldwin’s Annals of Yale
  College, published in 1831, it is described as a publication
  “honorable to the science of our common country,” and having “an
  additional value as being adopted as the acknowledged organ of the
  Connecticut Academy of Arts and Sciences.”


Many active campaigns were carried on over the country through paid
agents to obtain new subscribers for the Journal and it was doubtless
due to these efforts that the nominal subscription list was, at times,
as already noted, relatively large as compared with that of a later
date. The new subscribers in many cases, however, did not remain
permanently interested, often failed to pay their bills, and the
uncertain and varying demand upon the supply of printed copies was
doubtless one reason why many single numbers became early out of print.

An interesting sidelight is thrown upon the efforts of Silliman to
interest the public in his work, at its beginning, by a letter to the
editor from Thomas Jefferson, then seventy-five years of age. The writer
is indebted to Mr. Robert B. Adam of Buffalo for a copy of this letter
and its interest justifies its being reproduced here entire. The letter
is as follows:


                                               Monticello, Apr. 11. ’18.

  Sir

  The unlucky displacement of your letter of Mar 3 has been the cause of
  delay in my answer. altho’ I have very generally withdrawn from
  subscribing to or reading periodical publications from the love of
  rest which age produces, yet I willingly subscribe to the journal you
  propose from a confidence that the talent with which it will be edited
  will entitle it to attention among the things of select reading for
  which alone I have time now left. be so good as to send it by mail,
  and the receipt of the 1st number will be considered as announcing
  that the work is commenced and the subscription money for a year shall
  be forwarded. Accept the assurance of my great esteem and respect.

                                                           Th. Jefferson

  Professor Silliman.


_Contributors._—An interesting summary is also given by Silliman of the
contributors to the Journal and the extent of their work (vol. =50=, pp.
xii, xiii); he says:


  We find that there have been about 600 contributors of original matter
  to the Journal, and we have the unexpected satisfaction of believing
  that probably five-sixths of them are still living; for we are not
  certain that more than fifty are among the dead; of perhaps fifty more
  we are without information, and if that additional number is to be
  enrolled among the “stelligeri,” we have still 500 remaining. Among
  them are not a few of the veterans with whom we began our career, and
  several of these are still active contributors. Shall we then conclude
  that the peaceful pursuits of knowledge are favorable to long life?
  This we think is, _cœteris paribus_, certainly true: but in the
  present instance, another reason can be assigned for the large amount
  of survivorship. As the Journal has advanced and death has removed its
  scientific contributors, younger men and men still younger, have
  recruited the ranks, and volunteers have enlisted in numbers
  constantly increasing, so that the flower of the host are now in the
  morning and meridian of life.

  We have been constantly advancing, like a traveller from the
  equinoctial towards the colder zones,—as we have increased our
  latitude, stars have set and new stars have risen, while a few
  planetary orbs visible in every zone, have continued to cheer us on
  our course.

  The number of articles, almost exclusively original, contained in the
  Journal is about 1800, and the Index will show how many have been
  contributed by each individual; we have doubtless included in this
  number _some few_ articles republished from foreign Journals—but we
  think they are even more than counterbalanced by original
  communications without a name and by editorial articles, both of which
  have been generally omitted in the enumeration.

  Of smaller articles and notices in the Miscellany, we have not made
  any enumeration, but they evidently are more numerous than the regular
  articles, and we presume that they may amount to at least 2500.

  Of party, either in politics or religion, there is no trace in our
  work; of personalities there are none, except those that relate to
  priority of claims or other rights of individuals. Of these
  vindications the number is not great, and we could heartily have
  wished that there had been no occasion for any.


_General Scope of Articles._—Many references will be found in the
chapters following which throw light upon the character and scope of the
papers published in the Journal, particularly in its early years; a few
additional statements here may, however, prove of interest.

One feature that is especially noticeable is the frequent publication of
articles planned to place before the readers of the Journal in full
detail subjects to which they might not otherwise have access. These are
sometimes translations; sometimes republications of articles that had
already appeared in English periodicals; again, they are exhaustive and
critical reviews of important memoirs or books. The value of this
feature in the early history of the Journal, when the distribution of
scientific literature had nothing of the thoroughness characteristic of
recent years, is sufficiently obvious.

It is also interesting to note the long articles of geological
description and others giving lists of mineral or botanical localities.
Noteworthy, too, is the attempt to keep abreast of occurring phenomena
as in the many notes on tornadoes and storms by Redfield, Loomis, etc.;
on auroras at different localities; on shooting stars by Herrick,
Olmstead and others.

The wide range of topics treated of is quite in accordance with the plan
of the editor as given on an earlier page. Some notes, taken more or
less at random, may serve to illustrate this point. An extended and
quite technical discussion of “Musical Temperament” opens the first
number (=1=, pp. 9–35) and is concluded in the same volume (pp.
176–199). An article on “Mystery” is given by Mark Hopkins, A.M., “late
a tutor of Williams College” (=13=, 217, 1828). There is an essay on
“Gypsies” by J. Griscom (from the Revue Encyclopédique) in volume =24=
(pp. 342–345, 1833), while some notes on American gypsies are added in
vol. =26= (p. 189, 1834). The “divining rod” is described at length in
vol. =11= (pp. 201–212, 1826), but without giving any comfort to the
credulous; on the contrary the last paragraph states that “the
pretensions of diviners are worthless, etc.” A long article by J. Finch
on the forts of Boston harbour appeared in 1824 (=8=, 338–348); the
concluding paragraph seems worthy of quotation:


  “Many centuries hence, if despotism without, or anarchy within, should
  cause the republican institutions of America to fade, then these
  fortresses ought to be destroyed, because they would be a constant
  reproach to the people; but until that period, they should be
  preserved as the noblest monuments of liberty.”


The promise to include the fine arts is kept by the publication of
various papers, as of the Trumbull paintings (=16=, 163, 1829); also by
a series of articles on “architecture in the United States” (=17=, 99,
1830; =18=, 218, 220, 1830) and others. Quite in another line is the
paper by J. W. Gibbs (=33=, 324, 1838) on “Arabic words in English.” A
number of related linguistic papers by the same author are to be found
in other volumes. Papers in pure mathematics are also not infrequent,
though now not considered as falling within the field of the Journal.

Applied science takes a prominent place through all the volume of the
First Series. An interesting paper is that on Eli Whitney, containing an
account of the cotton gin; this is accompanied by an excellent portrait
(=21=, 201–264, 1832). The steam engine and its application are
repeatedly discussed and in the early volumes brief accounts are given
of the early steamboats in use; for example, between Stockholm and St.
Petersburg (=2=, 347, 1820); Trieste and Venice (=4=, 377, 1822); on the
Swiss Lakes (=6=, 385, 1823). The voyage of the first Atlantic
steamboat, the “Savannah,” which crossed from Savannah to Liverpool in
1819, is described (=38=, 155, 1840); mention is also made of the “first
iron boat” (=3=, 371, 1821; =5=, 396, 1822). A number of interesting
letters on “Steam Navigation” are given in vol. =35=, 160, 162, 332,
333, 336; some of the suggestions seem very quaint, viewed in the light
of the experience of to-day.

A very early form of explosive engine is described at length by Samuel
Morey (=11=, 104, 1826); this is an article that deserves mention in
these days of gasolene motors. Even more interesting is the description
by Charles Griswold (=2=, 94, 1820) of the first _submarine_ invented by
David Bushnell and used in the Revolutionary War in August, 1776. An
account is also given of a dirigible balloon that may be fairly regarded
as the original ancestor of the Zeppelin (see =11=, 346, 1826). The
whole subject of aërial navigation is treated at length by H. Strait
(=25=, pp. 25, 26, 1834) and the expression of his hopes for the future
deserve quotation:


  “Conveyance by air can be easily rendered as safe as by water or land,
  and more cheap and speedy, while the universal and uniform diffusion
  of the air over every portion of the earth, will render aërial
  navigation preferable to any other. To carry it into effect, there
  needs only an immediate appeal on a sufficiently large scale, to
  experiment; reason has done her part, when experiment does hers,
  nature will not refuse to sanction the whole. Aërial navigation will
  present the works of nature in all their charms; to commerce and the
  diffusion of knowledge, it will bring the most efficient aid, and it
  can thus be rendered serviceable to the whole human family.”


A subject of quite another character is the first discussion of the
properties of chloroform (chloric ether) and its use as an anæsthetic
(Guthrie, =21=, 64, 405, 1832; =22=, 105, 1832; Levi Ives, =21=, 406).
Further interesting communications are given of the first analyses of
the gastric juice and the part played by it in the process of digestion.
Dr. William Beaumont of St. Louis took advantage of a patient who
through a gun-shot wound was left with a permanent opening into his
stomach through which the gastric juice could be drawn off. The results
of Dr. Beaumont and of Professor Robley Dunglison, to whom samples were
submitted, are given in full in the life of Beaumont by Jesse S. Myer
(St. Louis, 1912). The interest of the matter, so far as the Journal is
concerned, is chiefly because Dr. Beaumont selected Professor Silliman
as a chemist to whom samples for examination were also submitted. An
account of Silliman’s results is given in the Beaumont volume referred
to (see also =26=, 193, 1834). Desiring the support of a chemist of
wider experience in organic analysis, he also sent a sample through the
Swedish consul to Berzelius in Stockholm. After some months the sample
was received and it is interesting to note in a perfectly fresh
condition; it is to be regretted, however, that the Swedish chemist
failed to add anything to the results already obtained in this country
(=27=, 40b, 1835).

The above list, which might be greatly extended, seems to leave little
ground for the implied criticism replied to by Silliman as follows
(=16=, p. v, 1829):


  A celebrated scholar, while himself an editor, advised me, in a
  letter, to introduce into this Journal as much “_readable_” matter as
  possible: and there was, pretty early, an earnest but respectful
  recommendation in a Philadelphia paper, that Literature, in imitation
  of the London Quarterly Journal of Science, &c. should be in form,
  inscribed among the titles of the work.


                 _The Second, Third and Fourth Series._

The SECOND SERIES of the Journal, as already stated, began with January,
1846. Up to this time the publication had been a quarterly or two
volumes annually of two numbers each. From 1846 until the completion of
an additional fifty volumes in 1871, the Journal was made a bimonthly,
each of the two yearly volumes having three numbers each. Furthermore, a
general index was given for each period of five years, that is for every
ten volumes.

[Illustration: Edward S. Dana]

Much more important than this change was the addition to the editorial
staff of James Dwight Dana, Silliman’s son-in-law. Dana returned from
the four-years cruise of the Wilkes Exploring Expedition in 1842; he
settled in New Haven, was married in 1844, and in 1850 was appointed
Silliman professor of Geology in Yale College. He was at this time
actively engaged in writing his three quarto reports for the Expedition
and hence did not begin his active professional duties in Yale College
until 1856. Part of his inaugural address was quoted on an earlier page.

Dana had already performed the severe labor of preparing the complete
index to the First Series, a volume of about 350 pages, finally issued
in 1847. From the beginning of the Second Series he was closely
associated with his brother-in-law, the younger Silliman. Later the
editorial labor devolved more and more upon him and the larger part of
this he carried until about 1890. His work, was, however, somewhat
interrupted during periods of ill health. This was conspicuously true
during a year’s absence in Europe in 1859–60, made necessary in the
search for health; during these periods the editorial responsibility
rested entirely upon the younger Silliman. Of Dana’s contributions to
science in general this is not the place to speak, nor is the present
writer the one to dwell in detail upon his work for the Journal. This
subject is to such an extent involved in the history of geology and
zoology, the subjects of several succeeding chapters, that it is
adequately presented in them.

It may, however, be worth stating that in the bibliography accompanying
the obituary notice of Dana (=49=, 329–356, 1895) some 250 titles of
articles in the Journal are enumerated; these aggregate approximately
2800 pages. The number of critical notes, abstracts, book reviews, etc.,
could be also given, were it worth while, but what is much more
significant in this connection, than their number or aggregate length,
is the fact that these notices are in a large number of cases—like those
of Gray in botany—minutely critical and original in matter. They thus
give the writer’s own opinion on a multitude of different subjects. It
was a great benefit to Dana, as it was to science also, that he had this
prompt means at hand of putting before the public the results of his
active brain, which continued to work unceasingly even in times of
health prostration.

This may be the most convenient place to add that as Dana became
gradually less able to carry the burden of the details involved in
editing the Journal in addition to his more important scientific labors,
particularly from 1890 on, this work devolved more and more upon his
son, the present editor, whose name was added to the editorial staff in
1875, with volume =9=, of the Third Series. The latter has served
continuously until the present time, with the exception of absences, due
to ill health, in 1893–94 and in 1903; during the first of these
Professor Henry S. Williams and during the second Professor H. E.
Gregory occupied the editorial chair.


The THIRD SERIES began in 1871, after the completion of the
one-hundredth volume from the beginning in 1818. At this date the
Journal was made a monthly and as such it remains to-day. Fifty volumes
again completed this series, which closed in 1895.

The FOURTH SERIES began with January, 1896, and the present number for
July, 1918, is the opening one of the forty-sixth volume or, in other
words,—the one hundred and ninety-sixth volume of the entire issue since
1818. The Fourth Series, according to the precedent established, will
end with 1920.


_Associate Editors._—In 1851 the new policy was introduced of adding
“Associate Editors” to the staff. The first of these was Dr. Wolcott
Gibbs of Cambridge. He began his duties with the eleventh volume of the
Second Series in 1851 and continued them with unceasing care and
thoroughness for more than twenty years. In a note dated Jan. 1, 1851
(=11=, 105), he says:


  It is my intention in future to prepare for the columns of this
  Journal abstracts of the more important physical and chemical memoirs
  contained in foreign scientific journals, accompanied by references,
  and by such critical observations as the occasion may demand.
  Contributions of a similar character from others will of course not be
  excluded by this arrangement, but I shall hold myself responsible only
  for those notices which appear over my initials.


The departments covered by Dr. Gibbs, in his excellent monthly
contributions, embraced chemistry and physics, and these subjects were
carried together until 1873 when they were separated and the physical
notes were furnished, first by Alfred M. Mayer and later successively by
E. C. Pickering (from 1874), J. P. Cooke (from 1877), and John
Trowbridge (from 1880). The first instalment of the long series of notes
in chemistry and chemical physics by George F. Barker was printed in
volume =50=, 1870. He came in at first to occasionally relieve Dr.
Gibbs, but soon took the entire responsibility. His name was placed
among the associate editors on the cover in 1877 and two years later Dr.
Gibbs formally retired. It may be added that from the beginning in 1851
to the present time, the notes in “Chemistry and Physics” have been
continued almost without interruption.

The other departments of science have been also fully represented in the
notes, abstracts of papers published, book notices, etc., of the
successive numbers, but as with the chemistry and physics the subject of
botany was long treated in a similar formal manner. For the notes in
this department, the Journal was for many years indebted to Dr. Asa
Gray, who became associate editor in 1853, two years after Gibbs,
although he had been a not infrequent contributor for many years
previously. Gray’s contributions were furnished with great regularity
and were always critical and original in matter. They formed indeed one
of the most valuable features of the Journal for many years; as
botanists well appreciate, and, as Professor Goodale has emphasized in
his chapter on botany, Gray’s notes are of vital importance in the
history of the development of his subject. With Gray’s retirement from
active duty, his colleague, George W. Goodale, took up the work in 1888
and in 1895 William G. Farlow, also of Cambridge, was added as an
associate editor in cryptogamic botany. At this time, however, and
indeed earlier, the sphere of the Journal had unavoidably contracted and
botany perforce ceased to occupy the prominent place it had long done in
the Journal pages.

This is not the place to present an appreciation of the truly
magnificent work of Asa Gray. It may not be out of place, however, to
call attention to the notice of Gray written for the Journal by his
life-long friend, James D. Dana (=35=, 181, 1888). The opening paragraph
is as follows:


  “Our friend and associate, Asa Gray, the eminent botanist of America,
  the broad-minded student of nature, ended his life of unceasing and
  fruitful work on the 30th of January last. For thirty-five years he
  has been one of the editors of this Journal, and for more than fifty
  years one of its contributors; and through all his communications
  there is seen the profound and always delighted student, the
  accomplished writer, the just and genial critic, and as Darwin has
  well said, ‘The lovable man.’”


The third associate editor, following Gray, was Louis Agassiz, whose
work for science, particularly in his adopted home in this country,
calls for no praise here. His term of service extended from 1853 to 1866
and, particularly in the earlier years, his contributions were numerous
and important. The next gentleman in the list was Waldo I. Burnett, of
Boston, who served one year only, and then followed four of Dana’s
colleagues in New Haven, of whose generosity and able assistance it
would be impossible to say too much. These gentlemen were Brush in
mineralogy; Johnson in chemistry, particularly on the agricultural side;
Newton in mathematics and astronomy, whose contributions will be spoken
of elsewhere; and Verrill—a student of Agassiz—in zoology.

All of these gentlemen, besides their frequent and important original
articles, were ever ready not only to give needed advice, but also, to
furnish brief communications, abstracts of papers and book reviews, and
otherwise to aid in the work. Verrill particularly furnished the Journal
a long list of original and important papers, chiefly in systematic
zoology, extending from 1865 almost down to the present year. His
abstracts and book notices also were numerous and trenchant and it is
not too much to say that without him the Journal never could have filled
the place in zoology which it so long held. Much later the list of New
Haven men was increased by the addition of Henry S. Williams (1894), and
O. C. Marsh (1895).

[Illustration: Wolcott Gibbs]

Of the valuable work of those more or less closely associated in the
conduct of the Journal at the present time, it would not be appropriate
to speak in detail. It must suffice to say that the services rendered
freely by them have been invaluable, and to their aid is due a large
part of the success of the Journal, especially since the Fourth Series
began in 1896. But even this statement is inadequate, for the
editor-in-chief has had the generous assistance of other gentlemen,
whose names have not been placed on the title page, and who have also
played an important part in the conduct of the Journal. This policy,
indeed, is not a matter of recent date. Very early in the First Series,
Professor Griscom of Paris, as already noted, furnished notes of
interesting scientific discoveries abroad. Other gentlemen have from
time to time acted in the same capacity. The most prominent of them was
Professor Jerome Nicklès of Nancy, France, who regularly furnished a
series of valuable notes on varied subjects, chiefly from foreign
sources, extending from 1852 to 1869. On the latter date he met an
untimely death in his laboratory in connection with experiments upon
hydrofluoric acid (=47=, 434, 1869).

It may be added, further, that one of the striking features about the
Journal, especially in the earlier half century of its existence, is the
personal nature of many of its contributions, which were very frequently
in the form of letters written to Benjamin Silliman or J. D. Dana. This
is perhaps but another reflection of the extent to which the growth of
the magazine centered around these two men, whose wide acquaintance and
broad scientific repute made of the Journal a natural place to record
the new and interesting things that were being discovered in science.

The following list gives the names and dates of service, as recorded on
the Journal title pages, of the gentlemen formally made Associate
Editors:

            Wolcott Gibbs       (2) 11, 1851 to (3) 18, 1879
            Asa Gray             „  15, 1853 „   „  34, 1887
            Louis Agassiz        „  16, 1853 „  (2) 41, 1866
            Waldo I. Burnett     „  16, 1853 „   „  17, 1853
            George J. Brush      „  35, 1863 „  (3) 18, 1879
            Samuel W. Johnson    „  35, 1863 „   „  18, 1879
            Hubert A. Newton    (2) 38, 1864 to (4)  1, 1896
            Addison E. Verrill   „  47, 1869
            Alfred M. Mayer     (3)  5, 1873 to (3)  6, 1873
            Edward C. Pickering  „   7, 1874 „   „  13, 1877
            George F. Barker     „  14, 1877 „  (4) 29, 1910
            Josiah P. Cooke      „  14, 1877 „  (3) 47, 1894
            John Trowbridge     (3) 19, 1880
            George W. Goodale    „  35, 1888
            Henry S. Williams    „  47, 1894
            Henry P. Bowditch    „  49, 1895 to (4)  8, 1899
            William G. Farlow    „  49, 1895
            Othniel C. Marsh     „  49, 1895 to (4)  6, 1899
            Henry A. Rowland    (4)  1, 1896 „   „  10, 1900
            Joseph S. Diller     „   1, 1896
            Louis V. Pirsson     „   7, 1899
            William M. Davis     „   9, 1900
            Joseph S. Ames       „  12, 1901
            Horace L. Wells      „  18, 1904
            Herbert E. Gregory   „  18, 1904
            Horace S. Uhler      „  33, 1912


                    _Present and Future Conditions._

The field to be occupied by the “American Journal of Science and Arts,”
as seen by its founder in 1818 and presented by him in the first number,
as quoted entire on an earlier page, was as broad as the entire sphere
of science itself. It thus included all the departments of both pure and
applied science and extended even to music and fine arts also. As the
years went by, however, and the practical applications of science
greatly increased, technical journals started up, and the necessity of
cultivating this constantly expanding field diminished. It was not,
however, until January, 1880, that “the Arts” ceased to be a part of the
name by which the Journal was known.

About the same date also—or better a little earlier—began an increasing
development of scientific research, particularly as fostered by the
graduate schools of our prominent universities. The full presentation of
this subject would require much space and is indeed unnecessary as the
main facts must be distinct in the mind of the reader. It is only right,
however, that the large part played in this movement by the Johns
Hopkins University (founded in 1876) should be mentioned here.

As a result of this movement, which has been of great benefit in
stimulating the growth of science in the country, many new journals of
specialized character have come into existence from time to time.
Further localization and specialization of scientific publication have
resulted from the increased activity of scientific societies and
academies at numerous centers and the springing into existence thereby
of new organs of publication through them, as also through certain of
the Government Departments, the Carnegie Institution, and certain
universities and museums.

As bearing upon this subject, the following list of the more prominent
scientific periodicals started in this country since 1867 is not without
interest:

 1867–    .  American Naturalist.

 1875–    .  Botanical Bulletin; later Botanical Gazette.

 1879–1913.  American Chemical Journal.

 1880–1915.  School of Mines Quarterly.

 1883–    .  Science.

 1885–    .  Journal of Heredity.

 1887–    .  Journal of Morphology.

 1887–1908.  Technology Quarterly.

 1888–1905.  American Geologist.

 1891–    .  Journal of Comparative Neurology.

 1893–    .  Journal of Geology.

 1893–    .  Physical Review.

 1895–    .  Astrophysical Journal.

 1896–    .  Journal of Physical Chemistry.

 1896–    .  Terrestrial Magnetism.

 1897–1899.  Zoological Bulletin; followed by

 1900–    .  Biological Bulletin.

 1901–    .  American Journal of Anatomy.

 1904–    .  Journal of Experimental Zoology.

 1905–    .  Economic Geology.

 1906–    .  Anatomical Record.

 1907–    .  Journal of Economic Entomology.

 1911–    .  Journal of Animal Behavior.

 1914–    .  American Journal of Botany.

 1916–    .  Genetics.

 1918–    .  American Journal of Physical Anthropology.

The result of the whole movement has been of necessity to narrow, little
by little, the sphere of a general scientific periodical such as the
Journal has been from the beginning. The exact change might be studied
in detail by tabulating as to subjects the contents of successive
volumes, decade by decade, from 1870 down. It is sufficient, here,
however, to recognize the general fact that while the number of original
papers published in the periodicals of this country, in 1910, for
example, was very many times what it was in 1825, a large part of these
have naturally found their home in periodicals devoted to the special
subject dealt with in each case. That this movement will continue,
though in lessened degree now that the immediate demand is measurably
satisfied, is to be expected. At the same time it has not seemed wise,
at any time in the past, to formally restrict the pages of the Journal
to any single group of subjects. The future is before us and its
problems will be met as they arise. At the moment, however, there seems
to be still a place for a scientific monthly sufficiently broad to
include original papers of important general bearing even if special in
immediate subject. In this way it would seem that “Silliman’s Journal”
can best continue to meet the ideals of its honored founder, modified as
they must be to meet the change of conditions which a century of
scientific investigation and growth have wrought. Incidentally it is not
out of place to add that a self-supporting, non-subsidized scientific
periodical may hope to find a larger number of subscribers from among
the workers in science and the libraries if it is not too restricted in
scope.

The last subject touched upon introduces the essential matter of
financial support without which no monthly publication can survive. With
respect to the periodicals of recent birth, listed above, it is safe to
say that some form of substantial support or subsidy—often very
generous—is the rule, perhaps the universal one. This has never been the
case with the American Journal. The liberality and broad-minded attitude
of Yale College in the early days, and of the Yale University that has
developed from it, have never been questioned. At the same time the
special conditions have been such as to make it desirable that the
responsibility of meeting the financial requirements should be carried
by the editors-in-chief. At present the Yale Library gives adequate
payment for certain publications received by the Journal in exchange,
though for many years they were given to it as a matter of course, free
of charge. Beyond this there is nothing approaching a subsidy.

The difficulties on the financial side met with by the elder Silliman
have been suggested, although not adequately presented, in the various
statements quoted from early volumes. The same problems in varying
degree have continued for the past sixty years. Since 1914 they have
been seriously aggravated for reasons that need not be enlarged upon.
Prior to that date the subscription list had, for reasons chiefly
involved in the development of special journals, been much smaller than
the number estimated by Silliman, for example, in volume =50= (p. xiv),
although there has been this partial compensation that the considerable
number of well-established libraries on the subscription list has meant
a greater degree of stability and a smaller proportion of bad accounts.
The past four years, however, the Journal, with all similar undertakings
here and elsewhere, has been compelled to bear its share of the burden
of the world war in diminished receipts and greatly increased expenses.
It is gratifying to be able to acknowledge here the generosity of the
authors, or of the laboratories with which they have been connected, in
their willingness not infrequently to give assistance, for example, in
the payment of more or less of the cost of engravings, or in a few
special cases a large portion of the total cost of publication. In this
way the problem of ways and means, constantly before the editor who
bears the sole responsibility, has been simplified.

It should also be stated that as those immediately interested have
looked forward to the present anniversary, it has been with the hope
that this occasion might be an appropriate one for the establishment of
a “Silliman Fund” to commemorate the life and work of Benjamin Silliman.
The income of such a fund would lift from the University the burden that
must unavoidably fall upon it when the responsibility for the conduct of
the Journal can no longer be carried by members of the family including
the editor and—as in years long past—a silent partner whose aid on the
business side has been essential to the efficiency and economy of the
enterprise. Present conditions are not favorable for such a movement,
although something has been already accomplished in the desired
direction. At the present time every patriotic citizen must feel it his
first duty to give his savings as well as his spare income to the
support of the National Government in the world struggle for freedom in
which it is taking part. But, whatever the exact condition of the future
may be, it cannot be questioned that the Journal founded by Benjamin
Silliman in 1818 will survive and will continue to play a vital part in
the support and further development of science.

The present year of 1918 finds the world at large, and with it the world
of science, painfully crushed beneath the overwhelming weight of a world
war of unprecedented severity. The four terrible years now nearly
finished have seen a fearful destruction of life and property which must
have a sad influence on the progress of science for many years to come.
Only in certain restricted lines has there been a partial compensation
in the stimulating influence due to the immediate necessities connected
with the great conflict. One hundred years ago “the reign of war” was
keenly in the mind of the editor in beginning his work, but for him,
happily, the long period of the Napoleonic wars was already in the past,
as also the brief conflict of 1812, in which this country was engaged
and in which Silliman himself played a minor part. We, too, must
believe, no matter how serious the outlook of the present moment, that a
fundamental change will come in the not distant future; the nations of
the world must sooner or later turn once more to peaceful pursuits and
the scientific men of different races must become again not enemies but
brothers engaged in the common cause of uplifting human life. The peace
that we look forward to to-day is not for this country alone, but a
peace which shall be a permanent blessing to the entire world for ages
to come.


NOTE.—The portrait which forms the frontispiece of this volume has been
reproduced from the plate in volume =50= (1847). The original painting
was made by H. Willard in 1835, when Silliman was in Boston engaged in
delivering the Lowell lectures; he was then nearly fifty-six years of
age. The engraving, as he states elsewhere, was made from this painting
for the Yale Literary Magazine, and was published in the number for
December, 1839.

It is interesting to quote the remarks with which the editor introduces
the portrait (=50=, xviii, 1847). He says:


  The portrait prefixed to this volume was engraved for a very different
  purpose and for others than the patrons of this Journal. It has been
  suggested by friends, whose judgment we are accustomed to respect,
  that it ought to find a place here, since it is regarded as an
  authentic, although, perhaps, a rather austere resemblance. In
  yielding to this suggestion, it may be sufficient to quote the
  sentiment of Cowper on a similar occasion, who remarked—“that after a
  man has, for many years, turned his mind _inside out_ before the
  world, it is only affectation to attempt to hide his face.”


                                _Notes._

Footnote 1:

  The statements given are necessarily much condensed, without an
  attempt to follow all changes of title; furthermore, the dates of
  actual publication for the academies given above are often somewhat
  vaguely recorded. For fuller information see Scudder’s “Catalogue of
  Scientific Serials, 1633–1876,” Cambridge, 1876; also H. Carrington
  Bolton’s “Catalogue of Scientific and Technical Periodicals,
  1665–1882” (Smithsonian Institution, 1885). The writer is much
  indebted to Mr. C. J. Barr, Assistant Librarian of Yale University
  Library, for his valuable assistance in this connection.

Footnote 2:

  The following footnote accompanies the opening article of the first
  volume of the Journal. “From the MS. papers of the Connecticut
  Academy, now published by permission.” Similar notes appear elsewhere.
  Ed.




                                   II
   A CENTURY OF GEOLOGY.—THE PROGRESS OF HISTORICAL GEOLOGY IN NORTH
                                AMERICA

                          By CHARLES SCHUCHERT


                            _Introduction._

The American Journal of Science, “one of the greatest influences in
American geology,” founded in 1818, has published a little more than
92,000 pages of scientific matter. Of geology, including mineralogy,
there appear to be upward of 20,000 pages. What a vast treasure house of
geologic knowledge is stored in these 194 volumes, and how well the
editors have lived up to their proposed “plan of work” as stated in the
opening volume, where Silliman says: “It is designed as a deposit for
original American communications” in “the physical sciences ... and
especially our mineralogy and geology” (=1=, v, 1818)! Not only is it
the oldest continuously published scientific journal of this country,
but it has proved itself to be “perhaps the most important geological
periodical in America” (Merrill). It is impossible to adequately present
in this memorial volume of the Journal the contents of the articles on
the geological sciences.

Editor Silliman was not only the founder of the Journal, but the
generating center for the making of geologists and promoting geology
during the rise of this science in America. For nearly three decades,
the workers came to him for counsel and help, and he had a kind paternal
word for them all. This influence is also shown in the many letters
which were addressed to him, and which he published in the Journal. A
similar influence, paternal care, and constructive criticism were
continued by James D. Dana, and especially in his earlier career as
editor.

Not including mineralogy, there are in the Journal upward of 1500
distinct articles on geology. Of these, over 400 are on vertebrate
paleontology, about 325 on invertebrate paleontology, and 90 on
paleobotany. Of articles bearing on historical geology there are about
160, and on stratigraphic geology more than 360. In addition to all
this, there are more than 2000 pages of geologic matter relating to
books and of letters communicated to the editors Silliman and Dana. We
may summarize with Doctor Merrill’s statement in his well-known
Contributions to the History of American Geology:


  “From its earliest inception geological notes and papers occupied a
  prominent place in its pages, and a perusal of the numbers from the
  date of issue down to the present time will, alone, afford a fair idea
  of the gradual progress of American geology.”


Before presenting a synopsis of the more important steps in the progress
of historical geology in America, it will be well to introduce a rapid
survey of the rise of geology in Europe, for, after all, American
geology grew out of that of England, France and Germany. This dependence
was conspicuously true during the first four decades of the previous
century. With the rise of the first New York State Survey (1836–1843)
and that of Pennsylvania (1836–1844, 1858), American geology became more
or less independent of Europe. Finally, this article will conclude with
a survey of the rise of paleometeorology, paleogeography, evolution, and
invertebrate paleontology.


                    _The Rise of Geology in Europe._

_Mineral Geology._—The geological sciences had their rise in the study
of minerals as carried on by the German chemist and physician George
Bauer (1494–1555), better known as Agricola. Bauer originated the
critical study of minerals, but did not distinguish his “fossilia,” the
remains of organisms, from the inorganic crystal forms. Mineral geology
endured until the close of the eighteenth century.

_Cosmogonists._—Then came the expounders of the earth’s origin, the
cosmogonists of the sixteenth to the end of the eighteenth centuries.
The fashion of this time was to write histories of the earth derived out
of the imagination.

_Earliest Historical Geology._—Even though Giovanni Arduino (1713–1795)
of Padua was not the first to classify the rocks into three series
according to their age, he did this more clearly than any one else
before his time. The rocks about Verona he grouped in 1759 into Primary,
Secondary, Tertiary, and Volcanic. This three-fold classification came
into general use, though modified with time.

Early in the nineteenth century it had become plain that formations of
very varying ages were included in each one of the three series. Through
the study of the fossils and the recognition of the fact that mountain
ranges have been raised at various times, causing younger fossiliferous
strata to take on the characters of the Primary, it was seen that these
terms of Arduino had lost their original significance.

The first one to describe in detail a local stratigraphic sequence was
Johann Gottlob Lehmann (died 1767). In 1756 he published “one of the
classics of geological literature,” distinguishing clearly thirty
successive sedimentary deposits, some of which he said had fossils, but
he did not use them to distinguish the strata.

What Lehmann did for the Permian system, George Christian Füchsel
(1722–1773) did even better for the Triassic of Thuringia, in 1762 and
1773. He pointed out not only the sequence, but also how the gently
inclined strata rest upon the older upturned masses of the mountains;
also that some formations have only marine fossils, while others have
only terrestrial forms and thus indicate the proximity of land. The
deformed strata he thought had fallen into the hollows within the earth,
great caverns that had also consumed much of the oceanic waters and had
in so doing greatly lowered the sea-level. It was Füchsel who first
introduced the theory of universal formations, and who defined the term
formation, using it as we now do, system or period. Even though Lehmann
and Füchsel showed that there was a definite order and process in the
formation of the earth’s crust, their example was barren of followers
until the beginning of the eighteenth century.

_Wernerian Geology or Geognosy._—We come now to the time of Abraham
Gottlob Werner (1749–1817), who from 1775 to 1817 was professor of
mining and mineralogy in the Freiberg Academy of Mines. Geikie, in his
most interesting Founders of Geology, says that Werner “bulks far more
largely in the history of geology than any of those with whom up to the
present we have been concerned—a man who wielded an enormous authority
over the mineralogy and geology of his day.” “Although he did great
service by the precision of his lithological characters and by his
insistence on the doctrine of geological succession, yet as regards
geological theory, whether directly by his own teaching, or indirectly
by the labors of his pupils and followers, much of his influence was
disastrous to the higher interests of geology.”

Werner arranged the crust of the earth into a series of formations, as
had been done previously by Lehmann and Füchsel, and one of his
fundamental postulates was that all rocks were chemically precipitated
in the ocean as “universal formations.” For this reason Werner’s school
were called the Neptunists. Nowhere, however, did he explain how and
where the deep and primitive ocean had disappeared.

According to Werner, the first formed or oldest rocks were the
chemically deposited Primitive strata, including granite and other
igneous and metamorphic rocks. On these followed the Transition rocks,
the earliest sediments of mechanical origin, and above them the Floetz
rocks, a term for the horizontal stratified rocks. These last he said
were partly of chemical but chiefly of mechanical origin. Last of all
came the Alluvial series.

The existence of volcanoes had been pointed out long before Werner’s
time by the Italian school of geologists, but as for “the universality
and potency of what is now termed igneous action,” all was “brushed
aside by the oracle of Freiberg.” Reactions between the interior and
exterior of our earth “were utterly antagonistic to Werner’s conception
of the structure and history of the earth.” To him, volcanoes were
“burning mountains” that arose from the combustion of subterranean beds
of coal, spontaneously ignited.

The breaking down of the Wernerian doctrines began with two of Werner’s
most distinguished pupils, D’Aubuisson de Voisins (1769–1819) and Von
Buch. The former in 1803 had accepted Werner’s aqueous origin of basalt,
but after studying the celebrated and quite recent volcanic area of
Auvergne he recanted in 1804. Here he saw the basaltic rocks lying upon
and cutting through granite, and in places more than 1200 feet thick.
“If these basaltic rocks were lavas,” says Geikie, “they must, according
to the Wernerian doctrine, have resulted from the combustion of beds of
coal. But how could coal be supposed to exist under granite, which was
the first chemical precipitate of a primeval ocean?”

Leopold von Buch (1774–1853), “the most illustrious geologist that
Germany has produced,” after two years spent in Norway was satisfied
“that the rocks in the Christiania district could not be arranged
according to the Wernerian plan, which there completely broke down. Von
Buch found a mass of granite lying among fossiliferous limestones which
were manifestly metamorphosed, and were pierced by veins of granite,
porphyry, and syenite.” Even so, he was not ready to abandon the
teachings of his master. After a study of the mountain systems of
Germany, however, “he declared that the more elevated mountains had
never been covered by the sea, as Werner had taught, but were produced
by successive ruptures and uplifts of the terrestrial crust” (Geikie).

_Rise of Geology and Conformism._—Modern geology has its rise in James
Hutton (1726–1797) of Edinburgh, Scotland. In 1785 and 1795, Hutton
published his Theory of the Earth, with Proofs and Illustrations. His
“immortal theory” is his only work on geology. “Fortunately for Hutton’s
fame and for the onward march of geology, the philosopher numbered among
his friends the illustrious mathematician and natural philosopher, John
Playfair (1748–1819), who had been closely associated with him in his
later years, and was intimately conversant with his geological
opinions.” In 1802, Playfair published his Illustrations of the
Huttonian Theory of the Earth, of which Geikie says, “Of this great
classic it is impossible to speak too highly,” as it is at the basis of
all modern geology.

One of Hutton’s fundamental doctrines is that the earth is internally
hot and that in the past large masses of molten material, the granites,
have been intruded into the crust. It was these igneous views that led
to his followers being called the Plutonists. Another of his great
doctrines was that “the ruins of an earlier world lie beneath the
secondary strata,” and that they are separated by what is now known as
unconformity. He clearly recognized a lost interval in the broken
relation of the structures, and that the ruins, the detrital materials,
of one world after another are superposed in the structure of the earth.

Hutton also held that the deformation of once horizontally deposited
strata was probably brought about at different periods by great
convulsions that shook the very foundations of the earth. After a
convulsion, there was a long time of erosion, represented by the
unconformity. Geikie says, “The whole of the modern doctrine of earth
sculpture is to be found in the Huttonian theory.”

The Lyellian doctrine of metamorphism had its origin in Hutton, for he
showed that invading igneous granite had altered, through its heat and
expanding power, the originally waterlaid sediments, and that the
schists of the Alps had been born of the sea like other stratified
rocks.

Hutton is the father of the Uniformitarian principle, for he “started
with the grand conception that the past history of our globe must be
explained by what can be seen to be happening now, or to have happened
only recently. The dominant idea in his philosophy is that the present
is the key to the past.” This principle has been impressed on all later
geologists by Sir Charles Lyell, and is the chief cornerstone of modern
geology.

The principle of uniformitarianism has underlain geologic interpretation
since the days of Hutton, Playfair, and Lyell. However, it is often
applied too rigidly in interpretations based upon the present
conditions, because in the past there were long times when the
topographic features of the earth were very different from those of
to-day. Throughout the Paleozoic, and, less markedly, the Mesozoic, the
oceans flooded the lands widely (at times over 60 per cent of the total
area), highlands were inconspicuous, sediments far scarcer, and climates
warm and equable throughout the world. Highland conditions, and
especially the broadly emergent continents of the present, were only
periodically present in the Paleozoic and then for comparatively short
intervals between the periods. Therefore rates of denudation, solution,
sedimentation, and evolution have varied greatly throughout the
geological ages. These differences, however, relate to degrees of
operation, and not to kinds of processes; but the differences in degree
of operation react mightily on our views as to the age of the earth.

Geologic time had, for Hutton, no “vestige of a beginning, no prospect
of an end.” In other words, geologic time is infinite. He did not,
however, discover a method by which the chronology of the earth could be
determined.

_First Important Text-books._—In 1822 appeared the ablest text-book so
far published, and the pattern for most of the later ones, Outlines of
the Geology of England and Wales, by W. D. Conybeare (1787–1857) and W.
Phillips (1775–1828). “In this excellent volume all that was then known
regarding the rocks of the country, from the youngest formations down to
the Old Red Sandstone, was summarized in so clear and methodical a
manner as to give a powerful impulse to the cultivation of geology in
England” (Geikie). This book is reviewed at great length by Edward
Hitchcock in the Journal (=7=, 203, 1824).

To indicate how far historical geology had progressed up to 1822 in
England, a digest of the geological column as presented in this
text-book is given in the following table, along with other information.

A text-book writer of yet greater influence was Charles Lyell
(1797–1875), whose Principles of Geology appeared in three volumes
between 1830 and 1833. This and his other books were kept up to date
through many editions, and his Elements of Geology is, as Geikie says,
“the hand book of every English geologist” working with the
fossiliferous formations.


                _The Rise of Geology in North America._

_The Generating Centers._—In America, geology had its rise independently
in three places: in the two scientific societies of Boston and
Philadelphia, and dominantly in Benjamin Silliman of Yale College.
Stated in another way, we may say that geology in America had its origin
in the following pioneers and founders: first, in William Maclure at
Philadelphia, and next in Benjamin Silliman at New Haven. Through the
influence of the latter, Amos Eaton, the botanist, became a geologist
and taught geology at Williams College and later at the Rensselaer
School in Troy, New York. Through the same influence Rev. Edward
Hitchcock also became a geologist and taught the subject after 1825 at
Amherst College.

Silliman was the first to take up actively the teaching of mineralogy
and geology based on collections of specimens. He spread the knowledge
in popular lectures throughout the Eastern States, graduated many a
student in the sciences, making of some of them professional teachers
and geologists, provided all with a journal wherein they could publish
their research, organized the first geological society and through his
students the first official geological surveys, and by kind words and
acts stimulated, fostered, and held together American scientific men for
fifty years. Of him it has been truly said that he was “the guardian of
American science from its childhood.”

_The American Academy in Boston._—The second oldest scientific society,
but the first one to publish on geological subjects, was the American
Academy of Arts and Sciences of Boston, instituted and publishing since
1780. Up to the time of the founding of this Journal, there had appeared
in the publications of the American Academy about a dozen papers of a
geologic character, none of which need to be mentioned here excepting
one by S. L. and J. F. Dana, entitled “Outlines of the Mineralogy and
Geology of Boston,” published in 1818. This is an early and important
step in the elucidation of one of the most intricate geologic areas, and
is further noteworthy for its geologic map, the third one to appear, the
older ones being by Maclure and Hitchcock (Merrill).

                     THE GEOLOGICAL COLUMN IN 1822

 ═══════════════════════════════════╤═════════════╤═════════════
   Present American classification  │Conybeare and│   C. & P.
                                    │Phillips 1822│   orders
 ───────────────────────────────────┼─────────────┼─────────────
                                    │             │  Superior
 Psychozoic or Recent               │Alluvial     │    Order
                                    │             │
 ───────────┬───────────────────────┼─────────────┼─────────────
 Cenozoic   │Pleistocene            │Diluvial     │      „
            │            │          │Upper Marine │
            │            │          │  formation  │
            │            │          │  (Crag,     │
      „     │Pliocene    │Neogene   │  Bagshot    │      „
            │            │          │  sand, and  │
            │            │          │  Isle of    │
            │            │          │  Wight)     │
      „     │Miocene     │    „     │      „      │      „
      „     │                       │Fresh-water  │      „
            │                       │  formations │
      „     │Oligocene   │Paleogene │London Clay  │      „
      „     │Eocene      │    „     │Plastic Clay │      „
 ───────────┼────────────┴──────────┼─────────────┼─────────────
            │                       │             │
            │                       │             │ Supermedial
 Mesozoic   │Cretaceous             │Chalk        │    Order
            │                       │             │
            │                       │             │
            │                       │Beds between │
            │                       │  Chalk and  │
            │                       │  Oolite     │
            │                       │  Series     │
      „     │Comanchian 1887        │  (Chalk     │      „
            │                       │  Marle,     │
            │                       │  Green Sand,│
            │                       │  Weald Clay,│
            │                       │  Iron Sand) │
 ───────────┼───────────────────────┼─────────────┼─────────────
            │                       │Upper Oolitic│
            │                       │  division   │
            │                       │  (Purbeck   │
      „     │Jurassic 1829          │  beds,      │      „
            │                       │  Portland   │
            │                       │  Oolite,    │
            │                       │  Kimmeridge │
            │                       │  Clay)      │
            │                       │Middle       │
            │                       │  Oolitic    │
      „     │           „           │  division   │      „
            │                       │  (Coral Rag,│
            │                       │  Oxford     │
            │                       │  Clay)      │
            │                       │Lower Oolitic│
            │                       │  division   │
            │                       │  (Cornbrash │
            │                       │  Stonesfield│
            │                       │  Slate,     │
            │                       │  Forest     │
            │                       │  Marble,    │
      „     │           „           │  Great      │      „
            │                       │  Oolite,    │
            │                       │  Fullers’   │
            │                       │  Earth,     │
            │                       │  Inferior   │
            │                       │  Oolite,    │
            │                       │  Sand and   │
            │                       │  Marlestone)│
      „     │           „           │Lias         │      „
 ───────────┼───────────────────────┼─────────────┼─────────────
      „     │Triassic 1834          │New Red      │      „
            │                       │  Sandstone  │
 ───────────┼───────────────────────┼─────────────┼─────────────
 Paleozoic  │Permian 1841           │Magnesian    │      „
            │                       │  Limestone  │
 ───────────┼───────────────────────┼─────────────┼─────────────
            │                       │             │  Medial or
      „     │                       │Coal Measures│Carboniferous
            │                       │             │    Order
      „     │Pennsylvanian 1891     │             │      „
            │                       │Millstone    │
      „     │Mississippian 1869     │  Grit and   │      „
            │                       │  Shale      │
      „     │                       │Old Red      │      „
            │                       │  Sandstone  │
      „     │Devonian 1839          │             │      „
 ───────────┼───────────────────────┼─────────────┼─────────────
            │                       │Unresolved   │
            │                       │  Submedial  │
      „     │Silurian 1835          │  and        │
            │                       │  Inferior   │
            │                       │  Orders     │
      „     │Ordovician 1879        │      „      │
      „     │(=Lower Silurian 1835) │      „      │
      „     │Cambrian 1833          │      „      │
 ───────────┼────────────┬──────────┼─────────────┼─────────────
 Proterozoic│Keweenawan  │Huronian  │      „      │
            │            │  1852    │             │
      „     │Animikian   │    „     │      „      │
      „     │Huronian    │    „     │      „      │
      „     │Sudburian   │    „     │      „      │
 ───────────┼────────────┼──────────┼─────────────┼─────────────
 Archeozoic │Keewatin    │Laurentian│      „      │
            │            │  1853    │             │
      „     │Coutchiching│    „     │      „      │
 ───────────┴────────────┴──────────┴─────────────┴─────────────

 ═══════════════════════════════════╤══════════╤════════════
   Present American classification  │Wernerian │   Other
                                    │  orders  │  writers
 ───────────────────────────────────┼──────────┼────────────
                                    │  Newest  │  Tertiary
 Psychozoic or Recent               │  Floetz  │   Class
                                    │  Class   │
 ───────────┬───────────────────────┼──────────┼────────────
 Cenozoic   │Pleistocene            │    „     │     „
            │            │          │          │
            │            │          │          │
            │            │          │          │
      „     │Pliocene    │Neogene   │    „     │     „
            │            │          │          │
            │            │          │          │
            │            │          │          │
      „     │Miocene     │    „     │    „     │     „
      „     │                       │    „     │     „
            │                       │          │
      „     │Oligocene   │Paleogene │    „     │     „
      „     │Eocene      │    „     │    „     │     „
 ───────────┼────────────┴──────────┼──────────┼────────────
            │                       │Primitive │ Primitive
            │                       │Transition│Intermediate
 Mesozoic   │Cretaceous             │and Floetz│    and
            │                       │ Classes  │ Secondary
            │                       │          │  classes
            │                       │          │
            │                       │          │
            │                       │          │
            │                       │          │
      „     │Comanchian 1887        │    „     │     „
            │                       │          │
            │                       │          │
            │                       │          │
            │                       │          │
 ───────────┼───────────────────────┼──────────┼────────────
            │                       │          │
            │                       │          │
            │                       │          │
      „     │Jurassic 1829          │    „     │     „
            │                       │          │
            │                       │          │
            │                       │          │
            │                       │          │
            │                       │          │
            │                       │          │
      „     │           „           │    „     │     „
            │                       │          │
            │                       │          │
            │                       │          │
            │                       │          │
            │                       │          │
            │                       │          │
            │                       │          │
            │                       │          │
            │                       │          │
            │                       │          │
      „     │           „           │    „     │     „
            │                       │          │
            │                       │          │
            │                       │          │
            │                       │          │
            │                       │          │
            │                       │          │
            │                       │          │
      „     │           „           │    „     │     „
 ───────────┼───────────────────────┼──────────┼────────────
      „     │Triassic 1834          │    „     │     „
            │                       │          │
 ───────────┼───────────────────────┼──────────┼────────────
 Paleozoic  │Permian 1841           │    „     │     „
            │                       │          │
 ───────────┼───────────────────────┼──────────┼────────────
            │                       │          │
      „     │                       │    „     │     „
            │                       │          │
      „     │Pennsylvanian 1891     │    „     │     „
            │                       │          │
      „     │Mississippian 1869     │    „     │     „
            │                       │          │
      „     │                       │    „     │     „
            │                       │          │
      „     │Devonian 1839          │    „     │     „
 ───────────┼───────────────────────┼──────────┼────────────
            │                       │          │
            │                       │          │
      „     │Silurian 1835          │    „     │     „
            │                       │          │
            │                       │          │
      „     │Ordovician 1879        │    „     │     „
      „     │(=Lower Silurian 1835) │    „     │     „
      „     │Cambrian 1833          │    „     │     „
 ───────────┼────────────┬──────────┼──────────┼────────────
 Proterozoic│Keweenawan  │Huronian  │    „     │     „
            │            │  1852    │          │
      „     │Animikian   │    „     │    „     │     „
      „     │Huronian    │    „     │    „     │     „
      „     │Sudburian   │    „     │    „     │     „
 ───────────┼────────────┼──────────┼──────────┼────────────
 Archeozoic │Keewatin    │Laurentian│    „     │     „
            │            │  1853    │          │
      „     │Coutchiching│    „     │    „     │     „
 ───────────┴────────────┴──────────┴──────────┴────────────

_Early Geology in Philadelphia._—The oldest scientific society is the
American Philosophical Society of Philadelphia, started by the
many-sided Benjamin Franklin in 1769, and which has published since
1771. Up to the time of the founding of the Journal in 1818, there had
appeared in the publications of this society thirteen papers of a
geologic nature, nearly all small building stones in the rising geologic
story of North America. The only fundamental ones were Maclure’s
Observations of 1809 and 1817. Later, in this same city, there was
organized another scientific society that came to be for a long time the
most active one in America. This was the Academy of Natural Sciences,
started in 1812 with seven members, but it was not until 1817 and the
election of William Maclure as its first president that the work of the
Academy was of a far-reaching character. Here was built up not only a
society for the advancement of the natural sciences and publications for
the dissemination of such knowledge, but, what is equally important, the
first large library and general museum.

William Maclure (1763–1840), correctly named by Silliman the “father of
American geology,” was born and educated in Scotland, and died near
Mexico City. A merchant of London until 1796, when he had already
amassed “a considerable fortune,” he made a first short visit to New
York City in 1782. In 1796 he again came to America, this time to become
a citizen of this country and a liberal patron of science.

About 1803, single-handed and unsustained by government patronage,
Maclure interested himself most zealously and efficiently in American
geology. In 1809 he published his Observations on the Geology of the
United States, Explanatory of a Geological Map. This work he revised “on
a yet more extended scale,” issuing it in 1817 with 130 pages of text,
accompanied by a large colored geological map.

_Silliman, the Pioneer Promoter of Geology._—In 1806 when Benjamin
Silliman (1779–1864) began actively to teach chemistry and mineralogy,
all the sciences in America were in a very backward state, and the earth
sciences were not recognized as such in the curricula of any of our
colleges. Silliman gave his first lecture in chemistry on April 4, 1804.
In the summer of that year, Yale College asked him to go to England to
purchase material for the College, and great possibilities for
broadening his knowledge now loomed before him. As Silliman himself
(=43=, 225, 1842) has told the interesting story of his sojourn in
England and Scotland, it is worth while to restate a part of it here.


  “Passing over to England in the spring of 1805, and fixing my
  residence for six months in London, I found there no school, public or
  private, for geological instruction, and no association for the
  cultivation of the science, which was not even named in the English
  universities.” In geology “Edinburgh was then far in advance of
  London.... Prof. Jameson having recently returned from the school of
  Werner, fully instructed in the doctrines of his illustrious teacher,
  was ardently engaged to maintain them, and his eloquent and acute
  friend, the late Dr. John Murray, was a powerful auxiliary in the same
  cause; both of these philosophers strenuously maintaining the
  ascendancy of the aqueous over the igneous agencies, in the geological
  phenomena of our planet.

  On the other hand, the disciples and friends of Dr. Hutton were not
  less active. He died in 1797, and his mantle fell upon Sir James Hall,
  who, with Prof. Playfair and Prof. Thomas Hope, maintained with signal
  ability, the igneous theory of Hutton. It did not become one who was
  still a youth and a novice, to enter the arena of the geological
  tournament where such powerful champions waged war; but it was very
  interesting to view the combat, well sustained as it was on both
  sides, and protracted, without a decisive issue, into a drawn
  battle....

  The conflicts of the rival schools of Edinburgh—the Neptunists and the
  Vulcanists, the Wernerians and the Huttonians, were sustained with
  great zeal, energy, talent, and science; they were indeed marked too
  decidedly by a partisan spirit, but this very spirit excited untiring
  activity in discovering, arranging, and criticising the facts of
  geology. It was a transition period between the epoch of geological
  hypotheses and dreams, which had passed by, and the era of strict
  philosophical induction, in which the geologists of the present day
  are trained....

  I was a diligent and delighted listener to the discussions of both
  schools. Still the igneous philosophers appeared to me to assume more
  than had been proved regarding internal heat. In imagination we were
  plunged into a fiery Phlegethon, and I was glad to find relief in the
  cold bath of the Wernerian ocean, where my predilections inclined me
  to linger.”


_Silliman’s Students and Their Publications._—Silliman’s first student
to take up geology as a profession was Denison Olmstead (1791–1859),
educator, chemist, and geologist, who was graduated from Yale in 1813.
Four years later he was under special preparation with Silliman in
mineralogy and geology, and in that year was appointed professor of
chemistry in the University of North Carolina. In 1824–1825 Olmstead
issued a Report on the Geology of North Carolina, which is the first
official geological report issued by any state in America, “a
conspicuous and solitary instance,” according to Hitchcock’s review of
it (=14=, 230, 1828), “in which any of our state governments have
undertaken thoroughly to develop their mineral resources.”

Amos Eaton (1776–1842), lawyer, botanist, surveyor, and one of the
founders of American geology, was a graduate of Williams College in the
class of 1799. He studied with Silliman in 1815, attending his lectures
on chemistry, geology, and mineralogy. He also enjoyed access to the
libraries of Silliman and of the botanist, Levi Ives, in which works on
botany and materia medica were prominent, and was a diligent student of
the College cabinet of minerals. He settled as a lawyer and land agent
in Catskill, New York, and here in 1810 he gave a popular course of
lectures on botany, believed to have been the first attempted in the
United States.

In 1818 appeared Eaton’s first noteworthy geological publication, the
Index to the Geology of the Northern States, a text-book for the classes
in geology at Williamstown. The controlling principle of this book was
Wernerism, a false doctrine from which Eaton was never able to free
himself. This book was “written over anew” and published in 1820.

While at Albany in 1818, Governor De Witt Clinton asked Eaton to deliver
a course of lectures on chemistry and geology before the members of the
legislature of New York. It is believed that Eaton is the only American
having this distinction, and because of it he became acquainted with
many leading men of the state, interesting them in geology and its
application to agriculture by means of surveys. In this way was sown the
idea which eventually was to fructify in that great official work: The
Natural History of New York. (See =43=, 215, 1842; and Youmans’ sketch
of Eaton’s life, Pop. Sci. Monthly, Nov. 1890.)

Edward Hitchcock (1793–1864), reverend, state geologist, college
president, and another of the founders of American geology, was largely
self-taught. Previous to 1825, when he entered the theological
department of Yale College, he had met Amos Eaton, who interested him in
botany and mineralogy, and between 1815 and 1819 he had made lists of
the plants and minerals found about his native town, Deerfield,
Massachusetts. Therefore, while studying theology at Yale it was natural
for him also to take up mineralogy and geology with Silliman, whose
acquaintance he had made at least as early as 1818.

Hitchcock, who was destined to be one of the most prominent figures of
his time, was appointed in 1825 to the chair of chemistry and natural
history at Amherst College. His first geologic paper, one of five pages,
appeared in 1815. Three years later appeared his more important paper on
the Geology and Mineralogy of a Section of Massachusetts, New Hampshire,
and Vermont (=1=, 105, 436, 1818). This is also noteworthy for its
geological map, the next one to be published after those of Maclure of
1809 and 1817. In 1823 came a still greater work, A Sketch of the
Geology, Mineralogy, and Scenery of the Regions contiguous to the River
Connecticut (=6=, 1, 200, 1823; =7=, 1, 1824). Here the map above
referred to was greatly improved, and the survey was one of the most
important of the older publications.

Youmans in his account of Hitchcock (Pop. Sci. Monthly, Sept. 1895)
says:


  “The State of Massachusetts commissioned him to make a geological
  survey of her territory in 1830. Three years were spent in the
  explorations, and the work was of such a high character that other
  States were induced to follow the example of Massachusetts.... The
  State of New York sought his advice in the organization of a survey,
  and followed his suggestions, particularly in the division of the
  territory into four parts, and appointed him as the geologist of the
  first district. He entered upon the work, but after a few days of
  labor he found that he must necessarily be separated from his family,
  much to his disinclination. He also conceived the idea of urging a
  more thorough survey of his own State; hence he resigned his
  commission and returned home. The effort for a resurvey of
  Massachusetts was successful, and he was recommissioned to do the
  work. The results appeared in 1841 and 1844.”


Oliver P. Hubbard was assistant to Silliman in 1831–1836, and then up to
1866 taught chemistry, mineralogy, and geology at Dartmouth College.
James G. Percival was graduated at Yale in 1815, and in 1835 he and C.
U. Shepard of Amherst College were appointed state geologists of
Connecticut. Their report was issued in 1842.

James Dwight Dana (1813–1895) was undoubtedly the ablest of all of
Silliman’s students. Graduated at Yale in 1833, he spent fifteen months
in the United States Navy as instructor in mathematics, cruising off
France, Italy, Greece, and Turkey. In 1836 he was assistant to Silliman,
and in 1837, at the age of twenty-four years, he published his widely
used System of Mineralogy. Two years later Dana joined the Wilkes
Exploring Expedition as mineralogist, returning to America in 1842; his
geological results of this expedition were published in 1849. In 1863,
during the Rebellion, he published his Manual of Geology, and through
four editions it remained for forty years the standard text-book for
American geologists.

_First American Geological Society._—The founding in 1807 of the
Geological Society of London, the parent of geological societies,
undoubtedly had its stimulating effect on Silliman, and with his marked
organizing ability he began to think of forming an American society of
the same kind. This he brought about the year following the appearance
of the Journal, that is, in 1819. The American Geological Society, begun
in 1819 (=1=, 442, 1819), was terminated in 1830 (=17=, 202, 1830). The
first meeting (September 6, 1819) and all the subsequent ones were held
in the cabinet of Yale College. The brief records of the doings of this
society are printed in volumes =1=, =10=, =15=, and =18= of the Journal.
Silliman was the attraction at the meetings, surrounded by his mineral
cabinet, and he gave “the true scientific dress to all the naked
mineralogical subjects” discussed.


                 _Wernerian Geology in North America._

_The Father of American Geology._—Historical Geology begins in America
with William Maclure’s Observations on the Geology of the United States,
issued in 1809. This was the first important original work on North
American geology, and its colored geological map was the first one of
the area east of the Mississippi River. The classification was
essentially the Wernerian system. All of the strata of the Coastal
Plain, now known to range from the Lower Cretaceous to Recent, were
referred to the Alluvial. To the west, over the area of the Piedmont,
were his Primitive rocks, while the older Paleozoic formations of the
Appalachian ranges were referred to the Transition. West of the folded
area, all was Floetz or Secondary, or what we now know as Paleozoic
sedimentaries. The Triassic of the Piedmont area and that of Connecticut
he called the Old Red Sandstone, and the coal formations of the interior
region he said rested upon the Secondary. The second edition of the work
in 1817 was much improved, along with the map, which was also printed on
a more correct geographic base. (For greater detail, see Merrill,
Contributions to the History of American Geology, 1906.)

Even though Maclure’s geologic maps are much generalized, and the scheme
of classification adopted a very broad one, they are in the main
correct, even if they do emphasize unduly the rather simple geologic
structure of North America. This fact is patent all through Maclure’s
description. Cleaveland also refers to it in his treatise of 1816, and
Silliman in the opening volume of the Journal (=1=, 7, 1818) says: “The
outlines of American geology appear to be particularly grand, simple,
and instructive.” Then, all the kinds of rocks were comprehended under
four classes, Primitive, Transition, Alluvial, and Volcanic. It is also
interesting to note here that in 1822 Maclure had lost faith in the
aqueous origin of the igneous rocks and writes of the Wernerian system
as “fast going out of fashion” (=5=, 197, 1822), while Hitchcock said
about the same thing in 1825 (=9=, 146).

_The Work of Eaton._—Amos Eaton, after traveling 10,000 miles and
completing his Erie Canal Report in 1824, “reviewed the whole line
several times,” and published in 1828 in the Journal (=14=, 145) a paper
on Geological Nomenclature, Classes of Rocks, etc. The broader
classification is the Wernerian one of Primitive, Transition, and
Secondary classes. Under the first two he has fossiliferous early
Paleozoic formations, but does not know it, because he pays no attention
anywhere to the detail of the entombed fossils, and all of his Secondary
is what we now call Paleozoic. The correlations of the latter are faulty
throughout.

Then came his paper of 1830, Geological Prodromus (=17=, 63), in which
he says: “I intend to demonstrate ... that all geological strata are
arranged in five analogous series; and that each series consists of
three formations; viz., the Carboniferous [meaning mud-stones],
Quartzose, and Calcareous.” We seem to see here expressed for the first
time the idea of “cycles of sedimentation,” but Eaton does not emphasize
this idea, and the localities given for each “formation” of “analogous
series” demonstrate beyond a doubt that he did not have a sedimentary
sequence. The whole is simply a jumble of unrelated formations that
happen to agree more or less in their physical characters.

“I intend to demonstrate,” he says further, “that the detritus of New
Jersey, embracing the marle, which contains those remarkable fossil
relics, is antediluvial, or the genuine Tertiary formation.” This
correlation had been clearly shown by Finch in 1824 (=7=, 31) and yet
both are in error in that they do not distinguish the included
Cretaceous marls and greensands as something apart from the Tertiary.

One gets impatient with the later writings of Eaton, because he does not
become liberalized with the progressive ideas in stratigraphic geology
developing first in Europe and then in America, especially among the
geologists of Philadelphia. Therefore it is not profitable to follow his
work further.

_Early American Text-books of Geology._—The first American text-book of
geology bears the date of Boston 1816 and is entitled An Elementary
Treatise on Mineralogy and Geology, its author being Parker Cleaveland
of Bowdoin College. The second edition appeared in 1822. It also had a
geologic map of the United States, practically a copy of Maclure’s. To
mineralogy were devoted 585 pages, and to geology 55, of which 37
describe rocks and 5 the geology of the United States. The chronology is
Wernerian. Of “geological systems” there are two, “primitive and
secondary rocks.”

In 1818 appeared Amos Eaton’s Index to the Geology of the Northern
States, having 54 pages, and in 1820 came the second edition, “wholly
written over anew,” with 286 pages. The theory of the later edition is
still that of Werner, with “improvements of Cuvier and Bakewell,” and
yet one sees now-a-days but little in it of the far better English
text-book. Eaton did very little to advance philosophic geology in
America. What is of most value here are his personal observations in
regard to the local geology of western Massachusetts, Connecticut,
southwestern Vermont, and eastern New York (=1=, 69, 1819; also Merrill,
p. 234).

We come now to the most comprehensive and advanced of the early
text-books used in America. This is the third English edition of Robert
Bakewell’s Introduction to Geology (400 pages, 1829), and the first
American edition “with an Appendix Containing an Outline of his Course
of Lectures on Geology at Yale College, by Benjamin Silliman” (128
pages). Bakewell’s good book is in keeping with the time, and while not
so advanced as Conybeare and Phillips’s Outlines of 1822, yet is far
more so than Silliman’s appendix. The latter is general and not specific
as to details; it is still decidedly Wernerian, though in a modified
form. Silliman says he is “neither Wernerian nor Huttonian,” and yet his
summary on pages 120 to 126 shows clearly that he was not only a
Wernerian but a pietist as well.


      _Unearthing of the Cenozoic and Mesozoic in North America._

_The Discerning of the Tertiary._—The New England States, with their
essentially igneous and metamorphic formations, could not furnish the
proper geologic environment for the development of stratigraphers and
paleontologists. So in America we see the rise of such geologists first
in Philadelphia, where they had easy access to the horizontal and highly
fossiliferous strata of the coastal plain. The first one to attract
attention was Thomas Say, after him came John Finch, followed by Lardner
Vanuxem, Isaac Lea, Samuel G. Morton, and T. A. Conrad. These men not
only worked out the succession of the Cenozoic and the upper part of the
Mesozoic, but blazed the way among the Paleozoic strata as well.

Thomas Say (1787–1834), in 1819, was the first American to point out the
chronogenetic value of fossils in his article, Observations on some
Species of Zoophytes, Shells, etc., principally Fossil (=1=, 381). He
correctly states that the progress of geology “must be in part founded
on a knowledge of the different genera and species of reliquiæ, which
the various accessible strata of the earth present.” Say fully realizes
the difficulties in the study of fossils, because of their fragmental
character and changed nature, and that their correct interpretation
requires a knowledge of similar living organisms.

The application of what Say pointed out came first in John Finch’s
Geological Essay on the Tertiary Formations in America (=7=, 31, 1824).
Even though the paper is still laboring under the mineral system and
does not discern the presence of Cretaceous strata among his Tertiary
formations, yet Finch also sees that “fossils constitute the medals of
the ancient world, by which to ascertain the various periods.”

Finch now objects to the wide misuse in America of the term alluvial and
holds that it is applied to what is elsewhere known as Tertiary. He
says:


  “Geology will achieve a triumph in America, when the term alluvial
  shall be banished from her Geological Essays, or confined to its
  legitimate domain, and then her tertiary formations will be seen to
  coincide with those of Europe, and the formations of London, Paris,
  and the Isle of Wight, will find kindred associations in Virginia, the
  Carolinas, Georgias, the Floridas, and Louisiana.”


The formations as he has them from the bottom upwards are: (1)
Ferruginous sand, (2) Plastic clay, (3) Calcaire Silicieuse of the Paris
Basin, (4) London Clay, (5) Calcaire Ostrée, (6) Upper marine formation,
(7) Diluvial.

The grandest of these early stratigraphic papers, however, is that by
Lardner Vanuxem (1792–1848), of only three pages, entitled “Remarks on
the Characters and Classification of Certain American Rock Formations”
(=16=, 254, 1829). Vanuxem, a cautious man and a profound thinker, had
been educated at the Paris School of Mines. James Hall told the writer
in a conversation that while the first New York State Survey was in
operation, all of its members looked to Vanuxem for advice.

In the paper above referred to, Vanuxem points out in a very concise
manner that:


  “The alluvial of Mr. Maclure ... contains not only well characterized
  alluvion, but products of the tertiary and secondary classes. Littoral
  shells, similar to those of the English and Paris basins, and pelagic
  shells, similar to those of the chalk deposition or latest secondary,
  abound in it. These two kinds of shells are not mixed with each other;
  they occur in different earthy matter, and, in the southern states
  particularly, are at different levels. The incoherency or earthiness
  of the mass, and our former ignorance of the true position of the
  shells, have been the sources of our erroneous views.”


The second error of the older geologists, according to Vanuxem, was the
extension of the secondary rocks over “the western country, and the back
and upper parts of New York.” They are now called Paleozoic. Some had
even tried to show the presence of Jurassic here because of the
existence of oölite strata. “It was taken for granted, that all
horizontal rocks are secondary, and as the rocks of these parts of the
United States are horizontal in their position, so they were supposed to
be secondary.” He then shows on the basis of similar Ordovician fossils
that the rocks of Trenton Falls, New York, recur at Frankfort in
Kentucky, and at Nashville in Tennessee.

“It is also certain that an uplifting or downfalling force, or both,
have existed, but it is not certain that either or both these forces
have acted in a uniform manner.... Innumerable are the facts, which have
fallen under my observation, which show the fallacy of adopting
inclination for the character of a class,” such as the Transition class
of strata. He then goes on to say that in the interior of our country
the so-called secondary rocks are horizontal and in the mountains to the
east the same strata are highly inclined. “The analogy, or identity of
rocks, I determine by their fossils in the first instance, and their
position and mineralogical characters in the second or last instance.”

It appears that Isaac Lea (1792–1886) in his Contributions to Geology,
1833, was the first to transplant to America Lyell’s terms, Pliocene,
Miocene, and Eocene, proposed the previous year. The celebrated
Claiborne locality was made known to Lea in 1829, and in the work here
cited he describes from it 250 species, of which 200 are new. The
horizon is correlated with the London Clay and with the Calcaire
Grossier of France, both of Eocene time (=25=, 413, 1834).

Timothy A. Conrad began to write about the American Tertiary in 1830,
and his more important publications were issued at Philadelphia. His
papers in the Journal begin with 1833 and the last one on the Tertiary
is in 1846.

The Tertiary faunas and stratigraphy have been modernized by William H.
Dall in his monumental work of 1650 pages and 60 plates entitled
“Contributions to the Tertiary Fauna of Florida” (1885–1903). Here more
than 3160 forms of the Atlantic and Gulf deposits are described, but in
order to understand their relations to the fossil faunas elsewhere and
to the living world, the author studied over 10,000 species. Since then,
many other workers have interested themselves in the Tertiary problems.
Much good work is also being done in the Pacific States where the
sequence is being rapidly developed.

_The Discerning of the Eastern Cretaceous._—The Cretaceous sequence was
first determined by that “active and acute geologist,” Samuel G. Morton
(1799–1851), but that these rocks might be present along the Atlantic
border had been surmised as early as 1824 by Edward Hitchcock (=7=,
216). Vanuxem, as above pointed out, indicated the presence of the
Cretaceous in 1829. In this same year Morton proved its presence before
the Philadelphia Academy of Natural Sciences.

Between 1830 and 1835 Morton published a series of papers in the Journal
under the title “Synopsis of the Organic Remains of the Ferruginous Sand
Formation of the United States, with Geological Remarks” (=17=, 274, _et
seq._). In these he describes the Cretaceous fossils and demonstrates
that the “Diluvial” and Tertiary strata of the Atlantic border also have
a long sequence of Cretaceous formations. In the opening paper he
writes: “I consider the marl of New Jersey as referable to the great
ferruginous sand series, which in Prof. Buckland’s arrangement is
designated by the name of green sand.... On the continent this series is
called the ancient chalk ... lower chalk,” etc. Again, the marls of New
Jersey are “geologically equivalent to those beds which in Europe are
interposed between the white chalk and the Oölites.” This correlation is
with the European Lower Cretaceous, but we now know the marls to be of
Upper Cretaceous age. Although Eaton objected strenuously to Morton’s
correlation, we find M. Dufresnoy of France saying, “Your limestone
above green sand reminds me very much of the Mæstricht beds,” a
correlation which stands to this day (=22=, 94, 1832). In 1833 Morton
announces that the Cretaceous is known all along the Atlantic and Gulf
border, and in the Mississippi valley. “The same species of fossils are
found throughout,” and none of them are known in the Tertiary. He now
arranges the strata of the former “Alluvial” as follows:

 Modern   │Alluvial.
     „    │Diluvial.
 ─────────┼─────────────────────────────────────────────────────────────
 Tertiary │Upper Tertiary (Upper Marine).
     „    │Middle Tertiary (London Clay).
     „    │Lower Tertiary (Plastic Clay).
 ─────────┼─────────────────┬───────────────────────────────────────────
 Secondary│Calcareous Strata│Cretaceous group, or Ferruginous Sand
          │                 │  series (=24=, 128).
     „    │Ferruginous Sand │                     „

_Western Cretaceous._—In 1841 and 1843 J. N. Nicollet announced the
discovery of Cretaceous in the Rocky Mountain area. Of 20 species of
fossils collected by him, 4 were said to occur on the Atlantic border,
and of the 200 forms of the Atlantic slope only 1 was found in Europe.
Here we see pointed out a specific dissimilarity between the continents,
and a similarity between the American areas of Cretaceous deposits
(=41=, 181; =45=, 153).

The Cretaceous of the Rocky Mountains was clearly developed by F. V.
Hayden in 1855–1888 and by F. B. Meek (1857–1876). Other workers in this
field were Charles A. White (1869–1891), and R. P. Whitfield
(1877–1889). Since 1891 T. W. Stanton has been actively interpreting its
stratigraphy and faunas.

_Cretaceous and Comanche of Texas._—The broader outlines of the
Cretaceous of Texas had been described by Ferdinand Roemer in 1852 in
his good work, Kreidebildungen von Texas, but it was not until 1887 that
Robert T. Hill showed in the Journal (=33=, 291) that it included two
great series, the Gulf series, or what we now call Upper Cretaceous, and
a new one, the Comanche series. This was a very important step in the
right direction. Since then the Comanche series has been regarded by
some stratigraphers as of period value, while others call it Lower
Cretaceous; the rest of the Texas Cretaceous is divided by Hill into
Middle and Upper Cretaceous. On the other hand, Lower Cretaceous strata
had been proved even earlier in the state of California, for here in
1869 W. M. Gabb (1839–1878) and J. D. Whitney (1819–1896) had defined
their Shasta group, which was wholly distinct faunally from the Comanche
of Texas and the southern part of the Great Plains country.

_Jurassic and Triassic of the West._—In 1864, the Geological Survey of
California proved the presence of marine Upper Triassic in that State,
and since then it has been shown that not only is all of the Triassic
present in Idaho (where it has been known since 1877), Oregon, Nevada,
and California, but that the Upper Triassic is of very wide distribution
throughout western North America. Jurassic strata, on the other hand,
were not shown to be present in California until 1885, while in the
Rocky Mountain area of the United States there was long known an
unresolved series of “Red Beds” situated between the Carboniferous and
Cretaceous. This gave rise to the “Red Bed problem,” the history of
which is given by C. A. White in the Journal (=17=, 214, 1879). In 1869,
F. V. Hayden announced the discovery of marine Jurassic fossils in this
series, and since then they have come to be known as the Sundance fauna,
extending from southern Utah and Colorado into Alaska. Above lie the
dinosaur-bearing fresh-water deposits, since 1894 known as the Morrison
beds. In 1896, O. C. Marsh (1831–1899) announced the presence of
Jurassic fresh-water strata along the Atlantic coast (=2=, 433), but
to-day only a small part of them are regarded as of the age of the
Morrison, while the far greater part are referred to the Comanche or
Lower Cretaceous. The red beds below the Jurassic of the Rocky Mountain
area have during the past twenty years been shown to be in part of Upper
Triassic age and of fresh-water origin, while the greater lower part is
connected with the Carboniferous series and is made up of brackish— and
fresh-water deposits of probable Permian time.

_Triassic of Atlantic States._—The fresh-water Triassic of the Atlantic
border states was first mentioned by Maclure (1817), who regarded it as
the equivalent of the Old Red Sandstone of Europe. In this he was
followed by Hitchcock in 1823 (=6=, 39), the latter saying that above it
lies “the coal formation,” which is true for Europe, but in America the
coal strata are older than these red beds, now known to be of Triassic
age.

The first one to question this correlation was Alexandre Brongniart, who
had received from Hitchcock rock specimens and a fossil fish which he
erroneously identified with a Permian species, and accordingly referred
the strata to the Permian (=3=, 220, 1821; =6=, 76, pl. 9, figs. 1, 2,
1823). The discerning Professor Finch in 1826 remarked that the red beds
of Connecticut appear to belong “to the new or variegated sandstone,”
because of eight different criteria that he mentions. Of these, but two
are of value in correlation, their “geological position” and the
presence of bones other than fishes. In the Connecticut area, however,
the geological position cannot be determined even to-day, and in Finch’s
time the bones of dinosaurs were unknown. Finch then goes on to point
out the occurrences of Old Red Sandstone in Pennsylvania, but all of the
places he refers to are either younger or older in time. Here we again
see the fatality of trying to make positive correlations on the basis of
lithology and color (=10=, 209, 1826). In 1835, however, Hitchcock
showed that the bones that had been found in 1820 were those of a
saurian, and accordingly referred the strata of the Connecticut valley
to the New Red Sandstone, a term that then covered both the Permian and
the Triassic. In 1842, W. B. Rogers referred the beds to the Jurassic,
on the basis of plants from Virginia. In 1856, W. C. Redfield
(1789–1857), because of the fishes, advocated a Lias, or Jurassic age,
and proposed the name Newark group for all the Triassic deposits of the
Atlantic border. More recently, on the basis of the plants studied by
Newberry, Fontaine, Sturr, and Ward, and the vertebrates described by
Marsh and Lull, the age has been definitely fixed as Upper Triassic (see
Dana’s Manual of Geology, 740, 1895).


            _Unearthing of the Paleozoic in North America._

_Permian of the United States._—In Europe, previous to 1841, the
formations now classed as Permian were included in the New Red
Sandstone, and with the Carboniferous were referred to the Secondary. In
that year Murchison proposed the period term Permian. In 1845 came the
classic Geology of Russia in Europe and the Ural Mountains, by
Murchison, Keyserling, and De Verneuil. In this great work the authors
separated out of the New Red the Magnesian Limestone of Great Britain
and the Rothliegende marls, Kupferschiefer, and Zechstein of Germany,
and with other formations of the Urals in Russia, referred them to the
Permian system. This step, one of the most discerning in historical
geology, was all the more important because they closed the Paleozoic
era with the Permian, beginning the Secondary, or Mesozoic, with the New
Red Sandstone or the Triassic period. There is a good review of this
work by D. D. Owen (1807–1860) in the Journal for 1847 (=3=, 153).

Owen, though accepting the Permian system, is not satisfied with its
reference to the Paleozoic, and he sets the matter forth in the Journal
(=3=, 365, 1847). He doubts “the propriety of a classification which
throws the Permian and Carboniferous systems into the Paleozoic period.”
This is mainly because there is no “evidence of disturbance or
unconformability” between the Permian and Triassic systems. Rather
“there is so complete a blending of adjacent strata” that it is only in
Russia that the Permian has been distinguished from the Triassic. This
view of Owen’s was not only correct for Russia but even more so for the
Alps and for India, and it has taken a great deal of work and discussion
to fix upon the disconformable contact that distinguishes the Paleozoic
from the Mesozoic in these areas. In other words, there was here at this
time no mountain making. Then Owen goes on to state that because the
Permian of Europe has reptiles, he sees in them decisive Mesozoic
evidence. “These are certainly strong arguments in favor of placing, not
only the Permian, but also the Carboniferous group in the Mesozoic
period, and terminating the Paleozoic division with the commencement of
the coal measures.” To this harking backward the geologists of the world
have not agreed, but have followed the better views of Murchison and his
associates.

In 1855 G. G. Shumard discovered, and in 1860 his brother B. F. Shumard
(1820–1869) announced, the presence of Permian strata in the Guadalupe
Mountains of Texas, and in 1902 George H. Girty (=14=, 363) confirmed
this. Girty regards the faunas as younger than any other late Paleozoic
ones of America, and says: “For this reason I propose to give them a
regional name, which shall be employed in a force similar to
Mississippian and Pennsylvanian.... The term Guadalupian is suggested.”

G. C. Swallow (1817–1899) in 1858 was the first to announce the presence
of Permian fossils in Kansas, and this led to a controversy between
himself and F. B. Meek, both claiming the discovery. It is only in more
recent years that it has been generally admitted that there is Permian
in that state, in Oklahoma, and in Texas. This admission came the more
readily through the discovery of many reptiles in the red beds of Texas,
and through the work of C. A. White, published in 1891, The Texan
Permian and its Mesozoic Types of Fossils (Bull. U. S. Geological
Survey, No. =77=).

[Illustration: James Hall]

_Carboniferous Formations._—The coal formations are noted in a general
way throughout the earliest volumes of the Journal. The first accounts
of the presence of coal, in Ohio, are by Caleb Atwater (=1=, 227, 239,
1819), and S. P. Hildreth (=13=, 38, 40, 1828). The first coal plants to
be described and illustrated were also from Ohio, in an article by
Ebenezer Granger in 1821 (=3=, 5–7). The anthracite field was first
described in 1822 by Zachariah Cist (=4=, 1) and then by Benjamin
Silliman (=10=, 331–351, 1826); that of western Pennsylvania was
described by William Meade in 1828 (=13=, 32).

The Lower Carboniferous was first recognized by W. W. Mather in 1838
(=34=, 356). Later, through the work of Alexander Winchell (1824–1891),
beginning in 1862 (=33=, 352) and continuing until 1871, and through the
surveys of Iowa (1855–1858), Illinois (essentially the work of A. H.
Worthen, 1858–1888), Ohio (1838, Mather, etc.), and Indiana (Owen, etc.,
1838), there was eventually worked out the following succession:

         Permian period.
             Upper Barren series.
                 Dunkard group.
                 Washington group.
         Pennsylvanian period.
             Upper Productive Coal series. Monongahela series.
             Lower Barren Coal Measures. Conemaugh series.
             Lower Productive Coal Measures. Allegheny series.
             Pottsville series.

_The New York System._—We now come to the epochal survey of the State of
New York, one that established the principles of, and put order into,
American stratigraphy from the Upper Cambrian to the top of the
Devonian. No better area could have been selected for the establishing
of this sequence. This survey also developed a stratigraphic
nomenclature based on New York localities and rock exposures, and made
full use of the entombed fossils in correlation. Incidentally it
developed and brought into prominence James Hall, who continued the
stratigraphic work so well begun and who also laid the foundation for
paleontology in America, becoming its leading invertebrate worker.

This work is reviewed at great length in the Journal in the volumes for
1844–1847 by D. D. Owen. Evidently it followed too new a plan to receive
fulsome praise from conservative Owen, as it should have. He remarks
that the volumes “are not a little prolix, are voluminous and expensive,
and do not give as clear and connected a view of the geological features
of the state as could be wished.... We are of the opinion that before
this work can become generally useful and extensively circulated, it
must be condensed and arranged into one compendious volume” (=46=, 144,
1844). This was never done and yet the work was everywhere accepted at
once, and to this end undoubtedly Owen’s detailed review helped much.

The Natural History Survey of New York was organized in 1836 and
completed in 1843. The state was divided into four districts, and to
these were finally assigned the following experienced geologists. The
southeastern part was named the First District, with W. W. Mather
(1804–1859) as geologist; the northeastern quarter was the Second
District, with Ebenezer Emmons (1799–1863) in charge; the central
portion was the Third District, under Lardner Vanuxem (1792–1848); while
the western part was James Hall’s (1811–1898) Fourth District.
Paleontology for a time was in charge of T. A. Conrad (1830–1877); the
mineralogical and chemical work was in the hands of Lewis C. Beck; the
botanist was John Torrey; and the zoologist James DeKay.

The New York State Survey published six annual reports of 1675 pages
octavo, and four final geological reports with 2079 pages quarto.
Finally in 1846 Emmons added another volume on the soils and rocks of
the state, in which he also discussed the Taconic and New York systems;
it has 371 pages. With the completion of the first survey, Hall took up
his life work under the auspices of the state—his monumental work,
Paleontology of New York, in fifteen quarto volumes of 4539 pages and
1081 plates of fossils. In addition to all this, there are his annual
and other reports to the Regents of the State, so that it is safe to say
that he published not less than 10,000 pages of printed matter on the
geology and paleontology of North America.

In regard to this great series of works, all that can be presented here
is a table of formations as developed by the New York State Survey.
Practically all of its results and formation names have come into
general use, with the exception of the Taconic system of Emmons and the
division terms of the New York system. (See p. 88.)

The New York State Survey, begun in 1836, was continued by James Hall
from 1843 to 1898. During this time he was also state geologist of Iowa
(1855–1858) and Michigan (1862). Since 1898, John M. Clarke has ably
continued the Geological Survey of New York, the state which continues
to be, in science and more especially in geology and paleontology, the
foremost in America.

_Western Extension of the New York system._—Before Hall finished his
final report, we find him in 1841 on “a tour of exploration through the
states of Ohio, Indiana, Illinois, a part of Michigan, Kentucky, and
Missouri, and the territories of Iowa and Wisconsin.” This tour is
described in the Journal (=42=, 51, 1842) under the caption “Notes upon
the Geology of the Western States.” His object was to ascertain how far
the New York system as the standard of reference “was applicable in the
western extension of the series.” In a general way he was very
successful in extending the system to the Mississippi River, and he
clearly saw “a great diminution, first of sandy matter, and next of
shale, as we go westward, and in the whole, a great increase of
calcareous matter in the same direction.” He also clearly noted the
warped nature of the strata, the “anticlinal axis,” since known as the
Cincinnati and Wabash uplifts and the Ozark dome.

Hall, however, fell into a number of flagrant errors because of a too
great reliance on lithologic correlation and supposedly similar
sequence. For instance, the Coal Measures of Pennsylvania were said to
directly overlap the Chemung group of southern New York, and now he
finds the same condition in Ohio, Indiana, and Illinois, failing to see
that in most places between the top of the New York system and the Coal
Measures lay the extensive Mississippian series, one that he generally
confounded with the Chemung, or included in the “Carboniferous group.”
He states that the Portage of New York is the same as the Waverly of
Ohio, and at Louisville the Middle Devonian waterlime is correlated with
the similar rock of the New York Silurian. Hall was especially desirous
of fixing the horizon of the Middle Ordovician lead-bearing rocks of
Illinois, Wisconsin, and Iowa, but unfortunately correlated them with
the Niagaran, while the Middle Devonian about Columbus, Ohio, and
Louisville, Kentucky, he referred to the same horizon. The
Galena-Niagaran error was corrected in 1855, but the Devonian and
Mississippian ones remained unadjusted for a long time, and in Iowa
until toward the close of the nineteenth century.

    _The Geological Column of the New York Geologists of 1842–1843,
                    according to W. W. Mather 1842._

 Quaternary system           │Alluvial division.
              „              │Quaternary division.
              „              │Drift division.
 ────────────────────────────┼────────────────────────────┬────────────
 Tertiary system             │These strata are included in│
                             │  the next lower division.  │
 ────────────────────────────┼────────────────────────────┼────────────
                             │Long Island division. Equals│New Red
                             │  the Tertiary and          │  system of
 Upper Secondary system      │  Cretaceous marls, sands,  │  Emmons and
                             │  and clays of the coastal  │  Hall.
                             │  plain of New Jersey.      │
              „              │Trappean division. The      │     „
                             │  Palisades                 │
              „              │Red Sandstone division.     │     „


  Coal system of Mather, and Carboniferous system of Hall.

  Old Red system of Catskill Mountains of Emmons; Catskill division of
  Mather and Hall; and Catskill group of Vanuxem.


        _According to Hall 1843, and essentially Vanuxem 1842._

                             │Chemung, Portage or Nunda (divided into
                             │  Cashaqua, Gardeau, Portage), Genesee,
 Erie division [Devonian]    │  Tully, Hamilton (divided into
                             │  Ludlowville; Encrinal, Moscow), and
                             │  Marcellus.
 ────────────────────────────┼────────────────────────────────────────
                             │Corniferous, Onondaga, Schoharie,
 Helderberg series           │  Cauda-alli, Oriskany, Upper
   [Devonian-Silurian]       │  Pentamerus, Encrinal, Delthyris,
                             │  Pentamerus, Waterlime, Onondaga salt
                             │  group.
 ────────────────────────────┼────────────────────────────────────────
 Ontario division [Silurian] │Niagara, Clinton, and Medina.
 ────────────────────────────┼────────────────────────────────────────
                             │Oneida or Shawangunk, Grey sandstone,
 Champlain division          │  Hudson River group, Utica, Trenton,
   [Silurian-Ordovician-Upper│  Black River including Birdseye and
   Cambrian]                 │  Chazy, Calciferous sandrock, and
                             │  Potsdam.


   _According to Emmons 1842, Mather 1843, Vanuxem 1842, Hall 1843._

 Taconic System [Ordovician  │Granular quartz, Stockbridge limestone,
   and Lower Cambrian]       │  Magnesian slate, and Taconic slate.
 ────────────────────────────┼────────────────────────────────────────
 Primary or Hypogene system  │Metamorphic and Primary rocks.

_Correlations with Europe._—The first effort toward correlating the New
York system with those of Europe was made by Conrad in his Notes on
American Geology in 1839 (=35=, 243). Here he compares it on faunal
grounds with the Silurian system. A more sustained effort was that of
Hall in 1843 (=45=, 157), when he said that the Silurian of Murchison
was equal to the New York system and embraced the Cambrian, Silurian,
and Devonian, which he considered as forming but one system. Hall in
1844 and Conrad earlier were erroneously regarding the Middle Devonian
of New York (Hamilton) as “an equivalent of the Ludlow rocks of Mr.
Murchison” (=47=, 118, 1844).

In 1846 E. P. De Verneuil spent the summer in America with a view to
correlating the formations of the New York system with those of Europe.
At this time he had had a wide field experience in France, Germany, and
Russia, was president of the Geological Society of France, and
“virtually the representative of European geology” (=2=, 153, 1846).
Hall says, “No other person could have presented so clear and perfect a
coup d’oeil.” De Verneuil’s results were translated by Hall and with his
own comments were published in the Journal in 1848 and 1849 under the
title “On the Parallelism of the Paleozoic Deposits of North America
with those of Europe.” De Verneuil was especially struck with the
complete development of American Paleozoic deposits and said it was the
best anywhere. On the other hand, he did not agree with the detailed
arrangement of the formations in the various divisions of the New York
system, and Hall admitted altogether too readily that the terms were
proposed “as a matter of concession, and it is to be regretted that such
an artificial classification was adopted.” De Verneuil’s correlations
are as follows:

The Lower Silurian system begins with the Potsdam, the analogue of the
Obolus sandstone of Russia and Sweden. The Black River and Trenton hold
the position of the Orthoceras limestones of Sweden and Russia, while
the Utica and Lorraine are represented by the Graptolite beds of the
same countries. Both correlations are in partial error. He unites the
Chazy, Birdseye, and Black River in one series, and in another the
Trenton, Utica, and Lorraine. Of species common to Europe and America he
makes out seventeen.

In the Upper Silurian system, the Oneida and Shawangunk are taken out of
the Champlain division, and, with the Medina, are referred to the
Silurian, along with all of the Ontario division plus the Lower
Helderberg. The Clinton is regarded as highest Caradoc or as holding a
stage between that and the Wenlock. The Niagara group is held to be the
exact equivalent of the Wenlock, “while the five inferior groups of the
Helderberg division represent the rocks of Ludlow.” We now know that
these Helderberg formations are Lower Devonian in age. De Verneuil
unites in one series the Waterlime, Pentamerus, Delthyris, Encrinal, and
Upper Pentamerus. Of identical species there are forty common to Europe
and America.

The Devonian system De Verneuil begins, “after much hesitation,” with
the Oriskany and certainly with the five upper members of Hall’s
Helderberg division, all of the Erie and the Old Red Sandstone. He also
adjusts Hall’s error by placing in the Devonian the Upper Cliff
limestone of Ohio and Indiana, regarded by the former as Silurian. The
Oriskany is correlated with the grauwackes of the Rhine, and the
Onondaga or Corniferous with the lower Eifelian. Cauda-galli, Schoharie,
and Onondaga are united in one series; Marcellus, Hamilton, Tully, and
Genesee in another; and Portage and Chemung in a third. Of species
common to Europe and America there are thirty-nine.

The Waverly of Ohio and that near Louisville, Kentucky, which Hall had
called Chemung, De Verneuil correctly refers to the Carboniferous, but
to this Hall does not consent. De Verneuil points out that there are
thirty-one species in common between Europe and America. “And as to
plants, the immense quantity of terrestrial species identical on the two
sides of the Atlantic, proves that the coal was formed in the
neighborhood of lands already emerged, and placed in similar physical
conditions.”

An analysis of the Paleozoic fossils of Europe and America leads De
Verneuil to “the conviction that identical species have lived at the
same epoch in America and in Europe, that they have had nearly the same
duration, and that they succeeded each other in the same order.” This he
states is independent of the depth of the seas, and of “the upheavings
which have affected the surface of the globe.” The species of a period
begin and drop out at different levels, and toward the top of a system
the whole takes on the character of the next one. “If it happens that in
the two countries a certain number of systems, characterized by the same
fossils, are superimposed in the same order, whatever may be, otherwise,
their thickness and the number of physical groups of which they are
composed, it is philosophical to consider these systems as parallel and
synchronous.”

Because of the dominance of the sandstones and shales in eastern New
York, De Verneuil holds that a land lay to the east. The many fucoids
and ripple-marks from the Potsdam to the Portage indicated to him
shallow water and nearness to a shore.

_The Oldest Geologic Eras._—We have seen in previous pages how the
Primitive rocks of Arduino and of Werner had been resolved, at least in
part, into the systems of the Paleozoic, but there still remained many
areas of ancient rocks that could not be adjusted into the accepted
scheme. One of the most extensive of these is in Canada, where the
really Primitive formations, of granites, gneisses, schists, and even
undetermined sediments, abound and are developed on a grander scale than
elsewhere, covering more than two million square miles and overlain
unconformably by the Paleozoic and later rocks. The first to call
attention to them was J. I. Bigsby, a medical staff officer of the
British Army, in 1821 (=3=, 254). It was, however, William E. Logan
(1798–1875), the “father of Canadian geology,” who first unravelled
their historical sequence. At first he also called them Primary, but
after much work he perceived in them parallel structures and
metamorphosed sediments, underlain by and associated with pink granites.
For the oldest masses, essentially the granites, he proposed the term
Laurentian system (1853, 1863) and for the altered and deformed strata,
the name Huronian series (1857, 1863). Overlying these unconformably was
a third series, the copper-bearing rocks. Since his day a great host of
Canadian and American geologists have labored over this, the most
intricate of all geology, and now we have the following tentative
chronology (Schuchert and Barrell, =38=, 1, 1914):

            Late Proterozoic era.
                Keweenawan, Animikian and Huronian periods.
            Early Proterozoic era.
                Sudburian period or older Huronian.
            Archeozoic era.
                Grenville series, etc.
            Cosmic history.


                   _The Taconic System Resurrected._

The Taconic system was first announced by Ebenezer Emmons in 1841, and
clearly defined in 1842. It started the most bitter and most protracted
discussion in the annals of American geology. After Emmons’s subsequent
publications had put the Taconic system through three phases, Barrande
of Bohemia in 1860–1863 shed a great deal of new and correct light upon
it, affirming in a series of letters to Billings that the Taconic
fossils are like those of his Primordial system, or what we now call the
Middle Cambrian (=31=, 210, 1861, _et seq._).

In a series of articles published by S. W. Ford in the Journal between
1871 and 1886, there was developed the further new fact that in
Rensselaer and Columbia counties, New York, the so-called Hudson River
group abounds in “Primordial” fossils wholly unlike those of the
Potsdam, and which Ford later on spoke of as belonging to “Lower
Potsdam” time.

James D. Dana entered the field of the Taconic area in 1871 and
demonstrated that the system also abounds in Ordovician fossiliferous
formations. Then came the far-reaching work of Charles D. Walcott,
beginning in 1886, which showed that all through eastern New York and
into northern Vermont the Hudson River group and the Taconic system
abound not only in Ordovician but also in Cambrian fossils. Finally in
1888 Dana presented a Brief History of Taconic Ideas, and laid away the
system with these words (=36=, 27):


  “It is almost fifty years since the Taconic system made its abrupt
  entrance into geological science. Notwithstanding some good points, it
  has been through its greater errors, long a hindrance to progress here
  and abroad ... But, whether the evil or the good has predominated, we
  may now hope, while heartily honoring Professor Emmons for his earnest
  geological labors and his discoveries, that Taconic ideas may be
  allowed to be and remain part of the past.”


As an epitaph Dana placed over the remains of the Taconic system the
black-faced numerals =1841–1888=. That the remains of the system,
however, and the term Taconic are still alive and demanding a rehearing
is apparent to all interested stratigraphers. This is not the place to
set the matter right, and all that can be done at the present time is to
point out what are the things that still keep alive Emmons’s system.

In the typical area of the Taconic system, i. e., in Rensselaer County,
Emmons in 1844–1846 produced the fossils _Atops trilineatus_ and
_Elliptocephala asaphoides_. S. W. Ford, as stated above, later produced
from the same general area many other fossils that he demonstrated to be
older than the Potsdam sandstone. To this time he gave the name of Lower
Potsdam, thus proving on paleontological grounds that at least some part
of the Taconic system is older than the New York system, and therefore
older than the Hudson River group of Ordovician age.

In 1888 Walcott presented his conclusions in regard to the sequence of
the strata in the typical Taconic area and to the north and south of it.
He collected Lower Cambrian fossils at more than one hundred localities
“within the typical Taconic area,” and said that the thickness of his
“terrane No. 5” or “Cambrian (Georgia),” now referable to the Lower
Cambrian, is “14,000 feet or more.” He demonstrated that the Lower
Cambrian is infolded with the Lower and Middle Ordovician, and confirmed
Emmons’s statement that the former rests upon his Primary or
Pre-Cambrian masses. Elsewhere, he writes: “To the west of the Taconic
range the section passes down through the limestone (3) [of Lower and
Middle Ordovician age] to the hydromica schists (2) [whose age may also
be of early Ordovician], and thence to the great development of slates
and shales with their interbedded sparry limestones, calciferous and
arenaceous strata, all of which contain more or less of the
Olenellus ... fauna.” He then knew thirty-five species in Washington
County, New York (=35=, 401, 1888).

Finally in 1915 Walcott said that in the Cordilleran area of America
there was a movement that brought about changes “in the sedimentation
and succession of the faunas which serve to draw a boundary line between
the Lower and Middle Cambrian series.... The length of this period of
interruption must have been considerable ... and when connection with
the Pacific was resumed a new fauna that had been developing in the
Pacific was then introduced into the Cordilleran sea and constituted the
Middle Cambrian fauna. The change in the species from the Lower to the
Middle Cambrian fauna is very great.” He then goes on to show that in
the Appalachian geosyncline there was another movement that shut out the
Middle Cambrian _Paradoxides_ fauna of the Atlantic realm from this
trough, and all deposition as well.

_Conclusions._—Accordingly it appears that everywhere in America the
Lower Cambrian formations are separated by a land interval of long
duration from those of Middle Cambrian time. These formations therefore
unite into a natural system of rocks or a period of time. Between Middle
and Upper Cambrian time, however, there appears to be a complete
transition in the Cordilleran trough, binding these two series of
deposits into one natural or diastrophic system. Hence the writer
proposes that the Lower Cambrian of America be known as the Taconic
system. The Middle and Upper Cambrian series can be continued for the
present under the term Cambrian system, a term, however, that is by no
means in good standing for these formations, as will be demonstrated
under the discussion of the Silurian controversy.


                      _The Silurian Controversy._

Just as in America the base of the Paleozoic was involved in a
protracted controversy, so in England the Cambrian-Silurian succession
was a subject of long debate between Sedgwick and Murchison, and among
the succeeding geologists of Europe. The history of the solution is so
well and justly stated in the Journal by James D. Dana under the title
“Sedgwick and Murchison: Cambrian and Silurian” (=39=, 167, 1890), and
by Sir Archibald Geikie in his Text-book of Geology, 1903, that all that
is here required is to briefly restate it and to bring the solution up
to date.

Adam Sedgwick (1785–1873) and R. I. Murchison (1792–1871) each began to
work in the areas of Cambria (Wales) and Siluria (England) in 1831, but
the terms Cambrian and Silurian were not published until 1835. Murchison
was the first to satisfactorily work out the sequence of the Silurian
system because of the simpler structural and more fossiliferous
condition of his area. Sedgwick, on the other hand, had his academic
duties to perform at Cambridge University, and being an older and more
conservative man, delayed publishing his final results, because of the
further fact that his area was far more deformed and less fossiliferous.
In 1834 they were working in concert in the Silurian area, and Sedgwick
said: “I was so struck by the clearness of the natural sections and the
perfection of his workmanship that I received, I might say, with
implicit faith everything which he then taught me.... The whole
‘Silurian system’ was by its author placed _above_ the great undulating
slate-rocks of South Wales.” At that time Murchison told Sedgwick that
the Bala group of the latter, now known to be in the middle of the Lower
Silurian, could not be brought within the limits of the Silurian system,
and added, “I believe it to plunge under the true Llandeilo-flags,” now
placed next below the Bala and above the Arenig, which at the present is
regarded as at the base of the Ordovician.

The Silurian system was defined in print by Murchison in July, 1835, the
Upper Silurian embracing the Ludlow and Wenlock, while the Lower
Silurian was based on the Caradoc and Llandeilo. Murchison’s monumental
work, The Silurian System, of 100 pages and many plates of fossils,
appeared in 1838.

The Cambrian system was described for the first time by Sedgwick in
August, 1835, but the completed work—a classic in geology—Synopsis of
the Classification of the British Palæozoic Rocks, along with M’Coy’s
Descriptions of British Palæozoic Fossils, did not appear until
1852–1855. Sedgwick’s original Upper Cambrian included the greater part
of the chain of the Berwyns, where he said it was connected with the
Llandeilo flags of the Silurian. The Middle Cambrian comprised the
higher mountains of Cærnarvonshire and Merionethshire, and the Lower
Cambrian was said to occupy the southwest coast of Cærnarvonshire, and
to consist of chlorite and mica schists, and some serpentine and
granular limestone. In 1853 it was seen that the fossiliferous Upper
Cambrian included the Arenig, Llandeilo, Bala, Caradoc, Coniston,
Hirnant, and Lower Llandovery. On the other hand, it was not until long
after Murchison and Sedgwick passed away that the Middle and Lower
Cambrian were shown to have fossils, but few of those that characterize
what is now called Lower, Middle, and Upper Cambrian time.

Not until long after the original announcement of the Cambrian system
did Sedgwick become aware “of the unfortunate mischief-involving fact”
that the most fossiliferous portion of the Cambrian—the Upper
Cambrian—and at that time the only part yielding determinable fossils,
when compared with the Lower Silurian was seen to be an equivalent
formation but with very different lithologic conditions. He began to see
in 1842 that his Cambrian was in conflict with the Silurian system, and
four years later there were serious divergencies of views between
himself and Murchison. The climax of the controversy was attained in
1852, when Sedgwick was extending his Cambrian system upwards to include
the Bala, Llandeilo, and Caradoc, a proceeding not unlike that of
Murchison, who earlier had been extending his Silurian downward through
all of the fossiliferous Cambrian to the base of the Lingula flags.

Dana in his review of the Silurian-Cambrian controversy states: “The
claim of a worker to affix a name to a series of rocks first studied and
defined by him cannot be disputed.” We have seen that Murchison had
priority of publication in his term Silurian over Sedgwick’s Cambrian,
but that in a complete presentation, both stratigraphically and
faunally, the former had years of prior definition. What has even more
weight is that geologists nearly everywhere had accepted Murchison’s
Silurian system as founded upon the Lower and Upper Silurian formations.
A nomenclature once widely accepted is almost impossible to dislodge.
However, in regard to the controversy it should not be forgotten that it
was only Murchison’s _Lower_ Silurian that was in conflict with
Sedgwick’s _Upper_ Cambrian. As for the rest of the Cambrian, that was
not involved in the controversy.

Dana goes on to state that science may accept a name, or not, according
as it is, or is not, needed. In the progress of geology, he thought that
the time had finally been reached when the name Cambrian was a
necessity, and he included both Cambrian and Silurian in the geological
record. The “Silurian,” however, included the Lower and Upper
Silurian—not one system of rocks, but two.

It is now twenty-seven years since Dana came to this conclusion, at a
time when it was believed that there was more or less continuous
deposition not only between the formations of a system but between the
systems themselves as well. To-day many geologists hold that in the
course of time the oceans pulsate back and forth over the continents,
and accordingly that the sequence of marine sedimentation in most places
must be much broken, and to-day we know that the breaks or land
intervals in the marine record are most marked between the eras, and
shorter between all or at least most of the periods. Furthermore, in
North America, we have learned that the breaks between the systems are
most marked in the interior of the continent and less so on or toward
its margins.

Hardly any one now questions the fact of a long land interval between
the Lower Silurian and Upper Silurian in England, and it is to
Sedgwick’s credit that he was the first to point out this fact and also
the presence of an unconformity. It therefore follows that we cannot
continue to use Silurian system in the sense proposed by Murchison,
since it includes two distinct systems or periods. Dana, in the last
edition of his Manual of Geology (1895), also recognizes two systems,
but curiously he saw nothing incongruous in calling them “Lower Silurian
era” and “Upper Silurian era.” It certainly is not conducive to clear
thinking, however, to refer to two systems by the one name of Silurian
and to speak of them individually as Lower and Upper Silurian, thus
giving the impression that the two systems are but parts of one—the
Silurian. Each one of the parts has its independent faunal and physical
characters.

We must digress a little here and note the work of Joachim Barrande
(1799–1883) in Bohemia. In 1846 he published a short account of the
“Silurian system” of Bohemia, dividing it into étages lettered C to H.
Between 1852 and 1883 he issued his “Système Silurien du Centre de la
Bohème,” in eighteen quarto volumes with 5568 pages of text and 798
plates of fossils—a monumental work unrivalled in paleontology. In the
first volume the geology of Bohemia is set forth, and here we see that
étages A and B are Azoic or pre-Cambrian, and C to H make up his
Silurian system. Etage C has his “Primordial fauna,” now known to be of
Paradoxides or Middle Cambrian time, while D is Lower Silurian, E is
Upper Silurian, F is Lower Devonian, and G and H are Middle Devonian.
From this it appears that Barrande’s Silurian system is far more
extensive than that of Murchison, embracing twice as many periods as
that of England and Wales.

About 1879 there was in England a nearly general agreement that Cambrian
should embrace Barrande’s Primordial or Paradoxides faunas, and in the
North Wales area be continued up to the top of the Tremadoc slates.
To-day we would include Middle and Upper Cambrian. Lower Cambrian in the
sense of containing the Olenellus faunas was then unknown in Great
Britain.

Lapworth, recognizing the distinctness of the Lower Silurian as a
system, proposed in 1879 to recognize it as such, and named it
Ordovician, restricting Silurian to Murchison’s Upper Silurian. This
term has not been widely used either in Great Britain or on the
Continent, but in the last twenty years has been accepted more and more
widely in America. Even here, however, it is in direct conflict with the
term Champlain, proposed by the New York State Geologist in 1842.

In 1897 the International Geological Congress published E. Renevier’s
Chronographie Géologique, wherein we find the following:

                  │Upper or Silurian         │Ludlowian (Murchison
 Silurian Period. │  (Murchison, restricted, │  1839).
                  │  1835).                  │
         „        │            „             │Wenlockian (Murchison
                  │                          │  1839).
         „        │            „             │Landoverian (Murchison).
 ─────────────────┼──────────────────────────┼──────────────────────────
         „        │Middle or Ordovician      │Caradocian (Murchison
                  │  (Lapworth 1879).        │  1839).
         „        │            „             │Landeilian (Murchison
                  │                          │  1839).
         „        │            „             │Arenigian (Sedgwick 1847).
 ─────────────────┼──────────────────────────┼──────────────────────────
                  │Lower or Cambrian         │
         „        │  (Sedgwick, restricted,  │Potsdamian (Emmons 1838).
                  │  1835).                  │
         „        │            „             │Menevian (Salter and Hicks
                  │                          │  1865).
         „        │            „             │Georgian (Hitchcock 1861).

Regarding this period, which, by the way, is not very unlike that of
Barrande, Renevier remarks that it is “as important as the Cretaceous or
the Jurassic. Lapworth even gives it a value of the first order equal to
the Protozoic era.”

In the above there is an obvious objection in the double usage of the
term Silurian, and this difficulty was met later on in Lapparent’s
Traité by the proposal to substitute Gothlandian for Silurian. Of this
change Geikie remarks: “Such an arrangement ... might be adopted if it
did not involve so serious an alteration of the nomenclature in general
use.” On the other hand, if diastrophism and breaks in the stratigraphic
and faunal sequence are to be the basis for geologic time divisions, we
cannot accept the above scheme, for it recognizes but one period where
there are at least four in nature.

_Conclusions._—We have arrived at a time when our knowledge of the
stratigraphic and faunal sequence, plus the orogenic record as
recognized in the principle of diastrophism, should be reflected in the
terminology of the geologic time-table. It would be easy to offer a
satisfactory nomenclature if we were not bound by the law of priority in
publication, and if no one had the geologic chronology of his own time
ingrained in his memory. In addition, the endless literature, with its
accepted nomenclature, bars our way. Therefore with a view of creating
the least change in geologic nomenclature, and of doing the greatest
justice to our predecessors that the present conditions of our knowledge
will allow, the following scheme is offered:


  Silurian period. Llandovery to top of Ludlow in Europe.
  Alexandrian-Cataract-Medina to top of Manlius in America.

  Champlain (1842) or Ordovician (1879) period. Arenig to top of Caradoc
  in Europe. Beekmantown to top of Richmondian in America.

  Cambrian period. In the Atlantic realm, begins with the Paradoxides,
  and in the Pacific, with the Bathyuriscus and Ogygopsis faunas. The
  close is involved in Ulrich’s provisionally defined Ozarkian system.
  When the latter is established, the Ozarkian period will hold the time
  between the Ordovician and the Cambrian.

  Taconic period. For the world-wide Olenellus or Mesonacidæ faunas.


                           _Paleogeography._

When geologists began to perceive the vast significance of Hutton’s
doctrine that “the ruins of an earlier world lie beneath the secondary
strata,” and that great masses of bedded rocks are separated from one
another by periods of mountain making and by erosion intervals, it was
natural for them to look for the lands that had furnished the debris of
the accumulated sediments. In this way paleogeography had its origin,
but it was at first of a descriptive and not of a cartographic nature.

The word paleogeography was proposed by T. Sterry Hunt in 1872 in a
paper entitled “The Paleogeography of the North American Continent,” and
published in the Journal of the American Geographical Society for that
year. It has to do, he says, with the “geographical history of these
ancient geological periods.” It was again prominently used by Robert
Etheridge in his presidential address before the Geological Society of
London in 1881. Since Canu’s use of the term in 1896, it has been
frequently seen in print, and now is generally adopted to signify the
geography of geologic time.

The French were the first to make paleogeographic maps, and Jules Marcou
relates in 1866 that Elie de Beaumont, as early as March, 1831, in his
course in the College of France and at the Paris School of Mines, used
to outline the relation of the lands and the seas in the center of
Europe at the different great geologic periods. His first printed
paleogeographic map appeared in 1833, and was of early Tertiary time.
Other maps by Beaumont were published by Beudant in 1841–1842. The
Sicilian geologist Gemmellaro published six maps of his country in 1834,
and the Englishman De La Beche had one in the same year. In America the
first to show such maps was Arnold Guyot in his Lowell lectures of 1848.
James D. Dana published three in the 1863 edition of his Manual of
Geology. Of world paleogeographic maps, Jules Marcou produced the first
of Jurassic time, publishing it in France in 1866, but the most
celebrated of these early attempts was the one by Neumayr published in
1883 in connection with his Ueber klimatische Zonen während der Jura-
und Kreidezeit.

The first geologist to produce a series of maps showing the progressive
geologic geography of a given area was Jukes-Brown, who in the volume
entitled “The Building of the British Isles,” 1888, included fifteen
such maps. Karpinsky published fourteen maps of Russia, and in 1896 Canu
in his Essai de paléogéographie has fifty-seven of France and Belgium.
Lapparent’s Traité of 1906 is famous for paleogeographic maps, for he
has twenty-three of the world, thirty-four of Europe, twenty-five of
France, and ten taken from other authors. Schuchert in 1910 published
fifty-two to illustrate the paleogeography of North America, and also
gave an extended list of such published maps. Another article on the
subject is by Th. Arldt, “Zur Geschichte der Paläogeographischen
Rekonstructionen,” published in 1914. Edgar Dacqué in 1913 also produced
a list in his Paläogeographischen Karten, and two years later appeared
his book of 500 pages, Grundlagen und Methoden der Paläogeographie,
where the entire subject is taken up in detail.

_Conclusions._—Since 1833 there have been published not less than 500
different paleogeographic maps, and of this number about 210 relate to
North America. Nevertheless paleogeography is still in its infancy, and
most maps embrace too much geologic time, all of them tens of thousands,
and some of them millions of years. The geographic maps of the present
show the conditions of the strand-lines of to-day, and those made fifty
years ago have to be revised again and again if they are to be of value
to the mariner and merchant. Therefore in our future paleogeographic
maps the tendency must ever be toward smaller amounts of geologic time,
if we are to show the actual relation of water to land and the movements
of the periodic floodings. Moreover, the ancient shore lines are all
more or less hypothetic and are drawn in straight or sweeping curves,
unlike modern strands with their bays, deltas, and headlands, and the
ancient lands are featureless plains. We must also pay more attention to
the distribution of brackish- and fresh-water deposits. The periodically
rising mountains will be the first topographic features to be shown upon
the ancient lands, and then more and more of the drainage and the
general climatic conditions must be portrayed. In the seas, depth,
temperature, and currents are yet to be deciphered. Finally, other base
maps than those of the geography of to-day will have to be made,
allowing for the compression of the mountainous areas, if we are to show
the true geographic configurations of the lands and seas of any given
geologic time.


                          _Paleometeorology._

In accordance with the Laplacian theory, announced at the beginning of
the nineteenth century, all of the older geologists held that the earth
began as a hot star, and that in the course of time it slowly cooled and
finally attained its present zonal cold to tropical climatic conditions.
That the earth had very recently passed through a much colder climate, a
glacial one, came into general acceptance only during the latter half of
the previous century.

_Rise._—Our knowledge of glacial climates had its origin in the Alps,
that wonderland of mountains and glaciers. The rise of this knowledge in
the Alps is told in a charming and detailed manner by that erratic
French-American geologist, Jules Marcou (1824–1898), in his Life,
Letters, and Works of Louis Agassiz, 1896. He relates that the Alpine
chamois hunter Perraudin in 1815 directed the attention of the engineer
De Charpentier to the fact “that the large boulders perched on the sides
of the Alpine valleys were carried and left there by glaciers.” For a
long time the latter thought the conclusion extravagant, and in the
meantime Perraudin told the same thing to another engineer, Venetz. He,
in 1829, convinced of the correctness of the chamois hunter’s views,
presented the matter before the Swiss naturalists then meeting at St.
Bernard’s. Venetz “told the Society that his observations led him to
believe that the whole Valais has been formerly covered by an immense
glacier and that it even extended outside of the canton, covering all
the Canton de Vaud, as far as the Jura Mountains, carrying the boulders
and erratic materials, which are now scattered all over the large Swiss
valley.” Eight years earlier, in 1821, similar views had been presented
by the same modest naturalist before the Helvetic Society, but it was
not until 1833 that De Charpentier found the manuscript and had it
published. Venetz’s conclusions were that all of the glaciers of the
Bagnes valley “have very recognizable moraines, which are about a league
from the present ice.” “The moraines ... date from an epoch which is
lost in the night of time.” Then in 1834 De Charpentier read a paper
before the same society, meeting at Lucerne. “Seldom, if ever, has such
a small memoir so deeply excited the scientific world. It was received
at first with incredulity and even scorn and mockery, Agassiz being
among its opponents.” The paper was published in 1835, first at Paris,
then at Geneva, and finally in Germany. It “attracted much attention,
and the smile of incredulity with which it was received when read at
Lucerne soon changed into a desire to know more about it.”

Louis Agassiz (1807–1873), who had long been acquainted with his
countryman, De Charpentier, spent several months with him in 1836, and
together they studied the glaciers of the Alps. Agassiz was at first
“adverse to the hypothesis, and did not believe in the great extension
of glaciers and their transportation of boulders, but on the contrary,
was a partisan of Lyell’s theory of transport by icebergs and
ice-cakes ... but from being an adversary of the glacial theory, he
returned to Neuchâtel an enthusiastic convert to the views of Venetz and
De Charpentier.... With his power of quick perception, his unmatched
memory, his perspicacity and acuteness, his way of classifying, judging
and marshalling facts, Agassiz promptly learned the whole mass of
irresistible arguments collected patiently during seven years by De
Charpentier and Venetz, and with his insatiable appetite and that
faculty of assimilation which he possessed in such a wonderful degree,
he digested the whole doctrine of the glaciers in a few weeks.”

In July, 1837, Agassiz presented as his presidential address before the
Helvetic Society his memorable “Discours de Neuchâtel,” which was “the
starting point of all that has been written on the Ice-age,”—a term
coined at the time by his friend Schimper, a botanist. The first part of
this address is reprinted in French in Marcou’s book on Agassiz. The
address was received with astonishment, much incredulity, and
indifference. Among the listeners was the great German geologist Von
Buch, who “was horrified, and with his hands raised towards the sky, and
his head bowed to the distant Bernese Alps, exclaimed: ‘O Sancte de
Saussure, ora pro nobis!’” Even De Charpentier “was not gratified to see
his glacial theory mixed with rather uncalled for biological problems,
the connection of which with the glacial age was more than problematic.”
Agassiz was then a Cuvierian catastrophist and creationist, and advanced
the idea of a series of glacial ages to explain the destruction of the
geologic succession of faunas! Curiously, this theory was at once
accepted by the American paleontologist T. A. Conrad (=35=, 239, 1839).

The classics in glacial geology are Agassiz’s Etudes sur les Glaciers,
1840, and De Charpentier’s Essai sur les Glaciers, 1841. Of the latter
book, Marcou states that it has been said: “It is impossible to be truly
a geologist without having read and studied it.” In the English language
there is Tyndall’s Glaciers of the Alps, 1860.

The progress of the ideas in regard to Pleistocene glaciation is
presented in the following chapter by H. E. Gregory.

_Older Glacial Climates._—Hardly had the Pleistocene glacial climate
been proved, when geologists began to point out the possibility of even
earlier ones. An enthusiastic Scotch writer, Sir Andrew Ramsay, in 1855
described certain late Paleozoic conglomerates of middle England, which
he said were of glacial origin, but his evidence, though never
completely gainsaid, has not been generally accepted. In the following
year, an Englishman, Doctor W. T. Blanford, said that the Talchir
conglomerates of central and southern India were of glacial origin, and
since then the evidence for a Permian glacial climate has been steadily
accumulating. Africa is the land of tillites, and here in 1870
Sutherland pointed out that the conglomerates of the Karroo formation
were of glacial origin. Australia also has Permian glacial deposits, and
they are known widely in eastern Brazil, the Falkland Islands, the
vicinity of Boston, and elsewhere. So convincing is this testimony that
all geologists are now ready to accept the conclusion that a glacial
climate was as wide-spread in early Permian time as was that of the
Pleistocene.[3]

In South Africa, beneath the marine Lower Devonian, occurs the Table
Mountain series, 5000 feet thick. The series is essentially one of
quartzites, with zones of shales or slates and with striated pebbles up
to 15 inches long. The latter occur in pockets and seem to be of glacial
origin. There are here no typical tillites, and no striated undergrounds
have so far been found. While the evidence of the deposits appears to
favor the conclusion that the Table Mountain strata were laid down in
cold waters with floating ice derived from glaciers, it is as yet
impossible to assign these sediments a definite geologic age. They are
certainly not younger than the Lower Devonian, but it has not yet been
established to what period of the early Paleozoic they belong.

In southeastern Australia occur tillites of wide distribution that lie
conformably beneath, but sharply separated from the fossiliferous marine
Lower Cambrian strata. David (1907), Howchin (1908), and other
Australian geologists think they are of Cambrian time, but to the writer
they seem more probably late Proterozoic in age. In arctic Norway Reusch
discovered unmistakable tillites in 1891, and this occurrence was
confirmed by Strahan in 1897. It is not yet certainly known what their
age is, but it appears to be late Proterozoic rather than early
Paleozoic. Other undated Proterozoic tillites occur in China (Willis and
Blackwelder 1907), Africa (Schwarz 1906), India (Vredenburg 1907),
Canada (Coleman 1908), and possibly in Scotland.

The oldest known tillites are described by Coleman in 1907, and occur at
the base of the Lower Huronian or in early Proterozoic time. They extend
across northern Ontario for 1000 miles, and from the north shore of Lake
Huron northward for 750 miles.

_Fossils as Climatic Indexes._—Paleontologists have long been aware that
variations in the climates of the past are indicated by the fossils, and
Neumayr in 1883 brought the evidence together in his study of climatic
zones mentioned elsewhere. Plants, and corals, cephalopods, and
foraminifers among marine animals, have long been recognized as
particularly good “life thermometers.” In fact, all fossils are climatic
indicators to some extent, and a good deal of evidence concerning
paleometeorology has been discerned in them. This evidence is briefly
stated in the paper by Schuchert already alluded to, and in W. D.
Matthew’s Climate and Evolution, 1915.

_Sediments as Climatic Indexes._—Johannes Walther in the third part of
his Einleitung—Lithogenesis der Gegenwart, 1894—is the first one to
decidedly direct attention to the fact that the sediments also have
within themselves a climatic record. In America Joseph Barrell has since
1907 written much on the same subject. On the other hand, the periodic
floodings of the continents by the oceans, and the making of mountains,
due to the periodic shrinkage of the earth, as expressed in T. C.
Chamberlin’s principle of diastrophism and in his publications since
1897, are other criteria for estimating the climates of the past.

_Conclusions._—In summation of this subject Schuchert says:


  “The marine ‘life thermometer’ indicates vast stretches of time of
  mild to warm and equable temperatures, with but slight zonal
  differences between the equator and the poles. The great bulk of
  marine fossils are those of the shallow seas, and the evolutionary
  changes recorded in these ‘medals of creation’ are slight throughout
  vast lengths of time that are punctuated by short but decisive periods
  of cooled waters and great mortality, followed by quick evolution, and
  the rise of new stocks. The times of less warmth are the _miotherm_
  and those of greater heat the _pliotherm_ periods of Ramsay.

  On the land the story of the climatic changes is different, but in
  general the equability of the temperature simulates that of the
  oceanic areas. In other words, the lands also had long-enduring times
  of mild to warm climates. Into the problem of land climates, however,
  enter other factors that are absent in the oceanic regions, and these
  have great influence upon the climates of the continents. Most
  important of these is the periodic warm-water inundation of the
  continents by the oceans, causing insular climates that are milder and
  moister. With the vanishing of the floods somewhat cooler and
  certainly drier climates are produced. The effects of these periodic
  floods must not be underestimated, for the North American continent
  was variably submerged at least seventeen times, and over an area of
  from 154,000 to 4,000,000 square miles.

  When to these factors is added the effect upon the climate caused by
  the periodic rising of mountain chains, it is at once apparent that
  the lands must have had constantly varying climates. In general the
  temperature fluctuations seem to have been slight, but geographically
  the climates varied between mild to warm pluvial, and mild to cool
  arid. The arid factor has been of the greatest import to the organic
  world of the lands. Further, when to all of these causes is added the
  fact that during emergent periods the formerly isolated lands were
  connected by land bridges, permitting intermigration of the land
  floras and faunas, with the introduction of their parasites and
  parasitic diseases, we learn that while the climatic environment is of
  fundamental importance it is not the only cause for the more rapid
  evolution of terrestrial life....

  Briefly, then, we may conclude that the markedly varying climates of
  the past seem to be due primarily to periodic changes in the
  topographic form of the earth’s surface, plus variations in the amount
  of heat stored by the oceans. The causation for the warmer
  interglacial climates is the most difficult of all to explain, and it
  is here that factors other than those mentioned may enter.

  Granting all this, there still seems to lie back of all these theories
  a greater question connected with the major changes in
  paleometeorology. This is: What is it that forces the earth’s
  topography to change with varying intensity at irregularly rhythmic
  intervals?... Are we not forced to conclude that the earth’s shape
  changes periodically in response to gravitative forces that alter the
  body-form?”


                              _Evolution._

Modern evolution, or the theory of life continuously descending from
life with change, may be said to have had its first marked development
in Comte de Buffon (1707–1788), a man of wealth and station, yet an
industrious compiler, a brilliant writer, and a popularizer of science.
He was not, however, a true scientific investigator, and his monument to
fame is his Histoire Naturelle, in forty-four volumes, 1749–1804. A. S.
Packard in his book on Lamarck, his Life and Work, 1901, concludes in
regard to Buffon as follows:


  “The impression left on the mind, after reading Buffon, is that even
  if he threw out these suggestions and then retracted them, from fear
  of annoyance or even persecution from the bigots of his time, he did
  not himself always take them seriously, but rather jotted them down as
  passing thoughts.... They appeared thirty-four years before Lamarck’s
  theory, and though not epoch-making, they are such as will render the
  name of Buffon memorable for all time.”


Chevalier de Lamarck (1744–1829) may justly be regarded as the founder
of the doctrine of modern evolution. Previous to 1794 he was a believer
in the fixity of species, but by 1800 he stood definitely in favor of
evolution. Locy in his Biology and its Makers, 1908, states his theories
in the following simplified form:


  “Variations of organs, according to Lamarck, arise in animals mainly
  through use and disuse, and new organs have their origin in a
  physiological need. A new need felt by the animal [due to new
  conditions in its life, or the environment] expresses itself on the
  organism, stimulating growth and adaptations in a particular
  direction.”


To Lamarck, “inheritance was a simple, direct transmission of those
superficial changes that arise in organs within the lifetime of an
individual owing to use and disuse.” This part of his theory has come to
be known as “the inheritance of acquired characters.”

Georges Cuvier (1769–1832), a peer of France, was a decided believer in
the fixity of species and in their creation through divine acts. In 1796
he began to see that among the fossils so plentiful about Paris many
were of extinct forms, and later on that there was a succession of
wholly extinct faunas. This at first puzzling phenomenon he finally came
to explain by assuming that the earth had gone through a series of
catastrophes, of which the Deluge was the most recent but possibly not
the last. With each catastrophe all life was blotted out, and a new
though improved set of organisms was created by divine acts. The
Cuvierian theory of catastrophism was widely accepted during the first
half of the nineteenth century, and in America Louis Agassiz was long
its greatest exponent. It was this theory and the dominance of the
brilliant Cuvier, not only in science but socially as well, that blotted
out the far more correct views of the more philosophical Lamarck, who
held that life throughout the ages had been continuous and that through
individual effort and the inheritance of acquired characters had evolved
the wonderful diversity of the present living world.

In 1830 there was a public debate at Paris between Cuvier and Geoffroy
Saint-Hilaire, the one holding to the views of the fixity of species and
creation, the other that life is continuous and evolves into better
adapted forms. Cuvier, a gifted speaker and the greatest debater zoology
ever had, with an extraordinary memory that never failed him, defeated
Saint-Hilaire in each day’s debate, although the latter was in the
right.

A book that did a great deal to prepare the English-speaking people for
the coming of evolution was “Vestiges of Creation,” published in 1844 by
an unknown author. In Darwin’s opinion, “the work, from its powerful and
brilliant style ... has done excellent service ... in thus preparing the
ground for the reception of analogous views.” This book was recommended
to the readers of the Journal (=48=, 395, 1845) with the editorial
remark that “we cannot subscribe to all of the author’s views.”

We can probably best illustrate the opinions of Americans on the
question of evolution just before the appearance of Darwin’s great work
by directing attention to James D. Dana’s Thoughts on Species (=24=,
305, 1857). After reading this article and others of a similar nature by
Agassiz, one comes to the opinion that unconsciously both men are
proving evolution, but consciously they are firm creationists. It is
astonishing that with their extended and minute knowledge of living
organisms and their philosophic type of mind neither could see the true
significance of the imperceptible transitions between some species,
which if they do not actually pass into, at least shade towards, one
another.

Dana speaks of “the endless diversities in individuals” that compose a
species, and then states that a living species, like an inorganic one,
“is based on a specific amount or condition of concentered force defined
in the act or law of creation.” Species, he says, are permanent, and
hybrids “cannot seriously trifle with the true units of nature, and at
the best, can only make temporary variations.” “We have therefore reason
to believe from man’s fertile intermixture, that he is one in species:
and that all organic species are divine appointments which cannot be
obliterated, unless by annihilating the individuals representing the
species.”

Through the activities of the French the world was prepared for the
reception of evolution, and now it was already in the minds of many
advanced thinkers. In 1860 Asa Gray sent to the editor of the Journal
(=29=, 1) an article by the English botanist, Joseph D. Hooker, entitled
“On the Origination and Distribution of Species,” with these significant
remarks:


  “The essay cannot fail to attract the immediate and profound attention
  of scientific men.... It has for some time been manifest that a
  re-statement of the Lamarckian hypothesis is at hand. We have this, in
  an improved and truly scientific form, in the theories which, recently
  propounded by Mr. Darwin, followed by Mr. Wallace, are here so ably
  and altogether independently maintained. When these views are fully
  laid before them, the naturalists of this country will be able to take
  part in the interesting discussion which they will not fail to call
  forth.”


Hooker took up a study of the flora of Tasmania, of which the above
cited article is but a chapter, with a view to trying out Darwin’s
theory, and he now accepts it. He says, “Species are derivative and
mutable.” “The limits of the majority of species are so undefinable that
few naturalists are agreed upon them.”

Asa Gray had received from Darwin an advance copy of the book that was
to revolutionize the thought of the world, and at once wrote for the
Journal a Review of Darwin’s Theory on the Origin of Species by means of
Natural Selection (=29=, 153, 1860). This is a splendid, critical but
just, scientific review of Darwin’s epoch-making book. Evidently views
similar to those, of the English scientist had long been in the mind of
Gray, for he easily and quickly mastered the work. He is easy on Dana’s
Thoughts on Species, which were idealistic and not in harmony with the
naturalistic views of Darwin. On the other hand, he contrasts Darwin’s
views at length with those of the creationists as exemplified by Louis
Agassiz, and says “The widest divergence appears.”

Gray says in part:


  “The gist of Mr. Darwin’s work is to show that such varieties are
  gradually diverged into species and genera through natural selection;
  that natural selection is the inevitable result of the struggle for
  existence which all living things are engaged in; and that this
  struggle is an unavoidable consequence of several natural causes, but
  mainly of the high rate at which all organic beings tend to increase.

  Darwin is confident that intermediate forms must have existed; that in
  the olden times when the genera, the families and the orders diverged
  from their parent stocks, gradations existed as fine as those which
  now connect closely related species with varieties. But they have
  passed and left no sign. The geological record, even if all displayed
  to view, is a book from which not only many pages, but even whole
  alternate chapters have been lost out, or rather which were never
  printed from the autographs of nature. The record was actually made in
  fossil lithography only at certain times and under certain conditions
  (i.e., at periods of slow subsidence and places of abundant sediment);
  and of these records all but the last volume is out of print; and of
  its pages only local glimpses have been obtained. Geologists, except
  Lyell, will object to this,—some of them moderately, others with
  vehemence. Mr. Darwin himself admits, with a candor rarely displayed
  on such occasions, that he should have expected more geological
  evidence of transition than he finds, and that all the most eminent
  paleontologists maintain the immutability of species.

  The general fact, however, that the fossil fauna of each period as a
  whole is nearly intermediate in character between the preceding and
  the succeeding faunas, is much relied on. We are brought one step
  nearer to the desired inference by the similar ‘fact,’ insisted on by
  all paleontologists, that fossils from two consecutive formations are
  far more closely related to each other, than are the fossils of two
  remote formations.

  It is well said that all organic beings have been formed on two great
  laws; Unity of type, and Adaptation to the conditions of existence....
  Mr. Darwin harmonizes and explains them naturally. Adaptation to the
  conditions of existence is the result of Natural Selection; Unity of
  type, of unity of descent.”


Gray’s article was soon followed by another one from Agassiz on
Individuality and Specific Differences among Acalephs, but the running
title is “Prof. Agassiz on the Origin of Species” (=30=, 142, 1860).
Agassiz stoutly maintains his well known views, and concludes as
follows:


  “Were the transmutation theory true, the geological record should
  exhibit an uninterrupted succession of types blending gradually into
  one another. The fact is that throughout all geological times each
  period is characterized by definite specific types, belonging to
  definite genera, and these to definite families, referable to definite
  orders, constituting definite classes and definite branches, built
  upon definite plans. Until the facts of Nature are shown to have been
  mistaken by those who have collected them, and that they have a
  different meaning from that now generally assigned to them, I shall
  therefore consider the transmutation theory as a scientific mistake,
  untrue in its facts, unscientific in its method, and mischievous in
  its tendency.”


Dana, in reviewing Huxley’s well known book, Man’s Place in Nature
(=35=, 451, 1863), holds that man is apart from brute nature because man
exhibits “extreme cephalization” in that he has arms that no longer are
used in locomotion but go rather with the head, and because he has a far
higher mentality and speech. As for the Darwinian theory, the evidence,
he says, “comes from lower departments of life, and is acknowledged by
its advocates to be exceedingly scanty and imperfect.”

The growth of evolution is set forth in the Journal in Asa Gray’s
article on Charles Darwin (=24=, 453, 1882), which speaks of the latter
as “the most celebrated man of science of the nineteenth century,” and,
in addition, as “one of the most kindly and charming, unaffected,
simple-hearted, and lovable of men.” In regard to the rise of evolution
in America, more can be had from Dana’s paper on Asa Gray (=35=, 181,
1888). Here we read, as a sequel to his Thoughts on Species, that the
“paper may be taken, perhaps, as a culmination of the past, just as the
new future was to make its appearance.” Finally, in this connection
there should be mentioned O. C. Marsh’s paper on Thomas Henry Huxley
(=50=, 177, 1895), wherein is recorded the latter’s share in the
upbuilding of the evolutionary theory.

We have seen that originally Dana was a creationist, but in the course
of his long and fruitful life he gradually became an evolutionist, and
rather a Neo-Lamarckian than a Darwinian. This change may be traced in
the various editions of his Manual of Geology, and in the last edition
of 1895 he says his “speculative conclusions” of 1852 in regard to the
origin of species are not in “accord with the author’s present
judgment.” “The evidence in favor of evolution by variation is now
regarded as essentially complete.” On the other hand, while man is
“unquestionably” closely related in structure to the man-apes, yet he is
not linked to them but stands apart, through “the intervention of a
Power above Nature.... Believing that Nature exists through the will and
ever-acting power of the Divine Being, and ... that the whole Universe
is not merely dependent on, but actually is, the Will of one Supreme
Intelligence, Nature, with Man as its culminant species, is no longer a
mystery.”

In America most of the paleontologists are Neo-Lamarckian, a school that
was developed independently by E. D. Cope (1840–1897) through the
vertebrate evidence, and by Alpheus Hyatt (1838–1902) mainly on the
evidence of the ammonites. They hold that variations and acquired
characters arise through the effects of the environment, the mechanics
of the organism resulting from the use and disuse of organs, etc. One of
the leading exponents of this school is A. S. Packard, whose book on
Lamarck, His Life and Work, 1901, fully explains the doctrines of the
Neo-Lamarckians.


               _The Growth of Invertebrate Paleontology._

How and by whom paleontology has been developed has been fully stated in
the Journal in a very clear manner by Professor Marsh in his memorable
presidential address of 1879, History and Methods of Palæontological
Discovery (=18=, 323, 1879), and by Karl von Zittel in his most
interesting book, History of Geology and Palæontology, 1901. In this
discussion we shall largely follow Marsh.

The science of paleontology has passed through four periods, the first
of them the long _Mystic period_ extending up to the beginning of the
seventeenth century, when the idea that fossils were once living things
was only rarely perceived. The second period was the _Diluvial period_
of the eighteenth century, when nearly everyone regarded the fossils as
remains of the Noachian deluge. With the beginnings of the nineteenth
century there arose in western Europe the knowledge that fossils are the
“medals of creation” and that they have a chronogenetic significance;
also that life had been periodically destroyed through world-wide
convulsions in nature. From about 1800 to 1860 was the time of the
creationists and catastrophists, which may be known as the _Catastrophic
period_. The fourth period began in 1860 with Darwin’s Origin of
Species. Since that time the theory of evolution has pervaded all work
in paleontology, and accordingly this time may be known as the
_Evolutionary period_.

_Mystic Period._—The Mystic period in paleontology begins with the
Greeks, five centuries before the present era, and continues down to the
beginning of the seventeenth century of our time. Some correctly saw
that the fossils were once living marine animals, and that the sea had
been where they now occur. Others interpreted fossil mammal bones as
those of human giants, the Titans, but the Aristotelian view that they
were of spontaneous generation through the hidden forces of the earth
dominated all thought for about twenty centuries.

In the sixteenth century canals were being dug in Northern Italy, and
the many fossils so revealed led to a fierce discussion as to their
actual nature. Leonardo da Vinci (1452–1519) opposed the commonly
accepted view of their spontaneous generation and said that they were
the remains of once living animals and that the sea had been where they
occur. “You tell me,” he said, “that Nature and the influence of the
stars have formed these shells in the mountains; then show me a place in
the mountains where the stars at the present day make shelly forms of
different ages, and of different species in the same place.” However,
nothing came of his teachings and those of his countryman Fracastorio
(1483–1553), who further ridiculed the idea that they were the remains
of the deluge. The first mineralogist, Agricola, described them as
minerals—fossilia—and said that they arose in the ground from fatty
matter set in fermentation by heat. Others said that they were freaks of
nature. Martin Lister (1638–1711) figured fossils side by side with
living shells to show that they were extinct forms of life. In the
seventeenth century, and especially in Italy and Germany, many books
were published on fossils, some with illustrations so accurate that the
species can be recognized to-day. Finally, toward the close of this
century the influence of Aristotle and the scholastic tendency to
disputation came more or less to an end. Fossils were already to many
naturalists once living plants and animals. Marsh states: “The many
collections of fossils that had been brought together, and the
illustrated works that had been published about them, were a foundation
for greater progress, and, with the eighteenth century, the second
period in the history of paleontology began.”

_Diluvial Period._—During the eighteenth century many more books on
fossils were published in western Europe, and now the prevalent
explanation was that they were the remains of the Noachian deluge. For
nearly a century theologians and laymen alike took this view, and some
of the books have become famous on this account, but the diluvial views
sensibly declined with the close of the eighteenth century.

The true nature of fossils had now been clearly determined. They were
the remains of plants and animals, deposited long before the deluge,
part in fresh water and part in the sea. “Some indicated a mild climate,
and some the tropics. That any of these were extinct species, was as yet
only suspected.” Yet before the close of the century there were men in
England and France who pointed out that different formations had
different fossils and that some of them were extinct. These views then
led to many fantastic theories as to how the earth was formed—dreams,
most of them have been called. Marsh says:


  “The dominant idea of the first sixteen centuries of the present era
  was, that the universe was made for Man. This was the great obstacle
  to the correct determination of the position of the earth in the
  universe, and, later, of the age of the earth.... In a superstitious
  age, when every natural event is referred to a supernatural cause,
  science cannot live.... Scarcely less fatal to the growth of science
  is the age of Authority, as the past proves too well. With freedom of
  thought, came definite knowledge, and certain progress;—but two
  thousand years was long to wait.”


One of the most significant publications of this period was Linnæus’s
Systema Naturæ, which appeared in 1735. In this work was introduced
binomial nomenclature, or the system of giving each plant and animal
species a generic and specific name, as _Felis leo_ for the lion. The
system was, however, not established until the tenth edition of the work
in 1758, which became the starting point of zoological nomenclature.
Since then there has been added another canon, the law of priority,
which holds that the first name applied to a given form shall stand
against all later names given to the same organism.

_Catastrophic Period._—With the beginning of the nineteenth century
there started a new era in paleontology, and this was the time when the
foundations of the science were laid. The period continued for six
decades, or until the time of the Origin of Species. Marsh says that now
“method replaced disorder, and systematic study superseded casual
observation.” Fossils were accurately determined, comparisons were made
with living forms, and the species named according to the binomial
system. However, every species, recent and extinct, was regarded as a
separate creation, and because of the usually sharp separation of the
superposed fossil faunas and floras, these were held to have been
destroyed through a series of periodic catastrophes of which the
Noachian deluge was the last.

Lamarck between 1802 and 1806 described the Tertiary shells of the Paris
basin. Comparing them with the living forms, he saw that most of the
fossils were of extinct species, and in this way he came to be the
founder of modern invertebrate paleontology. He also maintained after
1801 that life has been continuous since its origin and that nature has
been uniform in the course of its development. Marsh adds:


  “His researches on the invertebrate fossils of the Paris Basin,
  although less striking, were not less important than those of Cuvier
  on the vertebrates; while the conclusions he derived from them form
  the basis of modern biology.”

  “Lamarck was the prophetic genius, half a century in advance of his
  time.”


Cuvier established comparative anatomy and vertebrate paleontology, and
was one of the first to point out that fossil animals are nearly all
extinct forms. He came to the latter conclusion in 1796 through a study
of fossil elephants found in Europe. “Cuvier enriched the animal kingdom
by the introduction of fossil forms among the living, bringing all
together into one comprehensive system.” This opened to him entirely new
views respecting the theory of the earth, and he devoted more than
twenty-five years to developing the theories of special creation and
catastrophism, described in his Discourse on the Revolutions of the
Surface of the Globe. “With all his knowledge of the earth, he could not
free himself from tradition, and believed in the universality and power
of the Mosaic deluge. Again, he refused to admit the evidence brought
forward by his distinguished colleagues against the permanence of
species, and used all his great influence to crush out the doctrine of
evolution, then first proposed” (Marsh).

In England it was William Smith (1769–1839) who independently discovered
the chronogenetic significance of fossils, and in their stratigraphic
superposition indicated the way for the study of historical geology. He
first published on this matter in 1799, but his completed statements
came in works entitled “Strata identified by Organized Fossils,”
1816–1820, and “Stratigraphical System of Organized Fossils,” 1817.

Invertebrate paleontology in America during the Catastrophic period had
its beginning in Lesueur, who in 1818 described the Ordovician gastropod
_Maclurites magna_. All of the paleontologists of this time were
satisfied to describe species and genera and to ascertain in a broad way
the stratigraphic significance of the fossil faunas and floras. James
Hall in 1854 (=17=, 312) knew of 1588 species, described and
undescribed, in the New York system, while in England Morris listed in
that year 8300 Paleozoic forms. In 1856 Dana recites the known fossil
species as follows (=22=, 333): The whole number of known American
species of animals of the Permian to Recent is about 2000; while in
Britain and Europe, there were over 20,000 species. In the Permian we
have none, while Europe has over 200 species. In the Triassic we have
none, Europe 1000 species; Jurassic 60, Europe over 4000; Cretaceous 350
to 400, Europe about 6000; Tertiary hardly 1500, Europe about 8000.
Since that time nearly all of the larger American Paleozoic faunas have
been developed, but there are thousands of species yet to be described.
Who the more prominent American paleontologists of this period were has
been told in the section on the development of the geological column.

The grander paleontologic results of the Catastrophic period have been
so well stated by Marsh that it is worth our while to repeat them here:


  “It had now been proved beyond question that portions at least of the
  earth’s surface had been covered many times by the sea, with
  alternations of fresh water and of land; that the strata thus
  deposited were formed in succession, the lowest of the series being
  the oldest; that a distinct succession of animals and plants had
  inhabited the earth during the different geological periods; and that
  the order of succession found in one part of the earth was essentially
  the same in all. More than 30,000 new species of extinct animals and
  plants had now been described. It had been found, too, that from the
  oldest formations to the most recent, there had been an advance in the
  grade of life, both animal and vegetable, the oldest forms being among
  the simplest, and the higher forms successively making their
  appearance.

  It had now become clearly evident, moreover, that the fossils from the
  older formations were all extinct species, and that only in the most
  recent deposits were there remains of forms still living.... Another
  important conclusion reached, mainly through the labors of Lyell, was,
  that the earth had not been subjected in the past to sudden and
  violent revolutions; but the great changes wrought had been gradual,
  differing in no essential respect from those still in progress.
  Strangely enough, the corollary to this proposition, that life, too,
  had been continuous on the earth, formed at that date no part of the
  common stock of knowledge. In the physical world, the great law of
  ‘correlation of forces’ had been announced, and widely accepted; but
  in the organic world, the dogma of the miraculous creation of each
  separate species still held sway.”


_Evolutionary Period._—This period begins with 1860 and the publication
of Darwin’s Origin of Species (late in 1859). It is the period of modern
paleontology, and is dominated by the belief that universal laws pervade
not only inorganic matter, but all life as well. Louis Agassiz had been
in America fourteen years when Darwin’s book appeared, and his wonderful
influence in bringing the zoology of our country to a high stand and the
further influence he exerted through his students was bound to react
beneficially on invertebrate paleontology. Shortly after the beginning
of this period, or in 1867, Alpheus Hyatt, one of Agassiz’s students,
began to apply the study of embryology to fossil cephalopods, showing
clearly that these shells retain a great deal of their growth stages or
ontogeny. This method of study was then followed by R. T. Jackson, C. E.
Beecher, and J. P. Smith, and has been productive of natural
classifications of the Cephalopoda, Brachiopoda, Trilobita, and
Echinoidea.

The dominant invertebrate paleontologist of this period was of course
James Hall, who described about 5000 species of American Paleozoic
fossils. He also built up the New York State Museum, while around his
private collections of fossils have been developed the American Museum
of Natural History in New York City and the Walker Museum at the
University of Chicago. In his most important laboratory of paleontology
at Albany, there have been trained either wholly or in part the
following paleontologists: F. B. Meek, C. A. White, R. P. Whitfield, C.
D. Walcott, C. E. Beecher, John M. Clarke, and Charles Schuchert.

In Canada, through the work of the Geological Survey of the Dominion,
came the paleontologists Elkanah Billings and, later on, J. F.
Whiteaves. The “father of Canadian paleontology,” Sir William Dawson,
who developed independently, was active in all branches of the science
and did much to unravel the geology of eastern Canada. No organism has
been more discussed and more often rejected and accepted as a fossil
than his “dawn animal of Canada,” _Eozoon canadense_, first described in
1865. His son, George M. Dawson, was one of the directors of the
Geological Survey of Canada. Finally the extensive paleontology of the
Cambrian of Canada was worked out by another self-made paleontologist,
G. F. Matthew.

_Paleobotany._—American paleobotany was developed during this, the
fourth period, through the state and national surveys, first in Leo
Lesquereux, a Swiss student induced by Agassiz to come to America, and
in J. S. Newberry. The second generation of paleobotanists is
represented by Lester F. Ward and W. N. Fontaine, and the third
generation, the present workers, includes F. H. Knowlton, David White,
Arthur Hollick, and E. W. Berry. A new line of paleobotanical work, the
histology of woody but pseudomorphous remains, has been developed by G.
R. Wieland.

The grander results of the study of paleontology during the evolutionary
period may be summed up with the conclusions of Marsh:


  “One of the main characteristics of this epoch is the belief that all
  life, living and extinct, has been evolved from simple forms. Another
  prominent feature is the accepted fact of the great antiquity of the
  human race. These are quite sufficient to distinguish this period
  sharply from those that preceded it.”

  Charles Darwin’s work at once aroused attention, and brought about in
  scientific thought a revolution which “has influenced paleontology as
  extensively as any other department of science.... In the [previous
  period] species were represented independently by parallel lines; in
  the present period, they are indicated by dependent, branching lines.
  The former was the analytic, the latter is the synthetic period.”


_Synthetic Period._—What is to be the next trend in paleontology?
Clearly it is to be the Synthetic period, one that Marsh in 1879
indicated in these words: “But if we are permitted to continue in
imagination the rapidly converging lines of research pursued to-day,
they seem to meet at the point where organic and inorganic nature become
one. That this point will yet be reached, I cannot doubt.”

This Synthetic period, foreshadowed also in Herbert Spencer’s Synthetic
Philosophy, has not yet arrived, but before long another great leader
will appear. We have the prophecy of his coming in such books as The
Fitness of the Environment, by Lawrence J. Henderson, 1913; The Origin
and Nature of Life, by Benjamin Moore, 1913; The Organism as a Whole, by
Jacques Loeb, 1916; and The Origin and Evolution of Life, by Henry F.
Osborn, 1917.

In all nature, inorganic and organic, there is continuity and
consistency, beauty and design. We are beginning to see that there are
eternal laws, ever interacting and resulting in progressive and
regressive evolutions. The realization of these scientific revelations
kindles in us a desire for more knowledge, and the grandest revelations
are yet before us in the synthesis of the sciences.


                                _Notes._

Footnote 3:

  For more detail in regard to these tillites and the older ones see
  Climates of Geologic Time, by Charles Schuchert, being Chapter XXI in
  Huntington’s Climatic Factor as Illustrated in Arid America,
  Publication No. 192 of the Carnegie Institution of Washington, 1914.
  Also Arthur P. Coleman’s presidential address before the Geological
  Society of America in 1915, Dry Land in Geology, published in the
  Society’s Bulletin, 27, 175, 1916.




                                  III
 A CENTURY OF GEOLOGY.—STEPS OF PROGRESS IN THE INTERPRETATION OF LAND
                                 FORMS

                         By HERBERT E. GREGORY


 The essence of physiography is the belief that land forms represent
merely a stage in the orderly development of the earth’s surface
features; that the various dynamic agents perform their characteristic
work throughout all geologic time. The formulation of principle and
processes of earth sculpture was, therefore, impossible on the
hypothesis of a ready-made earth whose features were substantially
unchangeable, except when modified by catastrophic processes. In 1821,
J. W. Wilson wrote in the Journal: “Is it not the best theory of the
earth, that the Creator, in the beginning, at least at the general
deluge, formed it with all its present grand characteristic
features?”[4] If so, a search for causes is futile, and the study of the
work performed by streams and glaciers and wind is unprofitable. The
belief in the Deluge as the one great geological event in the history of
the earth has brought it about that the speculations of Aristotle,
Herodotus, Strabo, and Ovid, and the illustrious Arab, Avicenna
(980–1037), unchecked by appeal to facts but also unopposed by
priesthood or popular prejudice, are nearer to the truth than the
intolerant controversial writings of the intellectual leaders whose
touchstone was orthodoxy. A few thinkers of the sixteenth century
revolted against the interminable repetition of error, and Peter
Severinus (1571) advised his students: “Burn up your books ... buy
yourselves stout shoes, get away to the mountains, search the valleys,
the deserts, the shores of the seas.... In this way and no other will
you arrive at a knowledge of things.” But the thoroughgoing
“diluvialist” who believed that a million species of animals could
occupy a 450–foot Ark, but not that pebbles weathered from rock or that
rivers erode, had no use for his powers of observation.

Sporadic germs of a science of land forms scattered through the
literature of the seventeenth and eighteenth centuries found an
unfavorable environment and produced inconspicuous growths. Even their
sponsors did little to cultivate them. Steno (1631–1687) mildly
suggested that surface sculpturing, particularly on a small scale, is
largely the work of running water, and Guettard (1715–1786), a truly
great mind, grasped the fundamental principles of denudation and
successfully entombed his views as well as his reputation in scores of
books and volumes of cumbrous diffuse writing.

At the beginning of the nineteenth century a sufficient body of
principles had been established to justify the recognition of an earth
science, geology, and the 195 volumes of the Journal thus far published
carry a large part of the material which has won approval for the new
science and given prominence to American thought. From the pages in the
Journal, the progress of geology may be illustrated by tracing the
fluctuation in the development of fact and theory as relates to valleys
and glacial features, the subjects to which this chapter is devoted.


                    _The Interpretation of Valleys._


                            _The Pioneers._

Desmarest (1725–1815) might be styled the father of physiography. By
concrete examples and sound induction he established (1774) the doctrine
that the valleys of central France are formed by the streams which
occupy them. He also made the first attempt to trace the history of a
landscape through its successive stages on the basis of known causes.
His methods and reasoning are practically identical with those of Dutton
working in the ancient lavas of New Mexico; and Whitney’s description of
the Table Mountains of California might well have appeared in
Desmarest’s memoirs.[5] The teachings of Desmarest were strengthened and
expanded by DeSaussure (1740–1799), the sponsor for the term, “Geology,”
(1779) who saw in the intimate relation of Alpine streams and valleys
the evidence of erosion by running water (1786).

The work of these acknowledged leaders of geological thought attracted
singularly little attention on the Continent, and Lamarck’s volume on
denudation (Hydrogéologie), which appeared in 1802, although an
important contribution, sank out of sight. But the seed of the French
school found fertile ground in Edinburgh, the center of the geological
world during the first quarter of the nineteenth century. Hutton’s
“Theory of the Earth, with Proofs and Illustrations,” in which the
guidance of DeSaussure and Desmarest is gratefully acknowledged,
appeared in 1795. The original publication aroused only local interest,
but when placed in attractive form by Playfair’s “Illustrations of the
Huttonian Theory” (1802), the problem of the origin and development of
land forms assumed a commanding position in geological thought. Hutton
was peculiarly fortunate in his environment. He had the support and
assistance of a group of able scientific colleagues as well as the
bitter opposition of Jameson and of the defenders of orthodoxy. His
views were discussed in scientific publications and found their way to
literary and theological journals. Hutton’s conception of the processes
of land sculpture—slow upheaving and slow degradation of mountains,
differential weathering, and the carving of valleys by streams—has a
very modern aspect. Playfair’s book would scarcely be out of place in a
twentieth century class room. The following paragraphs are quoted from
it:[6]


  “... A river, of which the course is both serpentine and deeply
  excavated in the rock, is among the phenomena, by which the slow waste
  of the land, and also the cause of that waste, are most directly
  pointed out.

  The structure of the vallies among mountains, shews clearly to what
  cause their existence is to be ascribed. Here we have first a large
  valley, communicating directly with the plain, and winding between
  high ridges of mountains, while the river in the bottom of it descends
  over a surface, remarkable, in such a scene, for its uniform
  declivity. Into this, open a multitude of transverse or secondary
  vallies, intersecting the ridges on either side of the former, each
  bringing a contribution to the main stream, proportioned to its
  magnitude; and, except where a cataract now and then intervenes, all
  having that nice adjustment in their levels, which is the more
  wonderful, the greater the irregularity of the surface. These
  secondary vallies have others of a smaller size opening into them;
  and, among mountains of the first order, where all is laid out on the
  greatest scale, these ramifications are continued to a fourth, and
  even a fifth, each diminishing in size as it increases in elevation,
  and as its supply of water is less. Through them all, this law is in
  general observed, that where a higher valley joins a lower one, of the
  two angles which it makes with the latter, that which is obtuse is
  always on the descending side; ... what else but the water itself,
  working its way through obstacles of unequal resistance, could have
  opened or kept up a communication between the inequalities of an
  irregular and alpine surface....

   ... The probability of such a constitution [arrangement of valleys]
  having arisen from another cause, is, to the probability of its having
  arisen from the running of water, in such a proportion as unity bears
  to a number infinitely great.

   ... With Dr. Hutton, we shall be disposed to consider those great
  chains of mountains, which traverse the surface of the globe, as cut
  out of masses vastly greater, and more lofty than any thing that now
  remains.

  From this gradual change of lakes into rivers, it follows, that a lake
  is but a temporary and accidental condition of a river, which is every
  day approaching to its termination; and the truth of this is attested,
  not only by the lakes that have existed, but also by those that
  continue to exist.”


                           _Steps Backward._

Even Hutton’s clear reasoning, firmly buttressed by concrete examples,
was insufficient to overcome the belief in ready-made or violently
formed valleys and original corrugations and irregularities of mountain
surface. The pages of the Journal show that the principles laid down by
Playfair were too far in advance of the times to secure general
acceptance. In the first volume of the Journal, the gorge of the French
Broad River is assigned by Kain to “some dreadful commotion in nature
which probably shook these mountains to their bases,”[7] and the gorge
of the lower Connecticut is considered by Hitchcock (1824)[8] as a
breach which drained a series of lakes “not many centuries before the
settlement of this country.” The prevailing American and English view
for the first quarter of the nineteenth century is expressed in the
reviews in this Journal, where the well-known conclusions of Conybeare
and Phillips that streams are incompetent to excavate valleys are quoted
with approval and admiration is expressed for Buckland’s famous
“Reliquiæ Diluvianæ,” a 300–page quarto volume devoted to proof of a
deluge. The professor at Yale, Silliman, and the professor at Oxford,
Buckland, saw that an acceptance of Hutton’s views involved a
repudiation of the Biblical flood, and much space is devoted to
combating these “erroneous” and “unscientific” views. For example,
Buckland says:[9]


  “... The general belief is, that existing streams, avalanches and
  lakes, bursting their barriers, are sufficient to account for all
  their phenomena, and not a few geologists, especially those of the
  Huttonian school, at whose head is Professor Playfair, have till
  recently been of this opinion.... But it is now very clear to almost
  every man, who impartially examines the facts in regard to existing
  vallies, that the causes now in action, mentioned above, are
  altogether inadequate to their production; nay, that such a
  supposition would involve a physical impossibility. We do not believe
  that one-thousandth part of our present vallies were excavated by the
  power of existing streams.... In very many cases of large rivers, it
  is found, that so far from having formed their own beds, they are
  actually in a gradual manner filling them up.

  Again; how happens it that the source of a river is frequently below
  the head of a valley, if the river excavated that valley?

  The most powerful argument, however, in our opinion, against the
  supposition we are combating, is the phenomena of transverse and
  longitudinal valleys; both of which could not possibly have been
  formed by existing streams.”


Phillips writes in 1829:[10] “The excavation of valleys can be ascribed
to no other cause than a great flood of water which overtopped the
hills, whose summits those vallies descend.”

Faith in Noah’s flood as the dominant agent of erosion rapidly lost
ground through the teaching of Lyell after 1830, but the theory of
systematic development of landscapes by rivers gained little. In fact,
Scrope in 1830,[11] in showing that the entrenched meanders of the
Moselle prove gradual progressive stream work, was in advance of his
English contemporary. Judged by contributions to the Journal, Lyell’s
teaching served to standardize American opinion of earth sculpture
somewhat as follows: The ocean is the great valley maker, but rivers
also make them; the position of valleys is determined by original or
renewed surface inequalities or by faulting; exceptional
occurrences—earthquakes, bursting of lakes, upheavals and
depressions—have played an important part. Hayes (1839)[12] thought that
the surface of New York was essentially an upraised sea-bottom modified
by erosion of waves and ocean currents. Sedgwick (1838)[13] considered
high-lying lake basins proof of valleys which were shaped under the sea.
Many of the valleys in the Chilian Cordillera were thought by Darwin
(1844) to have been the work of waves and tides, and water gaps are
ascribed to currents “bursting through the range at those points where
the strata have been least inclined and the height consequently is
less.” Speaking of the magnificent stream-cut canyons of the Blue
Mountains of New South Wales, gorges which lead to narrow exits through
monoclines, Darwin says: “To attribute these hollows to alluvial action
would be preposterous.”[14]

The influence of structure in the formation of valleys is emphasized by
many contributors to the Journal. Hildreth in 1836, in a valuable
paper,[15] which is perhaps the first detailed topographic description
of drainage in folded strata, expresses the opinion that the West
Virginia ridges and valleys antedated the streams and that water gaps
though cut by rivers involve pre-existing lakes. Geddes (1826)[16]
denied that Niagara River cut its channel and speaks of valleys which
“were valleys e’er moving spirit bade the waters flow.” Conrad
(1839)[17] discussed the structural control of the Mohawk, the Ohio, and
the Mississippi, and Lieutenant Warren (1859)[18] concluded that the
Niobrara must have originated in a fissure. According to Lesley
(1862)[19] the course of the New River across the Great Valley and into
the Appalachians “striking the escarpment in the face” is determined by
the junction of anticlinal structures on the north with faulted
monoclines toward the south; a conclusion in harmony with the views of
Edward Hitchcock (1841)[17] that major valleys and mountain passes are
structural in origin and that even subordinate folds and faults may
determine minor features. “Is not this a beautiful example of
prospective benevolence on the part of the Deity, thus, by means of a
violent fracture of primary mountains, to provide for easy
intercommunication through alpine regions, countless ages afterwards!”
The extent of the wandering from the guidance of DeSaussure and Playfair
after the lapse of 50 years is shown by students of Switzerland. Alpine
valleys to Murchison (1851) were bays of an ancient sea; Schlaginweit
(1852) found regional and local complicated crustal movements a
satisfactory cause, and Forbes (1863) saw only glaciers.


                      _Valleys Formed by Rivers._

One strong voice before 1860 appears to have called Americans back to
truths expounded by Desmarest and Hutton. Dana in 1850[20] amply
demonstrated that valleys on the Pacific Islands owe neither their
origin, position or form to the sea or to structural factors. They are
the work of existing streams which have eaten their way headwards. Even
the valleys of Australia cited by Darwin as type examples of ocean work
are shown to be products of normal stream work. Dana went further and
gave a permanent place to the Huttonian idea that many bays, inlets, and
fiords are but the drowned mouths of stream-made valleys. In the same
volume in which these conclusions appeared, Hubbard (1850)[21] announced
that in New Hampshire the “deepest valleys are but valleys of erosion.”
The theory that valleys are excavated by streams which occupy them was
all but universally accepted after F. V. Hayden’s description[22] of
Rocky Mountain gorges (1862) and Newberry’s interpretation of the
canyons of Arizona (1862); but the scientific world was poorly prepared
for Newberry’s statement:[23]


  “Like the great canons of the Colorado, the broad valleys bounded by
  high and perpendicular walls _belong to a vast system of erosion, and
  are wholly due to the action of water_.... The first and most
  plausible explanation of the striking surface features of this region
  will be to refer them to that embodiment of resistless power—the sword
  that cuts so many geological knots—volcanic force. The Great Canon of
  the Colorado would be considered a vast fissure or rent in the earth’s
  crust, and the abrupt termination of the steps of the table lands as
  marking lines of displacement. This theory though so plausible, and so
  entirely adequate to explain all the striking phenomena, lacks a
  single requisite to acceptance, and that is _truth_.”


With such stupendous examples in mind, the dictum of Hutton seemed
reasonable: “there is no spot on which rivers may not formerly have
run.”


                        _Denudation by Rivers._

The general recognition of the competency of streams to form valleys was
a necessary prelude to the broader view expressed by Jukes (1862)[24]


  “The surfaces of our present lands are as much carved and sculptured
  surfaces as the medallion carved from the slab, or the statue
  sculptured from the block. They have been gradually reached by the
  removal of the rock that once covered them, and are themselves but of
  transient duration, always slowly wasting from decay.”


Contributions to the Journal between 1850 and 1870 reveal a tendency to
accept greater degrees of erosion by rivers, but the necessary
end-product of subaërial erosion—a plain—is first clearly defined by
Powell in 1875.[25] In formulating his ideas Powell introduced the term
“base-level,” which may be called the germ word out of which has grown
the “cycle of erosion,” the master key of modern physiographers. The
original definition of base-level follows:


  “We may consider the level of the sea to be a grand base-level, below
  which the dry lands cannot be eroded; but we may also have, for local
  and temporary purposes, other base-levels of erosion, which are the
  levels of the beds of the principal streams which carry away the
  products of erosion. (I take some liberty in using the term ‘level’ in
  this connection, as the action of a running stream in wearing its
  channel ceases, for all practical purposes, before its bed has quite
  reached the level of the lower end of the stream. What I have called
  the base-level would, in fact, be an imaginary surface, inclining
  slightly in all its parts toward the lower end of the principal stream
  draining the area through which the level is supposed to extend, or
  having the inclination of its parts varied in direction as determined
  by tributary streams.)”


Analysis of Powell’s view has given definiteness to the distinction
between “base-level,” an imaginary plane, and “a nearly featureless
plain,” the actual land surface produced in the last stage of subaërial
erosion.

Following their discovery in the Colorado Plateau Province, denudation
surfaces were recognized on the Atlantic slope and discussed by McGee
(1888),[26] in a paper notable for the demonstration of the use of
physiographic methods and criteria in the solution of stratigraphic
problems. Davis (1889)[27] described the upland of southern New England
developed during Cretaceous time, introducing the term “peneplain,” “a
nearly featureless plain.” The short-lived opposition to the theory of
peneplanation indicates that in America at least the idea needed only
formulation to insure acceptance.

It is interesting to note that surfaces now classed as peneplains were
fully described by Percival (1842),[28] who assigned them to structure,
and by Kerr (1880),[29] who considered glaciers the agent. In Europe
“plains of denudation” have been clearly recognized by Ramsay (1846),
Jukes (1862), A. Geikie (1865), Foster and Topley (1865), Maw (1866),
Wynne (1867), Whitaker (1867), Macintosh (1869), Green (1882),
Richthofen (1882), but all of them were looked upon as products of
marine work, and writers of more recent date in England seem reluctant
to give a subordinate place to the erosive power of waves. Americans, on
the other hand, have been thinking in terms of rivers, and the great
contribution of the American school is not that peneplains exist, but
that they are the result of normal subaërial erosion. More precise field
methods during the past decade have revealed the fact that no one agent
is responsible for the land forms classed as peneplains; that not only
rivers and ocean, but ice, wind, structure, and topographic position
must be taken into account.

The recognition of rivers as valley-makers and of the final result of
stream work necessarily preceded an analysis of the process of subaërial
erosion. The first and last terms were known, the intermediate terms and
the sequence remained to be established. A significant contribution to
this problem was made by Jukes (1862).[34]


  “... I believe that the lateral valleys are those which were first
  formed by the drainage running directly from the crests of the chains,
  the longitudinal ones being subsequently elaborated along the strike
  of the softer or more erodable beds exposed on the flanks of those
  chains.”


Powell’s discussion of antecedent and consequent drainage (1875) and
Gilbert’s chapter on land sculpture in the Henry Mountain report (1880)
are classics, and McGee’s contribution[30] contains significant
suggestions, but the master papers are by Davis,[31] who introduces an
analysis of land forms based on structure and age by the statement:


  “Being fully persuaded of the gradual and systematic evolution of
  topographical forms it is now desired ... to seek the causes of the
  location of streams in their present courses; to go back if possible
  to the early date when central Pennsylvania was first raised from the
  sea, and trace the development of the several river systems then
  implanted upon it from their ancient beginning to the present time.”


That such a task could have been undertaken a quarter of a century ago
and to-day considered a part of everyday field work shows how completely
the lost ground of a half century has been regained and how rapid the
advance in the knowledge of land sculpture since the canyons of the
Colorado Plateau were interpreted.


                 _Features Resulting from Glaciation._


                         _The Problem Stated._

Early in the nineteenth century when speculation regarding the interior
of the earth gave place in part to observations of the surface of the
earth, geologists were confronted with perhaps the most difficult
problem in the history of the science. As stated by the editor of the
Journal in 1821:[32]


  “The almost universal existence of rolled pebbles, and boulders of
  rock, not only on the margin of the oceans, seas, lakes, and rivers;
  but their existence, often in enormous quantities, in situations quite
  removed from large waters; inland,—in high banks, embedded in strata,
  or scattered, occasionally, in profusion, on the face of almost every
  region, and sometimes on the tops and declivities of mountains, as
  well as in the vallies between them; their entire difference, in many
  cases, from the rocks in the country where they lie—rounded masses and
  pebbles of primitive rocks being deposited in secondary and alluvial
  regions, and vice versa; these and a multitude of similar facts have
  ever struck us as being among the most interesting of geological
  occurrences, and as being very inadequately accounted for by existing
  theories.”


The phenomena demanding explanation—jumbled masses of “diluvium,”
polished and striated rock, bowlders distributed with apparent disregard
of topography—were indeed startling. Even Lyell, the great exponent of
uniformitarianism, appears to have lost faith in his theories when
confronted with facts for which known causes seemed inadequate. The
interest aroused is attested by 31 titles in the Journal during its
first two decades, articles which include speculations unsupported by
logic or fact, field observation unaccompanied by explanation, field
observation with fantastic explanation, _ex-cathedra_ pronouncements by
prominent men, sound reasoning from insufficient data, and unclouded
recognition of cause and effect by both obscure and prominent men. With
little knowledge of glaciers, areal geology, or of structure and
composition of drift, all known forces were called in: normal
weathering, catastrophic floods, ocean currents, waves, icebergs,
glaciers, wind, and even depositions from a primordial atmosphere
(Chabier, 1823). Human agencies were not discarded. Speaking of a
granite bowlder at North Salem, New York, described by Cornelius
(1820)[33] as resting on limestone, Finch (1824)[34] says: “it is a
magnificent cromlech and the most ancient and venerable monument which
America possesses.” In the absence of a known cause, catastrophic
agencies seem reasonable.


                             _The Deluge._

In the seventh volume of the Journal (1824)[35] we read:


  “After the production of these regular strata of sand, clay,
  limestone, &c. came a terrible irruption of water from the north, or
  northwest, which in many places covered the preceding formations with
  diluvial gravel, and carried along with it those immense masses of
  granite, and the older rocks, which attest to the present day the
  destruction and ruin of a former world.”


Another author remarks:


  “We find a mantle as it were of sand and gravel indifferently covering
  all the solid strata, and evidently derived from some convulsion which
  has lacerated and partly broken up those strata....”


The catastrophe favored by most geologists was floods of water violently
released—“we believe,” says the editor, “that all geologists agree in
imputing ... the diluvium to the agency of a deluge at one period or
another.”[36] Such conclusions rested in no small way upon Hayden’s
well-known treatise on surficial deposits (1821),[37] a volume which
deserves a prominent place in American geological literature. Hayden
clearly distinguished the topographic and structural features of the
drift but found an adequate cause in general wide-spread currents which
“flowed impetuously across the whole continent ... from north east to
south west.” In reviewing Hayden’s book Silliman remarks:


  “The general cause of these currents Mr. Hayden concludes to be the
  deluge of Noah. While no one will object to the propriety of ascribing
  very many, probably most of our alluvial features, to that
  catastrophe, we conceive that neither Mr. Hayden, nor any other man,
  is bound to prove the immediate physical cause of that vindictive
  infliction.

  We would beg leave to suggest the following as a cause which _may_
  have aided in deluging the earth, and which, were there occasion,
  _might_ do it again.

  The existence of enormous caverns in the bowels of the earth, (so
  often imagined by authors,) appears to be no very extravagant
  assumption. It is true it cannot be proved, but in a sphere of eight
  thousand miles in diameter, it would appear in no way extraordinary,
  that many cavities might exist, which collectively, or even singly,
  might well contain much more than all our oceans, seas, and other
  superficial waters, none of which are probably more than a few miles
  in depth. If these cavities communicate in any manner with the oceans,
  and are (as if they exist at all, they probably are,) filled with
  water, there exist, we conceive, agents very competent to expel the
  water of these cavities, and thus to deluge, at any time, the dry
  land.”


The teachings of Hayden were favorably received by Hitchcock, Struder,
and Hubbard, and many Europeans. They found a champion in Jackson, who
states (1839):[38]


  “From the observations made upon Mount Ktaadn, it is proved, that the
  current did rush over the summit of that lofty mountain, and
  consequently the diluvial waters rose to the height of more than 5,000
  feet. Hence we are enabled to prove, that the ancient ocean, which
  rushed over the surface of the State, was at least a mile in depth,
  and its transporting power must have been greatly increased by its
  enormous pressure.”


Gibson, a student of western geology, reaches the same conclusion
(1836):[39]


  “That a wide-spread current, although not, as imagined, fed from an
  inland sea, once swept over the entire region between the Alleghany
  and the Rocky Mountains is established by plenary proof.”


Professor Sedgwick (1831) thought the sudden upheaval of mountains
sufficient to have caused floods again and again. The strength of the
belief in the Biblical flood, during the first quarter of the 19th
century, may be represented by the following remarks of Phillips
(1832):[40]


  “Of many important facts which come under the consideration of
  geologists, the ‘Deluge’ is, perhaps, the most remarkable; and it is
  established by such clear and positive arguments, that if any one
  point of natural history may be considered as proved, the deluge must
  be admitted to have happened, because it has left full evidence in
  plain and characteristic effects _upon the surface of the earth_.”


However, the theory of deluges, whether of ocean or land streams, did
not hold the field unopposed. In 1823, Granger,[41] an observer whose
contributions to science total only six pages, speaks of the striæ on
the shore of Lake Erie as


  “having been formed by the powerful and continued attrition of some
  hard body.... To me, it does not seem possible that water under any
  circumstances, could have effected it. The flutings in width, depth,
  and direction, are as regular as if they had been cut out by a
  grooving plane. This, running water could not effect, nor could its
  operation have produced that glassy smoothness, which, in many parts,
  it still retains.”


Hayes and also Conrad expressed similar views in the Journal 16 years
later.

The idea that ice was in some way concerned with the transportation of
drift has had a curious history. The first unequivocal statement, based
on reading and keen observation, was made in the Journal by Dobson in
1826:[42]


  “I have had occasion to dig up a great number of bowlders, of red
  sandstone, and of the conglomerate kind, in erecting a cotton
  manufactory; and it was not uncommon to find them worn smooth on the
  under side, as if done by their having been dragged over rocks and
  gravelly earth, in one steady position. On examination, they exhibit
  scratches and furrows on the abraded part; and if among the minerals
  composing the rock, there happened to be pebbles of feldspar, or
  quartz, (which was not uncommon,) they usually appeared not to be worn
  so much as the rest of the stone, preserving their more tender parts
  in a ridge, extending some inches. When several of these pebbles
  happen to be in one block, the preserved ridges were on the same side
  of the pebbles, so that it is easy to determine which part of the
  stone moved forward, in the act of wearing.

  These bowlders are found, not only on the surface, but I have
  discovered them a number of feet deep, in the earth, in the hard
  compound of clay, sand, and gravel....

  I think we cannot account for these appearances, unless we call in the
  aid of ice along with water, and that they have been worn by being
  suspended and carried in ice, over rocks and earth, under water.”


In Dobson’s day the hypothesis of “gigantic floods,” “debacles,”
“resistless world-wide currents,” was so firmly entrenched that the
voice of the observant layman found no hearers, and a letter from Dobson
to Hitchcock written in 1837 and containing additional evidence and
argument remained unpublished until Murchison, in 1842,[43] paid his
respects to the remarkable work of a remarkable man.[44]


  “I take leave of the glacial theory in congratulating American science
  in having possessed the original author of the best glacial theory,
  though his name had escaped notice; and in recommending to you the
  terse argument of Peter Dobson, a previous acquaintance with which
  might have saved volumes of disputation on both sides of the
  Atlantic.”


                        _Glaciers vs. Icebergs._

The glacial theory makes its way into geological literature with the
development of Agassiz (1837) of the views of Venetz (1833) and
Charpentier (1834), that the glaciers of the Alps once had greater
extent. The bold assumption was made that the surface of Europe as far
south as the shores of the Mediterranean and Caspian seas was covered by
ice during a period immediately preceding the present. The kernel of the
present glacial theory is readily recognizable in these early works, but
it is wrapped in a strange husk: it was assumed that the Alps were
raised by a great convulsion under the ice and that the erratics slid to
their places over the newly made declivities. The publication of the
famous “Etudes sur les Glaciers” (1840), remarkable alike for its
clarity, its sound inductions, and wealth of illustrations, brought the
ideas of Agassiz more into prominence and inaugurated a 30–years’ war
with the proponents of currents and icebergs. The outstanding objections
to the theory were the requirement of a frigid climate and the demand
for glaciers of continental dimensions; very strong objections, indeed,
for the time when fossil evidence was not available, the great polar ice
sheets were unexplored, and the distinction between till and waterlaid
drift had not been established.

The glacial theory was cordially adopted by Buckland (1841)[45] and in
part by Lyell in England but viewed with suspicion by Sedgwick, Whewell,
and Mantell. In America the response to the new idea was immediate.
Hitchcock (1841)[46] concludes an able discussion with the statement:
“So remarkably does it solve most of the phenomena of diluvial action,
that I am constrained to believe its fundamental principles to be
founded in truth.”

The theory formed the chief topic of discussion at the third and fourth
meetings of the Association of American Geologists and Naturalists
(1842, 1843) under the lead of a committee on drift consisting of
Emmons, W. B. Rogers, Vanuxem, Nicollet, Jackson, and J. L. Hayes. The
result of these discussions was a curious reaction. Hitchcock complained
that he “had been supposed to be an advocate for the unmodified glacial
theory, but he had never been a believer in it,” and Jackson spoke for a
number of men when he stated:[47]


  “This country exhibits no proofs of the glacial theory as taught by
  Agassiz but on the contrary the general bearing of the facts is
  against that theory.... Many eminent men incautiously embraced the new
  theory, which within two or three years from its promulgation, had
  been found utterly inadequate, and is now abandoned by many of its
  former supporters.”


Out of this symposium came also the strange contribution of H. D. Rogers
(1844),[48] who cast aside the teachings of deduction and observation
and returned to the views of the Medievalists.


  “If we will conceive, then, a wide expanse of waters, less perhaps
  than one thousand feet in depth, dislodged from some high northern or
  circumpolar basin, by a general lifting of that region of perhaps a
  few hundred feet, and an equal subsidence of the country south, and
  imagine this whole mass converted by earthquake pulsations of the
  breadth which such undulations have, into a series of stupendous and
  rapid-moving waves of translation, helped on by the still more rapid
  flexures of the floor over which they move, and then advert to the
  shattering and loosening power of the tremendous jar of the
  earthquake, we shall have an agent adequate in every way to produce
  the results we see, to float the northern ice from its moorings, to
  rip off, assisted with its aid, the outcrops of the hardest strata, to
  grind up and strew wide their fragments, to scour down the whole rocky
  floor, and, gathering energy with resistance, to sweep up the slopes
  and over the highest mountains.”


Because of the prominence of their author, Rogers’s views exerted some
influence and seemingly received support from England through the
elaborate mathematic discussions of Whewell (1848), who considered the
drift as “irresistible proof of paroxysmal action,” and Hopkins (1852),
who contended for “currents produced by repeated elevatory movements.”

After his arrival in America (1846), Agassiz’s influence was felt, and
his paper on the erratic phenomena about Lake Superior (1850),[49] in
which he called upon the advocates of water-borne ice to point out the
barrier which caused the current to subside, produced a salutary effect;
yet Desor (1852)[50] states that in the region described by Agassiz “the
assumption [of a general ice cap] is no longer admissible,” and that the
bowlders on Long Island “were transported on ice rafts along the sea
shore and stranded on the ridges and eminences which were then shoals
along the coast.” Twenty years of discussion were insufficient to
establish the glacial theory either in Europe or America. The consensus
of opinion among the more advanced thinkers in 1860 is expressed by
Dana:[51]


  “In view of the whole subject, it appears reasonable to conclude that
  the Glacier theory affords the best and fullest explanation of the
  phenomena over the general surface of the continents, and encounters
  the fewest difficulties. But icebergs have aided beyond doubt in
  producing the results along the borders of the continents, across
  ocean-channels like the German Ocean and the Baltic, and possibly over
  great lakes like those of North America. Long Island Sound is so
  narrow that a glacier may have stretched across it.”


Papers in the Journal of 1860–70 show a prevailing belief in icebergs,
but the evidence for land ice was accumulating as the deposits became
better known, and in 1871 field workers speak in unmistakable tones:[52]


  “It is still a mooted question in American geology whether the events
  of the Glacial era were due to _glaciers_ or _icebergs_.... American
  geologists are still divided in opinion, and some of the most eminent
  have pronounced in favor of icebergs.

  Since, then, icebergs cannot pick up masses tons in weight from the
  bottom of a sea, or give a general movement southward to the loose
  material of the surface; neither can produce the abrasion observed
  over the rocks under its various conditions; and inasmuch as all
  direct evidence of the submergence of the land required for an iceberg
  sea over New England fails, the conclusion appears inevitable that
  icebergs had nothing to do with the drift of the New Haven region, in
  the Connecticut valley; and, therefore, that the Glacial era in
  central New England was a _Glacier_ era.”


Matthew (1871)[53] reached the same conclusion for the Lower Provinces
of Canada. In spite of the increasing clarity of the evidence, the
battle for the glacial theory was not yet won. The remaining opponents
though few in number were distinguished in attainments. Dawson clung to
the outworn doctrine until his death in 1899.

An interesting feature of the history of glacial theories is the
calculation by Maclaren (1842)[54] that the amount of water abstracted
from the seas to form the hypothetical ice sheet would lower the ocean
level 350 feet—an early form of the glacial control hypothesis (see
Daly[55]).


                       _Extent of Glacial Drift._

By the middle of the nineteenth century, it was recognized that the
“drift,” whatever its origin, was not of world-wide extent. In America
its characteristic features were found best developed north of latitude
40 degrees; in Europe, the Alps, the Scottish Highlands, and Scandinavia
were recognized as type areas. The limits were unassigned, partly
because the field had not been surveyed, but largely because criteria
for the recognition of drift had not been established. The well-known
hillocks and ridges of “diluvium” and “alluvium” and “drift” of New
Jersey and Ohio, and the mounds of the Missouri Cotou elaborately
described by Catlin (1840)[56] bore little resemblance to the walls of
unsorted rock which stand as moraines bordering Alpine glaciers. The
Orange sand of Mississippi was included in the drift by Hilgard
(1866),[57] and the gravels at Philadelphia by Hall (1876).[58] Stevens
(1873)[59] described trains of glacial erratics at Richmond, Virginia,
and William B. Rogers (1876)[60] accounts for certain deposits in the
Potomac, James, and Roanoke rivers by the presence of Pleistocene ice
tongues or swollen glacial rivers, and remarks: “It is highly probable
that glacial action had much to do with the original accumulation of the
rocky debris on the flanks of the Blue Ridge, and in the Appalachian
valleys beyond.” Kerr (1881)[61] referred the ancient erosion surface of
the Piedmont belt in North Carolina to glacial denudation, De la Beche
compared the drift of Jamaica with that of New England, and Agassiz
interpreted soils of Brazil as glacial.

The first detailed description and unequivocal interpretation of either
terminal or recessional moraines is from the pen of Gilbert (1871),[62]
geologist of the Ohio Survey. In discussing the former outlet of Lake
Erie through the Fort Wayne channel, Gilbert writes:


  “The page of history recorded in these phenomena is by no means
  ambiguous. The ridges, or, more properly, the ridge which determines
  the courses of the St. Joseph and St. Marys rivers is a buried
  terminal moraine of the glacier that moved southwestward through the
  Maumee valley. The overlying Erie Clay covers it from sight, but it is
  shadowed forth on the surface of that deposit, as the ground is
  pictured through a deep and even canopy of snow. Its irregularly
  curved outline accords intimately with the configuration of the
  valley, and with the direction of the ice markings; its concavity is
  turned toward the source of motion; its greatest convexity is along
  the line of least resistance.

  South of the St. Marys river are other and numerous moraines
  accompanied by glacial striæ. Their character and courses have not yet
  been studied; but their presence carries the mind back to an epoch of
  the cold period, when the margin of the icefield was farther south,
  and the glacier of the Maumee valley was merged in the general mass.
  As the mantle of ice grew shorter—and, in fact, at every stage of its
  existence—its margin must have been variously notched and lobed in
  conformity with the contour of the country, the higher lands being
  first laid bare by the encroaching secular summer. Early in the
  history of this encroachment the glacier of the Maumee valley
  constituted one of these lobes, and has recorded its form in the two
  moraines that I have described.”


Three years after the recognition of moraines in the Maumee valley,
Chamberlin (1874)[63] showed that the seemingly disorganized mounds and
basins and ridges known as the Kettle range of Wisconsin is the terminal
moraine of the Green Bay glacier. At an earlier date (1864) Whittlesey
interpreted the kettles of the Wisconsin moraine as evidence of ice
blocks from a melting glacier and presented a map showing the “southern
limit of boulders and coarse drift.” In 1876 attention was called to the
terminal moraine of New England by G. Frederick Wright, who assigns the
honor of discovery to Clarence King.

[Illustration: G K Gilbert]

With the observations of Gilbert, Chamberlin, and King in mind, the
terminal moraine was traced by various workers across the United States
and into Canada and the extent of glacial cover revealed. Following 1875
the pages of the Journal contain many contributions dealing with the
origin and structure of moraines, eskers, kames, and drumlins. Before
1890 twenty-eight papers on the glacial phenomena of the Erie and Ohio
basin alone had appeared. By 1900 substantial agreement had been reached
regarding the significant features of the drift, the outline history of
the Great Lakes had been written, and the way had been paved for
stratigraphic studies of the Pleistocene, which bulk large in the pages
of the Journal for the last two decades.


                        _Epochs of Glaciation._

For a decade following the general acceptance of the glacial origin of
“diluvium,” the deposits were embraced as “drift” and treated as the
products of one long period of glacial activity, and throughout the
controversy of iceberg and glacier the unity of the glacial period was
unquestioned. Beds of peat and fossiliferous lacustrine deposits in
Switzerland, England, and in America and the recognition of an “upper”
and a “lower” diluvium by Scandinavian geologists suggested two epochs,
and as the examples of such deposits increased in number and it became
evident that the plant fossils represented forms demanding a genial
climate and that the phenomena were seen in many countries, the belief
grew that minor fluctuations or gradual recession of an ice sheet were
inadequate to account for the phenomena observed.

It is natural that this problem should have found its solution in
America, where the Pleistocene is admirably displayed, and where the
State and Federal surveys were actively engaged in areal mapping. In
1883 Chamberlin[64] presented his views under the bold title,
“Preliminary Paper on the Terminal Moraine of the Second Glacial Epoch,”
and the existence of deposits of two or more ice sheets and the features
of interglacial periods were substantially established by the
interesting debate in the Journal led by Chamberlin, Wright, Upham and
Dana.[65] Contributions since 1895 have been concerned with the degree
rather than the fact of complexity, and continued study has resulted in
the general recognition of five glacial stages in North America and four
in Europe.


                   _The Loess as a Glacial Deposit._

A curious side-product of the study of glaciation in North America is
the controversy over the origin of loess. The interest aroused is
indicated by scores of papers in American periodicals and State reports
of the last quarter of the 19th century—papers which bear the names of
prominent geologists.

The “loess” in the valley of the Rhine had long been known, but the
subject assumed prominence by the publication in 1866 of Pumpelly’s
Travels in China.[66] Wide-spread deposits 200 to 1,000 feet thick were
described as very fine-grained yellowish earth of distinctive structure
without stratification but penetrated by innumerable tubes and
containing land or fresh-water shells. Pumpelly considered these
deposits lacustrine, a view which found general acceptance though
combated by Kingsmill (1871),[67] who argued for marine deposition.
Baron Von Richthofen’s classic on China, which appeared in 1877,
amplifies the observations of Pumpelly and marshals the evidence to
support the hypothesis that the loess is wind-laid both on dry land and
within ancient salt lakes. The conclusions of Von Richthofen were
adopted by Pumpelly whose knowledge of the Chinese deposits,
supplemented by studies in Missouri, of which State he was director of
the Geological Survey in 1872–73, placed him in position to form a
correct judgment. He says:[68]


  “Recognizing from personal observation the full identity of character
  of the loess of northern China, Europe and the Missouri Valley, I am
  obliged to reject my own explanation of the origin of the Chinese
  deposits, and to believe with Richthofen that the true loess, wherever
  it occurs, is a sub-aerial deposit, formed in a dry central region,
  and that it owes its structure to the formative influence of a steppe
  vegetation.

  The one weak point of Richthofen’s theory is in the evident inadequacy
  of the current disintegration as a source of material. When we
  consider the immense area covered by loess to depths varying from 50
  to 2,000 feet, and the fact that this is only the very finest portion
  of the product of rock-destruction, and again that the accumulation
  represents only a very short period of time, geologically speaking,
  surely we must seek a more fertile source of supply than is furnished
  by the current decomposition of rock surface.

  It seems to me that there are two important sources: I. The silt
  brought by rivers, many of them fed by the products of glacial
  attrition flowing from the mountains into the central region. Where
  the streams sink away, or where the lakes which receive them have
  dried up, the finer products of the erosion of a large territory are
  left to be removed in dust storms.

  II. The second ... source is the residuary products of a secular
  disintegration.”


The evidence presented by Pumpelly for the eolian origin of
loess—structure, texture, composition, fossil content and topographic
position—is complete, and to him belongs the credit for the correct
interpretation of the Mississippi valley deposits. Unfortunately his
contribution came at a time when the geologists of the central States
were intent on tracing the paths and explaining the work of Pleistocene
glaciers, and the belief was strong that loess was some phase of glacial
work. Its position at the border of the Iowan drift so obviously
suggests a genetic relation that the fossil evidence of steppe climate
suggested by Binney in 1848[69] was minimized. Students of Pleistocene
geology in Minnesota, Iowa, Nebraska, Missouri, although less vigorous
in expression, were substantially in agreement with Hilgard (1879).[70]
“The sum total of anomalous conditions required to sustain the eolian
hypothesis partakes strongly of the marvellous.” The last edition of
Dana’s Manual, 1894, and of LeConte’s Geology, 1896, the two most widely
used text-books of their time, oppose the eolian theory, and Chamberlin,
in 1897,[71] states: “the aqueous hypothesis seems best supported so far
as concerns the deposits of the Mississippi Valley and western Europe”
(p. 795). Shimek, in papers published since 1896 has shown that aquatic
and glacial conditions can not account for the loess fossils, and the
return to the views of Pumpelly that the loess was deposited on land by
the agency of wind in a region of steppe vegetation is now all but
universal.


                          _Glacial Sculpture._

Within the present generation sculpture by glaciers has received much
attention and has involved a reconsideration of the ability of ice to
erode which in turn involves a crystallization of views of the mechanics
of moving ice. The evidence for glacier erosion has remained largely
physiographic and rests on a study of land forms. In fact, the
inadequacy of structural features or of river corrasion to account for
flat-floored, steep-walled gorges, hanging valleys, and many lake
basins, rather than a knowledge of the mechanics of ice has led to the
present fairly general belief that glaciers are powerful agents of rock
sculpture. The details of the process are not yet understood.

Erosion by glaciers enters the arena of active discussion in 1862–63.
The possibility had been suggested by Esmark (1827) and by Dana (1849)
in the description of fiords and by Hind (1855) with reference to the
origin of the Great Lakes. It appears full-fledged in Ramsay’s classic,
which was published simultaneously in England and in America.[72] The
argument runs as follows: There is a close association of ancient
glaciers and lakes especially in mountains; glaciers are amply able to
erode; evidences of faulting, special subsidence, river erosion, and
marine erosion are absent from the lake basins of Switzerland and Great
Britain. To quote Ramsay:


  “It required a solid body grinding steadily and powerfully in direct
  and heavy contact with and across the rocks to scoop out deep hollows,
  the situations of which might either be determined by unequal hardness
  of the rocks, by extra weight of ice in special places, or by
  accidental circumstances, the clue to which is lost from our inability
  perfectly to reconstruct the original forms of the glaciers.”

  “I believe with the Italian geologists, that all that the glaciers as
  a whole effected was only slightly to deepen these valleys and
  materially to modify their general outlines, and, further (a theory I
  am alone responsible for), to deepen them in parts more considerably
  when, from various causes, the grinding power of the ice was unusually
  powerful, especially where, as in the lowlands of Switzerland, the
  Miocene strata are comparatively soft.”


Whittlesey (1864)[73] considered that the rock-bound lakes and narrow
bays near Lake Superior were partly excavated by ice. LeConte (1875)[74]
records some significant observations in a pioneer paper on glacier
erosion which has not received adequate recognition. He says:


  “... I am convinced that a glacier, by its enormous pressure and
  resistless onward movement, is _constantly breaking off large blocks_
  from its bed and bounding walls. Its erosion is not only a grinding
  and scoring, but also a _crushing and breaking_. It makes by its
  erosion not only rock-meal, but also large _rock-chips_.... Its
  erosion is a constant process of alternate _rough hewing_ and
  _planing_.

  If Yosemite were unique, we might suppose that it was formed by
  violent cataclysms; but _Yosemite is not unique_ in _form_ and
  therefore probably not in _origin_. There are many Yosemites. It is
  more philosophical to account for them by the _regular_ operation of
  known causes. I must believe that all these deep perpendicular slots
  have been sawn out by the action of glaciers; the _peculiar
  verticality of the walls having been determined by the perpendicular
  cleavage structure_.”... A lake in Bloody Canyon “is a _pure rock
  basin scooped out by the glacier_ at this place.... These ridges
  [separating Hope, Faith, and Charity valleys] are in fact the lips of
  consecutive lake basins scooped out by ice.

  ... Water tends to form deep V-shaped canons, while ice produces broad
  valleys with lakes and meadows.... I know not how general these
  distinctions may be, but certainly the Coast range of this State is
  characterized by rounded summits and ridges, and deep V-shaped canons,
  while the high Sierras are characterized on the contrary by sharp,
  spire-like, comb-like summits, and broad valleys; and this difference
  I am convinced is due in part at least to the action of water on the
  one hand, and of ice on the other.”


King (1878)[75] assigned to glacial erosion a commanding position in
mountain sculpture. In regard to the Uintas, he says:


  “Glacial erosion has cut almost vertically down through the beds
  carving immense amphitheatres with basin bottoms containing numerous
  Alpine lakes.... Post-glacial erosion has done an absolutely trivial
  work. There is not a particle of direct evidence, so far as I can see,
  to warrant the belief that these U-shaped canons were given their
  peculiar form by other means than the actual ploughing erosion of
  glaciers....”


These contributions from the Cordilleras corroborating the conclusions
of Ramsay (1862), Tyndall (1862), Jukes (1862), Hector (1863), Logan
(1863), Close (1870), and James Geikie (1875), made little impression.
The views of Lyell (1833), Ball (1863), J. W. Dawson (1864), Falconer
(1864), Studer (1864), Murchison (1864, 1870), Ruskin (1865), Rutimeyer
(1869), Whymper (1871), Bonney (1873), Pfaff (1874), Gurlt (1874), Judd
(1876), prevailed, and the conclusions of Davis in 1882[76] fairly
expressed the prevailing belief in Europe and in America:


  “The amount of glacial erosion in the central districts has been very
  considerable, but not greatly in excess of pre-glacial soils and old
  talus and alluvial deposits. Most of the solid rock that was carried
  away came from ledges rather than from valleys; and glaciers had in
  general a smoothing rather than a roughening effect. In the outer
  areas on which the ice advanced it only rubbed down the projecting
  points; here it acted more frequently as a depositing than as an
  eroding agent.”


During the past quarter-century the cleavage in the ranks of geologists,
brought about by Ramsay’s classic paper, has remained. Fairchild and
others in America, Heim, Bonney, and Garwood in Europe argue for
insignificant erosion by glaciers; and Gannet, Davis, Gilbert, Tarr in
America followed by Austrian workers present evidence for erosion on a
gigantic scale. A perusal of the voluminous literature in the Journal
and elsewhere shows that the difference of opinion is in part one of
terms, the amount of erosion rather than the fact of erosion; it also
arises from failure to differentiate the work of mountain glaciers and
continental ice sheets, of Pleistocene glaciers and their present
diminished representatives. The irrelevant contribution of physicists
has also made for confusion.

It is interesting to note that the criteria for erosion of valleys by
glaciers has long been established and by workers in different
countries. Ramsay (1862) in England outlined the problem and presented
generalized evidence. Hector (1863) in New Zealand pointed out the
significance of discordant drainage, the “hanging valleys” of Gilbert.
The U-form, the broad lake-dotted floor, and the presence of cirques and
the process of plucking were probably first described by LeConte (1873)
in America. The truncation of valley spurs by glaciers pointed out by
Studer in the Kerguelen Islands (1878) was used by Chamberlin (1883) as
evidence of glacial scouring.


                             _Conclusion._

During the past century many principles of land sculpture have emerged
from the fog of intellectual speculation and unorganized observation and
taken their place among generally accepted truths. Many of them are no
longer subjects of controversy. Erosion has found its place as a major
geologic agent and has given a new conception of natural scenery. Lofty
mountains are no longer “ancient as the sun,” they are youthful features
in process of dissection; valleys and canyons are the work of streams
and glaciers; fiords are erosion forms; waterfalls and lakes are
features in process of elimination; many plains and plateaus owe their
form and position to long-continued denudation. Modern landscapes are no
longer viewed as original features or the product of a single agent
acting at a particular time, but as ephemeral forms which owe their
present appearance to their age and the particular forces at work upon
them as well as to their original structure.

It is interesting to note the halting steps leading to the present
viewpoint, to find that decades elapsed between the formulation of a
theory or the recording of significant facts and their final acceptance
or rejection, and to realize that the organization of principles and
observations into a science of physiography has been the work of the
present generation. Progress has been conditioned by a number of factors
besides the intellectual ability of individual workers.

The influence of locality is plainly seen. Convincing evidence of river
erosion was obtained in central France, the Pacific Islands, and the
Colorado Plateau—regions in which other causes were easily eliminated.
Sculpture by glaciers passed beyond the theoretical stage when the
simple forms of the Sierras and New Zealand Alps were described. The
origin of loess was first discerned in a region where glacial phenomena
did not obscure the vision. The complexity of the Glacial period
asserted by geologists of the Middle West was denied by eastern
students. The work of waves on the English coast impressed British
geologists to such an extent that plains of denudation and inland
valleys were ascribed to ocean work.

In the establishment of principles, the friendly interchange of ideas
has yielded large returns. Many of the fundamental conceptions of earth
sculpture have come from groups of men so situated as to facilitate
criticism. It is impossible, even if desirable, to award individual
credit to Venetz, Charpentier, and Agassiz in the formulation of the
glacial theory; and the close association of Agassiz and Dana in New
England and of Chamberlin and Irving in Wisconsin was undoubtedly
helpful in establishing the theory of continental glaciation. From the
intimate companionship in field and laboratory of Hutton, Playfair and
Hope, arose the profound influence of the Edinburgh school, and the
sympathetic cooperation of Powell, Gilbert, and Dutton has given to the
world its classics in the genetic study of land forms.

The influence of ideas has been closely associated with clarity,
conciseness, and attractiveness of presentation. Hutton is known through
Playfair, Agassiz’s contributions to glacial geology are known to every
student, while Venetz, Charpentier, and Hugi are only names. Cuvier’s
discourses on dynamical geology were reprinted and translated into
English and German, but Lamarck’s “Hydrogéologie” is known only to book
collectors. The verbose works of Guettard, although carrying the same
message as Playfair’s “Illustrations” and Desmarest’s “Memoirs,” are
practically unknown, as is also Horace H. Hayden’s treatise (1821) on
the drift of eastern North America. It has been well said that the
world-wide influence of American physiographic teaching is due in no
small part to the masterly presentations of Gilbert and Davis.

It is surprising to note the delays, the backward steps, and the
duplication of effort resulting from lack of familiarity with the work
of the pioneers. Sabine says in 1864:[77]


  “It often happens, not unnaturally, that those who are most occupied
  with the questions of the day in an advancing science retain but an
  imperfect recollection of the obligations due to those who laid the
  first foundations of our subsequent knowledge.”


The product of intellectual effort appears to be conditioned by time of
planting and character of soil as well as by quantity of seed. For
example: Erosion by rivers was as clearly shown by Desmarest as by Dana
and Newberry 50 years later. Criteria for the recognition of ancient
fluviatile deposits were established by James Deane in 1847 in a study
of the Connecticut Valley Triassic. Agassiz’s proof that ice is an
essential factor in the formation of till is substantially a duplication
of Dobson’s observations (1826).

The volumes of the Journal with their very large number of articles and
reviews dealing with geology show that the interpretation of land forms
as products of subaërial erosion began in France and French Switzerland
during the later part of the eighteenth century as a phase of the
intellectual emancipation following the Revolution. Scotland and England
assumed the leadership for the first half of the nineteenth century, and
the first 100 volumes of the Journal show the profound influence of
English and French teaching. In America, independent thinking, early
exercised by the few, became general with the establishment of the
Federal survey, the increase in university departments, geological
societies and periodicals, and has given to Americans the
responsibilities of teachers.


                            _Bibliography._

(In the following list “this Journal” refers to the American Journal of
Science.)

Footnote 4:

  Wilson, J. W., Bursting of lakes through mountains, this Journal, =3=,
  253, 1821.

Footnote 5:

  Whitney, J. D., Progress of the Geological Survey of California, this
  Journal, =38=, 263–264, 1864.

Footnote 6:

  Playfair, John, Illustrations of the Huttonian theory of the earth,
  Edinburgh, 1802.

Footnote 7:

  Kain, J. H., Remarks on the mineralogy and geology of northwestern
  Virginia and eastern Tennessee, this Journal, =1=, 60–67, 1819.

Footnote 8:

  Hitchcock, Edward, Geology, etc., of regions contiguous to the
  Connecticut, this Journal, =7=, 1–30, 1824.

Footnote 9:

  Buckland, Wm., Reliquiæ diluvianæ, this Journal, =8=, 150, 317, 1824.

Footnote 10:

  Phillips, John, Geology of Yorkshire, this Journal, =21=, 17–20, 1832.

Footnote 11:

  Scrope, G. P., Excavation of valleys, Geol. Soc., London, No. =14=,
  1830.

Footnote 12:

  Hayes, G. E., Remarks on geology and topography of western New York,
  this Journal, =35=, 88–91, 1839.

Footnote 13:

  Seventh Meeting of the British Association for the Advancement of
  Science, this Journal, =33=, 288, 1838.

Footnote 14:

  Darwin, Charles, Geological observations on the volcanic islands and
  parts of South America, etc., second part of the Voyage of the
  “Beagle,” during 1832–1836. London, 1844.

Footnote 15:

  Hildreth, S. P., Observations, etc., valley of the Ohio, this Journal,
  =29=, 1–148, 1836.

Footnote 16:

  Geddes, James, Observations on the geological features of the south
  side of Ontario valley, this Journal, =11=, 213–218, 1826.

Footnote 18:

  Warren, G. K., Preliminary report of explorations in Nebraska and
  Dakota, this Journal, =27=, 380, 1859.

Footnote 19:

  Lesley, J. P., Observations on the Appalachian region of southern
  Virginia, this Journal, =34=, review, 413–415, 1862.

Footnote 17:

  Conrad, T. A., Notes on American geology, this Journal, =35=, 237–251,
  1839.

Footnote 20:

  Dana, J. D., On denudation in the Pacific, this Journal, =9=, 48–62,
  1850.

  ——, On the degradation of the rocks of New South Wales and formation
  of valleys, this Journal, =9=, 289–294, 1850.

Footnote 21:

  Hubbard, O. P., On the condition of trap dikes in New Hampshire an
  evidence and measure of erosion, this Journal, =9=, 158–171, 1850.

Footnote 22:

  Hayden, F. V., Some remarks in regard to the period of elevation of
  the Rocky Mountains, this Journal, =33=, 305–313, 1862.

Footnote 23:

  Newberry, J. S., Colorado River of the West, this Journal, =33=,
  review, 387–403, 1862.

Footnote 24:

  Jukes, J. B., Address to the Geological Section of the British
  Association at Cambridge, Quart. Jour. Geol. Soc., 18, 1862, this
  Journal, =34=, 439, 1862.

Footnote 25:

  Powell, J. W., Exploration of the Colorado River of the West, 1875.
  For Powell’s preliminary article see this Journal, =5=, 456–465, 1873.

Footnote 26:

  McGee, W. J., Three formations of the Middle Atlantic slope, this
  Journal, =35=, 120, 328, 367, 448, 1888.

Footnote 27:

  Davis, W. M., Topographic development of the Triassic formation of the
  Connecticut Valley, this Journal, =37=, 423–434, 1889.

Footnote 28:

  Percival, J. G., Geology of Connecticut, 1842.

Footnote 29:

  Kerr, W. C., Origin of some new points in the topography of North
  Carolina, this Journal, =21=, 216–219, 1881.

Footnote 30:

  McGee, W. J., The classification of geographic forms by genesis, Nat.
  Geogr. Mag., =1=, 27–36, 1888.

Footnote 31:

  Davis, W. M., The rivers and valleys of Pennsylvania, Nat. Geogr.
  Mag., =1=, 183–253, 1889.

  ——, The rivers of northern New Jersey with notes on the classification
  of rivers in general, ibid., =2=, 81–110, 1890.

Footnote 32:

  Silliman, Benjamin, Notice of Horace H. Hayden’s geological essays,
  this Journal, =3=, 49, 1821.

Footnote 33:

  Cornelius, Elias, Account of a singular position of a granite rock,
  this Journal, =2=, 200–201, 1820.

Footnote 34:

  Finch, John, On the Celtic antiquities of America, this Journal, =7=,
  149–161, 1824.

Footnote 35:

  Finch, John, Geological essay on the Tertiary formations in America,
  this Journal, =7=, 31–43, 1824.

Footnote 36:

  Conybeare and Phillips, Outlines of the geology of England and Wales,
  this Journal, =7=, 210, 211, 1824.

Footnote 37:

  Hayden, Horace H., Geological essays, 1–412, 1821, this Journal, =3=,
  47–57, 1821.

Footnote 38:

  Jackson, C. T., Reports on the geology of the State of Maine, and on
  the public lands belonging to Maine and Massachusetts, this Journal,
  =36=, 153, 1839.

Footnote 39:

  Gibson, J. B., Remarks on the geology of the lakes and the valley of
  the Mississippi, this Journal, =29=, 201–213, 1836.

Footnote 40:

  Phillips, John, Geology of Yorkshire, this Journal, =21=, 14–15, 1832.

Footnote 41:

  Granger, Ebenezer, Notice of a curious fluted rock at Sandusky Bay,
  Ohio, this Journal, =6=, 180, 1823.

Footnote 42:

  Dobson, Peter, Remarks on bowlders, this Journal, =10=, 217–218, 1826.

Footnote 43:

  Murchison, R. I., Address at anniversary meeting of the Geological
  Society of London, this Journal, =43=, 200–201, 1842.

Footnote 44:

  Peter Dobson (1784–1878) came to this country from Preston, England,
  in 1809 and established a cotton factory at Vernon, Conn.

Footnote 45:

  Buckland, W., On the evidence of glaciers in Scotland and the north of
  England, Proc. London Geol. Soc., =3=, 1841.

Footnote 46:

  Hitchcock, Edward, First anniversary address before the Association of
  American Geologists, this Journal, =41=, 232–275, 1841.

Footnote 47:

  Third annual meeting of the Association of American Geologists and
  Naturalists, this Journal, =43=, 154, 1842; Abstract of proceedings of
  the fourth session of the Association of American Geologists and
  Naturalists, ibid., =45=, 321, 1843.

Footnote 48:

  Rogers, H. D., Address delivered before Association of American
  Geologists and Naturalists, this Journal, =47=, 275, 1844.

Footnote 49:

  Agassiz, Louis, The erratic phenomena about Lake Superior, this
  Journal, =10=, 83–101, 1850.

Footnote 50:

  Desor, E., On the drift of Lake Superior, this Journal, 13, 93–109,
  1852; Post-Pliocene of the southern States, etc., =14=, 49–59, 1852.

Footnote 51:

  Dana, J. D., Manual of geology, 546, Philadelphia, 1863.

Footnote 52:

  Dana, J. D., on the Quaternary, or post-Tertiary of the New Haven
  region, this Journal, =1=, 1–5, 1871.

Footnote 53:

  Matthew, G. F., Surface geology of New Brunswick, this Journal, =2=,
  371–372, 1871.

Footnote 54:

  Maclaren, Charles, The glacial theory of Prof. Agassiz, this Journal,
  =42=, 365, 1842.

Footnote 55:

  Daly, R. A., Problems of the Pacific Islands, this Journal, =41=,
  153–186, 1916.

Footnote 56:

  Catlin, George, Account of a journey to the Côteau des Prairies, this
  Journal, =38=, 138–146, 1840.

Footnote 57:

  Hilgard, E. W., Remarks on the drift of the western and southern
  States and its relation to the glacier and iceberg theories, this
  Journal, =42=, 343–347, 1866.

Footnote 58:

  Hall, C. E., Glacial phenomena along the Kittatinny or Blue Mountain,
  Pennsylvania, this Journal, =11=, review, 233, 1876.

Footnote 59:

  Stevens, R. P., On glaciers of the glacial era in Virginia, this
  Journal, =6=, 371–373, 1873.

Footnote 60:

  Rogers, W. B., On the gravel and cobble-stone deposits of Virginia and
  the Middle States, Proc. Boston Soc. Nat. Hist., 18, 1875; this
  Journal, =11=, 60–61, 1876.

Footnote 61:

  Kerr, W. C, Origin of some new points in the topography of North
  Carolina, this Journal, =21=, 216–219, 1881.

Footnote 62:

  Gilbert, G. K., On certain glacial and post-glacial phenomena of the
  Maumee valley, this Journal, =1=, 339–345, 1871.

Footnote 63:

  Chamberlin, T. C., On the geology of eastern Wisconsin, Geol. of
  Wisconsin, =2=, 1877; this Journal, 15, 61, 406, 1878.

Footnote 64:

  Chamberlin, T. C, Preliminary paper on the terminal moraine of the
  second glacial epoch, U. S. Geol. Survey, Third Ann. Rept., 291–402,
  1883.

Footnote 65:

  Wright, G. F., Unity of the glacial epoch, this Journal, =44=,
  351–373, 1892.

  Upham, Warren, The diversity of the glacial drift along its boundary,
  ibid., =47=, 358–365, 1894.

  Wright, G. F., Theory of an interglacial submergence in England,
  ibid., =43=, 1–8, 1892.

  Chamberlin, T. C., Diversity of the glacial period, ibid., =45=,
  171–200, 1983

  Dana, J. D., On New England and the upper Mississippi basin in the
  glacial period, ibid., =46=, 327–330, 1893.

  Wright, G. F., Continuity of the glacial period, ibid., =47=, 161–187,
  1894.

  Chamberlin, T. C. and Leverett, F., Further studies of the drainage
  features of the upper Ohio basin, ibid., =47=, 247–282, 1894.

Footnote 66:

  Pumpelly, Raphael, Geological researches in China, Japan, and
  Mongolia, Smithsonian Contributions, No. 202, 1866.

Footnote 67:

  Kingsmill, T. W., The probable origin of “loess” in North China and
  eastern Asia, Quart. Jour. Geol. Soc., =27=, No. 108, 1871.

Footnote 68:

  Pumpelly, Raphael, The relation of secular rock-disintegration to
  loess, glacial drift and rock basins, this Journal, =17=, 135, 1879.

Footnote 69:

  Binney, A., Some geologic features at Natchez on the Mississippi
  River, Proc. Boston Soc. Nat. Hist., =2=, 126–130, 1848.

Footnote 70:

  Hilgard, E. W., The loess of Mississippi Valley, and the eolian
  hypothesis, this Journal, =18=, 106–112, 1879.

Footnote 71:

  Chamberlin, T. C, Supplementary hypothesis respecting the origin of
  the loess of the Mississippi Valley, Jour. Geol., =5=, 795–802, 1897.

Footnote 72:

  Ramsay, A. C., On the glacial origin of certain lakes in Switzerland,
  the Black Forest, Great Britain, Sweden, North America, and elsewhere,
  Quart. Jour. Geol. Soc., 1862; this Journal, =35=, 324–345, 1863.
  Preliminary statements of this theory appeared in 1859 and 1860.

Footnote 73:

  Whittlesey, Charles, Smithsonian Contributions, No. 197, 1864.

Footnote 74:

  LeConte, Joseph, On some of the ancient glaciers of the Sierras, this
  Journal, =5=, 325–342, 1873, 10, 126–139, 1875.

Footnote 75:

  King, Clarence, U. S. Geol. Expl. 40th Par., 1, 459–529, 1878.

Footnote 76:

  Davis, W. M., Glacial erosion, Proc. Boston Soc. Nat. Hist., =22=,
  =58=, 1882.

Footnote 77:

  Sabine, Sir Edward, Address of the president of the Royal Society,
  this Journal, =37=, 108, 1864.




                                   IV
    A CENTURY OF GEOLOGY.—THE GROWTH OF KNOWLEDGE OF EARTH STRUCTURE

                           By JOSEPH BARRELL


                             _Introduction
                  The Intellectual Viewpoint in 1818._

In 1818, the year of the founding of the Journal, the natural sciences
were still in their infancy in Europe. Geology was still subordinate to
mineralogy, was hardly recognized as a distinct science, and consisted
in little more than a description of the character and distribution of
minerals and rocks. America was remote from the Old World centers of
learning. The energy of the young nation was absorbed in its own
expansion, and but a few of those who by aptitude were fitted to
increase scientific knowledge were even conscious of the existence of
such a field of endeavor. Under these circumstances the educative field
open to a journal of science in the United States was an almost virgin
soil. Original contributions could most readily be based upon the
natural history of the New World, and the founder of the Journal showed
insight appreciative of the situation in stating in the “Plan of the
Work” in the introduction to the first volume that “It will be a leading
object to illustrate AMERICAN NATURAL HISTORY, and especially our
MINERALOGY and GEOLOGY.”

At this time educated people were still satisfied that the whole
knowledge of the origin and development of the earth so far as man could
or should know it was embraced in the Book of Genesis. They were
inclined to look with misgiving at attempts to directly interrogate the
earth as to its history. Philosophers such as Descartes and Liebnitz,
the cosmogonists de Maillet and Buffon had been less instrumental in
developing science than in fitting a few facts and many speculations to
their systems of philosophy. By the opening of the nineteenth century,
however, men of learning were coming to appreciate that the way to
advance science was to experiment and observe, to collect facts and
discourage unfounded speculation. Silliman’s insight into the needs of
geologic science is shown in the following quotation (=1=, pp. 6, 7,
1818):


  “Our geology, also, presents a most interesting field of inquiry. A
  grand outline has recently been drawn by Mr. Maclure, with a masterly
  hand, and with a vast extent of personal observation and labour: but
  to fill up the detail, both observation and labour still more
  extensive are demanded; nor can the object be effected, till more good
  geologists are formed, and distributed over our extensive territory.

  To account for the formation and changes of our globe, by excursions
  of the imagination, often splendid and imposing, but usually
  visionary, and almost always baseless, was, till within half a
  century, the business of geological speculations; but this research
  has now assumed a more sober character; the science of geology has
  been reared upon numerous and accurate observations of _facts_; and
  standing thus upon the basis of induction, it is entitled to a rank
  among those sciences which Lord Bacon’s Philosophy has contributed to
  create. Geological researches are now prosecuted by actually exploring
  the structure and arrangement of districts, countries, and continents.
  The obliquity of the strata of most rocks, causing their edges to
  project in many places above the surface; their exposure, in other
  instances on the sides or tops of hills and mountains; or, in
  consequence of the intersection of their strata, by roads, canals, and
  river-courses, or by the wearing of the ocean; or their direct
  perforation, by the shafts of mines; all these causes, and others,
  afford extensive means of reading the interior structure of the globe.

  The outlines of American geology appear to be particularly grand,
  simple, and instructive; and a knowledge of the important facts, and
  general principles of this science, is of vast practical use, as
  regards the interests of agriculture, and the research for useful
  minerals. Geological and mineralogical descriptions, and maps of
  particular states and districts, are very much needed in the United
  States; and to excite a spirit to furnish them will form one leading
  object of this Journal.”


              _The Prolonged Influence of Outgrown Ideas._

Those interested in any branch of science should, as a matter of
education, read the history of that special subject. A knowledge of the
stages by which the present development has been attained is essential
to give a proper perspective to the literature of each period. Much of
the existing terminology is an inheritance from the first attempts at
nomenclature, or may rest upon theories long discarded. Popular notions
at variance with advanced teaching are often the forgotten inheritance
of a past generation.

Gneiss, trap, and Old Red Sandstone are names which we owe to Werner.
The “Tertiary period” and “drift” are relics of an early terminology.
The geology of tourist circulars still speaks of canyons as made by
“convulsions of nature.” Popular writers still attribute to geologists a
belief in a molten earth covered by a thin crust. Within the present
century the eighteenth century speculations of Werner and his
predecessors, postulating a supposed capacity of water to seep through
the crust into the interior of the earth, resulting in a hypothetical
progressive desiccation of the surface, views long abandoned by most
modern geologists, have been revived by an astronomer into a theory of
“planetology.”

A review of the literature of a century brings to light certain
tendencies in the growth of science. Each decade has witnessed a larger
accumulation of observed facts and a fuller classification of these
fundamental data, but the pendulum of interpretative theory swings away
from the path of progress, now to one side, now to the other, testing
out the proper direction. For decades the understanding of certain
classes of facts may be actually retrogressive. A retrospect shows that
certain minds, keen and unfettered by a prevailing theory, have in some
directions been in advance of their generation. But the judgment of the
times had not sufficient basis in knowledge for the separation and
acceptance of their truer views from the contemporaneous tangle of false
interpretations.

An interesting illustration of these statements regarding the slow
settling of opinion may be cited in regard to the significance of the
dip of the Triassic formations of the eastern United States. The strata
of the Massachusetts-Connecticut basin possess a monoclinal easterly dip
which averages about 20 degrees to the east. Those of the New
Jersey-Pennsylvania-Virginia basin possess a similar dip to the
northwest. Both basins are cut by great faults and the dip is now
accepted by practically all geologists as due to rotation of the crust
blocks away from a geanticlinal axis between the two basins. Edward
Hitchcock, whose work from the first shows an interpretative quality in
advance of his time, states in 1823 (=6=,74) regarding the dip of the
Connecticut valley rocks:


  “There is reason to believe that Mount Toby, the strata of which are
  almost horizontal, exhibits the original dip of these rocks, and that
  those cases in which they are more highly inclined are the result of
  some Plutonian convulsion. Such irregularity in the dip of coal fields
  is no uncommon occurrence.”


In Hitchcock’s Geology of Massachusetts, published in 1833, ten years
later, geological structure sections of the Connecticut Valley rocks are
given, the facts are discussed in detail and the dip ascribed to the
elevatory forces. He says (l. c., pp. 213, 223):


  “If it were possible to doubt that the new red sandstone formation was
  deposited from water, the surface of some of the layers of this shale
  would settle the question demonstrably. For it exhibits precisely
  those gentle undulations, which the loamy bottom of every river with a
  moderate current, presents. (No. 198.) But such a surface could never
  have been formed while the layers had that high inclination to the
  horizon, which many of them now present: so that we have here, also,
  decisive evidence that they have been elevated subsequently to their
  deposition....

  The objection of a writer in the American Journal of Science, that
  such a height of waters as would deposit Mount Toby, must have
  produced a lake nearly to the upper part of New Hampshire, in the
  Connecticut Valley, and thus have caused the same sandstone to be
  produced higher up that valley than Northfield, loses its force, when
  it is recollected that this formation was deposited before its strata
  were elevated. For the elevating force undoubtedly changed the
  relative level of different parts of the country. In this case, the
  disturbing force must have acted beneath the primary rocks. And
  besides, we have good evidence which will be shown by and by, that our
  new red sandstone was formed beneath the ocean. We cannot then reason
  on this subject from present levels.”


[Illustration: Courtesy of _Popular Science Monthly_.]

In 1840, H. D. Rogers, a geologist who has acquired a more widely known
name than Hitchcock, but who in reality showed an inferior ability in
interpretation, made the following statements in explanation of the
regional monoclinal dip of the New Jersey Triassic rocks averaging 15 to
20 degrees to the northwest:[78]


  “Their materials give evidence of having been swept into this estuary,
  or great ancient river, from the south and southeast, by a current
  producing an almost universal dip of the beds towards the northwest, a
  feature clearly not caused by any uplifting agency, but assumed
  originally at the time of their deposition, in consequence of the
  setting of the current from the opposite or southeastern shore.”


In 1842, at the third annual meeting of the Association of American
Geologists both H. D. and W. B. Rogers argued (=43=, 170, 1842) against
Sir Charles Lyell and E. Hitchcock that the present dip of the Triassic
was the original slope of deposition, stating among other reasons that
the footprints impressed upon the sediments often showed a slipping and
a pushing of the soft clay in the direction of the downhill slope. In
1858 H. D. Rogers still held to the same views of original dip,[79]
notwithstanding that a moderate amount of observation on the mud-cracked
and rain-pitted layers would have supplied the proof that such must have
dried as horizontal surfaces. The idea of inclined deposition is not yet
wholly dead as it has been suggested more than once within the present
generation as a means of escaping from the necessity of accepting the
very great thicknesses of this and similar formations. Thus, as Brögger
has remarked in another connection,—the ghosts of the old time stand
ever ready to reappear.

In the present essay on the rise of structural geology as reflected
through a century of publication in the Journal, attention will be given
especially to two fields, that of structures connected with igneous
rocks and that of structures connected with mountain making, and
emphasis will be placed upon the growth of understanding rather than
upon the accumulating knowledge of details. The growth in both of these
divisions of structural geology is well illustrated in the volumes of
the Journal.


            _Structures and Relationships of Igneous Rocks._


        _Opposed Interpretations of Plutonists and Neptunists._

During the first quarter of the nineteenth century the geologic
controversy between the Plutonists and Neptunists was at its height; the
Plutonists, following the Scotchman, Hutton, holding to the igneous
origin of basalt and granite, the Neptunists, after their German master,
Werner of Freiberg, maintaining that these rocks had been precipitated
from a primitive universal ocean. The Plutonists, although time has
shown them to have been correct in all essential particulars, were for a
generation submerged under the propaganda carried forward by the
disciples of Werner. The “Illustrations of the Huttonian Theory of the
Earth,” a remarkable classic, worthy of being studied to-day as well as
a century ago, was published in 1802 by John Playfair, professor of
mathematics in the University of Edinburgh and a friend of Hutton, who
had died five years previously. This volume was opposed by Robert
Jameson, professor of natural philosophy in the same university, who had
absorbed the ideas of the German school while at Freiberg and published
in 1808 a volume on the “Elements of Geognosy,” in which the philosophy
of Werner is followed throughout and even obsidian and pumice are argued
to be aqueous precipitates. The authority of the Wernerian autocracy
caused its nomenclature to be adopted in the new world, but strong
evidence against its interpretations was to be found in the actual
structural relations displayed by the igneous rocks.


            _Contributions on Volcanic and Intrusive Rocks._

The accumulation and study of facts constituted the best cure for an
erroneous theory. The publications of the Journal contributed toward
this end by articles along several lines. The most original
contributions were those which dealt with the areal and structural
geology of eastern North America, but equally valuable at that time for
the broadening of scientific interest were the studies on the volcanic
activities of the Hawaiian Islands, published through many years.
Perhaps most valuable from the educative standpoint were the extensive
republications in the Journal of the more important European researches,
making them accessible to American readers. In volume =13= (1828), for
example, a digest of Scrope’s work on volcanoes is given, covering forty
pages; and of Daubeny on active and extinct volcanoes, running over
seventy-five pages and extending into vol. =14=. Through these
comprehensive studies the nature of volcanic action became generally
understood during the first half of the nineteenth century and the
original publications in the Journal were valuable in giving a knowledge
of the activities of the Hawaiian volcanoes.

Early in the nineteenth century the whole of America still remained to
be explored by the geologist. The regions adjacent to the centers of
learning were among the first to receive attention and the Triassic
basin of Connecticut and Massachusetts yielded information in regard to
the nature of igneous intrusion. This basin, of unmetamorphic shales and
sandstones, is occupied by the Connecticut River except at its southern
end. The Formation contains within it sills, dikes, and outflows of
basaltic rocks which because of their superior resistance to erosion
constitute prominent hills, in places bounded by cliffs.

Silliman in 1806[80] described East Rock, New Haven, Connecticut, as a
whinstone, trap, or basalt, and accounted for its presence on the
supposition that it had


  “actually been melted in the bowels of the earth and ejected among the
  superior strata by the force of subterraneous fire, but never erupted
  like lava, cooling under the pressure of the superincumbent strata and
  therefore compact or nonvesicular, its present form being due to
  erosion.”


In these conclusions Silliman was correct. With but a limited amount of
experience he was able to discriminate between the intrusive and
effusive rocks and saw that the prominence of this hill was due to the
erosion of the sediments which once surrounded it.

An extensive paper on the geology of this region was published by Edward
Hitchcock in 1823,[81] then just thirty years of age. This paper shows
the evidence of extensive field observations, and his comments in regard
to the trap and granite are of interest. Hitchcock gives five pages to
the subject of “Greenstone Dykes in Old Red Sandstone” (=6=, 56–60,
1823) and makes the following statements:


  “Professor Silliman conducted me to an interesting locality of these
  in East-Haven. They occur on the main road from New-Haven to
  East-Haven, less than half a mile from Tomlinson’s bridge ... (p. 56).

  They are an interesting feature in our geology, and deserve more
  attention; and it is peculiarly fortunate that they should be situated
  so near a geological school and the first mineral cabinet in our
  country ... (p. 58).


                         Origin of Greenstone.

  Does the greenstone of the Connecticut afford evidence in favour of
  the Wernerian or of the Huttonian theory of its origin? Averse as I
  feel to taking a side in this controversy, I cannot but say, that the
  man who maintains, in its length and breadth, the original hypothesis
  of Werner in regard to the aqueous deposition of trap, will find it
  for his interest, if he wishes to keep clear of doubts, not to follow
  the example of D’Aubuisson, by going forth to examine the greenstone
  of this region, lest, like that geologist, he should be compelled, not
  only to abandon his theory, but to write a book against it. Indeed,
  when surveying particular portions of this rock, I have sometimes
  thought Bakewell did not much exaggerate when he said in regard to
  Werner’s hypothesis, that, ‘it is hardly possible for the human mind
  to invent a system more repugnant to existing facts.’

  On the other hand, the Huttonian would doubtless have his heart
  gladdened, and his faith strengthened by a survey of the greater part
  of this rock. As he looked at the dikes of the old red sandstone, he
  would almost see the melted rock forcing its way through the fissures;
  and when he came to the amygdaloidal, especially to that variety which
  resembles lava, he might even be tempted to apply his thermometer to
  it, in the suspicion that it was not yet quite cool ... (p. 59).

  By treating the subject in this manner I mean no disrespect to any of
  the distinguished men who have adopted either side of this question.
  To President Cooper especially, who regards the greenstone of the
  Connecticut as volcanic, I feel much indebted for the great mass of
  facts he has collected on the subject. And were I to adopt any
  hypothesis in regard to the origin of our greenstone, it would be one
  not much different from his” (p. 60).


By 1833 and more clearly in 1841 Hitchcock had come to recognize the
distinction between intrusive and extrusive basaltic sheets in the
Connecticut valley. Dawson also came to regard the Acadian sheets as
extrusive, and Emerson in 1882 recalled again the evidence for
Massachusetts (=24=, 195, 1882). Davis, however, went a step further and
by applying distinctive criteria not only separated intrusive and
extrusive sheets throughout the whole Triassic area, but by using basalt
flows as stratigraphic horizons unraveled for the first time the system
of faults which cut the Triassic system. His preliminary paper (=24=,
345, 1882) was followed by many others.

From 1880 onward begins the period of precise structural field work. The
older geologists mostly conceived their work after reconnaissance
methods. From 1870 to 1880 a group of younger men entered geology who
paid close attention to the solid geometry and mechanics of earth
structures. In their hands physical and dynamical geology began to
assume the standing of a precise and quantitative science. In the field
of intrusive rocks the opening classic was by Gilbert, who in his volume
on the geology of the Henry Mountains, published in 1880, made
laccoliths known to the world. With the beginning of this new period we
may well leave the subject of intrusive rocks and turn to the progress
of knowledge in regard to those deeper and vaster bodies now known as
batholiths. These, since erosion does not expose their bottoms, Daly
separates from intrusives and classifies as subjacent. The batholiths
consist typically of granite and granodiorite, and introduce us to the
problem of granite.


            _Views on the Structural Relations of Granite._

Conscientious field observations were sufficient to establish the true
nature of the intrusive and extrusive rocks. The case was very
different, however, with the nature and relations of the great bodies of
granite, which may be taken in the structural sense as including all the
visibly crystalline acidic and intermediate rocks, known more
specifically as granite, syenite, and diorite.

The large bodies of granite, structurally classified as stocks, or
batholiths, commonly show wedges, tongues, or dike networks cutting into
the surrounding rocks. The relations, however, are not all so simple as
this. Granites may cover vast areas, they are usually the older rocks,
they are generally associated with regional metamorphism of the intruded
formations, which metamorphism is now understood to be due chiefly to
the heat and mineralizers given off from the granite magma, associated
with mashing and shearing of the surrounding rocks. The granite was
often injected in successive stages which alternated with the stages of
regional mashing. A parallel or gneissic structure is thus developed
which is in part due to mashing, in part to igneous injection. Where the
ascent of heat into the cover is excessive, or where blocks are detached
and involved in the magma, the latter may dissolve some of the older
cover rocks, even where these were of sedimentary origin.

Thus between mashing, injection, and assimilation the genetic
relationships of a batholith to its surroundings are in many instances
obscure. Nevertheless, attention to the larger relations shows that the
molten magma originated at great depths in the earth’s crust, far below
the bottoms of geosynclines, and consists of primary igneous material,
not of fused sediments. From those depths it has ascended by various
processes into the outer crust, where it crystallized into granite
masses, to be later exposed by erosion. The amount of material which can
be dissolved and assimilated must be small in comparison with the whole
body of the magma. The original composition of the magma was probably
basic, nearer that of a basalt than that of a granite. Differentiation
of the molten mass is thought to cause the upper and lower parts of the
chamber to become unlike, the lighter and more acidic portion giving
rise to the great bodies of granite. With the exception of certain
border zones the whole, however, is regarded as igneous rock risen from
the depths.

The complex border relations, but more particularly certain academic
hypotheses, led to a period of misunderstanding and retrogression in
regard to the nature of granites. It constitutes an interesting
illustration of the possibility of a wrong theory leading interpretation
astray, chiefly through the magnification of minor into major factors.
This history illustrates the dangers of qualitative science as compared
to quantitative, of a single hypothesis as matched against the method of
multiple working hypothesis. This flux of opinion in regard to the
nature of granites may be traced through the volumes of the Journal.

E. Hitchcock in 1824 (=6=, 12) noted that in places granite appeared
bedded, but in other places existed in veins which cut obliquely across
the strata. Silliman, although careful not to deny the aqueous origin of
some basalts, yet held that the field evidence of New England indicates
for that region the igneous or Huttonian origin of trap and granite
(=7=, 238, 1824).

In 1832 the following article by Hitchcock appeared in the Journal
(=22=, 1, 70):


  Report on the Geology of Massachusetts; examined under the direction
  of the Government of that State, during the years 1830 and 1831; by
  Edward Hitchcock, Prof. of Chemistry and Natural History in Amherst
  College.

  A footnote adds that this is “published in this Journal by consent of
  the Government of Massachusetts, and intended to appear also in a
  separate form, and to be distributed among the members of the
  Legislature of the same State, about the time of its appearance in
  this work. It is, we believe, the first example in this country, of
  the geological survey of an entire State.”


This article includes a geological map of the state and covers the
subject of economic geology. The report brought forth the following
remarks from a French reviewer in the _Revue Encyclopédique_, Aug. 1832,
quoted in the Journal (=23=, 389, 1833):


  “A single glance at this report, is sufficient to convince any one of
  the utility of such a work, to the state which has undertaken it; and
  to regret that there is so very small a part of the French territory,
  whose geological constitution is as well known to the public, as is
  now the state of Massachusetts. France has the greater cause to regret
  her being distanced in this race by America, from her having a corps
  of mining engineers, who if they had the means, would, in a very short
  time furnish a work of the same kind, still more complete, of each of
  the departments.”


The complete report published in 1833 is a work of 700 pages. Pages 465
to 517 are devoted to the subject of granite. Numerous detailed sketches
are given showing contact relations. Nine pages are given to theoretical
considerations and many lines of proof are given that granite is an
igneous rock, molten from the internal heat of the earth, and intruded
into the sedimentary strata. His statement is the clearest published in
the world, so far as the writer is aware, up to that date, and marks
Edward Hitchcock as one of the leading geologists of his generation in
Europe as well as America. Unfortunately his views were largely lost to
sight during the following generation.

In 1840 the first American edition of Mantell’s Wonders of Geology gave
currency to the idea that granite is proved to be of all geological ages
up to the Tertiary (=39=, 6, 1840). In 1843 J. D. Dana pointed out
(=45=, 104) that schistosity was no evidence of sedimentary origin. He
regarded most granites as igneous as shown by their structural
relations, but considers that some may have had a sedimentary origin.


        _Rise and Decline of the Metamorphic Theory of Granite._

Up to 1860 granite was regarded on the basis of the facts of the field
as essentially an intrusive rock, but gneiss as a metamorphic product
mostly of sedimentary origin. It seemed as though sound methods of
research and interpretation were securely established. Nevertheless, a
new era of speculation and a modified Wernerism arose at that time with
a paper by T. Sterry Hunt, marking a retrogression in the theory of
granite which lasted until his death in 1892.

In November, 1859, Hunt read before the Geological Society of London a
paper on “Some Points in Chemical Geology” in which he announced that
igneous rocks are in all cases simply fused and displaced sediments, the
fusion taking place by the rise of the earth’s internal heat into deeply
buried and water-soaked masses of sediments (see =30=, 133, 1860). The
germ of this idea of aqueo-igneous fusion was far older, due to Babbage
and John Herschel, neither of them geologists, but such sweeping
extensions of it had never before been published. Hunt had the advantage
of a wide acquaintanceship with geological literature and chemistry. He
wrote plausibly on chemical and theoretical geology, but his views were
not controlled by careful field observations. In fact he wrote
confidently on regions which apparently he had never seen and where a
limited amount of field work would have shown him to have been
fundamentally in error. A man of egotistical temperament, he sought to
establish priority for himself in many subjects and in order to cover
the field made many poorly founded assertions. Building on to another
Wernerian idea, he held that many metamorphic minerals had a chronologic
value comparable to fossils—staurolite for example indicating a
pre-Silurian age—and on this basis divided the crystalline rocks into
five series. Although there is much of value buried in Hunt’s work it is
difficult to disentangle it, with the result that his writings were a
disservice to the science of geology. Although carrying much weight in
his lifetime, they have passed with his death nearly into oblivion.

Marcou, with a limited knowledge of American geology, and but little
respect for the opinions of others, had published a geologic map of the
United States containing gross errors. In support of his views he read
in November, 1861, a paper on the Taconic and Lower Silurian Rocks of
Vermont and Canada. In the following year he was severely reviewed by
“T,” who states positively in controverting Marcou (=33=, 282, 283,
1862) that “the granites (of the Green Mountains) are evidently strata
altered in place.”


  “Mr. Marcou should further be informed that the granites of the Alpine
  summits, instead of being, as was once supposed, eruptive rocks, are
  now known to be altered strata of newer Secondary and Tertiary age. A
  simple structure holds good in the British Islands, where as Sir
  Roderick Murchison has shown in his recent Geological map of Scotland,
  Ben Nevis and Ben Lawers are found to be composed of higher strata,
  lying in synclinals. This great law of mountain structure would alone
  lead us to suppose that the gneiss of the Green mountains, instead of
  being at the base, is really at the summit of the series....

  We cannot here stop to discuss Mr. Marcou’s remark about ‘the
  unstratified and oldest crystalline rocks of the White mountains’
  which he places beneath the lower Taconic series. Mr. Lesley has shown
  that these granites are stratified, and with Mr. Hunt, regards them as
  of Devonian Age. (This Journal, vol. =31=, p. 403.) Mr. Marcou has
  come among us with notions of mountains upheaved by intrusive
  granites, and similar antiquated traditions, now, happily for science,
  well nigh forgotten.”


It is seen that Marcou, notwithstanding the general character of his
work, happened to be nearer right in some matters than were his critics,
and that “T” had adopted to the limit the views of Hunt.

The recovery of geology from this period of confusion was partly owing
to the slow accumulation of opposed facts; especially to a recognition
of the fact that the overplaced relation of the granite gneisses in
western Scotland was due to great overthrusts; also to the evidence of
the clearly intrusive nature of many of the Cordilleran granites. The
recovery of a sounder theory was hastened, however, by the application
of criticisms by J. D. Dana in the Journal. In 1866 (=42=, 252) Dana
pointed out that sedimentary rocks in Pennsylvania, in Nova Scotia, and
other regions which had been buried to a depth of at least 16,000 feet
are not metamorphic. Mere depth of burial of sediments was not
sufficient therefore to produce metamorphism and aqueo-igneous fusion.
The baseless and speculative character of the use of minerals as an
index of age and of Hunt’s interpretation of New England geology in
general was shown by Dana in 1872 (=3=, 91). The following year Dana
pointed out clearly that igneous eruptions in general have been derived
from a deep-seated source and did not come from the aqueo-igneous fusion
of sediments. As to gradations between true igneous rocks and fused and
displaced sediments he makes the following statements (=6=, 114, 1873):


  “Again, the plastic rock-material that may be derived from the fusion
  or semifusion of the supercrust, (that is, of rocks originally of
  sedimentary origin,) gives rise to “igneous” rocks often not
  distinguishable from other igneous rocks, when it is ejected through
  fissures far from its place of origin; while crystalline rocks are
  simply _metamorphic_ if they remain in their original relations to the
  associated rocks, or nearly so.

  Between these latter igneous rocks and the metamorphic there may be
  indefinite gradations, as claimed by Hunt. But if our reasonings are
  right, the great part of igneous rocks can be proved to have had no
  such supercrust origin. The argument from the presence of moisture or
  of hydrous minerals in such rocks in favor of their origin from the
  fusion of sediments has been shown to be invalid.”


The injected marginal rocks and the post-intrusive metamorphism of most
of the New England granites has, however, obscured more or less their
real igneous nature so that the gradation from metamorphic sediments
through igneous gneisses to granites could be read in either direction.
These features misled Dana who accepted the prevailing idea of the
general metamorphic origin of granite. Dana makes the following
statement (=6=, 164, 1873):


  “But Hunt is right in holding that in general granite and syenite (the
  quartz-bearing syenite) are undoubtedly metamorphic rocks where not
  vein-formations, as I know from the study of many examples of them in
  New England; and the veins are results of infiltration through heated
  moisture from the rocks adjoining some part of the opened fissures
  they fill.”


Granite, although regarded at this time as the extreme of the
metamorphic series and originating from sediments, was looked upon as
typically Archean in age, though in some cases younger. Such a doctrine
permitted such extreme misinterpretations as that of Clarence King and
S. F. Emmons on the nature of the intrusive granite of the Little
Cottonwood canyon in the Wahsatch Range. This body cuts across 30,000
feet of Paleozoic rocks and to the careful observer, as later admitted
by Emmons, shows clear evidence of its transgressive nature. But at that
time it was generally considered that granite mountains were capable of
resisting the erosion of all geological time. Consequently it did not
seem incredible to King and his associates that here a great granite
range of Archean origin had stood up through Paleozoic time until
gradual subsidence had permitted it to be buried beneath 30,000 feet of
sediments.[82]

It may seem to the present day reader that such a misinterpretation,
doing violence to fundamental geologic knowledge as now recognized, was
inexcusable; but in the light of the history of geology as here detailed
it is seen to have been the interpretation natural to that time. It is
true that a careful examination of the facts of that very field would
have proved the post-Paleozoic and intrusive nature of that great
granite body now known as the Little Cottonwood batholith, but Emmons
has explained the rapid and partial nature of the observations which
they were compelled to make in order to keep up to their schedule of
progress (=16=, 139, 1903).

Whitney had found some years earlier that the granites of the Sierra
Nevada were igneous rocks intrusive into the Triassic and Jurassic
strata. The Lake Superior geologists began to show in the eighties that
granite was there an intrusive igneous rock. R. D. Irving and Wadsworth
noted these relations. Lawson in 1887 pointed out emphatically (=33=,
473) that the granites of the Rainy Lake region, although basal, were
younger than the schists which lay above them. The granite gneisses he
held were of clearly the same igneous origin as the granites and neither
gave any field evidence of being fused and displaced sediments. From
this time forward the truly igneous nature of granite became
increasingly accepted until now the notion of its being made of
sedimentary rocks softened and recrystallized by the rise of the
isogeotherms through deep burial is as obsolete as the still older
doctrine of the Neptunists that granite was laid down as a crystalline
precipitate on the floor of the primitive ocean.

The recognition of the truly igneous nature of granites has been
followed in the present generation by a series of studies on their
structural relations and mode of genesis. A number of important initial
articles on various aspects of structure and contact relations have
appeared in the Journal, but this sketch of the history of the subject
may well stop with the introduction to this modern period.


                         _Orogenic Structures._


                 _Views of Plutonists and Neptunists._

Orogenic structures are, as the name implies, those connected with the
birth of mountains. Nearly synonymous terms are deformative or secondary
structures. On a small scale this division embraces the phenomena
exposed in the rock ledge or quarry face, or in the dips and
dislocations varying from one exposure to another. These structures
include faults, folds, and foliation. On a larger scale are included the
relations of the different ranges of a mountain system to each other,
relations to previous geologic history, relations to the earth as a
whole, and to the forces which have generated the structures.

In order to see the stage of development of this subject in 1818 and its
progress as reflected through the publications of a century, more
particularly in the Journal, it is desirable to turn again to those two
treatises emanating from Edinburgh at the beginning of the nineteenth
century and representing two opposite schools of thought, the Plutonists
and Neptunists.

Playfair, in 1802, devotes nineteen pages to the subject of the
inflection and elevation of strata.[83] He places emphasis on the
characteristic parallelism of the strike of the folds throughout a
region, as shown through the intersection of the folds by a horizontal
plane of erosion. He contrasts this with the arches shown in a
transverse section and enlarges on our ability to study the deeply
buried strata through the denudation of the folded structure. He argues
from these relations that the structures can not be explained by the
vague appeal of the Neptunists to forces of crystallization, to slopes
of original deposition, or to sinking in of the roofs of caverns. The
causes he argues were heat combined with pressure. As to the directions
in which the pressure acted he is not altogether clear, but apparently
regards the pressure as acting in upward thrusts against the sedimentary
planes, the latter yielding as warped surfaces. His method of
presentation is that of inductive reasoning from facts, but he stopped
short of the conception of horizontal compression through terrestrial
contraction.

Jameson, professor of natural history in the same university, in 1808
contemptuously ignores the work of Hutton and Playfair in what he calls
the “_monstrosities_ known under the name of Theories of the Earth.” In
a couple of pages he confuses and dismisses the whole subject of
deformation. He states:[84]


  “It is therefore a fact, that all inclined strata, with a very few
  exceptions, have been formed so originally, and do not owe their
  inclination to a subsequent change.

  When we examine the structure of a mountain, we must be careful that
  our observations be not too micrological, otherwise we shall
  undoubtedly fail in acquiring a distinct conception of it. This will
  appear evident when we reflect that the geognostic features of Nature
  are almost all on the great scale. In no case is this rule to be more
  strictly followed than in the examination of the stratified structure.

  By not attending to this mode of examination, geognosts have fallen
  into numberless errors, and have frequently given to extensive tracts
  of country a most irregular and confused structure. Speculators
  building on these errors have represented the whole crust of the globe
  as an irregular and unseemly mass. It is indeed surprising, that men
  possessed of any knowledge of the beautiful harmony that prevails in
  the structure of organic beings could for a moment believe it
  possible, that the great fabric of the globe itself,—that magnificent
  display of Omnipotence,—should be destitute of all regularity in its
  structure, and be nothing more than a heap of ruins.”


This was the attitude of a leader of British opinion toward the subject
of deformational geology from which the infant science had to recover
before progress could be made. The early maps were essentially
mineralogical and lithological. The order of superposition and the
consequent sequence of age was regarded as settled by Werner in Germany
and not requiring investigation in America. The early examples of
structure were sections drawn with exaggerated vertical scales and those
of Maclure do not show detail.


                _Recognition of Appalachian Structures._

Following the founding of the Journal in 1818 there is observable a
growth in the quality and detail of geological mapping. Dr. Aiken,
professor of natural philosophy and chemistry in Mt. St. Mary’s College,
published in the Journal in 1834 (=26=, 219) a vertical section
extending between Baltimore and Wheeling, a distance of nearly 250
miles, on a scale of about 7 miles per inch. The succession of rocks is
carefully shown and the direction of dip, but no attempt is made to show
the underground relations, the stratigraphic sequence, and the folded
structures which are so clear in that Appalachian section. The text also
shows that the author had not recognized the folded structure.
Furthermore, where the folds cease at the Alleghany mountain front, the
flat strata are shown as resting unconformably on the folded rocks to
the east.

R. C. Taylor, geologist, civil and mining engineer, was from 1830 to
1835 the leading student of Pennsylvanian geology as shown by the
publication in 1835 of four papers aggregating over 80 pages in the
Transactions of the Geological Society of Pennsylvania. His work is
noticeable for accuracy in detail and no doubt was influential in
setting a high standard for the state geological survey which
immediately followed.

H. D. and W. B. Rogers have been given credit in this country, and in
Europe also, as being the leading expounders of Appalachian structure.
Merrill speaks of H. D. Rogers as unquestionably the leading structural
geologist of his time.[85] To the writer, this attributed position
appears to be due to his opportunities rather than to scientific acumen.
The magnificent but readily decipherable folded structure of
Pennsylvania, the relationships of coal and iron to this structure, the
considerable sums of money appropriated, and the work of a corps of able
assistants were factors which made it comparatively easy to reach
important results. In ability to weigh facts and interpret them Edward
Hitchcock showed much more insight than H. D. Rogers, while in the
philosophic and comprehensive aspects of the subject J. D. Dana far
outranks him.

H. D. Rogers in his first report on the geological survey of New Jersey,
1836, recognizes that the Cambro-Silurian limestones (lower Secondary
limestones) were deposited as nearly horizontal beds and the ridges of
pre-Cambrian gneiss (Primary) had been pushed up as anticlinal axes (p.
128). He also clearly recognized the distinction between slaty cleavage
and true dip as shown in the Ordovician slates (p. 97). Between 1836 and
1840 he had learned a great deal on the nature of folds as is shown in
his Pennsylvania report for 1839 and the structure sections in his New
Jersey report for 1840.

R. C. Taylor, who had now become president of the board of directors of
the Dauphin and Susquehanna Coal Company, published in the Journal in
1841 (=41=, 80) an important paper entitled “Notice of a Model of the
Western portion of the Schuylkill or Southern Coal Field of
Pennsylvania, in illustration of an Address to the Association of
American Geologists, on the most appropriate modes for representing
Geological Phenomena.” In this paper he calls attention to the value of
modeling as a means of showing true relations in three dimensions. He
condemns the custom prevalent among geologists of showing structure
sections with an exaggerated vertical scale with its resultant
topographic and structural distortions. Taylor was widely acquainted
with the structure of Pennsylvania, Maryland, and Virginia.


                 _Nature of Forces Producing Folding._

In 1825 Dr. J. H. Steele sent to Professor Silliman two detailed
drawings and description of an overturned fold at Saratoga Lake, New
York. As to the significance of this feature Steele makes the following
statement (=9=, 3, 1825):


  “It is impossible to examine this locality without being strongly
  impressed with the belief that the position which the strata here
  assume could not have been effected in any other way than by a power
  operating from beneath upwards and at the same time possessing a
  progressive force; something analogous to what takes place in the
  breaking up of the ice of large rivers. The continued swelling of the
  stream first overcomes the resistance of its frozen surface and having
  elevated it to a certain extent, it is forced into a vertical
  position, or thrown over upon the unbroken stratum behind, by the
  progressive power of the current.”


So far as the present writer is aware this is the first recognition in
geological literature of the evidence of a horizontally compressive and
overturning force as a cause of folding.

To E. Hitchcock belongs the credit of being the first to describe
overturning and inversion of strata on a large scale, but without
clearly recognizing it as such. In western Massachusetts metamorphism is
extreme in the lower Paleozoic rocks in the vicinity of the overthrust
mass of Archean granite-gneiss which constitutes the Hoosic range. The
Paleozoic rocks of the valley to the west are overturned and appear to
dip beneath the older rocks. Farther west the metamorphism fades out and
the series assumes a normal position. Such an inverted relation, up to
that time unknown, is described in 1833 as follows by Hitchcock in his
Geology of Massachusetts (pp. 297, 298):


  “But a singular anomaly in the superposition of the series of rocks
  above described, presents a great difficulty in this case. The strata
  of these rocks almost uniformly dip to the east: that is, the newer
  rocks seem to crop out beneath the older ones; so that the saccharine
  limestone, associated with gneiss in the eastern part of the range,
  seems to occupy the uppermost place in the series. Now as
  superposition is of more value in determining the relative ages of
  rocks than their mineral characters, must we not conclude that the
  rocks, as we go westerly from Hoosac mountain, do in fact belong to
  older groups? The petrifactions which some of them contain, and their
  decidedly fragmentary character, will not allow such a supposition to
  be indulged for a moment. It is impossible for a geologist to mistake
  the evidence, which he sees at almost every step, that he is passing
  from older to newer formations, just as soon as he begins to cross the
  valley of Berkshire towards the west. We are driven then to the
  alternative of supposing, either that there must be a deception in the
  apparent outcrop of the newer rocks from beneath the older, or that
  the whole series of strata has been actually thrown over, so as to
  bring the newest rocks at the bottom. The latter supposition is so
  improbable that I cannot at present admit it.”


Hitchcock tried to reconcile the evidence by a series of unconformities
and inclined deposition, but finds the solution unsatisfactory.

In this same year, 1833, Elie de Beaumont, a distinguished French
geologist, published his theory of the origin of mountains. He advanced
the idea that since the globe was cooling it was condensing, and the
crust, already cool, must suffer compression in adjusting itself to the
shrinking molten interior. He concluded from the evidence shown in
Europe that the collapse of the crust occurred violently and rapidly at
widely spaced intervals of time. This hypothesis introduced the idea of
mountain folding by horizontal compressive forces. The theoretical paper
of de Beaumont, together with further observations by Hitchcock and
others, led the latter in 1841 to a final belief in the inversion of
strata on a large scale by horizontal compression. His conclusions are
expressed in an important paper published in the Journal (=41=, 268,
1841) and given on April 8, 1841, as the First Anniversary Presidential
Address before the Association of American Geologists. This
comprehensive summary of American geology occupies 43 pages. Three pages
are given to the inverted structure of the Appalachians from which the
following paragraphs may be quoted:


  “We have all read of the enormous dislocations and inversions of the
  strata of the Alps; and similar phenomena are said to exist in the
  Andes. Will it be believed, that we have an example in the United
  States on a still more magnificent scale than any yet described?...

  Let us suppose the strata between Hudson and Connecticut rivers, while
  yet in the plastic state, (and the supposition may be extended to any
  other section across this belt of country from Canada to Alabama,) and
  while only slightly elevated, were acted upon by a force at the two
  rivers, exerted in opposite directions. If powerful enough, it might
  cause them to fold up into several ridges; and if more powerful along
  the western than the eastern side, they might fall over so as to take
  an inverted dip, without producing any remarkable dislocations, while
  subsequent denudation would give to the surface its present
  outline....

  Fourthly, we should readily admit that such a plication and inversion
  of the strata might take place on a small scale. If for instance, we
  were to press against the extremities of a series of plastic layers
  two feet long, they could easily be made to assume the position into
  which the rocks under consideration are thrown. Why then should we not
  be equally ready to admit that this might as easily be done, over a
  breadth of fifty miles, and a length of twelve hundred, provided we
  can find in nature, forces sufficiently powerful? Finally, such forces
  do exist in nature, and have often been in operation.”


The advanced nature of these conceptions may be appreciated by
contrasting them with those put forth by H. D. and W. B. Rogers on April
29, 1842, before the third annual meeting of the same body (=43=, 177,
1842) and repeated by them before the British Association at Manchester
two months later. In their own words, the Rogers brothers from their
studies on the folds shown in Pennsylvania and Virginia, conceived
mountain folds in general to be produced by much elastic vapor escaping
through many parallel fissures formed in succession, producing violent
propulsive wave oscillations on the surface of the fluid earth beneath a
thin crust. Thus actual billows are assumed to have rolled along through
the crust. They did not think tangential pressure alone could produce
folds. Such pressures were regarded as secondary, produced by the
propagation of the waves and the only expression of tangential forces
which they admitted was to fix the folds and hold them in position after
the violent oscillation had subsided (=44=, 360, 1843). The leading
British geologists De la Beche and Sedgwick criticized adversely this
remarkable theory, stating that they could see no such analogy in
mountain folds to violent earthquake waves and that in their opinion the
slow application of tangential force was sufficient to account for the
phenomena (=44=, 362–365, 1843).

H. D. Rogers in the prosecution of the geological survey of Pennsylvania
displayed notable organizing ability and persistence in accomplishment,
even to advancing personally considerable sums of money, trusting to the
state legislature to later reimburse him. Finally, after many delays by
the state, the publication was placed directly in his charge and he
produced in 1858 a magnificent quarto work of over 1,600 pages,
handsomely illustrated, and accompanied by an atlas. It is excellent
from the descriptive standpoint, standing in the first class. Measured
as a contribution to the theory of dynamical geology, the explanatory
portions were, however, thirty years behind the times. The same
hypotheses are put forth in 1858 as in 1842. There is no acceptance of
the views of Lyell concerning the uniformitarian principles expounded by
this British leader in 1830, or of the nature of orogenic forces as
published by Elie de Beaumont in 1833. Rogers rejects the view that
cleavage is due to compression and suggests “that both cleavage and
foliation are due to the parallel transmission of planes or waves of
heat, awakening the molecular forces, and determining their
direction.”[86] Thus a mere maze of words takes the place of inductive
demonstrations already published.

In following the play of these opposing currents of geologic thought we
reach now the point where a period of brilliant progress in the
knowledge of mountains and of continental structures begins in the work
of J. D. Dana. In 1842 Dana returned from the Wilkes Exploring
Expedition and the following year began the publication of the series of
papers which for the next half century marked him as the leader in
geologic theory in America. His work is of course to be judged against
the background of his times. His papers mark distinct advances in many
lines and are characterized throughout by breadth of conception and
especially by clear and logical thinking. His work was published very
largely in the Journal, of which after a few years he became chief
editor. His first contribution on the subject of mountain structures,
entitled “Geological results of the earth’s contraction in consequence
of cooling,” was published in 1847 (=3=, 176). The evidence of
horizontal pressure was first perceived in France as shown by the
features of the Alps. Elie de Beaumont connected it, by means of the
theory of a cooling and contracting globe, with the other large fact of
the increase of temperature with descent in the crust. Dana credits the
Rogers brothers with first making known the folded structures of the
Appalachians, but objects to their interpretation of origin. He showed
by means of diagrams that the folds are to be explained by lateral
pressure, the direction of overturning indicating the direction from
which the driving force proceeded.

The Rogers brothers and especially James Hall, in working out the
Appalachian stratigraphy, had noted that the formations, although
accumulating to a maximum thickness of between 30,000 and 40,000 feet,
showed evidences that the successive formations were deposited in
shallow water. It suggested to them that the weight of the accumulating
sediments was the cause of subsidence, each foot of sediment causing a
foot of down sinking. This idea has continued to run through various
text books in geology for half a century, yet Dana early saw the fallacy
and in 1863 in the first edition of his Manual of Geology (p. 717)
states “whether this is an actual cause or not in geological dynamics is
questionable.” In 1866 in an important article on “Observations on the
origins of some of the earth’s features,” Dana deals more fully and
finally with this subject (=42=, 205, 252, 1866). He shows that such an
effect of accumulating sediment postulates a delicate balance, a very
thin crust and no resistance below. If such a weakness were granted it
would be impossible for the earth to hold up mountains. Furthermore such
subsidence was not regular during its progress and finally in the long
course of geologic time gave place to a reverse movement of elevation.

Hall had pointed out the fact that the sediments were thickest on the
east in the region of mountain folding and thinned out to a fraction of
this thickness in the broad Mississippi basin. Hall argued that the mere
subsidence of the trough would produce the observed folding and that the
folding was unrelated to mountain making or crustal shortening. In
supposed proof he cited the fact that the Catskills consist of unfolded
rock, are higher than the folded region to the south, and nearly as high
as the highest metamorphic mountains to the east.[87] Hall and all his
contemporaries were handicapped in their geological theories by a
complete inappreciation of the importance of subaërial denudation. For
subscribing to these errors of their time even the ablest men should not
be held responsible. Hall was the most forcible personality in geology
in his generation. His contributions to paleontology were superb. His
perception of the relation existing between troughs of thick sediments
and folded structures was a contribution of the first importance; yet in
the structural field his argument as to the production of the
Appalachian folds by mere subsidence during deposition indicates a
remarkable inability to apply the logical consequences of his hypothesis
to the nature of the folds as already made known by the Rogers. Dana
pointed out in reply to Hall that the folding did not correspond to the
requirements of Hall’s hypothesis, especially as the folding took place
not during, but after the close of the vast Paleozoic deposition. Dana
states in conclusion on Hall’s hypothesis (=42=, 209, 1866) that “It is
a theory of the origin of mountains with the origin of mountains left
out.”


             _The Theory of Geosynclines and Geanticlines._

The fact that systems of folded strata lie along axes of especially
thick sediments and that this implied subsidence during deposition was
Hall’s contribution to geologic theory, but curiously enough he failed,
as shown, to connect it with the subsequent nature of mountain folding.
He did not see why such troughs should be weak to resist horizontal
compression. The clear recognition of this relationship was the
contribution of Le Conte, who in a paper on “A theory of the formation
of the great features of the earth’s surface” (=4=, 345, 460, 1872),
reached the conclusion that “mountain chains are formed by the mashing
together and the up-swelling of sea bottoms where immense thicknesses of
sediment have accumulated.”

As to the cause why mashing should take place along troughs of thick
sediments Le Conte adopts the hypothesis of aqueo-igneous fusion
proposed independently long before by Babbage and Herschel and
elaborated into a theory of igneous rocks by Hunt. Under this view, as
the older sediments became deeply buried, the heat of the earth’s
interior ascended into them, and since they included the water of
sedimentation a softening and metamorphism resulted. Dana had shown,
however, six years previously (=42=, 252, 1866), as the following
quotation will indicate, that metamorphism of sediments required more
than deep burial and that no such weakening as was postulated by
Herschel had occurred:


  “The correctness of Herschel’s principle cannot be doubted. But the
  question of its actual agency in ordinary metamorphism must be decided
  by an appeal to facts; and on this point I would here present a few
  facts for consideration.

  The numbers and boldness of the flexures in the rocks of most
  metamorphic regions have always seemed to me to bear against the view
  that the heat causing the change had ascended by the very quiet method
  recognized in this theory....

  But there are other facts indicating a limited sufficiency to this
  means of metamorphism. These are afforded by the great faults and
  sections of strata open to examination. In the Appalachian region,
  both of Virginia and Pennsylvania, faults occur, as described by the
  Professors Rogers, and by Mr. J. P. Lesley, which afford us important
  data for conclusions. Mr. Lesley, an excellent geologist and
  geological observer, who has explored personally the regions referred
  to, states that at the great fault of Juniata and Blair Cos.,
  Pennsylvania, the rocks of the Trenton period are brought up to a
  level with those of the Chemung, making a dislocation of at least
  16,000, and probably of 20,000, feet. And yet the Trenton limestone
  and Hudson River shales are not metamorphic. Some local cases of
  alteration occur there, including patches of roofing slate; but the
  greater part of the shales are no harder than the ordinary shales of
  the Pennsylvania Coal formation.

  At a depth of 16,000 feet the temperature of the earth’s crust,
  allowing an increase of 1° F. for 60 feet of descent, would be about
  330° F.; or with 1° F. for 50 feet, about 380° F.—either of which
  temperatures is far above the boiling point of water; and with the
  thinner crust of Paleozoic time the temperature at this depth should
  have been still higher. But, notwithstanding this heat, and also the
  compression from so great an overlying mass, the limestones and shales
  are not crystalline. The change of parts of the shale to roofing slate
  is no evidence in favor of the efficiency of the alleged cause; for
  such a cause should act uniformly over great areas.”


The next contribution to the theory of orogeny was a series of papers
published in 1873 by Dana, entitled “On some results of the earth’s
contraction from cooling, including a discussion on the origin of
mountains and the nature of the earth’s interior.”[88] This
contribution, viewed as a whole, ranks among the first half dozen papers
on the science of mountains. The following quoted paragraphs give a view
of the scope of this article:


                 “_Kinds and Structure of Mountains._”

  “While mountains and mountain chains all over the world, and low
  lands, also, have undergone uplifts, in the course of their long
  history, that are not explained on the idea that all mountain
  elevating is simply what may come from plication or crushing, the
  _component parts_ of mountain chains, or those simple mountains or
  mountain ranges that are the product of one _process of making_—may
  have received, _at the time of their original making_, no elevation
  beyond that resulting from plication.

  This leads us to a grand distinction in orography, hitherto neglected,
  which is fundamental and of the highest interest in dynamical geology;
  a distinction between—

  1. A simple or _individual_ mountain mass or range, which is the
  result of _one process of making_, like an individual in any process
  of evolution, and which may be distinguished as a _monogenetic_ range,
  being _one in genesis_; and

  2. A composite or _polygenetic_ range or chain, made up of two or more
  monogenetic ranges combined.

  The Appalachian chain—the mountain region along the Atlantic border of
  North America—is a _polygenetic_ chain; it consists, like the Rocky
  and other mountain chains, of several _monogenetic_ ranges, the more
  important of which are: 1. The Highland range (including the Blue
  Ridge or parts of it, and the Adirondacks also, if these belong to the
  same process of making) pre-Silurian in formation; 2. The Green
  Mountain range, in western New England and eastern New York, completed
  essentially after the Lower Silurian era or during its closing period;
  3. The Alleghany range, extending from southern New York southwestward
  to Alabama, and completed immediately after the Carboniferous age.

  The making of the Alleghany range was carried forward at first through
  a long-continued subsidence—a _geosynclinal_ (not a _true_ synclinal,
  since the rocks of the bending crust may have had in them many true or
  simple synclinals as well as anticlinals), and a consequent
  accumulation of sediments, which occupied the whole of Paleozoic time;
  and it was completed, finally, in great breakings, faultings and
  foldings or plications of the strata, along with other results of
  disturbance.

  These examples exhibit the characteristics of a large class of
  mountain masses or ranges. A geosynclinal accompanied by sedimentary
  depositions, and ending in a catastrophe of plications and
  solidification, are the essential steps, while metamorphism and
  igneous ejections are incidental results. The process is one that
  produces final stability in the mass and its annexation generally to
  the more stable part of the continent, though not stable against
  future oscillations of level of _wider range_, nor against denudation.

  It is apparent that in such a process of formation elevation by direct
  uplift of the underlying crust has no necessary place. The attending
  plications may make elevations on a vast scale and so also may the
  shoves upward along the lines of fracture, and crushing may sometimes
  add to the effect; but elevation from an upward movement of the
  downward bent crust is only an incidental concomitant, if it occur at
  all.

  We perceive thus where the truth lies in Professor Le Conte’s
  important principle. It should have in view alone _monogenetic_
  mountains and these only _at the time of their making_. It will then
  read, plication and shovings along fractures being made more prominent
  than crushing:

  Plication, shoving along fractures and crushing are the true sources
  of the elevation that takes place _during the making_ of geosynclinal
  monogenetic mountains.

  And the statement of Professor Hall may be made right if we recognize
  the same distinction, and, also, reverse the order and causal relation
  of the two events, accumulation and subsidence; and so make it read:

  Regions of monogenetic mountains were, previous, and preparatory, to
  the making of the mountains, areas each of a slowly progressing
  geosynclinal, and, _consequently_, of thick accumulations of
  sediments.

  The prominence and importance in orography of the mountain
  individualities described above as originating through a geosynclinal
  make it desirable that they should have a distinctive name; and I
  therefore propose to call a mountain range of this kind a
  _synclinorium_, from _synclinal_ and the Greek ὄρος, mountain.

  This brings us to another important distinction in orographic
  geology—that of a second kind of monogenetic mountain. The
  _synclinoria_ were _made through a progressing geosynclinal_. Those of
  the second kind, here referred to, were _produced by a progressing
  geanticlinal_. They are simply the upward bendings in the oscillations
  of the earth’s crust—the geanticlinal waves, and hardly require a
  special name. Yet, if one is desired, the term _anticlinorium_, the
  correlate of _synclinorium_, would be appropriate. Many of them have
  disappeared in the course of the oscillations; and yet, some may have
  been for a time—perhaps millions of years—respectable mountains.

  The geosynclinal ranges or synclinoria have experienced in almost all
  cases, since their completion, true elevation through great
  geanticlinal movements, but movements that embraced a wider range of
  crust than that concerned in the preceding geosynclinal movements,
  indeed a range of crust that comes strictly under the designation of a
  polygenetic mass.”


               “_The Condition of the Earth’s Interior._”

  “The condition of the earth’s interior is not among the geological
  results of contraction from cooling. But these results offer an
  argument of great weight respecting the earth’s interior condition,
  and make it desirable that the subject should be discussed in this
  connection. Moreover, the facts throw additional light on the
  preceding topic—the origin of mountains.

  It seems now to be demonstrated by astronomical and physical
  arguments—arguments that are independent, it should be noted, of
  direct geological observation—that the interior of our globe is
  essentially solid. But the great oscillations of the earth’s surface,
  which have seemed to demand for explanation a liquid interior, still
  remain facts, and present apparently a greater difficulty than ever to
  the geologist. Professor Le Conte’s views, in volume iv, were offered
  by him as a method of meeting this difficulty; yet, as he admits in
  his concluding remarks, the oscillations over the interior of a
  continent, and the fact of the greater movements on the borders of the
  larger ocean, were left by him unexplained. Yet these oscillations are
  not more real than the changes of level or greater oscillations which
  occurred along the sea border, where mountains were the final result;
  and this being a demonstrated truth, no less than the general solidity
  of the earth’s interior, the question comes up, how are the two truths
  compatible?

  The geological argument on the subject (the only one within our
  present purpose) has often been presented. But it derives new force
  and gives clearer revelations when the facts are viewed in the light
  of the principles that have been explained in the preceding part of
  this memoir.

  The Appalachian subsidence in the Alleghany region of 35,000 to 40,000
  feet, going on through all the Paleozoic era, was due, as has been
  shown, to an actual sinking of the earth’s crust through lateral
  pressure, and not to local contraction in the strata themselves or the
  terranes underneath. But such a subsidence is not possible, unless
  seven miles—that is, seven miles in maximum depth and over a hundred
  in total breadth—unless seven miles of _something_ were removed, in
  its progress, from the region beneath.

  If the matter beneath was not aërial, then liquid or viscous rock was
  pushed aside. This being a fact, it would follow that there existed,
  underneath a crust of unascertained thickness, a sea or lake of mobile
  (viscous or plastic) rock, as large as the sinking region; and also
  that this great viscous sea continued in existence through the whole
  period of subsidence, or, in the case of the Alleghany region, through
  all Paleozoic time—an era estimated on a previous page to cover at
  least thirty-five millions of years, if time since the Silurian age
  began embraced fifty millions of years.

  The facts thus sustain the statement that lateral pressure produced
  not only the subsidence of the Appalachian region through the
  Paleozoic, but also, cotemporaneously, and as its essential
  prerequisite, the rising of a sea-border elevation, or geanticlinal,
  parallel with it; and that both movements demanded the existence
  beneath of a great sea of mobile rock.”


The recognition of regional _warping_ as a major factor in the larger
structure of mountain systems, and the expression of that factor in the
terms geosyncline and geanticline forms a notable advance in geologic
thought. Subsequent folding on a regional scale results in the
development of synclinoria and anticlinoria. Van Hise has given these
latter terms wide currency, but apparently inadvertently has used
synclinorium in a different sense than that in which Dana defined it.
Dana gave the word to a mountain range made by the mashing and uplift of
a geosyncline, Van Hise defines it as a downfold of a large order of
magnitude, embracing anticlines and synclines within it; anticlinorium
he uses for a corresponding up fold.[89] Rice has called attention to
this change of definition,[90] but Van Hise’s usage is likely to
prevail, since they are needed terms for the larger mountain structure
and do not require a determination of the previous limits of upwarp and
downwarp,—of original denudation and deposition. Furthermore, a
geosyncline in mountain folding may have one side uplifted, the other
side depressed and there are reasons for regarding the folds of
Pennsylvania, Dana’s type synclinorium, as representing but the western
and downfolded side of the Paleozoic geosyncline. Under that view the
folded Appalachians of Pennsylvania constitute a synclinorium in both
the sense of Dana and Van Hise.


              _The Ultimate Cause of Crustal Compression._

The next important advance in the theory of mountains was made by C. E.
Dutton who in 1874 published in the Journal (=8=, 113–123) an article
entitled “A criticism upon the contractional hypothesis.” Dutton gives
reasons for holding that the amount of folding and shortening exhibited
in mountain ranges, especially those of Tertiary date, is very much
greater in magnitude and is different in nature and distribution from
that which would be given by the surficial cooling of the globe. The
following quotations cover the principal points in the argument:


  “The argument for the contractional hypothesis presupposes that the
  earth-mass may be considered as consisting of two portions, a cooled
  exterior of undetermined (though probably comparatively small) depth,
  inclosing a hot nucleus.... The secular loss of heat, it is assumed,
  would be greater from the hot nucleus than from the exterior, and the
  greater consequent contraction of the nucleus would therefore
  gradually withdraw the support of the exterior, which would collapse.
  The resulting strains upon the exterior would be mainly tangential.
  Owing to considerable inequalities in the ability of different
  portions to resist the strains thus developed, the yielding would take
  place at the lines, or regions of least resistance, and the effects of
  the yielding would be manifested chiefly, or wholly, at those places,
  in the form of mountain chains, or belts of table lands, and in the
  disturbances of stratification. The primary division of the surface
  into areas of land and water are attributed to the assumed smaller
  conductivity of materials underlying the land, which have been left
  behind in the general convergence of the surface toward the center.
  Regarding these as the main and underlying premises of the
  contractional argument, it is considered unnecessary to state the
  various subsidiary propositions which have been advanced to explain
  the determination of this action to particular phenomena, since the
  main proposition upon which they are based is considered untenable.

  There can be no reasonable doubt that the earth-mass consists of a
  cooled exterior inclosing a hot nucleus, and a necessary corollary to
  this must be secular cooling, probably accompanied by contraction of
  the cooling portions. But when we apply the known laws of thermal
  physics to ascertain the rate of this cooling, and its distribution
  through the mass, the objectionable character of the contractional
  hypothesis becomes obvious.

  That Fourier’s theorem, under the general conditions given, expresses
  the normal law of cooling, is admitted by all mathematicians who have
  examined it. The only ground of controversy must be upon the values to
  be assigned to the constants. But there seem to be no values
  consistent with probability which can be of help to the contractional
  hypothesis. The application of the theorem shows that below 200 or 300
  miles the cooling has, up to the present time, been extremely
  little.... At present, however, the unavoidable deduction from this
  theorem is that the greatest possible contraction due to secular
  cooling is insufficient in amount to account for the phenomena
  attributed to it by the contractional hypothesis.

  The determination of plications to particular localities presents
  difficulties in the way of the contractional hypothesis which have
  been underrated. It has been assumed that if a contraction of the
  interior were to occur, the yielding of the outer crust would take
  place at localities of least resistance. But this could be true only
  on the assumption that the crust could have a horizontal movement in
  which the nucleus does not necessarily share. A vertical section
  through the Appalachian region and westward to the 100th meridian
  shows a surface highly disturbed for about two hundred and fifty
  miles, and comparatively undisturbed for more than a thousand. No one
  would seriously argue that the contraction of the nucleus had been
  confined to portions underlying the disturbed regions: yet if the
  contraction was general, there must have been a large amount of slip
  of some portion of the undisturbed segment over the nucleus. Such a
  proposition would be very difficult to defend, even if the premises
  were granted. It seems as if the friction and adhesion of the crust
  upon the nucleus had been overlooked. Nor could this be small, even
  though the crust rested upon liquid lava. The attempts which some
  eminent geologists have recently made to explain surface corrugation
  by this method clearly show a neglect on their part to analyze
  carefully the system of forces which a contraction of the nucleus
  would generate in the crust. Their discussions have been argumentative
  and not analytical. The latter method of examination would have shown
  them certain difficulties irreconcilable with their knowledge of
  facts. Adopting the argumentative mode, and in conformity with their
  view regarding the exterior as a shell of insufficient coherence to
  sustain itself when its support is sensibly diminished, the tendency
  of corrugation to occur mainly along certain belts, with series of
  parallel folds, is not explained by assuming that these localities are
  regions of weakness. For a shrinkage of the nucleus would throw each
  elementary portion of the crust into a state of strain by the action
  of forces in all directions within its own tangent plane. A relief by
  a horizontal yielding in one direction would by no means be a general
  relief.”


Dutton’s criticisms robbed the current hypothesis of mountain-making of
its conventional basis without providing a new foundation. It was a
quarter of a century in advance of its time, has been seldom cited, and
seems to have had but little direct influence in shaping subsequent
thought. It, however, gave direction to Dutton’s views, and his later
papers were far-reaching in their influence.

If contraction from external cooling is not the cause of the compressive
forces it is necessary to seek another cause. Two years later, in 1876,
Dutton attempted to provide an answer to this open question.[91] A
review of this paper, evidently by J. D. Dana, is given in the Journal.
The following explanations of Dutton’s theory and of Dana’s comments
upon it are contained in a few paragraphs from this review (=12=, 142,
1876).


  “Captain Dutton presents in this paper the views brought out in his
  article in volume viii of this Journal, with fuller illustrations, and
  adds explanations of his theory of the origin of mountains. The
  discussion should be read by all desiring to reach right conclusions,
  it presenting many arguments from physical considerations against the
  contraction-theory, or that of the uplifting and folding of strata
  through lateral pressure. There is much to be learned before any
  theory of mountain-making shall have a sufficient foundation in
  observed facts to demand full confidence, and Captain Dutton merits
  the thanks of geologists for the aid he has given them toward reaching
  right conclusions. His discussions are not free from misunderstandings
  of geological facts, and if they fail to be finally received it will
  be for this reason.

  We here give in a brief form, and nearly in his own words, the
  principal points in his theory of mountain-making as explained in the
  later part of his memoir.

  Accepting the proposition that there is a plastic condition of rock
  beneath the earth’s crust and that metamorphism is a ‘hydrothermal
  process,’ and believing that ‘the penetration of water to profound
  depths [in the earth’s crust] is a well sustained theory,’ he says
  that great pressure and a temperature approaching redness are
  essential conditions of metamorphism.... ‘The heaviest portion would
  sink into the lighter colloid mass underneath, protruding it laterally
  beneath the lighter portions where, by its lighter density, it tends
  to accumulate.’ He adds: ‘The resulting movements would be determined,
  first, by the amount of difference in the densities of the upper and
  lower masses, and, second, by inequalities in the thickness of the
  strata: the forces now become adequate to the building of mountains
  and the plication of strata, and their modes of operation agree with
  the classes of facts already set forth as the concomitants of those
  features.’

  The views are next applied to a system of plications. ‘It has been
  indicated that plications occur where strata have rapidly accumulated
  in great volume and in elongated narrow belts; that the axes of
  plications are parallel to the axes of maximum deposit; and that the
  movements immediately followed the deposition’—the case of the
  Appalachians being an example in which the accumulations averaged
  40,000 feet. He observes: ‘Wherever the load of sediments becomes
  heaviest, there they sink deepest, protruding the colloid magma
  beneath them to the adjoining areas, which are less heavily weighted,
  forming at once both synclinals and anticlinals.’

  With regard to this new theory, we might reasonably question the
  existence of the colloid magma—a condition fundamental to the
  theory—and his evidence that water penetrates to profound depths in
  the earth’s crust sufficient to make hydrous rocks. We might ask for
  evidence that the rocks beneath the Cretaceous and Tertiary, and other
  underlying strata of the Uintahs, were in such a colloid state, and
  this so near the surface, that the ‘beds subsided by their gross
  weight as rapidly as they grew.’

  Again, he says that the movements of mountain-making ‘immediately
  followed the deposition.’ ‘Immediately’ sounds quick to one who
  appreciates the slowness of geological changes. The Carboniferous age
  was very long; and somewhere in that part of geological time, either
  before the age had fully ended, or some time after its close, the
  epoch of catastrophe began.”


We see foreshadowed in this paper the theory of isostasy, or condition
of vertical equilibrium in the crust which Dutton published in 1889.
This theory has borne remarkable fruit, but Dutton attempted to link to
it the horizontally compressive forces which have produced folding and
overthrusting. Willis in 1907[92] and Hayford in 1911, overlooking
Dana’s objections, have attempted to make a lateral isostatic undertow
the cause of all horizontal movements in the crust, adopting the
mechanism of Dutton. The present writer, although accepting the
principle of isostasy as an explanation of broad vertical movements, has
published papers which go to show the inadequacy of this hypothesis of
lateral pressure; inadequate in time relation, in amount, and in
expression.[93]

In 1903 it was determined by several physicists that the materials of
the earth’s crust were radioactive and must generate throughout geologic
time a quantity of heat which perhaps equalled that lost by radiation
into space. By 1907 this had become demonstrated. The remarkable
conclusion had been reached that the earth, although losing heat, is not
a cooling globe. Dutton’s contentions against mountain growth through
external cooling and contraction were thus unexpectedly, through a
wholly new branch of knowledge, demonstrated to be true.

Nevertheless, all students of orogeny are agreed that profound
compressive forces have been the chief agents in developing mountain
structures. Chamberlin was the first to arrive at the idea that the
shrinkage may originate in the deeper portions of the earth under the
urgency of the enormous pressures, apparently by giving rise to slow
recombinations of matter into denser forms.[94]


      _The New Era in the Interpretation of Mountain Structures._

In the meantime, between 1874 and 1904, another advance in the knowledge
of mountain structures was taking place in Europe. Suess studied the
distribution of mountain arcs over the earth and dwelt upon the
prevalence of overthrust structures; the backland being thrust toward
and over the foreland, the rise of the mountain arc or geanticline
depressing the foredeep or geosyncline. Bertrand and Lugeon from 1884 to
1900 were reinterpreting the Alpine structures on this basis. They
showed that the whole mountain system had been overturned and overthrust
from the south to an almost incredible degree. Enormous denudation had
later dissevered the northern outlying portions and given rise to
“mountains without roots,”—isolated outliers, consisting of overturned
masses of strata which had accumulated as sediments far to the southward
in another portion of the ancient geosyncline.

On a smaller scale similar phenomena are exhibited in the Appalachians.
Willis showed that the deep subsidence of the center of the geosyncline
gave an initial dip which determined the position of yielding under
compression. Laboratory experiments brought out the weakness of the
stratigraphic structure to resist horizontal compression. The nature of
the stratigraphic series was shown to determine whether the yielding
would be by mashing, competent folding, or breakage and overthrust. The
problem of mountain structures was thus brought into the realm of
mechanics. These results were published in three sources in 1893,—the
Transactions of the American Institute of Mining Engineers, the
thirteenth annual report of the United States Geological Survey, and the
Journal (=46=, 257, 1893).

Finally should be noted the contributions of the Lake Superior school of
geology, in which the work of Van Hise stands preeminent. Under the
economic stimulus given by the discovery and development of enormously
rich bodies of iron ore, hidden under Pleistocene drift and involved in
the complex structures of vanished mountain systems of ancient date,
structural geology and metamorphism have become exact sciences to be
drawn upon in the search for mineral wealth and yielding also rich
returns in a fuller knowledge of early periods of earth history.


             _Crust Movements as Revealed by Physiography._

During the last quarter of the nineteenth century another division of
geology, dominantly American, was taking form and growth,—the science of
land forms,—physiography. The history of that development is treated by
Gregory in the preceding chapter but some of its bearings upon theory,
in so far as they affect the subject of mountain origin, are necessarily
given here.

Powell, Dutton, and Gilbert in their explorations of the West saw the
stupendous work of denudation which had been carried to completion again
and again during the progress of geologic time. The mountain relief
consequently may be much younger than the folding of the rocks, and may
be largely or even wholly due to recurrent plateau movement, a doctrine
to which Dana had previously arrived. But the introduction of the idea
of the peneplain opened up a new field for exploration in the nature and
date of crust movements. Davis by this means began to study the later
chapters of Appalachian history, the most important early paper being
published in 1891.[95] Since then Davis, Willis, and many others have
found that, girdling the world, a large part of the mountainous relief
is due to vertical elevatory forces acting over regions of previous
folding and overthrust. In addition, great plateau areas of unfolded
rocks have been bodily lifted one to two miles, or more, above their
earlier levels. They may be broad geanticlinal arches or bounded by the
walls of profound fractures.

The linear mountain systems made from deep troughs of sediments have
come then to be recognized as but one of several classes of mountains.
This class, from its clear development in the Appalachians, and the fact
that many of the laws of mountain structure pertaining to it were first
worked out there, has been called by Powell the Appalachian type (=12=,
414, 1876). A classification of mountain systems was proposed by him in
which mountains are classified into two major divisions, those composed
of sedimentary strata altered or unaltered, and those composed in whole
or in part of extravasated material. The first class he subdivides into
six sub-classes of which the folded Appalachians illustrate one. It
appears to the writer that Powell’s classification gives
disproportionate importance to certain types which he described; but
nevertheless, the fact that such a classification was made, indicates
the growth of a more comprehensive knowledge of mountains,—their origin,
structure, and history.


       _Relations of Crust Movements to Density and Equilibrium._

A recent important development in the fields of geophysics and major
crust movements consists in the incorporation into geology of the
doctrine of isostasy. The evidence was developed in the middle of the
nineteenth century by the geodetic survey of India which indicated that
the Himalayas did not exert the gravitative influence that their volume
called for. It was clear that the crust beneath that mountain system was
less dense than beneath the plains of India and still less dense than
the crust beneath the Indian Ocean. This relation between density and
elevation indicated some approach to flotational equilibrium in the
crust, comparable in its nature though not in delicacy of adjustment to
the elevation of the surface of an iceberg above the ocean level owing
to its depth and its density, less than that of the surrounding medium.
This important geological conception was kept within the confines of
astronomy and geodesy, however, until Dutton in 1876, but especially in
1889, brought it into the geologic field. A test of isostasy was made
for the United States by Putnam and Gilbert in 1895 and much more
elaborate investigations have since been made by Hayford and Bowie.
These investigations demonstrate the importance and reality of broad
warping forces acting vertically and related to the regional variations
of density in the crust.

There are consequently two major and unrelated classes of forces
involved in the making of mountain structures,—the irresistible
horizontal compressive forces, arising apparently from condensation deep
within the earth, and vertical forces originating in the outer envelopes
and tending toward a hydrostatic equilibrium. In this latter field of
investigation, America, since the initial paper by Dutton, has taken the
lead.


    _Conclusion on Contributions of America to Theories of Orogeny._

The sciences arose in Europe, but those which treated of the earth were
still in their infancy when transplanted to America. The first
comprehensive ideas on the nature of mountain structures arose in Great
Britain and France. These ideas served as a guide and stimulus to
observation in the recognition of deformations in the strata of the
Appalachian system. Since 1840, however, America has ceased to be a
pupil in this field of research but has joined as an equal with the two
older countries. New ideas have been contributed, new and striking
illustrations cited, first by the scientists of one nation, next by
those of another. The composite mass of knowledge has grown as a common
possession. Nevertheless, a review of the progress since 1840 as
measured by the contribution of new ideas shows on the whole America at
least equal to its intellectual rivals, and at certain times actually
the leader. This is true of the science of geology as a whole and also
of the subdivision of orogeny.

Thus far no mention has been made of German geologists, with the
exception of Suess, an Austrian. German geology is voluminous and the
names of many well-known geologists could be cited. But this article has
sought to trace the origin and growth of fundamental ideas. The Germans
have been assiduous observers of detail; preeminent as systematizers and
classifiers, seldom originators. Even petrology, which might be regarded
as their especial field, was transplanted from Great Britain. In the
science of mountains they have followed in their fundamental ideas
especially the French.

Turning to the mediums of publication through which this progress of
knowledge in earth structures has been recorded, the American Journal of
Science stands foremost as the only continuous record for the whole
century in American literature, fulfilling for this country what the
Quarterly Journal of the Geological Society has done for Great Britain
since 1845, and the Bulletin de la Société Géologique for France since
1830.


                                _Notes._

Footnote 78:

  H. D. Rogers, Geology of New Jersey, Final Report, p. 115, 1840.

Footnote 79:

  H. D. Rogers, Geology of Pennsylvania, vol. 2, pt. II, pp. 761, 762,
  1858.

Footnote 80:

  Connecticut Academy of Arts and Sciences, 1810; quoted by G. P.
  Merrill in Contributions to the History of North American geology,
  Ann. Rpt. Smithsonian Institution for 1904, p. 216.

Footnote 81:

  A Sketch of the geology, mineralogy, and scenery of the regions
  contiguous to the river Connecticut; with a geological map and
  drawings of organic remains; and occasional botanical notices, the
  Journal, 6, 1–86, 201–236, 1823; 7, 1–30, 1824.

Footnote 82:

  Clarence King, U. S. Geol. Exploration of the Fortieth Parallel, vol.
  1, pp. 16, 44–48, 1878.

Footnote 83:

  Illustrations of the Huttonian Theory of the Earth, pp. 219–238, 1802.

Footnote 84:

  Robert Jameson, Elements of Geognosy, pp. 55–57, 1808.

Footnote 85:

  G. P. Merrill, Contributions to the History of American Geology.
  Report of the U. S. National Museum for 1904, p. 328.

Footnote 86:

  H. D. Rogers, Geology of Pennsylvania, vol. 2, p. 916, 1858.

Footnote 87:

  James Hall, Natural History of New York, Paleontology, vol. 3, pp.
  51–73, 1859.

Footnote 88:

  The Journal, 5, 423–443, 474, 475; 6, 6–14, 104–115, 161–172, 304,
  381, 382, 1873.

Footnote 89:

  C. R. Van Hise, Principles of North American Pre-Cambrian Geology, U.
  S. Geol. Surv., 16th Ann. Report, pt. I, pp. 607–612, 1896.

Footnote 90:

  W. N. Rice, On the use of the words synclinorium and anticlinorium,
  Science, 23, 286, 287, 1906.

Footnote 91:

  C. E. Dutton, Critical observations on theories of the earth’s
  physical evolution, The Penn Monthly, May and June, 1876.

Footnote 92:

  B. Willis, Research in China, vol. 2, 1907.

Footnote 93:

  Joseph Barrell, Science, 39, 259, 260, 1909; Jour. Geol., 22, 672–683,
  1914.

Footnote 94:

  T. C. Chamberlin, Geology, vol. 1, pp. 541, 542, 1904.

Footnote 95:

  W. M. Davis, The geological dates of origin of certain topographic
  forms on the Atlantic slope of the United States, Geol. Soc. Am.
  Bull., 2, 541–542, 545–586, 1891.




                                   V
               A CENTURY OF GOVERNMENT GEOLOGICAL SURVEYS

                          By GEORGE OTIS SMITH


            Director of the United States Geological Survey


 Even a Federal Bureau must be considered a product of evolution: the
past of the United States Geological Survey far antedates March 3, 1879.
The scope of endeavor, the refinement of method, and especially the
personnel of the newly created service of that day were largely
inherited from pioneer organizations. Therefore a review of the
country’s record of surveys under Government auspices becomes more than
a grateful acknowledgment by the present generation of geologists of the
credit due to those who blazed the way; it shows the sequence and
progress in the contributions made by geologic science to industry.

The earlier stages in industrial evolution mentioned by
Hess[96]—exploitation, development, and maturity—determine a somewhat
similar progressive development in geologic investigation, so that
geographic exploration and geologic reconnaissance of the broadest type
are the normal contribution of exact science whenever and wherever a
nation is in the state of exploitation and initial development of its
mineral and agricultural resources. The refinements of detailed surveys
and quantitative examinations belong rather to the next stage of
intensive utilization, or, indeed, they are the essentials preliminary
to full use. Thus regrets that the results of present-day work were not
available fifty years ago are largely vain: the fathers may not have
been without the vision; they simply did the work as their day and
generation needed it done.

Twenty years ago S. F. Emmons, in a presidential address before the
Geological Society of Washington, divided the history of Governmental
surveys in this country into two periods, separated in a general way by
the Civil War. The first of these was the period of geographic
exploration, the second that of geologic exploration. Mr. Emmons of
course regarded this subdivision as not hard and fast, yet his dividing
line seems logical, for not only did the military activities in the East
necessarily suspend exploration in the West, but after the war national,
political, and economic considerations led naturally to the demand for a
more exact knowledge of the vast national domain in the West. Geography
and geology are so closely related that Mr. Emmons’s distinction of the
two periods is useful only with the limitations inferentially set by
himself—namely, that while geologic investigation entered into most of
the explorations of the earlier period, the geologist was regarded as
only an accessory in these exploring expeditions; on the other hand, in
the later surveys the topographic work was developed because it was
essential to the geologic investigations.

The year 1818 was a notable one in American geology, first of all in the
appearance of the American Journal of Science, itself so perfect a
vehicle for geological thought that, as is so well stated by Dr. G. P.
Merrill, “a perusal of the numbers from the date of issue down to the
present time will alone afford a fair idea of the gradual progress of
American geology.” The beginning of publications on New England geology
appeared that year in Edward Hitchcock’s first paper on the Connecticut
Valley (1, 105, 1818) and the Danas’ (S. L. and J. F.) detailed geologic
and mineralogic description of Boston and vicinity; and the “Index” of
Amos Eaton (noticed in this Journal, =1=, 69) was the first of that long
list of notable contributions to American stratigraphy that are to be
credited to the New York geologists.

In the present discussion, too, the year 1918 can be regarded as in a
way the centennial of Government geologic surveys, for it was in 1818
that Henry R. Schoolcraft began his trip to the Mississippi
Valley—perhaps the first geologic reconnaissance into the West—and it
was his work in the lead region which served to make him a member of the
Cass expedition sent out by the Secretary of War in 1820 to examine the
metallic wealth of the Lake Superior region. The earlier Government
explorations of Lewis and Clark, in 1803–7, and of Pike, in 1805–7, were
so exclusively geographic that geologic work under Federal auspices must
be regarded as beginning with Schoolcraft and with Edwin James, the
geologist of the expedition of Major Long in 1819–20 to the Rocky
Mountains. Both these observers published reports that are valuable as
contributions to the knowledge of littleknown regions.

Any description of geologic work under the Federal Government that
included no reference to the State surveys would be inadequate, for in
both date of execution and stage of development the work of the State
geologists must be given precedence. In Merrill’s Contributions to the
History of American Geology,[97] whose modest title fails even to
suggest that this work not only furnishes the most useful chronologic
record of the progress of the science on the American continent but is
in fact a very thesaurus of incidents touching the personal side of
geology, the author by his division of his subject shows that four
decades of the era of State surveys elapsed before the era of national
surveys began.

Thus the geologic surveys of some of the Eastern States antedate by
several decades any Federal organization of comparable geologic scope,
and in investigations directed to local utilitarian problems these
pioneer geologists working in the older settled States of the East were
in fact already conducting work as detailed in type as much of that
attempted by the Federal geologists of the later period. Even to-day it
is true in a general way that the State geologist can and should attack
many of his local problems with intensive methods and with detail of
results that are neither practicable nor desirable for the larger
interstate investigations or for examinations in newer territory. All
this relation of State and Federal work must be looked upon as normal
evolutionary development of geologic science in America.

One who reads the names of the Federal geologists of the early days,
beginning with Jackson and Owen and following with such leaders in
Federal work as Gilbert, Chamberlin, King, R. D. Irving, Pumpelly, Van
Hise, and Walcott, may note that these were all connected in their
earlier work with State surveys. Nor has the relation been one-sided,
for among the State geologists Whitney, Blake, Mather, Newberry, J. G.
Norwood, Purdue, Bain, Gregory, Ashley, Kirk, W. H. Emmons, DeWolf,
Mathews, Brown, Landes, Moore, and Crider received their field training
in part or wholly as members of a Federal Survey. Moreover, under the
present plan of effective cooperation of several of the State surveys
with the United States Geological Survey, it is often difficult to
differentiate between the two in either personnel or results, for it
even happens that the publishing organization may not have been the
major contributor. The full record of American geology, past and
present, can not be set forth in terms of Federal auspices alone.

The three decades preceding the Civil War, then, constitute the era of
State surveys, well described by Merrill as at first characterized by a
contagious enthusiasm for beginning geologic work, later by a more
normal condition in which every available geologist seems to have been
quietly at work, and finally by renewed activity in creating new
organizations. The net result was that Louisiana and Oregon seem to have
been the only States not having at least one geological survey.

[Illustration:

  From “Contributions to the History of American Geology”
  by George P. Merrills.
]

The first specific appropriation by the Federal Government for geologic
investigation appears to have been made in 1834, when a supplemental
appropriation for surveys of roads and canals under the War Department,
authorized in 1824, contained the item “of which sum five thousand
dollars shall be appropriated and applied to geological and
mineralogical survey and researches.” In July, 1834, Mr. G. W.
Featherstonhaugh was appointed United States geologist and employed
under Colonel Abert, U. S. Topographical Engineers, to “personally
inspect the mineral and geological character” of the public lands of the
Ozark Mountain region. Overlooking the incidental fact that this
Englishman—a man of scientific attainment and large interest in public
affairs—was never naturalized,[98] it must be placed to the credit of
this first of United States geologists that within seven months he
completed his field work and returned to Washington, and on February 17,
1835, his report was transmitted to Congress. Two years earlier
Featherstonhaugh had memorialized Congress for aid in the preparation of
a geologic map of the whole territory of the United States, and in
connection with this project he suggested that geology as an aid to
military engineering should have a place in the curriculum at West
Point. This first United States geologist also appears to have combined
an appreciation of the practical worth of “the mineral riches of our
country, their quality, quantity, and the facility of procuring them,”
with an interest in the more scientific side of geology, though his
hypotheses regarding both economic geology and stratigraphic and
structural geology have not won the endorsement of all later workers in
the same regions. In all these respects, however, Featherstonhaugh may
stand as a fairly good prototype. His contributions to international
affairs subsequent to his scientific service to the United States are of
interest; he served as one of Her Majesty’s commissioners in the
settlement of the Canadian-United States boundary question in 1839–40
and made an examination of the disputed area, and after the settlement
of this controversy he was appointed British Consul for the Department
of the Seine, France, where in 1848 he personally engineered the escape
of Louis Philippe from Havre.

The Federal geologic work thus started was soon continued in surveys of
wider scope and more thorough accomplishment. The position of the
Government as the proprietor of mineral lands in the Upper Mississippi
Valley led to their examination. These Government lands containing lead
had been reserved from sale for lease since 1807, although no leases
were issued until 1822. The amount of illegal entry and consequent
refusal of smelters and miners to pay royalty after 1834 forced the
issue upon the attention of Congress, and in 1839 President Van Buren
was requested to present to Congress a plan for the sale of the public
mineral lands. In carrying out this policy Dr. David Dale Owen was
selected to make the necessary survey.

Owen had served as an assistant on the State Survey of Tennessee and as
the first State geologist of Indiana, and he organized the new work
promptly and effectively. Although suffering from the handicap
unfortunately known by geologists of the present day—the receipt late in
the season (August 17, 1839) of authority to begin work—within exactly a
month he had his force of 139 assistants organized into 24 field
parties, instructed in “such elementary principles of geology as were
necessary to their performance of the duties required of them.” His plan
of campaign provided for a northward drive at a predetermined rate of
traverse for each party, with periodic reports to himself at appointed
stations, “to receive which reports and to examine the country in
person” he crossed the area under survey eleven times. The result of
such masterful leadership was the completion of the exploration of all
the lands comprehended in his orders in two months and six days, and his
report on this great area—about 11,000 square miles—bears date of April
2, 1840.

Eight years later Doctor Owen made a survey of an even larger area,
continuing his examination northward to Lake Superior. Again his report
was published promptly, and he continued for several years his
examination of the Northwest Territory, submitting his final report in
1851. It is interesting to note that in his earlier report Doctor Owen
subscribed himself as “Principal Agent to explore the Mineral Lands of
the United States,” but that in the later report he was “U. S. Geologist
for Wisconsin.” The two surveys together covered 57,000 square miles.

During the same period similar surveys were being made in northern
Michigan by Dr. Charles T. Jackson, 1847–48, and Foster and Whitney,
1849–51. These surveys also had been hastened by the “copper fever” of
1844–46, with wholesale issue of permits and leases, Congress in 1847
authorizing the sale of the mineral lands and a geological survey of the
Lake Superior district. The execution of these surveys under Jackson and
under Foster and Whitney and the prompt publication in 1851 of the maps
of the whole region materially helped to establish copper mining on a
more conservative basis. and the development of the Lake Superior region
was rapid.[99]

These land-classification surveys, with their definite purpose,
represent the best geologic work of the time. The plan necessitated
thoroughgoing field work with considerable detail and prompt publication
of systematic reports, and in the working up of the results specialists
like James Hall and Joseph Leidy contributed, while F. B. Meek was an
assistant of Owen. It is worthy of note that had not Doctor Houghton,
the State geologist of Michigan, met an untimely death in 1847,
effective cooperation of the State Survey with the Federal officials
would have combined geologic investigation with the execution of the
linear surveys.[100]

Belonging to the same period of geologic exploration was the service of
J. D. Dana, as United States Geologist on the Wilkes Exploring
Expedition, the disaster to which compelled his return from the Pacific
Coast overland and resulted in his geologic observations on Oregon and
northern California.

The military expeditions during the decade 1850–60 and the earlier
expeditions of Fremont added to the geographic knowledge of the Western
country and also contributed to geologic science, largely through
collections of rocks and fossils, usually reported on by the specialists
of the day. Thus the names of Hall, Conrad, Hitchcock, and Meek appear
in the published reports on these explorations, while Marcou, Blake,
Newberry, Gibbs, Evans, Hayden, Parry, Shumard, Schiel, Antisell, and
Engelmann were geologists attached to the field expeditions. In 1852
geologic investigation was seemingly so popular as to necessitate the
statutory prohibition “there shall be no further geological survey by
the Government unless hereafter authorized by law.”

Certain of these explorations had a specific purpose: several of them
sought a practical route for a transcontinental railroad; another a new
wagon road across Utah and Nevada; and one under Colonel Pope, with G.
G. Shumard as geologist, was sent out “for boring Artesian Wells along
the line of the 32d Parallel” in New Mexico. The published reports
varied greatly in scientific value and in carefulness of preparation,
while the publication of at least two reports was delayed until long
after the war, and the manuscript of another was lost. The report of the
expedition of Major Emory contained a colored geologic map of the
western half of the country, a pioneer publication, for the map prepared
by Marcou extended only to the 106th meridian.

Thus in the first period of Government surveys, covering about forty
years, the great West, with its wealth of public lands, was well
traversed by exploratory surveys, which furnished, however, only general
outlines for a comprehension of the stratigraphy and structure of
mountain and valley, plain and plateau. To an even less degree was there
any realization of the economic possibilities of the vast territory west
of the Mississippi. President Jefferson, in planning the Lewis and Clark
expedition, had stated his special interest in the mineral resources of
the region to be traversed. Nearly forty years later Doctor Owen was
strongly impressed with the commercial promise of the region he
surveyed. His reports contain analyses of ores and statistics of
production; he compared the lead output of Wisconsin, Iowa, and Illinois
with that of Europe and foretold the value of the iron, copper, and zinc
deposits of the area; he outlined the extent of the Illinois coal field;
and he laid equal emphasis upon the agricultural possibilities of the
region. Indeed, so optimistic were Owen’s general conclusions that he
referred to his separate township plats, with their detailed
descriptions, as the basis for his sanguine opinions, realizing that
“the explorer is apt to become the special pleader.” With equal breadth
of view and thoroughness of execution the surveys of Foster and Whitney
laid the foundation for the development of the copper and iron resources
of the Lake Superior region, and although these areas were largely
wilderness and not adapted to rapid traverse or easy observation the
reports on their explorations nevertheless compare most favorably with
the contributions of geologists working in the more hospitable regions
in the older States.

The period following the Civil War naturally became one of national
expansion, the faces of many were turned westward, and exploration of
the national domain for its industrial possibilities took on fresh
interest. Home-seekers and miners largely made up this army of peaceful
invasion, and the winning of the West began on a scale quite different
from that of the days of the military path-finding expeditions of
Fremont and other Army officers. Thus the nation was aroused to the task
of investigating its public lands and Congress gave the support needed
to make geologic exploration possible on a large scale.

Geologic surveys of a high order were continued in the older States, as
shown by the contributions during this period of J. P. Lesley and G. H.
Cook in the East, W. C. Kerr, E. W. Hilgard, and E. A. Smith in the
South, and J. S. Newberry, C. A. White, Raphael Pumpelly, T. C.
Chamberlin, Alexander Winchell, and T. B. Brooks in the Central States.
To the north the Canadian Survey, organized in 1841 under Logan, had
continued under the same sturdy leadership until 1869, when the
experienced and talented Doctor Selwyn became Director. As contrasted
with the short careers of most of the State Surveys and with the
temporary character of all of the Federal undertakings in geologic
investigation, the continuance of the Canadian Geological Survey for
more than half a century under two directors gave opportunity for
continuity of effort in making known to the people of the Dominion its
resources and at the same time contributing to the world much pure
science.

Passing with simple mention the two Government expeditions into the
Black Hills, which afforded opportunity for geologic exploration by N.
H. Winchell in 1874 and by Jenney and Newton in 1875, the record of
geologic work under Government auspices in the period immediately
following the Civil War groups itself around the names of four
leaders—Hayden, King, Powell, and Wheeler. The four organizations,
distinguished commonly by the names of these four masterful organizers,
occupied the Western field more or less continuously from 1867 to 1878,
and the sum total of their contributions to geography and geology was
large indeed. In the words of Clarence King,[101] “Eighteen hundred and
sixty-seven, therefore, marks, in the history of national geological
work, a turning point, when the science ceased to be dragged in the dust
of rapid exploration and took a commanding position in the professional
work of the country.” Together these four expeditions covered half a
million square miles, or more than a third of the area of the United
States west of the one-hundredth meridian, and the cost of all this work
was approximately two million dollars, which was a small fraction of its
value to the nation counting only the impetus given to settlement and
utilization.

As viewed from a distance of nearly half a century, these four surveys
differed much in plan of organization, scope of purpose, and success of
execution, so that comparison would have little value except as possibly
bearing upon the work of the larger organization which followed them and
became the heir not only to much that had been attained by these pioneer
surveys but also to the great task uncompleted by them. So, if in the
earliest days of the present United States Geological Survey there may
have been a certain partisanship in tracing derived characters in the
new organization, it is even now worth while to recognize the real
origin of much that is credited to present-day development.

Dr. F. V. Hayden was the first of these Survey leaders to engage in
geological exploration. He visited the Badlands as early as 1853, and
his connection with subsequent expeditions was interrupted only by his
service as a surgeon in the Federal Army during the war. In 1867,
however, Hayden resumed his geologic work as United States Geologist
in Nebraska, operating under direction of the Commissioner of the
General Land Office. In the following eleven years the activities of
the Hayden Survey—the “Geological and Geographical Survey of the
Territories”—extended into Wyoming, Colorado, New Mexico, Montana, and
Idaho, covering with areal surveys 107,000 square miles. This Survey,
as might be expected from the long experience of its leader, made
large contributions to stratigraphy, which involved notable
paleontologic work by Cope, Meek, and Lesquereux. Next in importance
was the structural work of A. C. Peale, W. H. Holmes, Capt. C. E.
Dutton, and Dr. Hayden himself, and the influence of these expeditions
in popularizing geology should not be overlooked. The expedition of
1871 into the geyser region on the upper Yellowstone resulted in the
creation of the first of the national parks. W. H. Holmes began his
artistic contributions to geology in 1872 with this Survey.
Topographic mapping was added to the geologic exploration, James T.
Gardner and A. D. Wilson joining the Hayden Survey after earlier
service on the King Survey and Henry Gannett being a member of
parties, first as astronomer and later as topographer in charge. The
accomplishment of the Hayden Survey itself and the later work of many
of its members show that this organization possessed a corps of strong
men.

The King Survey was a smaller organization, with Congressional
authorization of definite scope and a systematic plan of operation. The
beginning of construction of the Union Pacific terminated the period of
the railroad surveys under the War Department and afforded opportunity
for geologic work that would be more than exploratory: the opening up of
the new country made investigation of its resources logical. This fact
was recognized by Clarence King, who had traversed the same route as a
member of an emigrant train with his friend James T. Gardner. His plan
to make a geological cross section of the Cordilleras, with a study of
the resources along the route of the Pacific railroads, won the support
of Congress, and the “Geological Exploration of the Fortieth Parallel”
was authorized in 1867, with Clarence King as geologist in charge, under
the Chief of Engineers of the Army. Field work was begun in the summer
of that year, and it is interesting to note that Mr. King and his small
force of geological assistants—the two Hagues and S. F. Emmons—began at
the western end of this cross section, and in this and subsequent years
extended the survey from the east front of the Sierra Nevada to
Cheyenne, covering a belt of territory about 100 miles in width. This
comprehensive plan was carried out in the field operations, and the
scientific and economic results were systematically worked up in the
reports, which appeared in 1870–80. The only departure from this plan
was a study of the volcanic mountains Shasta, Rainier, and Hood, in
1870, occasioned by an unexpected and unsolicited appropriation for
field work, and that summer’s work resulted in the discovery of active
glaciers, the first known within the United States.

The Fortieth Parallel Survey is to be credited with contributions to the
knowledge of the stratigraphy of the West, the region traversed being
remarkably representative of the stratigraphic column, to which was
added the paleontologic work of Marsh, Meek, Hall, and Whitfield, while
the attempt was made to interpret the sedimentary record in terms of
Paleozoic, Mesozoic, and Tertiary geography. King’s plan of survey
included large use of topographic mapping with astronomic base and
triangulation control and contours based upon barometric elevations. The
results were pronounced by an unfriendly critic[102] as “very valuable,
especially from a geological point of view,” but unfortunate in being
the forerunner of work in which Government geologists “have presumed to
arrogate the control of the fundamental operations of a topographic
survey.” To the King Survey must be credited the introduction of
systematic contour mapping and the use of contour maps for purposes of
geology. In two other respects the King Survey contributed largely to
future Government work: microscopical petrography in the United States
may be said to have begun with the visit of Professor Zirkel to this
country as a member of this Survey in 1875, and the report of J. D.
Hague on “Mining Industry” was the fitting expression of the emphasis
then put on the study of the mineral resources of this newly opened
territory, a subject of investigation that was in large part the true
basis of King’s project rather than simply “the immediate excuse for the
Survey.” An earlier influence in the scientific study of ore deposits
had come from Von Richthofen’s investigation of the Comstock Lode in
1865 and his subsequent work with Whitney in California. The incident of
King’s relation to the diamond fraud in Arizona in 1872 furnished a
precedent for public servants of a later day; he investigated the
reported find from scientific interest but exposed it with all the zeal
of a publicist and truth lover. In a word, the Fortieth Parallel Survey
commands our admiration for its brilliant plan, thoroughgoing work in
field and office, and high quality of personnel.

[Illustration: J. W. Powell]

Major J. W. Powell began his large contribution to Government surveys
with his exploration of the Grand Canyon in 1869, the Congressional
recognition of his expedition being limited to an authorization for the
issue of rations by the War Department. Small appropriations were made
in the following years, and in 1874 full authorization was given for the
continuance of his survey in Utah under the Secretary of the Interior
and was followed by the adoption of the name “United States Geographical
and Geological Survey of the Rocky Mountain Region.” This organization
was the least pretentious of the four operating during this period—it
covered less area, expended less public money, and published much
less—but its contribution to American geology is not to be measured by
miles or pages but by ideas. Its physical environment favored this
survey, and in the work of Powell, Dutton, and Gilbert can be seen the
beginnings of physiography on the heroic scale exemplified in the Grand
Canyon and the High Plateaus. The first use of terms like “base-level of
erosion,” “consequent and antecedent drainage,” and “laccolith” marked
the introduction of new ideas in the interpretation of land sculpture
and geologic structure. The daring boat trip of Powell was no less
brilliant than his simple explanation of the Grand Canyon itself.

“The United States Geographical Surveys West of the 100th Meridian” was
the title given to the explorations made under Lieut. G. M. Wheeler, of
the Engineer Corps, which began with topographic reconnaissances in
Nevada, Utah, and Arizona, specifically authorized by Congress in 1872.
From the standpoint of American geology this could be better known as
the Gilbert Survey, Mr. G. K. Gilbert serving for the three years
1871–73, the later part of the time with the title of chief geological
assistant. Gilbert’s contributions included his description of Basin
Range structure, his first account of old Lake Bonneville, and his
discussion of the erosion phenomena of the desert country. J. J.
Stevenson also served later as a geologist of this Survey, and A. R.
Marvine, E. E. Howell, E. D. Cope, Jules Marcou, and I. C. Russell were
connected with the field parties. Captain Wheeler’s own claim for the
work of his Survey emphasized its geographic side, for he regarded the
results as the partial completion of a systematic topographic survey of
the country.

By 1878, when the Fortieth Parallel Survey had completed the work
planned by its chief, three of these independent surveys still contended
for Federal support and for scientific occupation of the most attractive
portions of the Western country. Unrestrained competition of this kind,
even in the public service, proves as wasteful as unregulated
competition in private business,[103] and Congress appealed to the
National Academy of Sciences for a plan for Government surveys to
“secure the best results at the least possible cost.” Under instructions
by Congress the National Academy considered all the work relating to
scientific surveys and reported to Congress a plan prepared by a special
committee, whose membership included the illustrious names of Marsh,
Dana, Rogers, Newberry, Trowbridge, Newcomb, and Agassiz. This report,
which was adopted by the Academy with only one dissenting vote, grouped
all surveys—geodetic, topographic, land parceling, and economic—under
two distinct heads, surveys of mensuration and surveys of geology. At
that time five independent organizations in three different departments
were carrying on surveys of mensuration, and the Academy recommended
that all such work be combined under the Coast and Geodetic Survey with
the new name Coast and Interior Survey. For the investigation of the
natural resources of the public domain and the classification of the
public lands a new organization was proposed, the United States
Geological Survey. The functions of these two surveys and of a third
coordinate bureau in the Interior Department, the Land Office, were
carefully defined and their interrelations fully recognized and provided
for in the plan presented to Congress. Viewed in the light of 39 years
of experience the National Academy plan would be indorsed by most of us
as eminently practical, and the report stands as a splendid example of
public service rendered by America’s leading scientists. The legislation
which embodied the entire plan, however, failed of passage in Congress.

The natural activity behind the scenes of the conflicting interests
represented by those connected with the several surveys may be seen in
the legislative history of the moves leading up to the creation of the
United States Geological Survey. In the last session of the 45th
Congress the special legislation embodying the recommendations of the
National Academy was included in the Legislative, Executive, and
Judicial Appropriation bill as it passed the House of Representatives,
while the Sundry Civil Appropriation bill carried an item simply making
effective the longer section in the other appropriation bill. The item
in the Legislative appropriation bill created the office of the Director
of the Geological Survey, provided his salary, and defined his duties,
as well as specifically terminating the operations of the three older
organizations. The item in the Sundry Civil bill as it passed the House
appropriated $100,000 for the new Geological Survey, but when this
appropriation bill was reported to the Senate a committee amendment
added the words “of the Territories,” and further amendments offered on
the floor changed the item so as to provide specifically and exclusively
for the continuation of the Hayden Survey. Other amendments provided
small appropriations for the completion of the reports of the Powell and
Wheeler surveys, and the bill passed the Senate in this form. The
Legislative Appropriation bill was similarly pruned, while in the
Senate, of all reference to the proposed new organization. This bill,
however, died in conference, but in the last hours of the session the
conferees on the Sundry Civil bill took unto themselves legislative
powers and transferred from the dead bill to the pending measure all the
language which constitutes the “organic act” of the United States
Geological Survey. This action was denounced in the Senate as “a wide
departure from the authority that is possessed by a conference
committee,” and it was further stated in debate that the inserted
provision which created a new office and discontinued the existing
surveys was one “which neither the Committee of the Senate nor the
Senate itself ever saw.” This assertion was perhaps parliamentarily
sound in that the language was new to the Sundry Civil bill, yet
actually the Senate had only two days before stricken the same proposed
legislation from the pending Legislative Appropriation bill. However,
the House conferees—Representatives Atkins of Tennessee, Hewett of New
York, and Hale of Maine—had realized their tactical advantage, and the
Senate, after a brief debate, voted on March 3 to concur in the report
of the committee of conference, thus reversing all their earlier action,
in which the friends of the Hayden and Wheeler organizations apparently
had commanded more votes than the advocates of the National Academy
plan.

Clarence King was appointed first Director of the United States
Geological Survey on April 3, 1879, and began the work of organization.
With his proven genius for administration, King promptly resolved the
doubt as to the meaning of the term “national domain” in the language
defining the duties of the Director by taking the conservative side and
limiting the work of the new organization to the region west of the 102d
meridian. This region was divided into four geological divisions, and
for economy of time and money field headquarters were established for
these divisions. The Division of the Rocky Mountains was placed under
Mr. Emmons as geologist in charge, the Division of the Colorado under
Captain Dutton, the Division of the Great Basin under Mr. Gilbert, and
the Division of the Pacific under Arnold Hague. The Division of the
Colorado was intended as merely temporary for the purpose of bringing to
completion the scientific work of the Powell Survey. Similarly Dr.
Hayden was given the opportunity to prepare a systematic digest of his
scientific results. This organization of the work and the selection of
geologists in charge showed the relation of the new and the old, and a
glance at the personnel of the new Survey indicates the extent to which
the geologic investigation of the Western country was to continue
without interruption. Of the twenty-four geologists and topographers
listed in the first administrative report, four had been connected with
the Powell Survey, two with the Hayden, three with the Wheeler, and five
with the King Survey.

[Illustration: Clarence King]

In planning the initial work of the United States Geological Survey, the
Director speaks of the “most important geological subjects” and “mining
industries,” of “instructive geological structure” and “great bullion
yield” in the same sentences, so that the intent was plain to make the
geologic investigations both theoretical and practical.

It was expected that the field of operations of this Federal Survey
would be at once extended by Congress over the whole United States, but
the measure making this extension, which would simply carry out the
intent of the framers of the legislation creating the new bureau, passed
the House alone, and it was only by subsequent modification of the
wording of appropriation items that the United States Geological Survey
became national in scope as well as in name. The critical question of
the effective coördination of State and Federal geologic surveys was met
by Director King, who corrected an erroneous impression “industriously
circulated” by stating his policy to be to urge the inauguration and
continuance of State surveys.[104] This was the initial step in the
cooperation between State and Federal surveys which became effective on
a large scale in subsequent years.

Though the Geological Survey has extended its operations over the whole
United States, its largest activities have always been directed toward
the exploration and development of the newer territory in the
public-land States. All four of its directors had their field training
in the West: the name of Major Powell, who succeeded King in 1880, is
inseparably connected with scientific exploration; Charles D. Walcott,
who was Director from 1894 to 1907, the period of the Survey’s greatest
expansion, made the largest contribution to the Paleozoic stratigraphy
and paleontology of the West; and the present Director spent seven field
seasons in the Northern Cascades and one in a mining district in Utah.
The scope of the activities both East and West as developed during the
39 years since the establishment of the new bureau can be best
described, perhaps, in terms of its present functions as expressed in
the organization of to-day.

The growth of the Survey is measured in the increase of annual
appropriation from $106,000 in 1879–80 to the amount available for the
current year—$1,925,520, not including half a million dollars from War
Department appropriations being spent in the topographic work of the
Survey. The corresponding increase in personnel has been from 39, listed
in the first report, to 911 holding regular appointments at the present
time, divided among the different branches as follows: A scientific
force of 173 in the Geologic Branch, 169 in the Water Resources Branch,
71 in the Topographic Branch, and 15 in the Land Classification Board,
with a clerical force of 168 divided among the same branches, and the
remainder the technical and clerical employees of the publication and
administrative branches. These personnel statistics are not expressive
of normal conditions, since a large number of the topographic engineers
are commissioned officers and thus are not included on the civilian
roll, while, on the other hand, the classification of the stock-raising
homestead lands makes the technical force of the Water Resources Branch
unusually large this year.

The primary aim of the Geological Survey is geologic, whether directed
by authority of law toward the “examination of the geological structure,
mineral resources, and products of the national domain,” toward the
preparation of the authorized “reports upon general and economic geology
and paleontology,” of the “geologic map of the United States,” or of the
“report on the mineral resources of the United States,” or toward the
“continuation of the investigation of the mineral resources of Alaska”
or “chemical and physical researches relating to the geology of the
United States.” The spirit and the purpose of the Survey’s work in all
these fields are not believed to have materially changed from those of
the founders of the science in America. From time to time too much
emphasis may have appeared to be laid upon applied geology as contrasted
with pure science, yet the report of the National Academy to Congress in
terms placed the stress upon economic resources and referred to
paleontology as “necessarily connected” with general and economic
geology. The practical purpose of geologic research under Government
auspices must be recognized by the administrator, whether he be the
paleontologist like Walcott, the philosopher like Powell, or the mining
geologist like King. That the task of steering the true course is no new
problem can be seen from the statement of Owen[105] written 70 years
ago, and these words describe conditions of Government geological work
even to-day:


  Scientific researches, which to some may seem purely speculative and
  curious, are essential as preliminaries to these practical results.
  Further than such necessity dictates, they have not been pushed,
  except as subordinate and incidental, and chiefly at such periods as,
  under the ordinary requirements of public service, might be regarded
  as leisure moments; so that the contributions to science thus
  incidentally afforded, and which a liberal policy forbade to neglect,
  may be considered, in a measure, a voluntary offering, tendered at
  little or no additional expense to the department.


The increased attention given to mineral resources has been a matter of
gradual growth. Mr. King early organized a Division of Mining Geology
with Messrs. Pumpelly, Emmons, and Becker as geologists in charge, to
whom were assigned the collection of mineral statistics for the Tenth
Census. These Survey geologists and Director King himself held
appointments as special agents of the Census Bureau, and on the staff
selected for this work appear the names of T. B. Brooks, Edward Orton,
T. C. Chamberlin, Eugene A. Smith, George Little, J. R. Proctor, R. D.
Irving, N. S. Shaler, John Hays Hammond, Bailey Willis, and G. H.
Eldridge, indicating the extent to which the supervision of these
inquiries was placed in the hands of economic geologists. This procedure
was reverted to by Director Walcott and in the last ten years has become
a well-established policy, the statistics of annual production of all
the important mineral products being under the charge of geologists, as
best qualified to comprehend the resources of the country. Another of
these special assistants in 1880 was Albert Williams, Jr., who became
the first chief of the Division of Mineral Resources, in 1882. The study
of ore deposits, which may be said to have begun with the King Survey,
was inspired by King’s own appreciation of the broad geologic relations
of the distribution of mineral wealth and by the detailed studies of
individual mining districts by his associates, “based upon facts
accurately determined in the light of modern geology.”

Geological surveys have been prosecuted in Alaska since 1895, and in the
last few years the annual appropriation for the work has been the same
as that made for the expenses of the whole Survey in the first year of
its history. The Division of Alaskan Mineral Resources is in fact a
geological survey in itself, except that it shares in the administrative
machinery of the larger organization and has the advantage of the
cooperation of the scientific specialists of the Survey as they may be
needed to supplement its own force. All the investigations in this
distant part of the country represent the Geological Survey at its best,
for here the organization’s long experience in the Western States can be
applied to most effective and helpful work on the frontier, where the
geologist and topographer in their exploration do not always follow the
prospector but often precede him. Undoubtedly no greater factor has
contributed to the development of Alaskan resources than this pioneer
work of the Federal Survey, yet the work has also contributed notable
additions to the sciences of geology and geography.

The first duty laid upon the Director of the Geological Survey in the
law of 1879 was “the classification of the public lands,” and this
phrase undoubtedly expressed the idea of the committee of the National
Academy. The same legislation, however, contained provision for the
further consideration by a commission of the classification and
valuation of the public lands, as also recommended by the National
Academy. Thus the decision of Director King that the classification
intended by Congress was scientific and was intended for general
information and not to aid the Land Office in the disposition of land by
sale or otherwise was really based upon the deliberate opinion of the
Public Lands Commission, of which he was a member, that classification
would seriously impede rapid settlement of the unoccupied lands. Nearly
forty years later those who are intrusted with the land-classification
work of the Geological Survey recognize this familiar argument, which
undoubtedly had much more force in that earlier stage of the utilization
of the Nation’s resources of land.[106] The conception of land
classification as a business policy on the part of the Government as a
landed proprietor belongs rather to this day of more intensive
development. At present current public-land legislation calls for
highest use, and hence official investigation of natural values and
possibilities must precede disposition. This type of mineral and
hydrographic classification of public lands has been in progress in
increasing amount since 1906, so that now the Geological Survey is the
kind of scientific adviser to the Secretary of the Interior and
Commissioner of the General Land Office that may have been contemplated
by the National Academy of Sciences in 1878. It is plain, however, to
everyone at all conversant with Western conditions that the recent
land-classification surveys in Wyoming, for instance—detailed geologic
surveys which form the basis for the valuation of public coal lands in
40–acre units—would have possessed no utility in 1871, when the
coal-land law was passed but when the demand for railroad fuel had just
begun.

The land-classification idea is of course the basis of the National
forest and irrigation movements. The laws of 1888 and 1896, which mark
the beginning of active endorsement by Congress of these conservation
movements, placed upon the Survey the duties of examining reservoir
sites and forest reserves respectively. The earlier of these laws began
the investigation of the water resources of the country, which is still
an important phase of the Survey’s activity, and led to the creation of
an independent organization—the Reclamation Service. It is easy to trace
the beginnings of Federal reclamation of arid lands in the pioneer work
of Powell, whose report in 1878 on the arid region of the United States
was the first adequate statement of the problem of largest use of these
lands in terms broader than those of individualistic endeavor. For
years, however, Powell’s appeal for Congressional consideration of this
National task was like the “voice of one crying in the wilderness.”

In a somewhat similar way the forestry surveys under the Geological
Survey helped in the organization of a separate bureau—now the Forest
Service. The other important Federal bureau tracing direct relationship
to the Survey is the Bureau of Mines, established in 1910, which
continued the investigations in mining technology specifically provided
for by Congress for six years under the Geological Survey but in some
degree begun in the early days of the Survey under Directors King and
Powell.

Another equally important organization of a public nature, though not a
Federal bureau, traces its beginnings to the Geological Survey: the
Geophysical Laboratory of the Carnegie Institution, which now exercises
so potent an influence over geologic investigation, had its origin in
the official work of the Geological Survey’s Division of Chemical and
Physical Research, and its personnel was at first largely recruited from
the Survey. The highly original experimental work of this laboratory has
extended far beyond the scope of the Survey’s work—at least far beyond
the scope possible with the Federal funds available—yet most of the
results of these investigations may eventually come under even a strict
construction of the language used in the Survey’s appropriation “for
chemical and physical researches relating to the geology of the United
States.”

The topographic work of the present Survey continues with constant
refinement of standards and economy of methods the work of the earlier
organizations. The primary purpose of these topographic surveys is to
provide the bases for geologic maps, yet these topographic maps, which
cover 40 per cent of the area of the United States, are used in every
type of civil engineering as well as by the public generally. The annual
distribution by sale of half a million of these maps is an index of
their value to the people.

The hot discussion that was waged for years on the question of military
versus scientific administration of topographic surveys is in striking
contrast with the present concentration of all the topographic mapping
under the Geological Survey in those areas where it may best serve the
needs of the Army. In 1916 Congress specifically recognized the
possibility of greater cooperation of this kind, both in the
appropriation made to the Geological Survey and in a special
appropriation made to the War Department. For a number of years indeed
special military information had been contributed to the Army by the
Survey topographers, but since March 26, 1917, every Geological Survey
topographer has worked exclusively on the program of military surveys
laid down by the General Staff of the Army, and the places of some of
the 44 Survey topographers now in France as engineer officers are filled
by 34 other reserve engineer officers detailed by order of the Secretary
of War to the Director of the Geological Survey to assist in this
military mapping and to receive instruction fitting them in turn for
topographic service in France.

The contribution of this civilian service to the military operations in
the present emergency forms a fitting conclusion to this review of a
century of Government surveys. At present 215 members of the Geological
Survey are in uniform, 107 as engineer officers, two of whom are on the
staff of the American Commanding General in France. In the war work
carried on in the United States the Survey’s contribution is by no means
limited to military mapping: the geologists are also mobilized for
meeting war needs, assisting in developing new sources of the essential
war minerals, in speeding up production of mineral products, in
collecting information for the purchasing officers both of our own and
of the Allied governments, in coöperating with the constructing
quarter-masters in the location of gravel and sand for structural use
and in both general and special examinations of underground water supply
and of drainage possibilities at cantonment sites, and in supplying the
Navy Department with similar technical data. A special contribution has
been the application to aërial surveys of photogrammetric methods
developed in the Alaskan topographic work and the perfection of a camera
specially adapted to airplane use. The utilization of the Survey’s map
engraving and printing plant for confidential and urgent work for both
the Army and Navy has necessitated postponement of current work for the
Geological Survey itself. Throughout the organization the records, the
methods, and the personnel which represent the product of many years of
scientific activity are all being utilized; thus is the experience of
the past translated into special service in the present crisis.


                                _Notes._

Footnote 96:

  Hess, R. H., Foundations of National Prosperity, p. 100.

Footnote 97:

  Report Nat’l Museum, 1904, pp. 189–733.

Footnote 98:

  Featherstonhaugh, J. D., Am. Geol., 3, 220, 1889.

Footnote 99:

  Whitney, Mineral Wealth of the United States, pp. 248–250.

Footnote 100:

  Foster and Whitney, 31st Cong., 1st session, House Doc. 69, pp. 13–14,
  1850.

Footnote 101:

  First Annual Rept. U. S. Geol. Survey, p. 4.

Footnote 102:

  Wheeler, Report 3d Internat’l Geog. Cong., p. 492, 1885.

Footnote 103:

  The views of the writer on “natural monopolies” in the Government
  service are set forth in an address delivered at the centennial
  celebration of the U. S. Coast and Geodetic Survey, April 5, 1916.
  (See Science, vol. 43, pp. 659–665, May 12, 1916.)

Footnote 104:

  For correspondence on this subject, see Minnesota Geol. Survey, Eighth
  Ann. Rept., 1880, p. 173.

Footnote 105:

  Owen, D. D., 30th Cong., 1st sess., Senate Doc. No. 57, p. 7, 1848.

Footnote 106:

  This essential difference between present-day requirements and the
  needs of earlier generations has been discussed by W. C. Mendenhall,
  the geologist in charge of the Land Classification Board of the
  Geological Survey: Proceedings 2d Pan-American Sci. Cong., 1915–16, 3,
  761.




                                   VI
             ON THE DEVELOPMENT OF VERTEBRATE PALEONTOLOGY

                         By RICHARD SWANN LULL


                            _Introduction._

Unlike its sister science of Invertebrate Paleontology, which has been
approached so largely from the viewpoint of stratigraphic geology, that
of the vertebrates is essentially a biologic science, having its
inception in the masterly work of Cuvier, who is also to be regarded as
the founder of comparative anatomy. For long decades, vertebrate
paleontology was simply a branch of comparative anatomy or morphology in
that it dealt almost exclusively with the form and other peculiarities
of fossil bones and teeth, often in a more or less fragmentary
condition, very little or no attention being paid to any other system of
the creature’s anatomy. Distribution both in space and in time was
recorded, but the value of vertebrates in stratigraphy was still to be
appreciated and has hardly yet come into its own. It is readily seen,
therefore, that the two departments of paleontology did not enlist the
same workers or even the same type of investigators, for while the two
sciences have much in common and should have more, the vertebratist
must, above all else, be a morphologist, with a keen appreciation of
form, and a mind capable of retaining endless structural details and of
visualizing as a whole what may be known only in part. The initial work
of the brilliant Cuvier set so high a standard of preparedness and
mental equipment that as a consequence, the number of those engaged in
vertebrate research has never been large as compared with the workers in
some other branches of science, but the results achieved by the few who
have consecrated their research to the fossil vertebrates has been in
the main of a high order.

At first, as has been emphasized, this work was largely morphological,
dealing both with the individual skeletal elements and later with the
bony framework as a whole. Then came the endeavor to clothe the bones
with sinews and with flesh—to imagine, in other words, the
life-appearance of the ages-departed form—with such of its habits as
could be deduced from structure of body, tooth, and limb. Next came the
working out of systematic series of vertebrates and their marshalling
into species, genera, and larger groups, and much time was thus spent,
especially when rapid discovery brought a continual stream of new forms
before the systematist, and hence some appreciation of the countless
hosts of bygone creatures which peopled the world in the geologic past.
This systematic work, however, was based upon the most painstaking
morphologic comparisons and so the science was still within the scope of
comparative anatomy.

In connection with taxonomic research came increasingly tangible
evidence in favor of the law of evolution; investigators turned to the
working out of phyletic series showing the actual record of the
successive evolutionary changes that the various races had undergone.
Coupled with this evolutionary evidence came an increased attention to
the sequential occurrence in successive geologic strata, and the
stratigraphic distribution of vertebrates became known with greater and
greater detail. Then followed the assemblage of faunas, which brought
the study of the fossil forms within the realm of historical geology,
rather than being the mere phylogeny of a single race, and the value of
vertebrate fossils as horizon markers became more and more appreciated
by the stratigrapher. They serve to supplement the knowledge gained from
the invertebrates, and in this connection are especially valuable in
that they often give data concerning continental formations about which
invertebrate paleontology is largely silent.


              _Rise of Vertebrate Paleontology in Europe._

To those who had been nurtured in the belief in a relatively recent
creation covering in its entirety a period of but six days, and
occurring but four millenniums before the time of Christ, the appearance
of the remains of creatures in the rocks, the like of which no man ever
saw alive, must have given scope to the wildest imaginings concerning
their origin and significance; for many believed that not only had no
new forms been added to the world’s fauna since the creation, except
possibly by hybridizing, but that none had become extinct save a very
few through the agency of human interference. The supposition was,
therefore, that such creatures as were thus discovered were still extant
in some more remote fastnesses of the world. Thus, our second president,
Thomas Jefferson, who wrote one of the first papers on American fossil
vertebrates, published in 1798, discussed therein the remains of a huge
ground-sloth which has since borne the name _Megalonyx jeffersoni_.
Jefferson, however, described the great claws as pertaining to a huge
leonine animal which he firmly believed was yet living among the
mountains of Virginia.

Cuvier (1769–1832) has been spoken of as the founder of our science. His
opportunity lay in the profusion of bones buried in the gypsum deposits
of Montmartre within the environs of the city of Paris. Cuvier’s studies
of these remains, done in the light of his very broad anatomical
knowledge, enabled him to prepare the first reconstructions of fossil
vertebrates ever attempted and to bring before the eyes of his
contemporaries a world peopled with forms which were utterly extinct.
That these creatures were no longer living, none was a better judge than
Cuvier, for his prominence was such that material was sent him from all
parts of the world, to which must be added that which he saw in his
visits to the various museums of Europe. He felt it safe, therefore, to
affirm the unlikelihood of any further discovery of unknown forms among
the great mammals of the present fauna of our globe, and few indeed have
been the additions since his day. To Cuvier is due not alone the
masterly contribution to the sister sciences of comparative anatomy and
vertebrate paleontology—the Ossements Fossiles (1812)—but he also
announced the presence in continental strata of a series of faunas which
showed a gradual organic improvement from the earliest such assemblage
to the most modern, an idea of the most fundamental importance and one
with which he is rarely credited. He believed in the sudden and complete
extinction of faunas, and the facts then known were in accord with this
idea, as no common genera nor transitional forms connected the creatures
of the Paris gypsum with the mastodons, elephants, and hippopotami which
the later strata disclosed. It is not remarkable, therefore, that Cuvier
advanced his theory of catastrophism to account for these extinctions.
He should not, however, according to Depéret, be credited with the idea
of successive re-creations, such as that held by D’Orbigny and others,
but of repopulation by immigration from some area which the catastrophe,
be it flood or other destructive agency, failed to reach.

Cuvier was followed in Europe by a number of illustrious men, none of
whom, however, with the exception of Sir Richard Owen, possessed his
breadth of knowledge of comparative anatomy upon which to base their
researches among the prehistoric. The more notable of them may be
enumerated before going on to a discussion of the American contributions
to the science.

They were, first, Louis Agassiz, a pupil of Cuvier and later a resident
of America, whose researches on the fossil fishes of Europe are a
monumental work, the result of ten years of investigation in all of the
larger museums of that continent, and which appeared in 1833–43, while
he was yet a young man. The fishes were practically the only fossil
vertebrates to come within the scope of his investigations, for his
later time was consumed in the study of glaciers and of recent marine
zoology. Another student of these most primitive vertebrates who left an
enduring monument was Johannes Mϋller. Huxley, Traquair, and Jaekel also
did masterly work upon this group, while Smith Woodward of the British
Museum is considered the highest living authority upon fossil fishes.

Of the Amphibia, the most famous foreign students were Brongniart,
Jaeger, Burmeister, Von Meyer, and Owen, although Owen’s claim to
eminence lies rather in the investigations of fossil reptiles which he
began in 1839 and continued over a period of fifty years of remarkable
achievement. Not only did he describe the dinosaurs of Great Britain in
a series of splendidly illustrated monographs, but extended his
researches to the curious reptilian forms from the Karroo formation of
South Africa. It was to him, moreover, that the establishment of the
true position of the famous _Archœopteryx_ as the earliest known bird
and not a reptile is due. Von Meyer also enriched the literature of
fossil reptiles, discussing exhaustively those occurring in Germany,
while Huxley’s classic work on the crocodiles as well as on dinosaurs,
and the labors of Buckland, Fraas, Koken, Von Huene, Gaudry, Hulke,
Seeley, and Lydekker have added immensely to our knowledge of the group.

Of the birds, which at best are rare as fossils, our knowledge,
especially of the huge flightless moas, is due largely again to Owen,
and his realization of the systematic position of _Archœopteryx_ has
already been mentioned.

The mammals were, perhaps, the most prolific source of paleontological
research during the nineteenth century, for, as Zittel has said,
Cuvier’s famous investigations on the fossil bones, mentioned above, not
only contain the principles of comparative osteology, but also show in a
manner which has never been surpassed how fossil vertebrates ought to be
studied, and what are the broad inductions which may be drawn from a
series of methodical observations. Such was Cuvier’s influence that
until Darwin began to interest himself in mammalian paleontology the
study of these forms was conducted entirely along the lines indicated by
the French savant. This was seen in a large work, Osteology of Recent
and Fossil Mammalia, by De Blainville, which, although not up to the
standard set by the master, is nevertheless a notable contribution, as
was also the Osteology prepared by Pander and D’Alton. A summary of the
knowledge of the fossil Mammalia up to the year 1847 is contained in
Giebel’s Fauna der Vorwelt, and Lydekker has done for the mammals in the
British Museum what Smith Woodward did for the fishes, producing vastly
more than the mere catalogue which the title implies.

The first work wherein the fossil mammals were treated genealogically
was Gaudry’s Enchaînements du Monde Animal, written in 1878. Other work
on the fossil Mammalia was done by Kaup, who described those from the
Mainz basin and from Epplesheim near Worms whence came one of the most
famous of prehistoric horses, the _Hipparion_; this horse, together with
the remarkable proboscidean _Dinotherium_, was described by Von Meyer.
One of the most remarkable discoveries, ranking in importance, perhaps,
next to Montmartre, was that of the Pliocene fauna of Pikermi near
Athens, Greece, first made known through the publications of A. Wagner
of Munich and later, and much more extensively, through that of Gaudry
(1862–1867). H. von Meyer was Germany’s best authority on fossil
Mammalia. After his death the work was carried on by Quenstedt, Oscar
Fraas, Schlosser, Koken, and Pohlig, among others.

In France, rich deposits of fossil mammals were discovered in the
Department of Puy-de-Dôme, the Rhone basin, Sansan, Quercy, and near
Rheims. These were described by a number of writers, notably Croizet and
Jobert, Pomel, Lartet, Filhol, and Lemoine.

Rütimeyer of Bâle was one of the most famous European writers on
mammalian paleontology, and his researches were both comprehensive and
clothed in such form as to give them a high place in paleontological
literature. He studied comparatively the teeth of ungulates, discussed
the genealogy of mammals, and the relationships of those of the Old and
New Worlds. He was an exponent of the law of evolution as set forth by
Darwin, and his “genealogical trees of the Mammalia show a complete
knowledge of all the data concerning the different members in the
succession, and are amongst the finest results hitherto obtained by
means of strict scientific methods of investigation” (Zittel, History of
Geology and Palæontology, 1901). The mammals of the Swiss Eocene have
been studied in much detail by Stehlin.

For Great Britain, the most notable contributors were Buckland in his
Reliquiæ Diluvianæ; Falconer, co-author with Cautley on the Tertiary
mammals of India; Charles Murchison, who wrote on rhinoceroses and
proboscideans; and more recently Bush, Flower, Lydekker, Boyd Dawkins,
L. Adams, and C. W. Andrews. But by far the most commanding figure of
all was Sir Richard Owen, who for half a century stood without a peer as
the greatest of authorities on fossil mammals. It was the Natural
History of the British Fossil Mammals and Birds, published in 1846, that
established Sir Richard’s reputation.

Russia has produced much mammalian material, especially from the
Tertiary of Odessa and Bessarabia, and from the Quaternary of northern
Russia and Siberia. These have been described mainly by J. F. Brandt, A.
von Nordmann, but especially by Mme. M. Pavlow of Moscow.

Forsyth-Major discovered in 1887 a fauna contemporaneous with that of
Pikermi in the Island of Samos in the Mediterranean.

One of the most remarkable recent discoveries of fossil localities was
that announced in 1901 by Mr. Hugh J. L. Beadnell of the Geological
Survey of Egypt and Doctor C. W. Andrews of the British Museum of
London, of numerous land and sea mammals of Upper Eocene and Lower
Oligocene age in northern Egypt. The exposures lay about 80 miles
southwest of Cairo in the Fayûm district and are the sediments of an
ancient Tertiary lake, a relic of which, Birket-el-Qurun, yet remains.
These beds contained ancient Hyracoidea, Sirenia, and Zeuglodontia, but
above all, ancestral Proboscidea which, together with those known
elsewhere, enabled Andrews to demonstrate the origin and evolutionary
features of this most remarkable group of beasts. This discovery in the
Fayûm lends color to the belief that Africa may have been the ancestral
home of at least five of the mammalian orders, those mentioned above,
together with the Embrithopoda, a group unknown elsewhere. This theory
had been advanced independently by Tullberg, Stehlin, and Osborn, before
the discovery in Egypt.

Another European worker of pre-eminence who wrote more broadly than the
faunal studies mentioned above was W. Kowalewsky. He discussed
especially the evolutionary changes of feet and teeth in ungulates, a
line of research afterward developed in greater detail by the Americans,
Cope and Osborn.

South America has yielded series of rich faunas which have been
exploited by the great Argentinian, Florentino Ameghino, and by the
Europeans, Owen, Gervais, Huxley, Von Meyer, and more recently by
Burmeister and Lydekker. Later exploration and research by Hatcher and
Scott of North America will be discussed further on in this paper.


                 _Vertebrate Paleontology in America._

_Early Writers._—Having thus summarized paleontological progress in the
Old World, we can turn to a consideration of the work done in the New,
especially in the United States, because while the Old World
investigation has been invaluable, a science of vertebrate paleontology,
very complete both as to its zoological and geological scope and in the
extent and value of published results, could be built exclusively upon
the discoveries and researches made by Americans. The science of
vertebrate paleontology may be said to have had its beginnings in North
America with the activities of Thomas Jefferson, who, like Franklin,
felt so strong an interest in scientific pursuits that even the graver
duties of the highest office in the gift of the American people could
not deter him from them. When in 1797 Jefferson came to be inaugurated
as vice-president of the United States, he brought with him to
Philadelphia not only his manuscript but the actual fossil bones upon
which it was based. Again in 1801 he was greatly interested in the
Shawangunk mastodon, despite heavy cares of state, and in 1808 made part
of the executive mansion in Washington serve as a paleontological
laboratory, displaying therein for study the bones of proboscideans and
their contemporaries which the Big Bone Lick of Kentucky had produced.
Jefferson’s work would not, perhaps, have been epoch-making were it not
for its unique chronological position in the annals of the science.

Jefferson was followed by another man—this time one whose diverging
lines of interest led him not into the realm of political service, but
of art, for Rembrandt Peale possessed an enviable reputation among the
early painters of America. Peale published in 1802 an account of the
skeleton of the “mammoth,” really the mastodon, _M. americanus_,
speaking of it as a nondescript carnivorous animal of immense size found
in America. It was because of the form of the molar teeth that Peale
said of it: “If this animal was indeed carnivorous, which I believe
cannot be doubted, though we may as philosophers regret it, as men we
cannot but thank Heaven that its whole generation is probably extinct.”

With the work of these men as a beginning, it is not strange that the
more conspicuous Pleistocene fossils of the East should have attracted
the attention of many subsequent writers in the first part of the
nineteenth century, nor that the early papers to appear in the Journal
should pertain to proboscideans or to the huge edentate ground-sloths
and the aberrant zeuglodons whose bones frequently came to light.
Therefore a number of men such as Koch, both Sillimans, J. C. Warren,
and others made these forms their chief concern.

_Fossil Footprints._—Among the early writers who concerned themselves
with these greater fossils was Edward Hitchcock, sometime president of
Amherst College, and a geologist of high repute among his
contemporaries. Hitchcock is, however, better and more widely known as
the pioneer worker on a series of phenomena displayed as in no other
place in the region in which he made his home. These are fossil
footprints impressed upon the Triassic rocks of the Connecticut valley.
It was in the Journal for the year 1836 (=29=, 307–340) that Hitchcock
first called attention to the footmarks, although they had been known
and discussed popularly for a number of years previous. James Deane, of
Greenfield, was perhaps the first to appreciate the scientific interest
of these phenomena, but deeming his own qualifications insufficient
properly to describe them, he brought them to the attention of
Hitchcock, and the interest of the latter never waned until his death in
1864. Hitchcock wrote paper after paper, publishing many of them in the
Journal, again in his Final Report on the Geology of Massachusetts
(1841), and later in quarto works, one in the Memoirs of the American
Academy of Arts and Sciences and the two others under the authority of
the Commonwealth, the Ichnology in 1858, and the Supplement in 1865, the
last being a posthumous work edited by his son, Charles H. Hitchcock.

Hitchcock’s conception of the track-makers was more or less imperfect
because of the fact that for a long time but a few fragmentary osseous
remains were known, either directly or indirectly associated with the
tracks, while on the other hand the bird-like character of many of the
latter and the discovery of huge flightless birds elsewhere on the globe
suggested a very close analogy if not a direct relationship. Hence “bird
tracks” they were straightway called, a designation which it has been
difficult to remove, even though in 1843 Owen called attention to the
need of caution in assuming the existence of so highly organized birds
at so early a period, especially when large _reptiles_ were known which
might readily form very similar tracks. The footprints are now believed
to be very largely of dinosaurian origin, and dinosaurs whose feet
corresponded in every detail with the footprints have actually come to
light within the same geologic and geographic limitations. This of
course refers to the bipedal, functionally three-toed tracks. Of the
makers of certain of the obscurer of the quadrupedal trails we are as
much in the dark to-day as were the first discoverers of a century ago,
so far as demonstrable proof is concerned. We assume, however, that they
were the tracks of amphibia and reptiles, beyond which we may not go
with certainty.

Agassiz, writing in 1865 (Geological Sketches), says:


  “To sum up my opinion respecting these footmarks, I believe that they
  were made by animals of a prophetic type, belonging to the class of
  reptiles, and exhibiting many synthetic characters. The more closely
  we study past creations, the more impressive and significant do the
  synthetic types, presenting features of the higher classes under the
  guise of the lower ones, become. They hold the promise of the future.
  As the opening overture of an opera contains all the musical elements
  to be therein developed, so this living prelude of the creative work
  comprises all the organic elements to be successively developed in the
  course of time.”


Of those whose work was contemporaneous with that of Hitchcock, but one,
W. C. Redfield, wrote on Triassic phenomena, and he concerned himself
mainly with the fossil fishes of that time, his first paper on this
subject appearing in 1837 in the Journal (=34=, 201), and the last
twenty years later.

_Paleozoic Vertebrates._—Later the vertebrates of the Paleozoic began to
attract attention, footprints from Pennsylvania being described by Isaac
Lea, beginning in 1849, a notice of his first paper appearing in the
Journal for that year (=9=, 124). Several papers followed on the reptile
_Clepsysaurus_. Alfred King also wrote on the Carboniferous ichnites,
his work slightly antedating that of Lea, but being less authoritative.

But by far the most illuminating of the mid-century writers on Paleozoic
vertebrates was Sir William Dawson, a very large proportion of whose
numerous papers relate to the Coal Measures of Nova Scotia and their
contained plant and animal remains. In 1853 appeared Dawson’s first
announcement, written in collaboration with Sir Charles Lyell, of the
finding of the bones of vertebrates within the base of an upright fossil
tree trunk at South Joggins. These bones were identified by Owen and
Wyman as pertaining to a reptilian or amphibian to which the name
_Dendrerpeton acadianum_ was given. Following this were several papers
published in the Quarterly Journal of the Geological Society, London,
describing more vertebrates and associated terrestrial molluscs. In 1863
Dawson summarized his discoveries in the Journal (=36=, 430–432) under
the title of “Air-breathers of the Coal Period,” a paper which was
expanded and published under the same title in the Canadian Naturalist
and Geologist for the same year. Dawson also printed in the same volume
the first account of reptilian(?) footprints from the coal. Thus from
time to time there emanated from his prolific pen the account of further
discoveries, both in bones and footprints, his final synopsis of the
air-breathing animals of the Paleozoic of Canada appearing in 1895. The
only other group of vertebrates which claimed his attention were certain
whales, on which he occasionally wrote.

_Fishes._—The fossil fishes from the Devonian of Ohio found their first
exponent in J. S. Newberry, appointed chief geologist of the second
geological survey of Ohio, which was established in 1869. These fishes
from the Devonian shales belonged for the greater part to the curious
group of armored placoderms, the remains of which consist very largely
of armor plates with little or no traces of internal skeleton. There was
also found in association a shark, _Cladoselache_, of such marvelous
preservation that from some of the Newberry specimens now in the
American Museum of Natural History, New York, Bashford Dean has
demonstrated the histology of muscle and visceral organs, in addition to
the very complete skeletal remains.

Newberry’s work on these forms, begun in 1868, has been carried to
further completion by Bashford Dean and his pupil L. Hussakof, as well
as by C. R. Eastman. Newberry’s other paleontological work was with the
Carboniferous fishes of Ohio, the Carboniferous and Triassic fishes of
the region from Sante Fé to the Grand and Green rivers, Colorado, and on
the fishes and plants of the Newark system of the Connecticut valley and
New Jersey. He also discussed certain mastodon and mammoth remains, and
those of the peccary of Ohio, _Dicotyles_.


                      _Joseph Leidy (1823–1891)._

We now come to a consideration of the work of Joseph Leidy, one of the
three great pioneers in American vertebrate paleontology, for if we
disregard the work of Hitchcock and others on the fossil footprints, few
of the results thus far obtained were based upon the fruits of organized
research. Leidy began his publication in 1847 and continued to issue
papers and books from time to time until the year 1892, having published
no fewer than 219 paleontological titles, and 553 all told. His earlier
paleontological researches were exclusively on the Mammalia, which were
then coming in from the newly discovered fossil localities of the West.
The discovery of these forms, one of the most notable events in the
history of our science, will bear re-telling.

The first announcement was made in 1847, when Hiram A. Prout of St.
Louis published in the Journal (3, 248–250) the description of the
maxillary bone of “_Palæotherium_” (= _Titanotherium proutii_)from near
White River, Nebraska. This at once drew the attention of geologists and
paleontologists to the Bad Lands, or Mauvaises Terres, which were to
prove so highly productive of fossil forms. About the same time S. D.
Culbertson of Chambersburg, Pennsylvania, submitted to the Academy of
Natural Sciences at Philadelphia some fossils sent to him from Nebraska
by Alexander Culbertson. These were afterward described by Leidy in the
Proceedings of the Academy, together with the paleotheroid jaw, in
addition to which three other collections which had been made were also
placed at his disposal for study.

This aroused the interest of Doctor Spencer F. Baird of the Smithsonian
Institution, who sent T. A. Culbertson to the Bad Lands to make further
collections. The latter was successful in securing a valuable series of
mammalian and chelonian remains. These, together with other specimens
from the same locality, were sent to Leidy, for, as Baird remarked,
Leidy, although only thirty years of age, was the only anatomist in the
United States qualified to determine their nature. The outcome of
Leidy’s study of this material was “The Ancient Fauna of Nebraska,”
published in 1853, and constituting the most brilliant work which up to
that time American paleontology had produced. Leidy’s determinations,
which are in the main correct, are the more remarkable when it is
realized that he had little recent osteological material for comparative
study. The forms thus described by him were new to science, of a more
generalized character than those now living, and yet their distinguished
describer recognized, either at that time or a little later, their true
relationship to the modern types. The extent of Leidy’s anatomical
knowledge was almost Cuvierian, and Cuvier-like he established the fact
of the presence of the rhinoceroses, then unheard of in the American
fauna, from a few small fragments of molar teeth, an opinion shortly to
be fully sustained through the finding of complete molars and the entire
skull of the _same individual animal_.

Leidy next turned his attention to the huge edentates, which he studied
exhaustively, publishing his results in the form of a memoir in 1855,
two years after the appearance of the “Ancient Fauna.”

Extinct fishes of the Devonian of Illinois and Missouri and the Devonian
and Carboniferous of Pennsylvania were made the subjects of his next
researches, after which he described the peccaries of Ohio, and later,
in a much larger and most important work, the Cretaceous reptiles of the
United States (1865). Most of the fossils discussed in this last work
are from the New Jersey Cretaceous marls and of them the most notable
was the herbivorous dinosaur _Hadrosaurus_, the structure and habits of
which, together with its affinities with the Old World iguanodons, Leidy
described in detail. From Leidy’s descriptions and with his aid,
Waterhouse Hawkins was enabled to restore a replica of the skeleton in a
remarkably efficient way. This restoration for a long time graced the
museum of the Philadelphia Academy of Natural Sciences and there was a
plaster replica of it in the United States National Museum. These,
together with plaster replicas of _Iguanodon_ from the Royal College of
Surgeons in London, gave to Americans their first real conceptions of
members of this most remarkable group. The associated fossils from the
New Jersey marls were chiefly crocodiles and turtles.

From 1853 to 1866 F. V. Hayden was carrying on a series of most
energetic explorations in the West, especially in Nebraska and Dakota as
then delimited, returning from each trip laden with fossils which were
given to Leidy for determination. The results appeared in 1869 in
Leidy’s Extinct Mammalian Fauna of Dakota and Nebraska, published as
volume =7= of the Journal of the Philadelphia Academy. In this large
volume no fewer than seventy genera and numerous species of forms, many
of them new to science, were described, representing many of the
principal mammalian orders; horses were, however, especially
conspicuous. This last group led Leidy to the conclusion, afterward
emphasized by Huxley, that North America was the home of the horse in
geologic time, there being here a greater representation of different
species than in any recent fauna of the world. Leidy’s interest in the
horses, for the forwarding of which he made a large collection of recent
material, extended over many years, as his first paper on the subject
bears the date of 1847, the last that of 1890.

Next came the discovery of Eocene material from the vicinity of Fort
Bridger, Wyoming, geologically older than the Nebraska and Dakota
formations. This, together with specimens from the Green River and
Sweetwater River deposits of Wyoming and the John Day River (Oligocene)
of Oregon, was also referred to Leidy, and added yet more to the list of
newly discovered species with which he had already become familiar in
his earlier researches. The results of this study were published by the
Hayden Survey in 1873, under the title “Contributions to the Extinct
Vertebrate Fauna of the Western Territories.” This was the last of
Leidy’s major works, but he continued up to the time of his death to
report to the Academy concerning the various fossil forms that were
submitted to him for identification. Of such reports the most important
was one on the fossils of the phosphate beds of South Carolina,
published in the Journal of the Academy in 1887.

As a paleontologist, Leidy ranks with Cope and Marsh high among those
who enriched the American literature of the subject, but it must be
remembered that this was but a single aspect of his many-sided
scientific career, for he made many contributions of high order to
botany, zoology, and general and comparative anatomy as well, nor did
his knowledge and usefulness as an instructor of his fellow men keep
within the limitations of these subjects.


                  _Othniel Charles Marsh (1831–1899)._

The sixth decade of the nineteenth century saw the beginning of the
labors of several paleontologists who, like Leidy, were destined to
raise the science of fossil vertebrates in America to the level of
attainment of the Old World. They were, among others, Othniel Charles
Marsh and Edward Drinker Cope. Of these the names of Marsh and Cope are
linked together by the brilliance of their attainments, their
contemporaneity, and the rivalry which the similarity of their pursuits
unfortunately engendered. Marsh produced his first paleontological paper
in 1862 (=33=, 278), Cope in 1864, but the latter died first, so that
his life of research was shorter.

[Illustration: O. C. Marsh]

To Professor Marsh should be given credit for the first organized
expedition designed exclusively for the collection of vertebrate
remains, the results of which contain so much material that it has not
yet entirely seen the light of scientific exposition. Marsh’s first trip
to the West was in 1868, the first formal expedition being organized two
years later. These expeditions, of which there were four, were privately
financed except for the material and military escort furnished by the
United States Government, and consisted of a personnel drawn entirely
from the graduate or undergraduate body of Yale University. These
parties explored Kansas, Nebraska, Wyoming, Utah, and Oregon, and
returned laden with material from the Cretaceous and Tertiary formations
of the West. Some of this is of necessity somewhat fragmentary, but type
after type was secured which, with his exhaustive knowledge of
comparative anatomy, enabled Marsh to announce discovery after discovery
of species, genera, families, and even orders of mammals, birds, and
reptiles which were unknown to science. The year 1873 saw the last of
the student expeditions, and thereafter until the close of his life the
work of collecting was done under Marsh’s supervision, but by paid
explorers, many of whom had been his scouts and guides in the formal
expeditions or had been especially trained by him in the East. In 1882,
after fourteen years of the experience thus gained, Marsh was appointed
vertebrate paleontologist to the United States Geological Survey, which
relieved him in part of the personal expense connected with the
collecting, although up to within a short time of his death his own
fortune was very largely spent in enlarging his collections. After his
connection with the Survey was established, Marsh had two main purposes
in view in making the collections: (1) to determine the geological
horizon of each locality where a large series of vertebrate fossils was
found, and (2) to secure from these localities large collections of the
more important forms sufficiently extensive to reveal, if possible, the
life histories of each. Marsh believed that the material thus secured
would serve as key or diagnostic fossils to all horizons of our western
geology above the Paleozoic, a belief in which he was in advance of his
time, for few of his contemporaries appreciated the value of vertebrates
as horizon markers. The result of the fulfilment of his second purpose
saw the accumulation of huge collections from all horizons above the
Triassic and some Paleozoic and Triassic as well. These contained some
very remarkable series, each of which Marsh hoped to make the basis of
an elaborate monograph to be published under the auspices of the Survey.
One can visualize the scope of his ambitions by the fact that no fewer
than twenty-seven projected quarto volumes, to contain at least 850
lithographic plates, were listed by him in 1877. These covered, among
other groups, the toothed birds (Odontornithes), Dinocerata, horses,
brontotheres, pterodactyls, mosasaurs and plesiosaurs, monkeys,
carnivores, perissodactyls and artiodactyls, crocodiles, lizards,
dinosaurs, various birds, proboscideans, edentates and marsupials, brain
evolution, and the Connecticut Valley footprints. Much was done towards
the preparation of these memoirs, as evidenced by the long list of
preliminary papers, admirably illustrated by woodcuts which were to form
the text figures of the memoirs, which appeared with great regularity in
the pages of the Journal for a period of thirty years. Of the actual
memoirs, however, but two had been published at the time of Marsh’s
death in 1899—the Odontornithes in 1880 and the Dinocerata in 1884. One
must not overlook, however, the epoch-making Dinosaurs of North America,
which was published by the Survey in 1896, although it was not in the
form nor had it the scope of the proposed monographs. This was not due
to lack of application, for Professor Marsh was an indefatigable worker,
but rather to the fact that the program was of such magnitude as to
necessitate a patriarchal life span for its consummation. As it is,
Professor Marsh’s fame rests first upon his ability and intrepidity as a
collector, ready himself to brave the very certain hardships and dangers
which beset the field paleontologist in the pioneer days, and also by
his judgment and command of men to secure the very adequate services of
others and so to direct their endeavors that the results were of the
highest value. The material witness to Marsh’s skill as a collector lies
in the collections of the Peabody Museum at Yale and in the Marsh
collection at the United States National Museum, the latter secured
through the funds of the United States Geological Survey. Together they
constitute what is possibly the greatest collection of fossil
vertebrates in America, if not in the world; individually, they are
second only to that of the American Museum in New York City, the result
of the combined labors of Osborn and Cope and their very able corps of
assistants.

As a scientist Marsh possessed in large measure that wide knowledge of
comparative anatomy so necessary to the vertebrate paleontologist, and
as a consequence was not only able to recognize affinities and classify
unerringly, but also to recognize the salient diagnostic features of the
form before him and in few words so to describe them as to render the
recognition of the species by another worker relatively easy. The
publication of hundreds of these specific diagnoses in the Journal
constitutes a very large and valuable part of that periodical’s
contribution to the advancement of our science. Marsh’s method of
indicating forms by so brief a statement leaves much to be done,
however, in the way of further description of his types, which in many
instances were but partially prepared.

Yet another important service which Marsh rendered to science was the
restoration of the creatures as a whole, made with the most painstaking
care and precision through assembling the drawings of the individual
bones. These restorations have become classic, embracing as they did a
score or more of forms, of beast, bird, and reptile. They also were
published first in the Journal, although they have subsequently been
reproduced in text-books and other works the world over. Part of Marsh’s
popular reputation, at least, which was second to that of no other
American in his line, was due to his skill in attaining publicity, for
his papers, of whatever extent, were carefully and methodically sent to
correspondents in the uttermost parts of the earth, and thus the Marsh
collection has reflected the fame of its maker.


                   _Edward Drinker Cope (1840–1897)._

The third great name in American vertebrate paleontology, that of Edward
Drinker Cope, stands out in sharp contrast with the other two, although
in the range of his interests he was probably more nearly comparable
with Leidy than with Marsh. The beginning of Cope’s scientific labors
dates from 1859, the year made famous in the annals of science by the
appearance of Darwin’s Origin of Species. It is not surprising,
therefore, that matters evolutional should have interested him to the
very end of his career. Cope was not merely a paleontologist, but was
interested in recent forms, especially the three lower classes of
vertebrates, to such an extent that his work therewith is highly
authoritative and in some respects epoch-making. Thirty-eight years of
almost continual toil were his, and the mere mass of his literary
productions is prodigious, especially when one realizes that, unlike
those of a writer of fiction, they were based on painstaking research
and philosophical thought. The greater part of Cope’s life was spent in
or near Philadelphia except for his western explorations, and he is best
known as professor of geology and paleontology in the University of
Pennsylvania, although he served other institutions as well.

Cope’s early work was among the amphibia and reptiles, his first
paleontological paper, the description of _Amphibamus grandiceps_,
appearing in 1865. This year he also began his studies of the mammals,
especially the Cetacea, both living and extinct, from the Atlantic
seaboard. The next year saw the beginning of his work on the material
from the Cretaceous marls of New Jersey, describing therefrom one of the
first carnivorous dinosaurs, _Lælaps_, to be discovered in America. In
1868 Cope began to describe the vertebrates from the Kansas chalk and
three years later made his first exploration of these beds. This led to
his connection with the United States Geological Survey of the
Territories under Hayden, and to continued exploration of Wyoming and
Colorado in 1872 and 1873. The material thus gained, consisting of
fishes, mosasaurs, dinosaurs, and other reptiles, was described in the
Transactions of the American Philosophical Society as well as in the
Survey Bulletins. In 1875 these results were summarized in a large
quarto volume entitled “Vertebrata of the Cretaceous formations of the
West.” Subsequent summers were spent in further exploration of the
Bridger, Washakie, and Wasatch formations of Wyoming, the Puerco and
Torrejon of New Mexico, and the Judith River of Montana. The material
gathered in New Mexico proved particularly valuable, and led to the
publication in 1877 of another notable volume entitled “Report upon the
Extinct Vertebrata obtained in New Mexico by Parties of the Expedition
of 1874.”

Material was now accumulating so fast as to necessitate the
concentration of Cope’s own time on research, so that, while he
continued to make brief journeys to the West, the real work of
exploration was delegated to Charles H. Sternberg and J. L. Wortman,
both of whom became subsequently very well known, the former as a
collector whose active service has not yet ceased, the latter as an
explorer and later an investigator of extremely high promise.

As early as 1865, Cope began no fewer than five separate lines of
research which he pursued concurrently for the remainder of his career.
On the fishes, he became a high authority in the larger classification,
owing to his researches into their phylogeny, for which a knowledge of
extinct forms is imperative. On amphibia, he wrote more voluminously
than any other naturalist, discussing not only the morphology but the
paleontology and taxonomy as well. In this connection must be mentioned
not only Cope’s exploration and collections in the Permian of Ohio and
Illinois, but especially the remains from the Texas Permian, first
received in 1877, upon which some of his most brilliant results were
based; these of course included reptilian as well as amphibian material.
His third line of research, the Reptilia, is in part included in the
foregoing, but also embraced the reptiles of the Bridger and other
Tertiary deposits, those of the Kansas Cretaceous, and the Cretaceous
dinosaurs.

Up to 1868 Leidy alone was engaged in research in the West, but that
year saw the simultaneous entrance of Marsh and Cope into this new field
of research, and their exploration and descriptions of similar regions
and forms soon led to a rivalry which in turn developed into a most
unfortunate series of controversies, mainly over the subject of
priority. This resulted in a permanent rupture of friendship and the
division of American workers into two opposing camps to the detriment of
the progress of our science. This breach has now been happily healed,
and for a number of years the degree of mutual good will and aid on the
part of our workers has been of the highest sort.

The extent of the western fossil area, and particularly the explorations
of three of Cope’s aids, Wortman in the Big Horn and Wasatch basins,
Baldwin in the Puerco of New Mexico, and Cummins in the Permian of
Texas, gave him so fruitful a field of endeavor that the occasion for
jealous rivalry was largely removed. The most manifest result of Cope’s
western work was the publication in 1883 of his Vertebrata of the
Tertiary Formations of the West, which formed volume =3= of the quarto
publications of the Hayden Survey. This huge book contains more than
1000 pages and 80 plates and has been facetiously called “Cope’s Bible.”

Cope’s philosophical contributions, which covered the domains of
evolution, psychology, ethics, and metaphysics, began in 1868 with his
paper on The Origin of Genera. In evolution he was a follower of
Lamarck, and as such, with Hyatt, Ryder, and Packard, was one of the
founders of the so-called Neo-Lamarckian School in America. Cope’s
principal contribution, set forth in his Factors of Organic Evolution,
is the idea of kinetogenesis or mechanical genesis, the principle that
all structures are the direct outcome of the stresses and strains to
which the organism is subjected. Weismann’s forcible attack on the
transmission theory did not shake Cope’s faith in these doctrines, for
he claimed that the paleontological evidence for the inheritance of such
characters as are apparently the result of _individual_ modification was
too strong to be refuted. Cope was more like Lamarck than any other
naturalist in his mental make-up as well as his ideas. He was also, like
Haeckel, given to working out the phylogeny of whatever type lay before
him, and in many instances arrived marvellously near the truth as we now
see it.

Associated for a while with A. S. Packard, Cope soon became chief editor
and proprietor of the American Naturalist, which was for many years his
main means of publication and thus served our science in a way
comparable to the Journal. As Osborn says by way of summation:


  “Cope is not to be thought of merely as a specialist in Paleontology.
  After Huxley he was the last representative of the old broad-gauge
  school of anatomists and is only to be compared with members of that
  school. His life work bears marks of great genius, of solid and
  accurate observation, and at times of inaccuracy due to bad logic or
  haste and overpressure of work.... As a comparative anatomist he ranks
  both in the range and effectiveness of his knowledge and his ideas
  with Cuvier and Owen.... As a natural philosopher, while far less
  logical than Huxley, he was more creative and constructive, his
  metaphysics ending in theism rather than agnosticism.”


                              _1870–1880._

The seventh decade was productive of comparatively few great names in
the history of our science, but two, J. A. Ryder and Samuel W.
Williston, being notable contributors. The former produced but few
papers and those between 1877 and 1892, yet they were of note and such
was their influence that he is named with Hyatt, Packard, and Cope as
one of the founders of the Neo-Lamarckian School of evolutionists in
America. Ryder was a particular friend and a colleague of Cope, as they
were both concerned with the back-boned animals, while the other two
were invertebratists. Ryder wrote on mechanical genesis of tooth forms
and on scales of fishes, also on the morphology and evolution of the
tails of fishes, cetaceans, and sirenians, and of the other fins of
aquatic types. He did, on the other hand, practically no systematic or
descriptive work.

Williston, on the contrary, has had a long and varied career as an
investigator and as an educator. Trained at Yale, he prepared for
medicine, and much of his teaching has been of human anatomy, both at
Yale and at the University of Kansas where he served for a number of
years as dean of the Medical School. He is also a student of flies, and
as such not only the foremost but indeed almost the only dipterologist
in the United States. But it is with his work as a vertebrate
paleontologist that we are chiefly concerned, and here again he stands
among the foremost. His initial work and training in this department of
science were with Marsh, for whom he spent many months in field work,
collecting largely in the Niobrara Cretaceous of Kansas. He did,
however, no research while with Marsh, owing to the latter’s
disinclination to foster such work on the part of his associates.
Williston began his publications in 1878 and has continued them until
the present, working mainly with Cretaceous mosasaurs, plesiosaurs, and
pterodactyls. Of late, since his transference to the University of
Chicago, where as professor of paleontology and director of the Walker
Museum he has served since 1902, his interest has lain mainly among the
Paleozoic reptiles and amphibia. Williston’s more notable works are
American Permian Vertebrates and Water Reptiles of the Past and Present,
wherein he sets forth his views of the phylogenesis and taxonomy of the
reptilian class. He is at present at work on the evolution of the
reptiles, a volume which is eagerly awaited by his colleagues. It is in
morphology that Williston’s greatest strength lies and some of his most
effective work on the mosasaurs has appeared in the Journal.


                              _1880–1900._

The next decade, that of 1880–1890, saw a number of notable additions to
the workers in vertebrate paleontology: Henry F. Osborn, W. B. Scott, R.
W. Shufeldt, J. L. Wortman, George Baur, F. A. Lucas, and F. W. True.
Shufeldt is our highest authority on the osteology of birds, both recent
and extinct, having recently described all of the extinct forms
contained in the Marsh collection; True wrote of Cetacea; Lucas of
marine and Pleistocene mammals and birds, and has also written popular
books on prehistoric life. Lucas’s greatest service, however, lies in
the museums, where he has manifested a genius second to none in the
installation of mute evidences of living and past organisms. Wortman was
for a time associated with Cope, later with Osborn in the American
Museum, again at the Carnegie Museum at Pittsburgh, and finally at Yale
in research on the Bridger Eocene portion of the Marsh collection. His
work has been chiefly the perfection of field methods in vertebrate
paleontology, and as a special investigator of Tertiary Mammalia,
treating the latter largely from the morphologic and taxonomic
standpoints. Wortman’s Yale results on the carnivores and primates of
the Eocene, as yet unfinished, were published in the Journal in
1901–1904.

William B. Scott is a graduate of Princeton, and has spent thirty-four
years in her service as Blair Professor of Geology and Paleontology. His
first publication, in 1878, issued in conjunction with Osborn and Speir,
described material collected by them in the Eocene formations of the
West, and since that time Scott’s research has been entirely with the
mammals, on which he is one of our highest authorities. His most notable
works have been a History of Land Mammals of the Western Hemisphere,
1913, and the results of the Patagonian expeditions by Hatcher, which
are published in a quarto series in conjunction with W. J. Sinclair,
although they are the authors of separate volumes, Scott’s work being
mainly on the carnivores and edentates of the Santa Cruz formation. It
is as a systematist in research and as an educator that Scott has
attained his highest usefulness.

The man who, next to the three pioneers, has attained the highest
reputation in vertebrate paleontologic research, is Henry Fairfield
Osborn. Graduate of Princeton in the same class that produced Scott,
Osborn served for a time as professor of comparative anatomy in that
institution, and in 1891 was called to New York to organize the
department of zoology in Columbia University and that of vertebrate
paleontology in the American Museum of Natural History. He had, early in
his career, gone west in company with Professor Scott, and had collected
material from the Eocene formation of Wyoming, upon which they based
their first joint paper in 1878, Osborn’s first independent production,
a memoir on two genera of Dinocerata, appearing in 1881. A number of
papers followed, on the Mesozoic Mammalia, on Cope’s tritubercular
theory, and on certain apparent evidences for the transmission of
acquired characters. It was, however, with his acceptance of the New
York responsibilities, especially at the American Museum, that Osborn’s
most significant work began. Aided first by Wortman and Earle, later by
W. D. Matthew and others, he has built up the greatest and most complete
collection of fossil vertebrates extant; its value, however, was largely
enhanced through the purchase of the private collection of Professor
Cope, which of course included a large number of types. The American
Museum collection thus contains not only a vast series of representative
specimens from every class and order of vertebrates, secured by purchase
or expedition from nearly all the great localities of the world, but an
exhibition series of skulls and partial and entire skeletons and
restorations which no other institution can hope to equal. Based upon
this wonderful material is a large amount of research, filling many
volumes, published for the greater part in the bulletin and memoirs of
the Museum. This research is not only the product of the staff,
including Walter Granger, Barnum Brown, W. D. Matthew, and W. K.
Gregory, but also of a number of other American and some foreign
paleontologists as well.

Professor Osborn’s own work has been voluminous, his bibliography from
1877 to 1916 containing no fewer than 441 titles, ranging over the
fields of paleontology,—which of course includes the greater
number—geology, correlation and paleogeography, evolutionary principles
exemplified in the Mammalia, man, neurology and embryology, biographies,
and the theory of education.

In paleontology, Osborn’s researches have been largely with the Reptilia
and Mammalia, partly morphological, but also taxonomic and evolutional.
Faunistic studies have also been made of the mammals. Of his published
volumes the most important are, first, the Age of Mammals (1910), in
which he treats not of evolutionary series of phylogenies, but of faunas
and their origin, migrations, and extinctions, and of the correlation of
Old and New World Tertiary deposits and their contents. Men of the Old
Stone Age (1916) is an exhaustive treatise and is the first full and
authoritative American presentation of what has been discovered up to
the present time throughout the world in regard to human prehistory. In
his latest volume, The Origin and Evolution of Life (1917), Osborn
presents a new energy conception of evolution and heredity as against
the prevailing matter and form conceptions. In this volume there is
summed up the whole story of the origin and evolution of life on earth
up to the appearance of man. This last book is novel in its conceptions,
but it is too early as yet to judge of the acceptance of Osborn’s theses
by his fellow workers in science.

Since the death of Professor Marsh, Osborn has served as vertebrate
paleontologist to the United States Geological Survey, and has in charge
the carrying through to completion of the many monographs proposed by
his distinguished predecessor. One of these, that on the horned
dinosaurs, has been completed by Hatcher and Lull (1907), another on the
stegosaurian dinosaurs has been carried forward by C. W. Gilmore of the
United States National Museum, while under Osborn’s own hand are the
memoirs on the titanotheres (aided by W. K. Gregory), the horses, and
the sauropod dinosaurs. Of these, the first, when it shall have been
completed, promises to be the most monumental and exhaustive study of a
group of fossil organisms ever undertaken.

As a leader in science, a teacher and administrator, Professor Osborn’s
rank is high among the leading vertebratists. He is remarkably
successful in his choice of assistants and in stimulating them in their
productiveness so that their combined results form a very considerable
share of the later literature in America.

The ninth decade ushered in the work of a valuable group of students, of
whom John Bell Hatcher should be mentioned in particular, as his work is
done. Graduate of Yale in 1884, he spent a number of years assisting his
teacher, Professor Marsh, mainly in the field, collecting during that
time, either for Yale or for the United States Geological Survey, an
enormous amount of very fine material, especially from the West,
although he also collected in the older Tertiary and Potomac beds near
Washington. In the West he secured no fewer than 105 titanothere skulls,
explored the Tertiary, Judith River, and Lance formations, collected and
in fact virtually discovered the remains of the Cretaceous mammals and
of the horned dinosaurs which he was later privileged to describe. He
then (1893) went to Princeton, which he served for seven years, his
principal work being explorations in Patagonia for the E. and M. Museum,
one direct result of which was the publication of a large quarto on the
narrative of the expedition and the geography and ethnography of the
region. Going to the Carnegie Museum in Pittsburgh in 1900, Hatcher
carried forward the work of exploration and collecting begun for that
institution by Wortman, and as a partial result prepared many papers,
the principal ones being memoirs on the dinosaurs _Haplocanthosaurus_
and _Diplodocus_. In 1903, with T. W. Stanton of the United States
Geological Survey, Hatcher explored the Judith River beds and together
they settled the vexatious problem of their age, the published results
appearing in 1905, after Hatcher’s death. His last piece of research,
begun in 1902 and continued until his death in 1904, was an elaborate
monograph on the Ceratopsia, one of the many projected by Marsh. Of this
memoir Hatcher had completed some 150 printed quarto pages, giving a
rare insight into the anatomy of these strange forms. The final
chapters, however, which were based very largely upon Hatcher’s own
opinions, had to be prepared by another hand.

Despite his early death, therefore, Hatcher rendered a very signal
service to American paleontology—in exploration, stratigraphy,
morphology, and systematic revision—and his activity in planning new
fields of research, such, for instance, as the exploration of the
Antarctic continent, gave promise of further high attainment, when his
hand was arrested by death.


                               _Summary._

It is not surprising that American vertebrate paleontology has arisen to
so high a plane, when one considers the material at its disposal. Having
a vast and virgin field for exploration, a sufficient number of
collectors, some of whom have devoted much of their lives to the work,
and a refinement of technique that permitted the preservation of the
fragmental and ill conserved as well as the finer specimens, the results
could hardly have been otherwise. Thus it has been possible to secure
material almost unique throughout the world for extent, for
completeness, and for variety. To this must be added a certain American
daring in the matter of the restoration of missing portions, both of the
individual bones and of the skeleton as a whole, such as European
conservatism will not as a rule permit. This work has for the most part
been done after the most painstaking comparison and research and is
highly justified in the accuracy of the results, which render the fabric
of the skeleton much more intelligible, both to the scientist and to the
layman. Material once secured and prepared is then mounted, and here
again American ingenuity has accomplished some remarkable results. Some
of the specimens thus mounted are so small and delicate as to require
holding devices comparable to those for the display of jewels; yet
others—huge dinosaurs the bones of which are enormously heavy, but so
brittle that they will not bear even the weight of a process
unsupported—require a carefully designed and skilfully worked out series
of supports of steel or iron which must be perfectly secure and at the
same time as inconspicuous as possible. And of late the lifelike pose of
the individual skeleton has been augmented by the preparation of groups
of several animals which collectively exhibit sex, size, or other
individual variations and the full mechanics of the skeleton under the
varying poses assumed by the creature during life.

The work of further restoration has been rendered possible through
comparative anatomical study, enabling us to essay restorations in
entirety by means of models and drawings, clothing the bones with sinews
and with flesh and the flesh with skin and hair, if such the creature
bore; while the laws of faunal coloration have permitted the coloring of
the restoration in a way which if not the actual hue of life is a very
reasonable possibility.

Thus the American paleontologists have blazed a trail which has been
followed to good effect by certain of their Old World colleagues.

With such means and methods and such material available, it is again not
surprising that American paleontology has furnished more and more of the
evidences of evolution, and disclosed to the eyes of scientists animal
relationships which were undreamed of by the systematist whose research
dealt only with the existing. It has also explained some vexatious
problems of animal distribution and of extinction, and has connected up
cause and effect in the great evolutionary movements which are recorded.

The results of systematic research have added hosts of new genera and
species and of families, but of orders there are relatively few.
Nevertheless a number, especially among reptiles and mammals, have come
to light as the fruits of American discovery. But aside from the dry
cataloguing of such groups, the American systematists have worked out
some very remarkable phylogenies and have thus clarified our vision of
animal relationships in a way which the recent zoologist could never
have done. In this connection, the Permian vertebrates, which have been
collected and studied with amazing success, principally by Williston and
Case, should be mentioned, although the work is yet incomplete. Some of
these forms are amphibian, others reptilian, yet others of such
character as to link the two classes as transitional forms. Of the
Mesozoic reptiles, a very remarkable assemblage has come to light, in a
degree of perfection unknown elsewhere. These are dinosaurs, of which
several phyla are now known; carnivores both great and small, some of
the latter being actually toothless; Sauropoda, whose perfection and
dimensions are incomparable except for those found in East Africa; and
predentates, armored, unarmored, and horned, the last exclusively
American. The unarmored trachodonts are now known in their entirety, for
not only has our West produced articulated skeletons but mummified
carcasses whose skin and other portions of their soft anatomy are
represented, and which are thus far without a parallel elsewhere in the
world. Other reptilian groups are well known, notably the Triassic
ichthyosaurs, and the mosasaurs and plesiosaurs of the Kansas chalk. The
last formation has also produced toothed birds, _Hesperornis_ and
_Ichthyornis_, which again are absolutely unique.

But it is in the mammalian class that the phylogenies become so highly
complete and of such great importance as evolutionary evidences, for
nowhere else than in our own West have such series been found as the
Dinocerata and creodonts among archaic forms, the primitive primates
from the Eocene, the carnivores such as the dogs and cats and
mustellids, but especially the hoofed orders such as the horses. Of
these hoofed orders, the classic American series of horses is complete,
that of the camels probably no less so, while much is known of the deer
and oreodonts, the last showing several parallel phyla, and of the
proboscideans, which while having their pristine home in the Old World
nevertheless soon sought the new where their remains are found from the
Miocene until their final and apparently very recent extinction. These
creatures show increase of bulk, perfection of feet and teeth,
development of various weapons, horns and antlers, which may be studied
in their relationship with the other organs to make the evolving whole,
or their evolution may be traced as individual structures which have
their rise, culmination, and sometimes their senile atrophy in a way
comparable to that of the representatives of the order as a whole. Thus,
for example, Osborn has traced the evolution of the molar teeth, and
Cope of the feet, while Marsh has shown that brain development runs a
similar course and that its degree of perfection within a group is a
potent factor for survival.

As a student of evolution, the paleontologist sees things in a very
different light from the zoologist. The latter is concerned largely with
matters of detail—with the inheritance of color or of the minor and more
superficial characteristics of animals—and the period of observation of
such phenomena is of necessity brief because of the mortality of the
observer. Whereas the paleontologist has a perspective which the other
lacks, since for him time means little in the terms of his own life, and
he can look into the past and see the great and fundamental changes
which evolution has wrought, the rise of phyla, of classes, of orders,
and he alone can see the orderliness of the process and sense the
majesty of the laws which govern it.


            _Influence of the American Journal of Science._

The influence of the American Journal of Science as a medium for the
dissemination of the results of vertebrate research has been in evidence
throughout this discussion, but it were well, perhaps, to emphasize that
service more fully. The Journal was, as we have seen, the chief outlet
for Professor Marsh’s research, for there were published in it during
his lifetime no fewer than 175 papers descriptive of the forms which he
studied, as well as a great part of the material in the published
monographs. As Marsh left very few manuscript notes, the importance of
these frequent publications in thus setting forth much that he thought
and learned concerning the material is very great indeed. The combined
titles of all other authors in the Journal in this line of research for
the century of its life fall far short of the number produced by Marsh
alone, as they include 136 all told, but the range of subjects is highly
representative of the entire field of vertebrate research. It should be
borne in mind, moreover, that Leidy, Cope, and Osborn each had another
medium of publication, which of course is true of other workers in the
great museums such as the American, National, and Carnegie, all of which
issue bulletins and quarto publications for the purpose of disseminating
the work of their staff. Many of the earlier announcements of the
discovery of vertebrate relics appeared in the Journal, as did
practically all the literature of the science of fossil footprints
(ichnology), except of course the larger quartos of Hitchcock and Deane.
Of the footprint papers by Hitchcock, Deane, and others, there were no
fewer than thirty-two, with a number of additional communications on
attendant phenomena bones and plants.

Up to 1847, except for a few foreign announcements, the Journal
published almost exclusively on eastern American paleontology, the only
exception being a notice of bones from Oregon by Perkins in 1842. In
1847 came the announcement of a western “Palæothere” by Prout, which
marked the beginning of the researches of Leidy and others in the Bad
Lands of the great Nebraska plains. The Journal thenceforth published
paper after paper on forms from all over North America, and on all
aspects of our science: discovery, systematic description, faunal
relationships, evolutionary evidences—thus showing that breadth and
catholicity which has made it so great a power in the advancement of
science.




                                  VII
                   THE RISE OF PETROLOGY AS A SCIENCE

                          By LOUIS V. PIRSSON


 This chapter is intended to present a brief sketch of the progress of
the science of petrology from its early beginnings down to the present
time. The field to be covered is so large that this can be done only in
broadest outline, and it has therefore been restricted chiefly to what
has been accomplished in America. Although the period covered by the
life of the Journal extends backward for a century it is, however,
practically only within the last fifty years that the rocks of the
earth’s crust have been made the subject of such systematic
investigation by minute and delicately accurate methods of research as
to give rise to a distinct branch of geologic science. It is not
intended of course to affirm by this statement that the broader features
of the rocks, especially those which may be observed in the field and
which concern their relations as geologic masses, had not been made the
object of inquiry before this time, since this is the very foundation of
geology itself. Moreover, a certain amount of investigation of rocks, as
to the minerals of which they were composed, the significance of their
textures, and their chemical composition, had been carried out,
concomitant with the growth from early times of geology and mineralogy.
Thus, in 1815, Cordier by a process of washing separated the components
of a basalt and by chemical tests determined the constituent minerals.
At the time the Journal was founded, and for many years following, the
genesis of rocks, especially of igneous rocks, was a subject of inquiry
and of prolonged discussion. The aid of the rapidly growing science of
chemistry was invoked by the geologists and analyses of rocks were made
in the attempt to throw light on important questions. It is remarkable,
also, how keen were the observations that the geologists of those days
made upon the rocks, as to their component minerals and structures,
aided only by the pocket lens. Many ideas were put forward, the
essentials of which have persisted to the present day and have become
interwoven into the science, whereas others gave rise to contentions
which have not yet been settled to the satisfaction of all. At times in
these earlier days the microscope was called into use to help in solving
questions regarding the finer grained rocks, but this employment, as
Zirkel has shown, was merely incidental, and no definite technique or
purpose for the instrument was established.

On the other hand, the fact that up to the middle of the last century a
large store of information relating to the occurrence of rocks, and to
the mineral composition of those of coarser grain, and somewhat in
respect to their structure, had been accumulated, caused attempts in one
way or another to find means of coördinating these data and to produce
classifications, such as those of Von Cotta and Cordier. The history of
these attempts at classification, before the revelations made by the use
of the microscope had become general, has been admirably reviewed by
Whitman Cross[107] and need not be further enlarged upon here.

That a considerable amount of work was done along chemical lines also is
testified to by the publication of Roth’s Tabellen in 1861, in which all
published analyses of rocks up to that date were collected. What was
accomplished during this period was done chiefly on the continent of
Europe, and little attention had been paid to the subject of rocks
either in America or in Great Britain—even so late as 1870 Geikie
remarks, as referred to by Cross,[108] that there was no good English
treatise on petrography, or the classification and description of rocks.
In this country still less had been accomplished, interest being almost
wholly confined to the vigorous and growing sciences of geology and
mineralogy. This was natural, for mineralogy is the chief buttress on
which the structure of petrology rests and must naturally develop first,
especially in a relatively new and unexplored region, whose mineral
resources first attract attention. The geologists in carrying out their
studies also observed the rocks as they saw them in the field and made
incidental reference to them, but investigations of the rocks themselves
was very little attempted. An inspection of the first two series of the
Journal shows relatively little of importance in petrology published in
this country; a few analyses of rocks, occasional mention of mineral
composition, of weathering properties, and notices of methods of
classification proposed by French and German geologists nearly exhaust
the list.


                   _Introduction of the Microscope._

The beginnings of a particular branch of science are generally obscure
and rooted so imperceptibly in the foundations on which it rests that it
is difficult to point to any particular place in its development and say
that this is the start. There are exceptions of course, like the
remarkable work of Willard Gibbs in physical chemistry, and it may
chance that the happy inspiration of a single worker may give such
direction to methods of investigation as to open the gates into a whole
new realm of research, and to thus create a separate scientific field,
as happened in Radiochemistry.

This is what occurred in petrology when Sorby in England, in 1858,[109]
pointed out the value of the microscope as an instrument of research in
geologic investigations, and demonstrated that its employment in the
study of thin sections of rocks would yield information of the highest
value. Others beside Sorby had made use of the microscope, as pointed
out by Zirkel,[110] but, as he indicates, no one before him had
recognized its value. During the next ten years or so, however, its
recognition was very slow and the papers published by Sorby himself were
mainly concerned in settling very special matters.

As Williams[111] has suggested, the greatest service of Sorby was,
perhaps, his instructing Zirkel in his ideas and methods, for the latter
threw himself whole-heartedly into the study of rocks by the aid of the
microscope and his discoveries stimulated other workers in this field in
Germany, his native country, until the dawning science of petrology
began to assume form. A further step forward was taken in 1873 in the
appearance of the text-books of Zirkel[112] and Rosenbusch[113] which
collated the knowledge which had been gained and furnished the
investigator more precise methods of work. It is difficult for the
student of to-day to realize how much had been learned in the interval
and, for that matter, how much has been gained since 1873, without an
inspection of these now obsolete texts. In 1863, Zirkel, who was then at
the beginning of his work, said in his first paper presented to the
Vienna Academy of Sciences[114] that if he confined himself chiefly to
the structure of the rocks investigated and of their component minerals,
and stated little as to what these minerals were, the reason for that
was because “although the microscope serves splendidly for the
investigation of the former relations, it promises very little help for
the latter. Labradorite, oligoclase and orthoclase, augite and
hornblende, minerals whose recognition offers the most important
problems in petrography, in most cases cannot be distinguished from one
another under the microscope.” How little could Zirkel have foreseen, at
this time, less than forty years later, that not only could labradorite
be accurately determined in a rock-section, but that in a few minutes by
the making of two or three measurements on a properly selected section,
its chemical composition and the crystallographic orientation of the
section itself could be determined!


                          _The Thin Section._

Before going further we may pause here a moment to consider the origin
and development of the thin section, without which no progress could
have been made in this field of research. When we reflect upon the
matter, it seems a marvelous thing indeed that the densest, blackest
rock can be made to yield a section of the ¹⁄₁₀₀₀ of an inch in
thickness, so thin and transparent that fine printing can be easily read
through it, and transmitting light so clearly that the most high-powered
objectives of the microscope can be used to discern and study the
minutest structures it presents with the same capacity that they can be
employed upon sections of organic material prepared by the microtome.
This is no small achievement.

The first thin sections appear to have been prepared in 1828 by William
Nicol of Edinburgh, to whom we owe the prism which carries his name. He
undertook the making of sections from fossil wood for the purpose of
studying its structure. The method he developed was in principle the
same as that employed to-day, where machinery is not used; that is, he
ground a flat smooth surface upon one side of a chip of his petrified
wood, then cemented this to a bit of glass plate with Canada balsam, and
ground down the other side until the section was sufficiently thin. This
method was used by others for the study of fossil woods, coal, etc., but
it was not applied to rocks until 1850, when Sorby used it for
investigating a calcareous grit. Oschatz, in Germany, also about this
time independently discovered the same method. A further advance was
made in melting the cement, floating off the slice, and transferring it
to a suitable object-glass with cover, a process still employed by many;
though most operators now cement the first prepared surface of the rock
chip directly to the object-glass, and mount the section without
transferring it.

Next came the use of machinery to save labor in grinding, and another
step was made in the introduction of the saw, a circular disk of sheet
iron whose edge was furnished with embedded diamond dust. This makes it
possible to cut relatively thin slices with comparative rapidity, but
the final grinding which requires experience and skill must still be
done by hand. Carborundum has also largely replaced emery. The skill and
technique of preparers has reached a point where sections of rocks of
the desired thinness (0·001 inch), and four or five inches square have
been exhibited.


                       _The Era of Petrography._

In these earlier days of the science, as noted above, great difficulty
was at first experienced in the recognition of the minerals as they were
encountered in the study of rocks under the microscope. At that time the
chemical composition and outward crystal form of minerals were
relatively much better known than their physical and, especially, their
optical properties and constants. Some beginnings in this had been made
by Brewster, Nicol, and other physicists, and the mineralogists had
commenced to study minerals from this viewpoint. Especially Des
Cloiseaux had devoted himself to determining the optical properties of
many minerals, and the writer, when a student in the laboratory of
Rosenbusch in 1890, well recalls the tribute that he paid to the work of
Des Cloiseaux for the aid which it had afforded him in his earlier
researches in petrography.

The twenty years following the publication of the texts of Rosenbusch
and Zirkel may be characterized as the era of microscopical petrography.
A distinction is drawn here between the latter word and petrology, a
distinction often overlooked, for _petrography_ means literally the
description of rocks, whereas _petrology_ denotes the science of rocks.
As time passed the broader and more fundamental features of rocks,
especially of igneous and metamorphic rocks, in addition to their
mineral constitution, were more studied and gained greater recognition,
petrography gradually became a department of the larger field of
petrology—the science of to-day.

The use of the microscope, as soon as the method became more generally
understood, opened up so vast a field for investigation that at first
the study and description of the rocks seemed of prime importance. This
was natural, for hitherto the finer grained rocks had for the most part
defied any adequate elucidation and here was a key which enabled one to
read the cipher. A flood of literature upon the composition, structure,
and other characters of rocks from all parts of the world began to
appear in ever increasing volume. The demands of the petrographers for a
greater and more accurate knowledge of the physical and optical
constants of minerals stimulated this side of mineralogy, and increasing
attention was given to investigations in this direction. No definite
line between the two closely related sciences could be drawn, and a
large part of the work published under the heading of petrography could
perhaps be as well, or better, described under the title of
micro-mineralogy. To some, in truth, the rocks presented themselves
simply as aggregates of minerals, occurring in fine grains.

The work of the German petrographers attracted attention and drew
students from all parts of the world to their laboratories, especially
to those of Zirkel and Rosenbusch. The great opportunities, facilities,
and freedom for work which the German universities had long offered to
foreign students of science naturally encouraged this. In France a
brilliant school of petrologists, under the able leadership of
Michel-Lévy and Fouqué, had arisen whose work has been continued by
Barrois, Lacroix and others, but the rigid structure of the French
universities at that period did not permit of the offering of great
inducements for the attendance of foreign students. The work of the
French petrographers will be noticed in another connection.

In Great Britain, the home of Sorby, the new science progressed at first
slowly, until it was taken up by Allport, Bonney, Judd, Rutley, and
others. In 1885 the evidence of the advance that had been made and of
the firm basis on which the new science was now placed appeared in
Teall’s great work, “British Petrography,” which marked an epoch in that
country in petrographic publication. This work was of importance also in
another direction than that of descriptive petrography, in that it
contains valuable suggestions for the application of the principles of
modern physical chemistry in solving the problems of the origin of
igneous rocks. In it, as in the publications of Lagorio, we see the
passage of the petrographic into the petrologic phase of the science.

The earliest publication in America of the results of microscopic
investigation of rocks that the writer has been able to find is by A. A.
Julien and C. E. Wright, chiefly on greenstones and chloritic schists
from the iron-bearing regions of upper Michigan.[115] Naturally, it was
of a brief and elementary character. In 1874 E. S. Dana read a paper
before the American Association for the Advancement of Science on the
result of his studies on the “Trap-rocks of the Connecticut valley,” an
abstract of which was published in this Journal.[116] Meanwhile Clarence
King, in charge of the 40th Parallel survey, feeling the need of a
systematic study of the crystalline rocks which had been encountered,
and finding no one in this country prepared to undertake it, had induced
Zirkel to give his attention to this task. The result of this labor
appeared in 1876 in a fine volume[117] which attracted great attention.
In the same year appeared also petrographical papers by J. H.
Caswell,[118] E. S. Dana[119] and G. W. Hawes.[120] The latter devoted
himself almost entirely to this field of research and may thus, perhaps,
be termed the earliest of the petrographers in this country. His work,
“The Mineralogy and Lithology of New Hampshire,” issued in 1878 as one
of the reports of the State Survey under Prof. C. H. Hitchcock, was the
first considerable memoir by an American. This was followed by various
papers, one on the “Albany Granite and its contact phenomena,”[121]
being of especial interest as one of the earliest studies of a contact
zone, and in the fullness of methods employed in attacking the problem
forecasting the change to the petrology era.

During the ten years following, or from 1880 to 1890, the new science of
petrography flourished and grew exceedingly. Many young geologists
abroad devoted themselves to this field of research and the store of
accumulated knowledge concerning rocks from all parts of the world, and
their relations grew apace. The work of Teall has been noticed and among
others might be mentioned the name of Brögger, whose first
contribution[122] in this field gave evidence that his publications
would become classics in the science.

In America there appeared in this period a number of eager workers,
trained in part in the laboratories of Rosenbusch and Zirkel, whose
researches were destined to place the science on the secure footing in
this country which it occupies to-day. Among the earlier of these may be
mentioned Whitman Cross, R. D. Irving, J. P. Iddings, G. H. Williams, J.
F. Kemp, J. S. Diller, B. K. Emerson, M. E. Wadsworth, G. P. Merrill, N.
H. Winchell, and F. D. Adams in Canada. Others were added yearly to this
group. As a result of their work a constantly growing volume of
information about the rocks of America became available, and one has
only to examine the files of the Journal and other periodicals and the
listed publications of the National and State Surveys to appreciate
this.

In the Journal, for example, we may refer to papers[123] by Emerson on
the Deerfield dike and its minerals, and on the occurrence of nephelite
syenite at Beemersville, N. J.; to various interesting articles by Cross
on lavas from Colorado and the pneumatolytic and other minerals
associated with them; to important papers by Iddings on the rocks of the
volcanoes of the Northwest, and those of the Great Basin, to primary
quartz in basalt, and the origin of lithophysæ; to the results of
researches by G. H. Williams on the rocks of the Cortlandt series, and
on peridotite near Syracuse, N. Y.; to papers by Diller on the
peridotites of Kentucky, and recent volcanic eruptions in California; to
articles by R. D. Irving on the copper-bearing and other rocks of the
Lake Superior region, and to Kemp on dikes and other eruptives in
southern New York and northern New Jersey. Other publications would
greatly extend this list.


                         _The Petrologic Era._

As the chief facts regarding rocks, especially igneous rocks, as to
their mineral and chemical composition, their structure and texture and
the limits within which these are enclosed, became better known; and the
relations, which these bear to the associations of rocks and their modes
of occurrence, began to be perceived, the science assumed a broader
aspect. The perception that rocks were no longer to be regarded merely
as interesting assemblages of minerals, but as entities whose characters
and associations had a meaning, increased. More and better rock analyses
stimulated interest on the chemical side and this and the genesis of
their minerals led to a consideration of the magmas and their functions
in rock-making. The fact that the different kinds of rocks were not
scattered indiscriminately, but that different regions exhibited certain
groupings with common characters, was noticed. These features led to
attempts to classify igneous rocks on different lines from those
hitherto employed, and to account for their origin on broad principles.
In other words, the descriptive science of petrography merged into the
broader one of petrology. No exact time can be set which marks this
passage, since the evolution was gradual. Yet for this country, in
reviewing the literature, for which the successive issues of the
“Bibliography of North American Geology” published by the U. S.
Geological Survey has been of the greatest value; the writer has been
struck by the fact that in the first volume containing the index of
papers down to and including 1891, the articles on subjects of this
nature are listed under the heading of _petrography_, whereas in the
second volume (1892–1900) they are grouped under _petrology_ and the
former heading is omitted. A justification for this is found in
examining the list of publications and noting their character. With some
reason, therefore, the beginning of this period may be placed as in the
early years of this decade. Furthermore, it was at this time that the
great work of Zirkel[124] began to appear, which sums up so completely
the results of the petrographic era. Rosenbusch[125] was formulating
more definitely his views on the division of rocks into magmatic groups,
as displayed by their associations in the field, and using this in
classification; an idea which, appearing first in the second edition of
his “Physiographie der massigen Gesteine,” finds fuller development in
the third and last editions of this work. In this country Iddings[126]
published an important paper, in which the family relationships of
igneous rocks and the derivation of diverse groups from a common magma
by differentiation are clearly brought out. The fundamental problems
underlying the genesis of igneous rocks had now been clearly recognized,
and with this recognition the science passed into the petrologic phase.
Brögger[127] also had ascribed to the alkalic rocks of South Norway a
common parentage and had pointed out their regional peculiarities.

From this time forward an attempt may be noted to find an analogy
between rocks and the forms of organic life and to apply those
principles of evolution and descent, which have proved so fruitful in
the advancement of the biological sciences, to the genesis and
classification of igneous rocks. This, perhaps, has on the whole been
more apparent than real, in the constant borrowing of terms from those
sciences to express certain features and relationships observed, or
imagined, to obtain among rocks. Nevertheless, the perception of certain
relations which we owe so largely to Rosenbusch and to Brögger[128] has
proved of undoubted value in furnishing a stimulus for the investigation
of new regions, and in affording indications of what the petrologist
should anticipate in his work.

Thus, the labors of the men previously mentioned, with those of Bayley,
Bascom, Cushing, Daly, Lane, Lawson, Lindgren, Pirsson, J. F. Williams,
Washington, and others, have thrown a flood of light upon the igneous
rocks of this continent, and has made it possible to draw many broad
generalizations concerning their origin and distribution. Thus, the
differentiated laccoliths of Montana[129] have been of service in
affording clear examples of the process of local differentiation. Many
papers published in the Journal during the last twenty years show this
evolution and growth of petrological ideas. The contributions from
American sources during this later period, and of which those in the
Journal form a considerable fraction, have indeed been of great weight
in shaping the development and future of the science.

By referring to the files of the Journal, it will be seen that they
cover a continually widening range of subjects concerning rocks, and
articles of theoretical interest are more and more in evidence, along
with those of a purely descriptive character.[130] Thus we find
discussions by Becker on the physical constants of rocks, on fractional
crystallization, and on differentiation; by Cross on classification; by
Adams on the physical properties of rocks; by Daly on the methods of
igneous intrusion; by Wright on schistosity; by Fenner on the
crystallization of basaltic magma; by Bowen on differentiation by
crystallization; by the writer on complementary rocks and on the origin
of phenocrysts; by Smyth on the origin of alkalic rocks; by Murgoci on
the genesis of riebeckite rocks; and by Barrell on contact-metamorphism.
These may serve as examples, selected almost at random, from the files
of the Journal, and we find with them articles descriptive of the
petrology of many particular regions, which often contain also matter of
general interest and importance, such as papers by Lindgren on the
granodiorite and related rocks of the Sierra Nevada; by Ransome on
latite; by Cross on the Leucite Hills; by Hague on the lavas of the
Yellowstone Park; by Pogue on ancient volcanic rocks from North
Carolina; by Warren on peridotites from Cumberland, R. I.; on sandstone
from Texas by Goldman; and on the petrology of various localities in
central New Hampshire by Washington and the writer. Such a list could of
course be much extended and other papers of importance be cited, but
enough has been said to indicate how important a repository of the
results of petrologic research the Journal has been and continues to be.

In thus looking backward over the list of active workers we are
involuntarily led to pause and reflect how great a loss American
petrology has sustained in the premature death of some of its most
brilliant and promising exponents; it is only necessary to recall the
names of R. D. Irving, G. H. Williams, G. W. Hawes, J. F. Williams and
Carville Lewis, to appreciate this.

The store of material gathered during these years has led to the
publication of extensive memoirs, in which the science is treated not
from the older descriptive side, but from the theoretical standpoint and
of classification.[131] In these works strong divergencies of views and
opinions are observed, which is a healthy sign in a developing science.

It should be also noted that along with this evolution on the
theoretical side there has been a constant improvement in the technique
of investigating rocks. It is only necessary to compare the older
handbooks of Zirkel and Rosenbusch with the many modern treatises on
petrographic methods to be assured of this.[132] It is due on the one
hand to the vast amount of careful work which has been done in
accurately determining the physical constants of rock-minerals[133] and
in arranging these for their determination microscopically, as in the
remarkable studies on the feldspars by Michel-Lévy, and on the other in
researches on the apparatus employed, and in consequent improvements in
them and in ways of using them, as exemplified in the delicately
accurate methods introduced by Wright.[134] The development of the
microscope itself as an instrument of research in this field and in
mineralogy deserves a further word in this connection. The first step
toward making the ordinary microscope of special use in this way was
taken by Henry Fox Talbot of England, when he introduced in 1834 the
employment of the recently invented nicol prisms for testing objects in
polarized light. The modern instrument may be said to date from the
design offered by Rosenbusch in 1876. Since that time there have been
constant improvements, almost year by year, until the instrument has
become one of great precision and convenience, remarkably well adapted
for the work it is called upon to perform, with special designs for
various kinds of use, and an almost endless number of accessory
appliances for research in different branches of mineralogy and
crystallography, as well as in petrography proper.[135] This also calls
to mind the fact that for the convenience of those who are not able to
use the microscope special manuals of petrology have been prepared in
which rocks are treated from the megascopic standpoint.[136]


                          _Metamorphic Rocks._

In this connection the metamorphic rocks should not be forgotten. They
afford indeed the most difficult problems with which the geologist has
to deal; every branch of geological science may in turn be called upon
to furnish its quota for help in solving them. Under the attack of
careful, accurate and persistent work in the field, under the microscope
and in the chemical laboratory, with the aid of the garnered knowledge
in petrology, stratigraphy, physiography, and other fields of geologic
science, their mystery has in large part given way. The inaugural work
of Lehmann, Lossen, Barrois, Bonney, Teall, and other European
geologists, was paralleled in America by that of R. D. Irving, owing to
whose efforts the Lake Superior region became the chief place of study
of the metamorphic rocks in this country. Irving soon obtained the
assistance of G. H. Williams, who had been engaged in the study of such
rocks, and the latter published a memoir on the greenstone schist areas
of Menominee and Marquette in Michigan[137] which will always remain one
of the classics in the literature of metamorphic rocks. Irving’s own
contributions to petrology, though valuable, were cut short by his
untimely death, but the study of this region under the direction of his
associate and successor, C. R. Van Hise, with his co-laborers, has
yielded a mass of information of fundamental importance in our
understanding of metamorphism and the crystalline schists. Its fruitage
appears in the memoir by Van Hise[138] which is the authoritative work
of reference on metamorphism, and in various publications by him and his
assistants, Bayley, Clements, Leith, and others. The work of the
Canadian geologists, and of Kemp, Cushing, Smyth and Miller in the
Adirondack region, should also be mentioned in connection with this
field of petrology.


                     _Chemical Analyses of Rocks._

It has been previously pointed out that, as the science of petrology
grew, chemical investigations of rocks in bulk were undertaken. The
object of such analyses was to obtain on the one hand a better control
over the mineral composition and on the other to gain an idea of the
nature of the magmas from which igneous rocks had formed. The earliest
analysis of an American rock of which I can find record is of a “wacke”
by J. W. Webster given in the first volume of the Journal, page 296,
1818.

During the next 40 years a few occasional analyses were undertaken by
American chemists, by C. T. Jackson, T. Sterry Hunt, and others. In
1861, Justus Roth published the first edition of his Tabellen, in which
he included all analyses which had been made to that date and which he
considered were worthy of preservation. Although, naturally, from the
status of analytical chemistry up to that time, most of these would now
be considered rather crude, the publication of the work was of great
service and marked an epoch in geochemistry. In these tables Roth lists
four analyses of American igneous rocks, two from the Lake Superior
region by Jackson and J. D. Whitney and two by European chemists, one of
whom was Bunsen. The material of the last two was a “dolerite” and the
same locality is given for each—“Sierra Nevada between 38° and 41°”
which was probably considered quite precise for western America in those
days.

From these feeble beginnings the forward progress of petrology on the
chemical side in this country has been a steady one until its
development has reached the point which will be indicated in what
follows.

The collection of material by the various State surveys and by those
initiated by the National Government led to an increasing number of
rocks being analyzed during the petrographic period. These became also
increasingly good in quality, like those published by G. W. Hawes in his
papers. When, however, chemists were appointed to definite positions on
the staffs of the Government surveys and especially when, after the
organization of the U. S. Geological Survey in 1879, a general central
laboratory was founded in 1883 with F. W. Clarke in charge, then a new
era in the chemical investigation of rocks may be said to have started.
In this connection should be mentioned the work of W. F. Hillebrand, who
set a standard of accuracy and detail in rock analysis which had not
hitherto been attempted. As a consequence of his accurate and thorough
methods and results the mass of analyses performed by him and his fellow
chemists in this laboratory affords us the greatest single contribution
to chemical petrology which has been made. Up to January, 1914, the
report of Clarke[139] lists some 8000 analyses of various kinds made in
this laboratory for geologic purposes. Nearly everywhere also a great
improvement in the quality of rock-analyses is to be noted, and in the
manuals of Hillebrand[140] and Washington[141] the rock analyst has now
at his command the methods of a greatly perfected technique which should
insure him the best results.

Roth’s Tabellen have been previously mentioned; several supplements were
published, but after his death a long interval elapsed before this
convenient and useful work was again taken up by Washington[142] and
Osann.[143] A new edition of Washington’s Tables has recently been
published, listing some 8600 analyses of igneous rocks made up to the
close of 1913.[144]

On the theoretical side also, where petrology passes into geology, the
investigator of to-day will find a mass of most useful and accurate data
well discussed in the modern representative of Bischof’s Chemical
Geology—Clarke’s Data of Geochemistry.[145] The advance on the chemical
side, therefore, has been quite commensurate with that in the microscope
as an instrument, and in the results obtained by it.


                        _Physico-Chemical Work._

The study of geological results by experimental methods, which should
gain information concerning the processes by which those results are
caused, and the conditions under which they operate, has been from the
earliest days of the developing science recognized as most important,
and the record of the literature shows considerable was done in this
direction. Experimental work in modern petrology may, however, be
considered to date from 1882 when Fouqué and Michel-Lévy[146] published
the results of their extensive researches on the synthesis of minerals
and rocks by pyrogenous methods. The brilliant experiments of the French
petrologists at once attracted attention, and since that time a
considerable volume of valuable work has been done in this field by a
number of men, among whom may be mentioned Morozewicz,[147]
Doelter,[148] Tamman,[149] and Meunier.[150] As this work continued the
results of the rapid advances made in physical chemistry began to be
applied in this field with increasing value. To J. H. L. Vogt we owe a
valuable series of papers,[151] in which the formation of minerals and
rocks from magmas is treated from this standpoint. Most important of all
for the future of petrology has been the founding in Washington of the
splendid research institution, the Carnegie Geophysical Laboratory,
under the leadership of Dr. A. L. Day with its corps of trained
physicists, chemists and petrologists, devoted to the solving of the
problems which the progress of geological science raises. The
publications of this institution (many of them published in the Journal)
are too numerous to be mentioned here; many of them treat successfully
of matters of the greatest importance in petrology. This is an earnest
of what we may hope in the future. The accumulation of the exact
physical and chemical data, which is its aim, will serve as a necessary
check to hypothetical speculation and bring petrology, and especially
petrogenesis, in line with the other more exact sciences by furnishing
quantitative foundations for its structure of theory to rest upon.

While the achievements of this great organization seem to minimize the
work of the individual investigator in this field, he may take heart by
observing the important results on the strength of rocks under various
conditions which have been obtained by Adams in recent years, data of
wide application in theoretical geology. In this field also a special
text has appeared in which the principles and acquired data are
given.[152]


                               _Summary._

In this brief retrospect, giving only the barest outlines and omitting
from necessity much of importance, we have seen petrology grow from
occasional crude experiments into a fully organized science in the last
half century. It has to-day a well-perfected technique, a large volume
of literature, texts treating of general principles, of methods of work,
descriptive handbooks on the morphological side, and has attained
general recognition as a field, which, though not large, is worthy of
the concentration of intellectual endeavor. Like other healthy growing
organisms it has given rise to offshoots, and the sciences of
metallography and of the micro-study of ore deposits, which are rapidly
assuming form, have branched from it.

What of the future? The old days of mostly descriptive work, and of
theorizing purely from observed results, have passed. The science has
entered upon the stage where work and theory must be continually brought
into agreement with chemical, physical and mathematical laws and data,
and in the application of these new problems present themselves. As we
climb, in fact, new horizons open to our view indicating fresh regions
for exploration, for acquiring human knowledge and for our satisfaction.


                            _Bibliography._

Footnote 107:

  W. Cross, Jour. Geology, =10=, 451, 1902.

Footnote 108:

  _Ibid._, p. 45.

Footnote 109:

  Sorby, Quart. Jour. Geol. Soc., =14=, 453, 1858.

Footnote 110:

  Zirkel, Einführung des Mikroskops in das mineralogisch-geologische
  Studium, 1881.

Footnote 111:

  Williams, G. H., Modern Petrography, 1886.

Footnote 112:

  Zirkel, Mikroskopische Beschaffenheit der Mineralien und Gesteine.

Footnote 113:

  Rosenbusch, Mikroskopische Physiographie der petrographisch wichtigen
  Mineralien.

Footnote 114:

  Zirkel, Mikroskopische Gesteinstudien, Sitzung vom 12 März, 1863.

Footnote 115:

  Julien and Wright, Geol. Surv. of Michigan, 2, 1873. Appendices A and
  C.

Footnote 116:

  Dana, E. S., the Journal, =8=, 390–392, 1874.

Footnote 117:

  Zirkel, Geological Exploration of the 40th Parallel; vol. VI,
  Microscopical Petrography.

Footnote 118:

  Caswell, Microscopical Petrography of the Black Hills. U. S. Geog. and
  Geol. Surv. Rocky Mts. Rep. on Black Hills of Dakota, 469–527. The
  separate copies issued bear the imprint 1876; the complete report
  1880.

Footnote 119:

  Dana, E. S., Igneous Rocks in the Judith Mts. Rep. of Reconnaissance
  Carroll, Mont., to Yellowstone Park in 1875. Col. Wm. Ludlow, War
  Dept., Washington, 105–106.

Footnote 120:

  Hawes, G. W., Rocks of the Chlorite Formation, etc., the Journal,
  =11=, 122–126, 1876. Greenstones of New Hampshire, etc, ibid., =12=,
  129–137, 1876.

Footnote 121:

  Hawes, G. W., the Journal, =21=, 21–32, 1881.

Footnote 122:

  Brögger, Die silurischen Etagen 2 und 3, Kristiania, 1882.

Footnote 123:

  The references for the papers alluded to, all of them in the Journal,
  are as follows:

      Emerson, =24=, 195–202, 270–278, 349–359, 1882;
      ——, =23=, 302–308, 1882.
      Cross, =27=, 94–96, 1884; =31=, 432–438, 1886; =39=, 359–370,
         1890; =41=, 466–475, 1891; =23=, 452–458, 1882.
      Iddings, =26=, 222–235, 1883;
      ——, =27=, 453–463, 1884;
      ——, =36=, 208–221, 1888;
      ——, =33=, 36–45, 1887.
      Williams, =31=, 26–41, 1886; =33=, 135–144, 191–199, 1887; =35=,
         433–448, 1888; =36=, 254–259, 1888.
      ——, =34=, 137–145, 1887.
      Diller, =32=, 121–125, 1886; =37=, 219–220, 1889;
      ——, =33=, 45–50, 1887.
      Irving (=26=, 27–32, 321–322, =27=, 130–134, 1883; =29=, 358–359,
         1885).
      Kemp (=35=, 331–332, 1888; =36=, 247–253, 1888; =38=, 130–134,
         1889).

Footnote 124:

  Zirkel, Lehrbuch der Petrographie, 2d ed., 1893.

Footnote 125:

  Hunter and Rosenbusch, Ueber Monchiquit, etc., Min. petr. Mitth.,
  =11=, 445, 1890. Rosenbusch, Ueber Structur und Class. der
  Eruptivgesteine, ibid., =12=, 351, 1891.

Footnote 126:

  Iddings, Origin of Igneous Rocks, Bull. Phil, Soc. Washington, =12=,
  89–213, 1892.

Footnote 127:

  Brögger, Mineralien der Syenit-pegmatit-gànge, etc., Zs. Kryst., =16=,
  1890.

Footnote 128:

  ——, Basic Eruptive Rocks of Gran, Quart. Jour. Geol. Soc., =50=, 15,
  1894; Grorudit-Tinguait-Serie, Vidensk. Skrift. 1 Math. nat. Kl., No.
  4, 1894.

Footnote 129:

  Weed and Pirsson, _e. g._ Shonkin Sag, the Journal, =12=, 1–17, 1901.

Footnote 130:

  The references for the articles mentioned (all in the Journal) are as
  follows:

      Becker, =46=, 1893; =4=, 257, 1897; =3=, 21–40, 1897.
      Cross, =39=, 657–661, 1915.
      Adams, =22=, 95–123, 1906; =29=, 465–487, 1910.
      Daly, =22=, 195–216, 1906; =26=, 17–50, 1908.
      Wright, =22=, 224–230, 1906.
      Fenner, =29=, 217–234, 1910.
      Bowen, =39=, 175–191; =40=, 161–185, 1915.
      Pirsson, =50=, 116–121, 1895; =7=, 271–280, 1899.
      Smyth, =36=, 33–46, 1913.
      Murgoci, =20=, 133–145, 1905.
      Barrell, =13=, 279–296, 1902.
      Lindgren, =3=, 301–314, 1897; =9=, 269–282, 1900.
      Ransome, =5=, 355–375, 1898.
      Cross, =4=, 115–141, 1897.
      Hague, =1=, 445–457, 1896.
      Pogue, =28=, 218–238, 1909.
      Warren, =25=, 12–36, 1908.
      Goldman, =39=, 261–288, 1915.
      Washington and Pirsson, Belknap Mts., =20=, 344–353, 1905; =22=,
         439–457, 493–515, 1906.
      ——, Red Hill, =23=, 257–276, 433–447, 1907.
      ——, Tripyramid Mt., =31=, 405–431, 1911.

Footnote 131:

  Quantitative Classification of Igneous Rocks, Cross, Iddings, Pirsson
  and Washington, Chicago, 1903.

  Petrogenesis, C. Doelter, Braunschweig, 1906.

  Igneous Rocks, vols. =1= and =2=, J. P. Iddings, New York, 1909 and
  1913.

  Problem of Volcanism, Iddings, New Haven, 1914.

  Natural History of Igneous Rocks, Alfred Harker, London, 1909.

  Igneous Rocks and their Origin, R. A. Daly, New York, 1914.

Footnote 132:

  Among these may be mentioned:

      Rosenbusch u. Wülfing, Physiog. der petrog. wicht. Min.,
         Stuttgart, 1905.
      Iddings, J. P., Rock-Minerals, 1st ed., New York, 1906.
      Johannsen, A., Manual of Petrographic Methods, New York, 1914.
      Winchell, N. H. and A. N., Elements of Optical Mineralogy, New
         York, 1909.

Footnote 133:

  We may mention here, for example, the work in mineralogy of Penfield,
  noticed in the accompanying chapter on mineralogy. In addition to the
  accurate determination of the composition and constants of many
  minerals, some of which have importance from the petrographic
  standpoint, we owe to him more than anyone the recognition of fluorine
  and hydroxyl in a variety of species, and thereby the perception of
  their pneumatolytic origin. His papers have been published almost
  entirely in the Journal.

Footnote 134:

  Wright, Methods of Petrographic-Microscopic Research, Carnegie Inst.,
  Washington, 1911, and various papers; many in the Journal.

Footnote 135:

  Conf. Wright’s work quoted above and the various manuals previously
  mentioned.

Footnote 136:

  Kemp, Hand-book of Rocks, 3d ed., New York, 1904. Pirsson, Rocks and
  Rock-Minerals, New York, 1910.

Footnote 137:

  Williams, G. H., U. S. Geol. Surv., Bull. =62=, Washington, 1890.

Footnote 138:

  Van Hise, Treatise on Metamorphism, U. S. Geol. Surv., Monograph =17=.

Footnote 139:

  F. W. Clarke, U. S. Geol. Surv., Bull. =591=, 1915.

Footnote 140:

  Hillebrand, Analysis of Silicate and Carbonate Rocks, U. S. Geol.
  Surv., Bull. =422=, 1910.

Footnote 141:

  Washington, Chemical Analysis of Rocks, pp. 200, New York, 1910.

Footnote 142:

  Id., Chemical Analyses of Igneous Rocks (1884–1900), U. S. Geol.
  Surv., Prof. Paper, No. =14=, 1903.

Footnote 143:

  Osann, Beitr. zu chem. Petrogr., II Teil. Anal. d. Eruptivgest.,
  1884–1900, Stuttgart, 1905.

Footnote 144:

  Washington, ibid., 2d ed., U. S. Geol. Surv., Prof. Paper =99=, pp.
  1216, 1917.

Footnote 145:

  Clarke, U. S. Geol. Surv., Bull. =616=, 1916.

Footnote 146:

  Fouqué and Michel-Lévy, Synthese des Mineraux et des Roches, Paris,
  1882.

Footnote 147:

  Morozewicz, Exper. Untersuch. u. Bildung der Min. im Magma, Min. petr.
  Mitt., =18=, 1898.

Footnote 148:

  Doelter, Synthetische Studien, N. Jahrb. Min. 1897, =1=, 1–26. Allg.
  chem. Mineralogie, etc.

Footnote 149:

  Tamman, Krystallisieren und Schmelzen, 1903.

Footnote 150:

  St. Meunier, Les Méthodes de Synthèse en Minéralogie, Paris, 1891.

Footnote 151:

  Vogt, Mineralbildung in Smelzmassen, Christiania, 1892;
  Silikatschmelzlösungen, =1= and =2=, 1903, 1904, and various other
  papers, esp. in Min. petr. Mitt., vols. =24= and =25=, 1906.

Footnote 152:

  H. E. Boeke, Grundlagen der physikalisch-chemischen Petrographie,
  Berlin, 1915.




                                  VIII
               THE GROWTH OF MINERALOGY FROM 1818 TO 1918

                           By WILLIAM E. FORD


 Mineralogy to-day would certainly be generally considered one of the
minor members of the group of the Geological Sciences. We commonly look
upon it in the light of an useful handmaiden, whose chief function is to
serve the other branches, and we are inclined to forget that, in
reality, mineralogy was the first to be recognized and, with
considerable truth, might be claimed as the mother of all the others.
Minerals, because of their frequent beauty of color and form, and their
uses as gems and as ornamental stones, were the first inorganic objects
to excite wonder and comment and we find many of them named and
described in very early writings. Theophrastus (368–284 B. C.), a famous
pupil of Aristotle, wrote a treatise “On Stones” in which he collected a
large amount of information about minerals and fossils. The elder Pliny
(23–79 A. D.), more than three centuries later, in his Natural History,
described and named many of the commoner minerals. At this time it was
natural that no clear distinction should be drawn between minerals and
rocks, or even between minerals and fossils. As long as all study of the
materials of the earth’s crust was concerned with their superficial
characters, it was logical to include everything under the single head.
There were some writers in the early centuries of the Christian era,
however, who believed that fossils had been derived from living animals
but the majority considered them to be only strange and unusual forms of
minerals. During many succeeding centuries little was added to the
general store of geological knowledge and it was not until the beginning
of the sixteenth century, that any further notable progress was made.
Agricola (1494–1555) was a physician, who, for a time, lived in the
mining district of Joachimstal. He studied and described the minerals
that he collected there. He was the first to give careful and critical
descriptions of minerals, of their crystals and general physical
properties. Unfortunately, he also did not realize the fundamental
distinction between fossils and minerals, and probably because of his
influence this error persisted, even until the middle of the eighteenth
century. But, naturally, as the number of scientific students increased,
the number of those who rejected this conclusion grew, until at last,
the true character of fossils was established. The keen interest in
minerals and fossils which was aroused by this controversy, together
with the rapid extension of mining operations, drew the attention of
scientific men to other features of the earth’s surface and led to a
more extended investigation of its characters and thus to the
development of geology proper. It is interesting to note also that
mineralogy was the first of the Geological Sciences to be officially
recognized and taught by the universities.

Although, as has been shown, the beginnings of mineralogy lie in the
remote past, the science, as we know it to-day, can be said to have had
practically its whole growth during the last one hundred years. Of the
more than one thousand mineral species that may now be considered as
definitely established hardly more than two hundred were known in the
year 1800 and these were only partially described or understood. It is
true that Haüy, the “father of crystallography,” had before this date
discovered and formulated the laws of crystal symmetry, and had shown
that rational relations existed between the intercepts upon the axes of
the different faces of a crystal. It was not until 1809, however, that
Wollaston described the first form of a reflecting goniometer, and thus
made possible the beginning of exact investigation of crystals. The
distinctions between the different crystal groups were developed by
Bernhardi, Weiss and Mohs between the years 1807 and 1820, while the
Naumann system of crystal symbols was not proposed until 1826. The fact
that doubly refracting minerals also polarize light was discovered by
Malus in 1808, and in 1813 Brewster first recognized the optical
differences between uniaxial and biaxial minerals. The modern science of
chemistry was also just beginning to develop at this period, enabling
mineralogists to make analyses more and more accurately and thus by
chemical means to establish the true character of minerals, and to
properly classify them.

Franz von Kobell, on page 372 of his “Geschichte der Mineralogie,”
somewhat poetically describes the condition of the science at this
period as follows: “With the end of the eighteenth and the commencement
of the nineteenth centuries exact investigations in mineralogy first
began. The mineralogist was no longer content with approximate
descriptions of minerals, but strove rather to separate the essential
facts from those that were accidental, to discover definite laws, and to
learn the relations between the physical and chemical characters of a
mineral. The use of mathematics gave a new aspect to crystallography,
and the development of the optical relationships opened a magnificent
field of wonderful phenomena which can be described as a garden gay with
flowers of light, charming in themselves and interesting in their
relations to the forces which guide and govern the regular structure of
matter.”

In the Medical Repository (vol. =2=, p. 114, New York, 1799), there
occurs the following notice: “Since the publication of the last number
of the Repository an Association has been formed in the city of New York
‘for the investigation of the Mineral and Fossil bodies which compose
the fabric of the Globe; and, more especially, for the Natural and
Chemical History of the Minerals and Fossils of the United States,’ by
the name and style of The American Mineralogical Society.” With this
announcement is given an advertisement in which the society “earnestly
solicits the citizens of the United States to communicate to them, on
all mineralogical subjects, but especially on the following: 1,
concerning stones suitable for gun flints; 2, concerning native
brimstone or sulphur; 3, concerning salt-petre; 4, concerning mines and
ores of lead.” Further the society asks “that specimens of all kinds be
sent to it for examination and determination.”

This marks apparently the beginning of the serious study of the science
of mineralogy in the United States. From this time on, articles on
mineralogical topics appeared with increasing frequency in the Medical
Repository. Most of these were brief and were largely concerned with the
description of the general characters and modes of occurrence of various
minerals. Nothing of much moment from the scientific point of view
appeared until many years later, but the growing interest in things
mineralogical was clearly manifest. An important stimulus to this
increasing knowledge and discussion was furnished by Col. George Gibbs
who, about the year 1808, brought to this country a large and notable
mineral collection. In the Medical Repository (vol. 11, p. 213, 1808),
is found a notice of this collection, a portion of which is reproduced
below:


                 “Gibbs’ grand Collection of Minerals.

  One of the most zealous cultivators of mineralogy in the United States
  is Col. G. Gibbs of Rhode Island and his taste and his fortune have
  concurred in making him the proprietor of the most extensive and
  valuable assortment of minerals that probably exists in America.

  This rich collection consists of the cabinets possessed by the late
  Mons. Gigot D’Orcy of Paris and the Count Gregoire de Rozamonsky, a
  Russian nobleman, long resident in Switzerland. To which the present
  proprietor has added a number, either gathered by himself on the spot,
  or purchased in different parts of Europe.... The whole consists of
  about twenty thousand specimens. A small part of this collection was
  opened to amateurs at Rhode Island, the last summer, and the next, if
  circumstances permit, the remainder will be exposed.”


In 1802 Benjamin Silliman was appointed professor of chemistry and
mineralogy in Yale College. After the Gibbs Collection was brought to
America he spent much time with the owner in studying it and, as a
result, Col. Gibbs offered to place the collection on exhibition in New
Haven if suitable quarters would be furnished by the college. This was
quickly accomplished and in 1810, 1811 and 1812 the collection was
transferred to New Haven and arranged for exhibition by Col. Gibbs.
Later, in 1825, it was purchased by Yale and served as the nucleus about
which the present Museum collection of the University has been formed.
There is no doubt but that the presence at this early date of this large
and unusual mineral collection had a great influence upon the
development of mineralogical science at Yale, and in the country at
large.

In the year 1810 Dr. Archibald Bruce started the “American Mineralogical
Journal,” the title page of which reads in part as follows: “The
American Mineralogical Journal, being a Collection of Facts and
Observations tending to elucidate the Mineralogy and Geology of the
United States of America, together with other Information relating to
Mineralogy, Geology and Chemistry, derived from Scientific Sources.”
Unfortunately the health of Dr. Bruce failed, and the journal lasted
only through its first volume. It had, however, “been most favorably
received,” as Silliman remarks, and it was felt that another journal of
a similar type should be instituted. Such a suggestion was made by Col.
Gibbs to Professor Silliman in 1817 and this led directly to the
founding of the American Journal of Science in 1818 under the latter’s
editorship. Although the field of the Journal at the very beginning was
made broad and inclusive it has always published many articles on
mineralogical subjects. Three of its editors-in-chief have been eminent
mineralogists, and without question it has been the most important
single force in the development of this science in the country. More
than 800 well-established mineral species have been described since the
year 1800, of which approximately 150 have been from American sources.
More than two-thirds of the articles describing these new American
minerals have first appeared in the pages of the Journal. While the
description of new species is not always the most important part of
mineralogical investigation, still these figures serve to show the large
part that the Journal has played in the growth of American mineralogy.

It is convenient to review the progress in Mineralogy according to the
divisions formed by the different series, consisting of fifty volumes
each, in which the Journal has been published. These divisions curiously
enough will be found to correspond closely to four quite definite phases
through which mineralogical investigation in America has passed. The
first series covered the years from 1817 to 1845. In looking through
these volumes one finds a large number of mineralogical articles, the
work of many contributors. The great majority of these papers are purely
descriptive in character, frequently giving only general accounts of the
mineral occurrences of particular regions. However, a number of articles
dealing with more detailed physical and chemical descriptions of rare or
new species also belong in this period. Among the mineralogists engaged
at this time in the description of individual species, none was more
indefatigable than Charles U. Shepard. He was graduated from Amherst
College in 1824, at the age of twenty. In 1827 he became assistant to
Professor Silliman in New Haven, continuing in this position for four
years. Later he was a lecturer in natural history at Yale, and was at
various times connected with Amherst College and the South Carolina
Medical College at Charleston. His articles on mineralogy were very
numerous. He assigned a large number of new names to minerals, although
with the exception of some half dozen cases, these have later been shown
to be varieties of minerals already known and described, rather than new
species. In spite, however, of his frequent hasty and inaccurate
decision as to the character of a mineral, his influence on the progress
of mineralogy was marked. His great enthusiasm and ceaseless industry
throughout a long life could not help but make a definite contribution
to the science. His “Treatise on Mineralogy” will be spoken of in a
later paragraph. He died in May, 1886, having published his last paper
in the Journal in the previous September.

The first book on mineralogy published in America was that by Parker
Cleaveland, professor of mathematics, natural philosophy, chemistry and
mineralogy in Bowdoin College. The first edition was printed in 1816 and
an exhaustive notice is given in the first volume of the Journal (1, 35,
308, 1818); a second edition followed in 1822. In his preface Cleaveland
gives an interesting discussion concerning the two opposing European
methods of classifying minerals. The German school, led by Werner,
classified minerals according to their external characters while the
French school, following Haüy, put the emphasis on the “true
composition.” Cleaveland remarks that “the German school seems to be
most distinguished by a technical and minutely descriptive language; and
the French, by the use of accurate and scientific principles in the
classification or arrangement of minerals.” He, himself, tried to
combine in a measure the two methods, basing the fundamental divisions
upon the chemical composition and using the accurate description of the
physical properties to distinguish similar species and varieties from
each other.

Cleaveland’s mineralogy was followed nearly twenty years later by the
Treatise on Mineralogy by Charles U. Shepard already mentioned. The
first part of this book was published in 1832. This contained chiefly an
account of the natural history classification of minerals according to
the general plan adopted by Mohs, the Austrian mineralogist. The second
part of the book, which appeared in 1835, gave the description of
individual species, the arrangement here being an alphabetical one
throughout. Subsequent editions appeared in 1844, 1852 and 1857.

James Dwight Dana was graduated from Yale College in 1833 at the age of
twenty. Four years later (1837) he published “The System of Mineralogy,”
a volume of 580 pages. The appearance of this book was an event of
surpassing importance in the development of the science. The book, of
course, depended largely upon the previous works of Haüy, Mohs, Naumann
and other European mineralogists, but was in no sense merely a
compilation from them. Dana, particularly in his discussion of
mathematical crystallography, showed much original thought. He also
proved his originality by proposing and using an elaborate system of
classification patterned after those already in use in the sciences of
botany and zoology. He later became convinced of the undesirability of
this method of classification and abandoned it entirely in the fourth
edition of the System, published in 1854, substituting for it the
chemical classification which, in its essential features, is in general
use to-day. The System of Mineralogy started in this way in 1837, has
continued by means of successive editions to be the standard reference
book in the subject. The various editions appeared as follows: I, 1837;
II, 1844; III, 1850; IV, 1854; V, 1868; VI, 1892 (by Edward S. Dana).

J. D. Dana also contributed numerous mineralogical articles to the first
series of volumes of the Journal. It is interesting to note that they
are chiefly concerned with the more theoretical aspects of the subject,
in fact they constitute practically the only articles of such a
character that appeared during this period. Among the subjects treated
were crystallographic symbols, formation of twin crystals;
pseudomorphism, origin of minerals in metamorphosed limestones, origin
of serpentine, classification of minerals, etc.

The volumes of the Second Series of the Journal covered the years from
1846 through 1870. This period was characterized by great activity in
the study of the chemical composition of minerals. A number of skilled
chemists, notably J. Lawrence Smith, George J. Brush and Frederick A.
Genth, began about 1850 a long series of chemical investigations of
American minerals. Very few articles during this time paid much
attention to the physical properties of the minerals under discussion,
practically no description of optical characters was attempted, and only
occasionally were the crystals of a mineral mentioned. J. D. Dana was
almost the only writer who constantly endeavored to discover the
fundamental characters and relationships in minerals. He published many
articles in these years which were concerned chiefly with the
classification and grouping of minerals, with similarities in the
crystal forms of different species, with relations between chemical
composition and crystal form, chemical formulas, mineral nomenclature,
etc. The following titles give an idea of the character of the more
important series of articles by him which belong to this category: On
the isomorphism and atomic volume of some minerals (=9=, 220, 1850);
various notes and articles on homœomorphism of minerals (=17=, 85, 86,
210, 430; =18=, 35, 131, 1854); on a connection between crystalline form
and chemical constitution, with some inferences therefrom (=44=, 89,
252, 398, 1867).

A great many new mineral names were proposed between 1850 and 1870, a
large number of which have continued to be well-recognized species. But
there was also a tendency, which has not wholly disappeared even now, to
base a mineral determination upon insufficient evidence, and to propose
a new species with but little justification for it. In this connection a
quotation from the introduction by J. D. Dana to the 3rd Supplement to
the System of Mineralogy (4th edition) published in the Journal (=22=,
page 246, 1856), will be of interest. He says:


  “It is a matter of regret, that mineral species are so often brought
  out, especially in this country, without sufficient investigation and
  full description. It is not meeting the just demands of the science of
  mineralogy to say that a mineral has probably certain constituents, or
  to state the composition in a general way without a complete and
  detailed analysis, especially when there are no crystallographic
  characters to afford the species a good foundation. We have a right to
  demand that those who name species, should use all the means the
  science of the age admits of, to prove that the species is one that
  nature will own, for only such belong to science, and if enough of the
  material has not been found for a good description there is not enough
  to authorize the introduction of a new name in the science. The
  publication of factitious species, in whatever department of science,
  is progress not towards truth, but into regions of error; and often
  much and long labor is required before the science recovers from these
  backward steps.”


J. Lawrence Smith was born in 1818 and died in 1883. He was a graduate
of the University of Virginia and of the Medical College of Charleston
and later spent three years studying in Paris. Shortly after the
completion of his studies he went to Turkey as an advisor to the
government of that country in connection with the growing of cotton
there. During this time he investigated the emery mines of Asia Minor,
and wrote a memoir upon them which was later published by the French
Academy. He served as professor of chemistry in the University of
Virginia and later held the same chair in the University of Illinois. He
published a long series of papers on the chemical composition of
minerals and meteorites, as well as on pure chemical subjects. Among the
more notable of his contributions are the “Memoir on Emery” (1850), a
series of papers on the “Reëxamination of American Minerals” (1853)
written with the collaboration of George J. Brush, and his “Memoir on
Meteorites” (1855).

[Illustration: Ge. J. Brush]

George J. Brush entered on his scientific career at the moment when
science and scientific methods of research were just beginning to be
appreciated in this country, and he soon became one of the leading
pioneers in the movement. While his half century of active service was
largely occupied by administrative duties in connection with the
Sheffield Scientific School, his interest in mineralogy never flagged.
His papers on mineralogical subjects number about thirty, all of which
were published in the Journal. These began in 1849, even before his
graduation from college, and continued until his last paper (in
collaboration with S. L. Penfield) appeared in 1883. Three of the early
papers were written with J. Lawrence Smith as noted above. These papers
first set in this country the standard for thorough and accurate
scientific mineral investigation. Later in life he was active in the
development of the remarkable mineral locality at Branchville, Conn.,
and, with the collaboration of E. S. Dana, published in the Journal
(1878–90) five important articles on its minerals. This locality, with
the exception of the zinc deposits at Franklin Furnace, N. J., was the
most remarkable yet discovered in this country. Nearly forty different
mineral species were found there, of which nine (mostly phosphates) were
new to science. There has certainly been no other series of descriptive
papers on a mineralogical locality of equal importance published in this
country.

In addition to publishing original papers, Brush did considerable
editorial work in connection with the fourth (1854) and fifth (1868)
editions of the System of Mineralogy and the Appendices to them. His
Manual of Determinative Mineralogy, with a series of determinative
tables adapted from similar ones by von Kobell, was first published in
1874. It was revised in 1878 and later rewritten by S. L. Penfield. This
book did much to make possible the rapid and accurate determination of
mineral species. Throughout his life, Brush was an enthusiastic
collector of minerals, building up the notable collection that now bears
his name. Perhaps, however, his most important contribution to the
development of mineralogy in America lay rather in his influence upon
his many students. With his enthusiasm for accurate and painstaking
investigation he was an inspiration to all who came in contact with him
and his own field and science in general owes much to that influence.

Among the early mineralogists in this country, who were concerned in the
chemical analyses of minerals, none accomplished more or better work
than Frederick A. Genth. He was born in Germany in 1820 and lived in
that country until 1848, when he came to the United States and settled
in Philadelphia. He had studied in various German universities and
worked under some of the most famous chemists of that time. His papers
in mineralogy number more than seventy-five, in the great majority of
which chemical analyses are given. He published fifty-four successive
articles, the greater part of which appeared in the Journal, which were
entitled Contributions to Mineralogy. In these he gave descriptions of
more than two hundred different minerals, most of which were accompanied
by analyses. He described more than a dozen new and well-established
mineral species. He was especially interested in the rarer elements and
many of his analyses were of minerals containing them. Especially
interesting was his work with the tellurides, the species coloradoite,
melonite and calaverite being first described by him. A long and
important investigation was recorded on Corundum, “Its Alterations and
Associate Minerals,” published in the Proceedings of the American
Philosophical Society in 1873 (=13=, 361). Dr. Genth died in 1893.

The period from 1860 until 1875 was not very productive in mineralogical
investigations. The first ten volumes of the Third Series of the
Journal, covering the years 1871–1876, contained mineralogical articles
by only some fifteen different authors. But from that time on, the
amount of work done and the number of investigators grew rapidly. With
this increase in activity came also a decided change in the character of
the work. The period between 1871 and 1895 can be characterized as one
in which all the various aspects of mineral investigation received more
nearly equal prominence. While the chemical composition of minerals
still held rightly its prominent place, the investigation of the
crystallographic and optical characters and the relationships existing
between all three were of much more frequent occurrence. Edward S. Dana
commenced his scientific work by publishing in 1872 an article on the
crystals of datolite which was probably the first American article
concerned wholly with the description of the crystallography of a
mineral. Samuel L. Penfield began his important investigations in 1877
and the first articles by Frank W. Clarke appeared during this period.
The first edition of the Text Book of Mineralogy by Edward S. Dana with
its important chapters on Crystallography and Optical Mineralogy was
published in 1877 and his revision of the System of Mineralogy (sixth
edition) appeared in 1892.

Unquestionably the foremost figure in American mineralogy during this
period was that of Samuel L. Penfield. He embodied in an unusual degree
the characters making for success in this science, for few investigators
in mineralogy have shown, as he did, equal facility in all branches of
descriptive mineralogy. He was a skilled chemist and possessed in a high
degree that ingenuity in manipulation so necessary to a great analyst.
He was also an accurate and resourceful crystallographer and optical
mineralogist. His contributions to the science of mineralogy can be
partially judged by the following brief summary of his work. He
published over eighty mineralogical papers, practically all of which
were printed in the Journal. These included the descriptions of fourteen
new mineral species, the establishment of the chemical composition of
more than twenty others, and the crystallization of about a dozen more.
By a series of brilliant investigations he established the isomorphism
between fluorine and the hydroxyl radical. He first enunciated the
theory that the crystalline form of a mineral was due to the mass effect
of the acid present rather than that of the bases. He contributed also a
number of articles on the stereographic projection and its use in
crystallographic investigations, devising a series of protractors and
scales to make possible the rapid and accurate use of this projection in
solving problems in crystallography.

Penfield was born in 1856, was graduated from the Sheffield Scientific
School in 1877 and immediately became an assistant in the chemical
laboratory of that institution. At this time he, together with his
colleague Horace L. Wells, made the analyses of the minerals from the
newly discovered Branchville locality. He spent the years 1880 and 1881
in studying chemistry in Germany, returning to Yale as an instructor in
mineralogy in the fall of 1881. Except for another semester in Europe at
Heidelberg he continued as instructor and professor of mineralogy in the
Sheffield Scientific School until his early death in 1906.

It is difficult to choose for mention the names of other investigators
in Mineralogy during this period. Toward its end a great many writers
contributed to the pages of the Journal, more than fifty different names
being counted for the volumes =41= to =50= of the Third Series. Many of
these are still living and still active in scientific research. Mention
should be made of Frank W. Clarke, who contributed many important
articles concerning the chemical constitution of the silicates. His work
on the mica and zeolite groups is especially noteworthy. The work of W.
H. Hillebrand, particularly in regard to his analytical investigations
of the minerals containing the rarer elements, was of great importance.
The name of W. E. Hidden should be remembered, because, with his keen
and discriminating eye and active search for new mineral localities, he
was able to make many additions to the science.

In glancing over the indices to the Journal the close interrelation of
mineralogy to the other sciences is strikingly shown by the fact that so
many scientists whose particular fields are along other lines have
published occasional mineralogical papers. Frequently a young man has
commenced with mineralogical investigations and then later been drawn
definitely into one of these allied subjects. Men, who have won their
reputation in chemistry, physics, and all the various divisions of
geology, even that of palaeontology, have all contributed articles
distinctly mineralogical in character. For this reason the number of
American writers who have published what may be called casual papers on
mineralogy is very great in comparison to the number of those who
continue such publications over a series of years.

That the subject of meteorites is one which has been constantly studied
by American mineralogists and petrographers is shown by the long list of
papers concerning it that have been published in the Journal; it should,
therefore, be considered briefly here. Many of these papers are short
and of a general descriptive nature but others which give more fully the
chemical, mineralogical and physical details are numerous. Among the
earlier writers on this subject Benjamin Silliman, Jr., and C. U.
Shepard should be mentioned. The latter was the first to recognize a new
mineral in the Bishopville meteorite which he called chladnite. The same
substance was afterwards found in a terrestial occurrence and was more
accurately described by Kenngott under the name of enstatite. J.
Lawrence Smith later showed that these two substances were identical.
Smith did a large amount of important chemical work on meteorites. He
was the first to note the presence of ferrous chloride in meteoric iron,
the mineral being afterwards named lawrencite in his honor. The
iron-chronium sulphide, daubreelite, was also first described by him.
Other names that should be mentioned in this connection are those of A.
W. Wright who studied the gaseous constituents of meteorites, G. F.
Kunz, W. E. Hidden, A. E. Foote and H. A. Ward, all of whom published
numerous descriptions of these bodies. Among the more recent workers in
this field the names of G. P. Merrill and O. C. Farrington deserve
especial mention.

The publication of the Fourth Series of the Journal began in 1896.
Although the years since then have seen a great amount of very important
work accomplished, the history of the period is fresh in the minds of
all and as the majority of the active workers are still living and
productive it seems hardly necessary to go into great detail concerning
it. Twenty years ago it seemed to some mineralogists that the science
could almost be considered complete. All the commoner minerals had
certainly been discovered and exhaustively studied. Little apparently
was left that could be added to our knowledge of them. New occurrences
would still be recorded, new crystal habits would be observed, and an
occasional new and small crystal face might be listed, but few facts of
great importance seemed undiscovered. This view was not wholly justified
because new facts of interest and importance have continuously been
brought forward, and the finding of new minerals does not appear to
diminish in amount with the years. The work of the investigators on the
United States Geological Survey along these lines is especially
noteworthy.

This last of our periods, however, is chiefly signalized by a
practically new development along the lines that might be characterized
as experimental mineralogy. New ways have been discovered in which to
study minerals. The important but hitherto baffling problems of their
genesis, together with their relations to their surroundings, and to
associated minerals, have been attacked by novel methods.

In this pioneer work that of the Geophysical Laboratory of the Carnegie
Institution of Washington has been of the greatest importance. This
laboratory was established in 1905 and, under the directorship of Arthur
L. Day, a notable corps of investigators has been assembled and
remarkable work already accomplished. While the field of investigation
of the laboratory is broader than that of mineralogy, including much
that belongs to petrography, vulcanology, etc., still the greater part
of the work done can be properly classed as mineralogical in character
and should be considered here. Because of its great value, however, it
was felt that an authoritative, although necessarily, under existing
conditions, a brief, account of it should be given. A concise summary of
the objects, methods and results of the investigations of the laboratory
has been kindly prepared by a member of its staff, Dr. R. B. Sosman, and
is given later.

During the last few years another line of investigation has been opened
by the discovery of the effect of crystalline structure upon X-rays.
Through the refraction or reflection of the X-ray by means of the
ordered arrangement of the particles forming the crystalline network, we
are apparently going to be able to discover much concerning the internal
structure of crystals. And, partly through these discoveries, is likely
to come in turn the solution of the hitherto insolvable mystery of the
constitution of matter. Without doubt the multitudinous facts of
mineralogy assembled during the past century by the painstaking
investigation of a large number of scientists are destined to play a
large part in the solution of this problem. Further, it does not seem
too bold a prophecy to suggest, that the time will come when it will be
possible to assemble all these unorganized facts that we know about
minerals into a harmonious whole and that we shall be then able to
formulate the underlying and fundamental principles upon which they all
depend. These are the great problems for the future of mineralogical
investigation.




                                   IX
 THE WORK OF THE GEOPHYSICAL LABORATORY OF THE CARNEGIE INSTITUTION OF
                               WASHINGTON

                            By R. B. SOSMAN


 There are three methods of approach to the great problem of rock
formation. The first undertakes to reproduce by suitable laboratory
experiments some of the observed changes in natural rocks. The second
seeks to apply the principles of physical chemistry to a great body of
carefully gathered statistics. The third method of attack is like the
first in being a laboratory method, and like the second in seeking to
apply existing knowledge to the association of minerals as found in
rocks, but in its procedure differs widely from both. It consists of
bringing together pure materials under measurable conditions, and thus
in establishing by strictly quantitative methods the relations in which
minerals can exist together under the conditions of temperature and
pressure that have the power to affect such relations.

It is to this third method of investigation of the problems of the rocks
that the Geophysical Laboratory has been devoted since its establishment
in 1905. It has proved entirely practicable to make quantitative studies
of the relations among the principal earth-forming oxides (silica,
alumina, magnesia, lime, soda, potash, and the oxides of iron) over a
very wide range of temperatures. The resources of physics have proved
adequate to establish temperature with a high degree of precision and to
measure the quantity of energy involved in the various reactions. The
chemist has been able to obtain materials in a high degree of purity,
and to follow out in detail the chemical relationships that exist among
the earth-forming oxides. The petrographic laboratory has been available
for the comparison of synthetic laboratory products with the
corresponding natural minerals.

It has also proved entirely practicable to extend the same methods of
research to some of the principal ore minerals such as the sulphides of
copper. Other information which is certain to be of ultimate economic
value has also come out of the thorough study of the silicates, which
are basic materials for the vast variety of industries which are classed
under the name of ceramic industries. The best example of this is the
facility with which the experience and the personnel of the laboratory
has been adapted to the very important problem of manufacturing an
adequate supply of optical glass for the needs of the United States in
the present war.

It has further been possible to show within the last two years that rock
formation in which volatile ingredients play a necessary and determining
part can be completely studied in the laboratory with as much precision
as though all the components were solids or liquids.

Along with the laboratory work on the formation of minerals and rocks
has gone an increasing amount of field work on the activities of
accessible volcanoes, such as Kilauea and Vesuvius, where the fusion and
recrystallization of rocks on a large scale can be observed and studied.

There was once a time when the confidence of the laboratory in the
capacity of physics and chemistry to solve geological problems was not
shared by all geologists. There were some who were inclined to view with
considerable apprehension the vast ramifications and complications of
natural rock formation as a problem impossible of adequate solution in
the laboratory. It is, therefore, a matter of satisfaction to all those
who have participated in these efforts to see the evidences of this
apprehension disappearing gradually as the work has progressed. A
careful appraisement of the situation to-day, after ten years of
activity, reveals the fact that the tangible grounds for anxiety about
the _accessibility_ of the problems which were confronted at first are
now for the most part dissipated.

It will not be possible to review in detail the lines of work sketched
above. An outline of the synthetic work on systems of the mineral oxides
and a paragraph on the volcano researches will perhaps suffice to
indicate the general plan and purpose of the laboratory’s work. It
should be added that the results of many of the researches of the
laboratory, detailed below, have been published in the pages of the
Journal (see =21=, 89, 1906, and later volumes).

_Mineral Researches._—The mineral studies include:

I. _One-component systems_: silica, with its numerous polymorphic forms
and their relations to temperature and the conditions of rock formation;
alumina; magnesia; and lime.

II. _Two-component systems_: silica-alumina, including sillimanite and
related minerals; silica-magnesia, including the tetramorphic
metasilicate MgSiO_{3}; silica-lime, including wollastonite; the alkali
silicates, particularly with reference to their equilibria with carbon
dioxide and with water; ferric oxide-lime; alumina-lime;
alumina-magnesia, including spinel; and hematite-magnetite, a
solid-solution series of an unusual type.

III. _Three-component systems_: silica-alumina-magnesia, completed but
not yet published; silica-alumina-lime, complete, including the
compounds that enter into the composition of portland cement;
silica-magnesia-lime, completed but not yet published, including,
however, published work on the diopside-forsterite-silica system, and on
the CaSiO_{3}-MgSiO_{3} series; and alumina-magnesia-lime.

IV. _Four components_: SiO_{2}-Al_{2}O_{3}-MgO-CaO: the incomplete
system anorthite-forsterite-silica; SiO_{2}-Al_{2}O_{3}-CaO-Na_{2}O: the
series of lime-soda feldspars (albite-anorthite), and the series
nephelite (carnegieite)-anorthite; SiO_{2}-Al_{2}O_{3}-Na_{2}O-K_{2}O:
the sodium-potassium nephelites.

V. _Five components_: SiO_{2}-Al_{2}O_{3}-MgO-CaO-Na_{2}O: the ternary
system diopside-anorthite-albite (haplo-basaltic and haplo-dioritic
magmas).

Fairly complete studies have also been made of the mineral sulphides of
iron, copper, zinc, cadmium, and mercury, and the conditions controlling
the secondary enrichment of copper sulphide ores are now being
investigated. In connection with the sulphide investigations, the
hydrated oxides of iron have been studied chemically and microscopically
and the results will soon be ready for publication.

Throughout the work the mere accumulation of bodies of facts has been
held to be secondary in importance to the development of new methods of
attack and the evaluation of new general principles, and the specific
problems studied have been selected from this point of view.

_Volcano Researches._—A branch of the laboratory’s work that is of
general as well as petrological interest is the study of active
volcanoes. Observations and collections have been made at Kilauea,
Vesuvius, Etna, Stromboli, Vulcano, and (through the courtesy of the
directors of the National Geographic Society) Katmai in Alaska. The
great importance of gases in volcanicity is emphasized by all the
studies. The active gases include hydrogen and water vapor, carbon
monoxide and carbon dioxide, and sulphur and its oxides, as well as a
variety of other compounds of lesser importance. The crater of Kilauea
proves to be an active natural gas-furnace, in which reactions are
continuously occurring among the gases, often resulting in making the
lava basin hotter at the surface than it is at some depth. These
reactions are being studied in the laboratory on mixtures of the pure
constituent gases in known proportions, in order to lay the foundation
for accurate interpretation and prediction concerning the gases as
actually collected from the volcanoes themselves.




                                   X
      THE PROGRESS OF CHEMISTRY DURING THE PAST ONE HUNDRED YEARS

                 By HORACE L. WELLS and HARRY W. FOOTE


                            _Introduction._

As we look back to the time of the founding of the Journal in 1818, we
see that the science of chemistry had recently made and was then making
great advances. That the scientific men of those days were much
impressed with what was being accomplished is well shown by the
following statement made in an early number of the Journal (=3=, 330,
1821) by its founder in reviewing Gorham’s Elements of Chemical Science.
He says: “The present period is distinguished by wonderful mental
activity; it might indeed be denominated as the intellectual age of the
world. At no former period has the mind of man been directed at one time
to so many and so useful researches.”

A very remarkable revolution in chemical ideas had recently taken place.
Soon after the discovery of oxygen by Priestley in 1774, and the
subsequent discovery by Cavendish that water was formed by the
combustion of hydrogen and oxygen, Lavoisier had explained combustion in
general as oxidation, thus overthrowing the curious old phlogiston
theory which had prevailed as the basis of chemical philosophy for
nearly a century.

The era of modern chemistry had thus begun, and the additional views
that matter was indestructible and that chemical compounds were of
constant composition had been generally accepted at the beginning of the
nineteenth century.

Dalton had announced his atomic theory in 1802, having based it largely
upon the law of multiple proportions which he had previously discovered,
and he had begun to express the formulas for compounds in terms of
atomic symbols.

In 1808 Gay-Lussac had discovered his law of gas combination in simple
proportions,[153] a law of supreme importance in connection with the
atomic theory, but neither he nor Dalton had seen this theoretical
connection. Avogadro had understood it, however, and in 1811 had reached
the momentous conclusion that all gases and vapors have equal numbers of
molecules in equal volumes at the same temperature and pressure.

Davy in 1807 had isolated the alkali-metals, sodium and potassium, by
means of electrolysis, thus practically dispelling the view that certain
earthy substances might be elementary; and about four years later he had
demonstrated that chlorine was an element, not an oxide as had been
supposed previously, thus overthrowing Lavoisier’s view that oxygen was
the characteristic constituent of all acids.

At the time that our period of history begins, the atomic theory had
been accepted generally, but in a somewhat indefinite form, since little
attention had been paid to Avogadro’s principle, and since Dalton had
used only the principle of greatest simplicity in writing the formulas
of compounds, considering water as HO and ammonia NH, for example. At
this time, however, Berzelius for ten or fifteen years had been devoting
tremendous energy to the task of determining the atomic weights of
nearly all of the elements then known by analyzing their compounds. He
had confirmed the law of multiple proportions, accepted the atomic
theory, and utilized Avogadro’s principle, and it is an interesting
coincidence that his first table of atomic weights was published in the
year 1818.

An interesting account of the views on chemistry held at about that time
was published in the Journal by Denison Olmsted (=11=, 349, 1826; =12=,
1, 1827), who had recently become professor of natural philosophy in
Yale College.

The most illustrious European chemists of that time were Berzelius of
Sweden, Davy of England, and Gay-Lussac of France, and the curious
circumstance may be mentioned that all three of them and also Benjamin
Silliman, the founder of the Journal, were born within a period of eight
months in 1778–1779.

In this country Robert Hare of Philadelphia and Benjamin Silliman were
undoubtedly the most prominent chemists of those days. Hare is best
known for his invention of the compound blowpipe, but his contributions
to the Journal were very numerous, beginning almost with the first
volume and continuing for over thirty years. Among the first of these
contributions was a most vigorous but well-merited attack upon a Doctor
Clark of Cambridge, England, who had copied his invention without giving
him proper credit. He begins (=2=, 281, 1820) by saying: “Dr. Clark has
published a book on the gas blowpipe in which he professes a sincere
desire to render everyone his due. That it would be difficult for the
conduct of any author to be more discordant with these professions, I
pledge myself to prove in the following pages.”

Hare also invented a galvanic battery which he called a “deflagrator,”
consisting of a large number of single cells in series. With this, using
carbon electrodes, he was able to obtain a higher temperature than with
his oxy-hydrogen blowpipe. He was the first to apply galvanic ignition
to blasting (=21=, 139, 1832), and he first carried out electrolyses
with the use of mercury as the cathode (=37=, 267, 1839). In this way he
prepared metallic calcium and other metals from solutions of their
chlorides, while the principle employed by him has in recent times been
used as the basis of a very important process for manufacturing caustic
potash and soda.

Silliman, who had become an intimate friend of Hare during two periods
of chemical study under Woodhouse in Philadelphia in 1802–1804, and who
soon afterwards spent fourteen months as a student abroad, chiefly in
England and Scotland, took a broad interest in science and gave much
attention to geology as well as to chemistry. In spite of this divided
interest and his work as a teacher, popular scientific lecturer, and
editor, he found time for a surprising amount of original chemical work.
For instance, using Hare’s deflagrator, he showed that carbon was
volatilized in the electric arc (=5=, 108, 1822); he was the first in
this country to prepare hydrofluoric acid (=6=, 354, 1823), and he first
detected bromine in one of our natural brines (=18=, 142, 1830).


                           _Atomic Weights._

As soon as the atomic theory was accepted, the relative weights of the
atoms became a matter of vital importance in connection with formulas
and chemical calculations. In advancing his theory, Dalton had made some
very rough atomic weight determinations, and it has been mentioned
already that Berzelius, at the time that our historical period begins,
was engaged in the prodigious task of accurately determining these
constants for nearly all the known elements. It is recorded that he
analyzed quantitatively no less than two thousand compounds in
connection with this work during his career. His table of 1818 has
proved to be remarkably accurate for that pioneer period, and it
indicates his remarkable skill as an analyst.

It is to be observed that Berzelius in this early table made use of
Avogadro’s principle in connection with elements forming gaseous
compounds, and thus obtained correct formulas and atomic weights in such
cases, but that in many instances his atomic weights and those now
accepted bear the relation of simple multiples to one another, because
he had then no means of deciding upon the formulas of many compounds
except the rule of assumed simplicity. For example, the two oxides of
iron now considered to be FeO and Fe_{2}O_{3} he regarded as FeO_{2} and
FeO_{3}, knowing as he did that the ratio of oxygen in them was 2 to 3,
and believing that a single atom of iron in each was the simplest view
of the case, so that as the consequence of these formulas the atomic
weight of iron was then considered to be practically twice as great in
its relation to oxygen as at present.

These old atomic weights of Berzelius, used with the corresponding
formulas, were just as serviceable for calculating compositions and
analytical factors as though the correct multiples had been selected. As
time went on, the true multiples were gradually found from
considerations of atomic heats, isomorphism, vapor densities, the
periodic law, and so on, and suitable changes were made in the chemical
formulas.

Berzelius used 100 parts of oxygen as the basis of his atomic weights, a
practice which was generally followed for several decades. Dalton,
however, had originally used hydrogen as unity as the basis, and this
plan finally came into use everywhere, as it seemed to be more logical
and convenient, because hydrogen has the smallest atomic weight, and
also because the atomic weights of a number of common elements appeared
to be exact multiples of that of hydrogen, thus giving simpler numbers
for use in calculations.

Within a few years a slight change has been made by the adoption of
oxygen as exactly 16 as the basis, which gives hydrogen the value of
1·008.

As early as 1815, Prout, an English physician, had advanced the view
that hydrogen is the primordial substance of all the elements, and
consequently that the atomic weights are all exact multiples of that of
hydrogen. This hypothesis has been one of the incentives to
investigations upon atomic weights, for it has been found that these
constants in the cases of a considerable number of the elements are very
close to whole numbers when based upon hydrogen as unity, or even still
closer when based upon oxygen as 16.

With our present knowledge Prout’s hypothesis may be regarded as
disproved for nearly all the elements whose atomic weights have been
accurately determined, but the close or even exact agreement with it in
a few cases is still worthy of consideration. There is an interesting
letter from Berzelius to B. Silliman, Jr., in the Journal (=48=, 369,
1845) in which Berzelius considers the theory entirely disproved.

For a long time entire reliance was placed upon the atomic weights
obtained by Berzelius, but it came to be observed that the calculation
of carbon from carbon dioxide appeared to give high results in certain
cases, so that doubt arose as to the accuracy of Berzelius’s work.
Consequently in 1840 Dumas, assisted by his pupil Stas, made a new
determination of the atomic weight of carbon, and found that the number
obtained by Berzelius, 12·12, was slightly too large. Subsequently Dumas
determined more than twenty other atomic weights, but this great amount
of work did not bring about any considerable improvement, for it appears
that Dumas did not greatly excel Berzelius in accuracy, and that the
latter had made one of his most noticeable errors in connection with
carbon.

Soon after assisting Dumas in the work upon carbon, Stas began his very
extensive and accurate, independent determinations, leading to the
publication of a book in 1867 describing his work. Stas made many
improvements in methods by the use of great care in purifying the
substances employed, and especially by using large quantities of
material in his determinations, thus diminishing the proportional errors
in weighing. His results, which dealt with most of the common elements,
were accepted with much confidence by chemists everywhere.

Stas reached the conclusion that there could be no real foundation for
Prout’s hypothesis, since so many of his atomic weights varied from
whole numbers, and this opinion has been generally accepted.

The first accurate atomic weight determination published in the Journal
was that by Mallett on lithium (=22=, 349, 1856; =28=, 349, 1859),
showing a result almost identical with that accepted at the present
time. Johnson and Allen’s determination (=35=, 94, 1863) on the rare
element cæsium was carried out with extraordinary accuracy. Lee, working
with Wolcott Gibbs, made good determinations on nickel and cobalt (=2=,
44, 1871). The work of Cooke on antimony (=15=, 41, 107, 1878) was
excellent.

Concerning the more recent work published elsewhere than in the Journal,
attention should be called particularly to the investigations that have
been carried on for the past twenty-five years by Richards and his
associates at Harvard University. Richards has shown masterly ability in
the selection of methods and in avoiding errors. His results have
displayed such marvelous agreements among repeated determinations by the
same and by different processes as to inspire the greatest confidence.
His work has been very extensive, and it is a great credit to our
country that this atomic weight work, so superior to all that has been
previously done, is being carried out here.

It may be mentioned that for a number of years the decision in regard to
the atomic weights to be accepted has been in the hands of an
International Committee of which our fellow countryman F. W. Clarke has
been chairman. In connection with this position and previously, Clarke
has done valuable service in re-calculating and summarizing atomic
weight determinations.


                        _Analytical Chemistry._

Analysis is of such fundamental importance in nearly every other branch
of chemical investigation that its development has been of the utmost
importance in connection with the advancement of the science. It
attained, therefore, a comparatively early development, and one hundred
years ago it was in a flourishing condition, particularly as far as
inorganic qualitative and gravimetric analysis were concerned. There is
no doubt that Berzelius, whose atomic weight determinations have already
been mentioned, surpassed all other analysts of that time in the amount,
variety, and accuracy of his gravimetric work. He lived through three
decades of our period, until 1848.

During the past century there has been constant progress in inorganic
analysis, due to improved methods, better apparatus and accumulated
experience. An excellent work on this subject was published by H. Rose,
a pupil of Berzelius, and the methods of the latter, with many
improvements and additions by the author and others, were thus made
accessible. Fresenius, who was born in 1818, did much service in
establishing a laboratory in which the teaching of analytical chemistry
was made a specialty, in writing text-books on the subject and in
establishing in 1862 the “Zeitschrift für analytische Chemie,” which has
continued up to the present time.

Besides Berzelius, who was the first to show that minerals were definite
chemical compounds, there have been many prominent mineral analysts in
Europe, among whom Rammelsberg and Bunsen may be mentioned, but there
came a time towards the end of the nineteenth century when the attention
of chemists, particularly in Germany, was so much absorbed by organic
chemistry that mineral analysis came near becoming a lost art there. It
was during that period that an English mineralogist, visiting New Haven
and praising the mineral analyses that were being carried out at Yale,
expressed regret that there appeared to be no one in England, or in
Germany either, who could analyze minerals.

The best analytical work done in this country in the early part of our
period was chiefly in connection with mineral analysis, and a large
share of it was published in the Journal. Henry Seybert, of
Philadelphia, in particular, showed remarkable skill in this direction,
and published numerous analyses of silicates and other minerals,
beginning in 1822. It was he who first detected boric acid in tourmaline
(=6=, 155, 1822), and beryllium in chrysoberyl (=8=, 105, 1824). His
methods for silicate analyses were very similar to those used at the
present time.

J. Lawrence Smith in 1853 described his method for determining alkalies
in minerals (=16=, 53), a method which in its final form (=1=, 269,
1871) is the best ever devised for the purpose. He also described (=15=,
94, 1853) a very useful method, still largely used in analytical work,
for destroying ammonium salts by means of aqua regia. Carey Lea (=42=,
109, 1866) described the well-known test for iodides by means of
potassium dichromate. F. W. Clarke (=49=, 48, 1870) showed that antimony
and arsenic could be quantitatively separated from tin by the
precipitation of the sulphides in the presence of oxalic acid. In 1864
Wolcott Gibbs (=37=, 346) began an important series of analytical notes
from the Lawrence Scientific School, and he worked out later many
difficult analytical problems, particularly in connection with his
extensive researches upon the complex inorganic acids.

From 1850 on, Brush and his students made many important investigations
upon minerals, and from 1877 Penfield (=13=, 425), beginning with an
analysis of a new mineral from Branchville, Connecticut, described by
Brush and E. S. Dana, displayed remarkable skill and industry in this
kind of work. Both of the writers of this article were fortunate in
being associated with Penfield in some of his researches upon minerals
and one of us began as he did with the Branchville work. It is probably
fair to say that Penfield did the most accurate work in mineral analysis
that has ever been accomplished, and that he was similarly successful in
crystallography and other physical branches of mineralogy.

The American analytical investigations that have been mentioned were all
published in the Journal, with the exception of a part of Gibbs’s work.
Many other American workers at mineral analysis might be alluded to
here, but only the excellent work of a number of chemists in the United
States Geological Survey will be mentioned. Among these Hillebrand
deserves particular praise for the extent of his investigations and for
his careful researches in improving the methods of rock analysis.

To our own Professor Gooch especial praise must be accorded for the very
large number of analytical methods that have been devised, or critically
studied, by him and his students, and for the excellent quality of this
work. The publications in the Journal from his laboratory began in 1890
(=39=, 188), and the extraordinary extent of this work is shown by the
fact that the three hundredth paper from the Kent Laboratory appeared in
May, 1918. These very numerous and important investigations have been of
great scientific and practical value, and they have formed a striking
feature of the Journal for nearly 30 years. In 1912 Gooch published his
“Methods in Chemical Analysis,” a book of over 500 pages, in which the
work in the Kent Chemical Laboratory up to that time was concisely
presented. Among the many workers who have assisted in these
investigations, P. E. Browning, W. A. Drushel, F. S. Havens, D. A.
Kreider, C. A. Peters, I. K. Phelps and R. G. Van Name are particularly
prominent. Besides many other useful pieces of apparatus, the perforated
filtering crucible was devised by Gooch, and this has brought his name
into everyday use in all chemical laboratories.

Volumetric analysis was originated by Gay-Lussac, who described a method
for chlorimetry in 1824, for alkalimetry in 1828, and for the
determination of silver and chlorides in 1832. Margueritte devised
titrations with potassium permanganate in 1846, while Bunsen, not far
from the same time, introduced the use of iodine and sulphur dioxide
solutions for the purpose of determining many oxidations and reductions.
We owe to Mohr some improvements in apparatus and a German text-book on
the subject, while Sutton wrote an excellent English work on volumetric
analysis, of which many editions have appeared.

While volumetric analysis began to be used less than one hundred years
ago, its applications have been gradually extended to a very great
degree, and it is not only exceedingly important in investigations in
pure chemistry, but its use is especially extensive in technical
laboratories where large numbers of rapid analyses are required.

Not a few volumetric methods have been devised or improved in the United
States, but mention will be made here only of Cooke’s important method
for the determination of ferrous iron in insoluble silicates, published
in the Journal (=44=, 347, 1867); to Penfield’s method for the
determination of fluorine in 1878; and to the more recent general method
of titration with an iodate in strong hydrochloric acid solutions, due
to L. W. Andrews, a number of applications of which have been worked out
in the Sheffield Laboratory.

A considerable amount of work with gases had been done by Priestley,
Scheele, Cavendish, Lavoisier, Dalton, Gay-Lussac, and others before our
hundred-year period began. Cavendish, about 1780, had analyzed
atmospheric air with remarkable accuracy, and had even separated the
argon from it and wondered what it was, and later Gay-Lussac had shown
great skill in the study of gas reactions. During our period gas
analysis has been further developed by many chemists. Bunsen, in
particular, brought the art to a high degree of perfection in the course
of a long period beginning about 1838, the last edition of his “Methods
of Gas Analysis” having been published in 1877.

Important devices for the simplification of gas analysis in order that
it might be used more conveniently for technical purposes have been
introduced by Orsat in France and by Winkler, Hempel and Bunte in
Germany.

It appears that our countryman Morley has surpassed all others in
accurate work with gases in connection with his determinations of the
combining weights and volumes of hydrogen and oxygen about the year
1891. Some of his publications have appeared in the Journal (=30=, 140,
1885; =41=, 220, 1891; and others).

Electrolytic analysis, involving the deposition of metals, or sometimes
of oxides, usually upon a platinum electrode, was brought into use in
1865 by Wolcott Gibbs through an article published in the Journal (=39=,
58, 1865). He there described the electrolytic precipitation of copper
and of nickel by the methods still in use. The application of the
process has been extended to a number of other metals, and it has been
largely employed, particularly in technical analyses. Important
investigations and excellent books on this subject have been the
contributions of Edgar F. Smith of the University of Pennsylvania, and
the useful improvement, the rotating cathode, was devised by Gooch and
described in the Journal (=15=, 320, 1903).


                     _General Inorganic Chemistry._

_The Chemical Symbols._—It is to Berzelius that we owe our symbols for
the atoms, derived usually from their Latin names, such as C for carbon,
Na for sodium, Cl for chlorine, Fe for iron, Ag for silver, and Au for
gold. We owe to him also the use of small figures to show the number of
atoms in a formula, as in N_{2}O_{5}. This was a marked improvement over
the hieroglyphic symbols proposed by Dalton, which were set down as many
times as the atoms were supposed to occur in formulas, forming groups of
curious appearance, but in some respects not unlike some of our modern
developed formulas. The advantages of Berzelius’s symbols were their
simplicity, legibility, and the fact that they could be printed without
the need of special type. It is true that at a later period Berzelius
used certain symbols with horizontal lines crossing them to represent
double atoms, and that these made some difficulty in printing. It should
be mentioned also that Berzelius at one time made an effort to simplify
formulas by placing dots over other symbols to represent oxygen, and
commas to represent sulphur atoms. Examples of these are:

               ĊaS⃛, calcium sulphate; F̋e, iron disulphide

This form of notation was quite extensively employed for a time,
especially by mineralogists, but it was entirely abandoned later.

It is interesting to notice that Dalton, who lived until 1844, to reach
the age of 78, differed from other chemists in refusing to accept the
letter-symbols of Berzelius. In a letter written to Graham in 1837 he
said: “Berzelius’s symbols are horrifying. A young student in chemistry
might as soon learn Hebrew as to make himself acquainted with them. They
appear like a chaos of atoms ... and to equally perplex the adepts of
science, to discourage the learner, as well as to cloud the beauty and
simplicity of the atomic theory.”

This forcibly expressed opinion was apparently tinged with self-esteem,
but there is no doubt that Dalton was sincere in believing that the
atoms were best represented by his circular symbols, because, as is well
known, he thought that all the atoms were spherical in form, and it is
evident that circles give the proper picture of spherical objects. At
the present time some insight as to the structure of atoms is being
gained, and it appears possible that the time may come when pictures of
their external appearance that are not wholly imaginary may be made.

_Changes in Formulas._—Even before the year 1826, Berzelius displayed
great skill in arriving at many formulas that agree with our present
ones, for example, H_{2}O for water, ZnCl_{2} for zinc chloride,
N_{2}O_{5} for nitric acid (anhydride), CaO for calcium oxide, CO and
CO_{2} for the oxides of carbon, and many others. But at the same period
other authorities, especially Gay-Lussac in France and Gmelin in
Germany, on account of a lack of appreciation for Avogadro’s principle
and for other reasons, such as the use of symbols to represent combining
weights rather than atoms, were using different formulas for some of
these compounds, such as HO, ZnCl and NO_{5}, so that their formulas for
many of the compounds of hydrogen, chlorine, nitrogen and several other
elements differed from those of Berzelius. The employment of different
formulas involved the use of different atomic or combining weights. For
example, with the formula H_{2}O for water the composition by weight
requires the ratio 1 to 16 for the weights of the hydrogen and oxygen
atoms, while with HO the ratio is 1 to 8.

Berzelius attempted to bring about greater uniformity in formulas and
atomic weights by making changes in his table of atomic weights
published in 1826. He practically doubled the relative atomic weights of
hydrogen, chlorine, nitrogen, and of the other elements that gave twice
as many atoms in his formulas as in those of others, and at the same
time he wrote the symbols of these elements with a bar across them to
indicate that they represented double atoms. For example, he wrote:

                            H̶O ZnC̶l N̶O_{5},

instead of

                      H_{2}O, ZnCl_{2} N_{2}O_{5}

This appears to have been an unfortunate concession to the views of
others on the part of Berzelius, for the barred symbols were not
generally adopted, partly on account of difficulties in printing, and
the great achievement in theory made by him was lost sight of for a long
period of time.

_The Law of Atomic Heats._—In 1819, Dulong and Petit of France, from
experiments upon the specific heats of a number of solid elementary
substances, came to the conclusion that the atoms of simple substances
have equal capacities for heat, or in other words, that the specific
heats of elements multiplied by their atomic weights give a constant
called the atomic heat. For instance, the specific heats of sulphur,
iron, and gold have been given as 0·2026, 0·110, and 0·0324, while their
atomic weights are about 32, 56, and 197, respectively; hence the atomic
heats obtained by multiplication are 6·483, 6·116, and 6·383.

Further investigations showed that the atomic heats display a
considerable variation. Those of carbon, boron, beryllium, and silicon
are very low at ordinary temperatures, although they increase and
approach the usual values at higher temperatures. More recent work has
shown, however, that the specific heats of other elements vary greatly
with the temperature, almost disappearing at the temperature of liquid
hydrogen, and hence possibly disappearing entirely at the absolute zero,
where the electrical resistance of the metals appears to vanish
likewise.

It has been found that most of the solid elements near ordinary
temperatures give atomic heats that are approximately 6·4. Berzelius
applied the law in fixing a number of atomic weights, and its importance
for this purpose is still recognized.

It may be mentioned here that two well-known Yale men, W. O. Mixter and
E. S. Dana, while students in Bunsen’s laboratory at Heidelberg in 1873,
made determinations of the specific heats of boron, silicon, and
zirconium. This was the first determination of this constant for
zirconium, and it was consequently important in establishing the atomic
weight of that element.

_Isomorphism and Polymorphism._—Mitscherlich observed in 1818 that
certain phosphates and arsenates have the same crystalline form, and
afterwards he reached the conclusion that identity in form indicates
similarity in composition in connection with the number of atoms and
their arrangement. This law of isomorphism was of much assistance in the
establishment of correct formulas and consequently of atomic weights.
For instance, since the carbonates of barium, strontium, and lead
crystallize in the same form, the oxides of these metals must have
analogous formulas. From such considerations Berzelius was able to make
several improvements in his atomic weight table of 1826.

Mitscherlich was the first to observe two forms of sulphur crystals, and
from this and other cases of dimorphism or of polymorphism it became
evident that analogous compounds were not necessarily always
isomorphous, a circumstance which has restricted the application of the
law to some extent.

Besides its application in fixing analogous formulas, the law of
isomorphism has come to be of much practical use in the understanding
and simplification of the formulas for minerals, for these natural
crystals very often contain several isomorphous compounds in varying
proportions, and an understanding of this “isomorphous replacement,” as
it is called, makes it possible to deduce simple general formulas for
them.

In some cases isomorphism takes place to a greater or less extent
between substances which are not chemically similar, and this brings
about a variation in composition which at times has caused confusion.
For instance, the mineral pyrrhotite has a composition which usually
varies between Fe_{7}S_{8} and Fe_{11}S_{12}, and both these formulas
have been assigned to it. It was recently shown by Allen, Crenshaw and
Johnston in the Journal (=33=, 169, 1912) that this is a case where the
compound FeS is capable of taking up various amounts of sulphur
isomorphously.

The idea of solid solution was advanced by van’t Hoff to explain the
crystallization of mixtures, including cases of evident isomorphism.
This view has been widely accepted, and it has been particularly useful
in cases where isomorphism is not evident. Solid solution between metals
has been found to be exceedingly common, many alloys being of this
character. A case of this kind was observed by Cooke and described in
the Journal (=20=, 222, 1855). He prepared two well-crystallized
compounds of zinc and antimony to which he gave the formulas Zn_{3}Sb
and Zn_{2}Sb, but he observed that excellent crystals of each could be
obtained which varied largely in composition from these formulas. As the
two compounds were dissimilar in their formulas and crystalline forms,
Cooke assumed that isomorphism was impossible and concluded “that it is
due to an actual perturbation of the law of definite proportions,
produced by the influence of mass.” We should now regard this as a case
of solid solution.

_A Lack of Confidence in Avogadro’s Principle._—One reason why chemists
were so slow in arriving at the correct atomic weights and formulas was
a partial loss of confidence in Avogadro’s principle. About 1826 the
young French chemist Dumas devised an excellent method for the
determination of vapor densities at high temperatures, and his results
and those of others showed some discrepancies in the expected densities.
For example, the vapor density of sulphur was found to be about three
times too great, that of phosphorus twice too great, that of mercury
vapor and that of ammonium chloride only about half large enough to
correspond to the values expected from analogy and other considerations.
Thus, one volume of oxygen with two volumes of hydrogen make two volumes
of steam, but only one third of a volume of sulphur vapor was found to
unite with two volumes of hydrogen to make two volumes of hydrogen
sulphide. Berzelius saw clearly that the results pointed to the
existence of such molecules as S_{6}, P_{4}, and Hg_{1}, but it was not
generally realized in those days that Avogadro’s rule is fundamentally
reliable, and Berzelius himself appears to have lost confidence in it on
account of these complications, for he did not apply Avogadro’s
principle to decisions about atomic weights, except in the cases of
substances gaseous at ordinary temperatures.

_Electro-chemical Theories._—The observation was made by Nicholson and
Carlisle in 1800 that water was decomposed into its constituent gases by
the electric current. Then in 1803 Berzelius and Hisinger found that
salts were decomposed into their bases and acids by the same agency, and
in 1807 Davy isolated potassium, sodium, and other metals afterwards, by
a similar decomposition. Since those early times a vast amount of
attention has been paid to the relation of electricity to chemical
changes, a relation that is evidently of great importance from the fact
that while electric currents decompose chemical compounds, these
currents, on the other hand, are produced by chemical reactions.

Berzelius was particularly prominent in this direction, and in 1819 he
published an elaborate electro-chemical theory. He believed that atoms
were electrically polarized, and that this was the cause of their
combination with one another. He extended this idea to groups of atoms,
particularly to oxides, and regarded these groups as positive or
negative, according to the excess of positive or negative electricity
derived from their constituent atoms and remaining free. He thus arrived
at his dualistic theory of chemical compounds, which attained great
prominence and prevailed for a long time in chemical theory. According
to this idea, each compound was supposed to be made up of a positive and
a negative atom or group of atoms. For example, the formulas for
potassium nitrate, calcium carbonate, and sulphuric acid corresponded to
K_{2}O.N_{2}O_{5}, CaO.CO_{2} and H_{2}O.SO_{3} where we now write
KNO_{3}, CaCO_{3} and H_{2}SO_{4}, and the theory was extended to
embrace organic compounds also.

The eminent English chemist and physicist Faraday announced the
important law of electro-chemical equivalents in 1834. This law shows
that the quantities of elements set free by the passage of a given
quantity of electricity through their solutions correspond to the
chemical equivalents of those elements. Faraday made a table of the
equivalents of a number of elements, regarding them important in
connection with atomic weights, but at that time no sharp distinction
was usually made between equivalents and atomic weights, and it was not
fully realized that one atom of a given element may be the electrical
equivalent of several atoms of another.

Faraday’s law, which is still regarded as fundamentally exact, has been
of much practical use in the measurement of electric currents and in
calculations connected with electro-chemical processes. In discussing
his experiments, Faraday made use of several new terms, such as
“electrolyte” for a substance which conducts electricity when in
solution, and is thus “electrolyzed,” “electrode,” “anode,” and
“cathode,” terms that have come into general use, and finally “ions” for
the particles that were supposed to “wander” towards the electrodes to
be set free there.

This term “ion” remained in comparative obscurity for more than half a
century, when it was brought into great prominence among chemists by
Arrhenius in connection with the ionic theory.

_Cannizzaro’s Ideas._—Up to about 1869 chaos reigned among the formulas
used by different chemists. Various compound radicals and numerous
type-formulas were employed, dualistic and unitary formulas of several
kinds were in use, but the worst feature of the situation was the fact
that more than one system of atomic weights was in vogue, so that water
might be written

                           HO, H̶O, or H_{2}0

and similar discrepancies might appear in nearly all formulas containing
elements of different valencies. In 1858, however, an article by the
Italian chemist Cannizzaro appeared in which the outlines of a course in
chemical philosophy were presented. This acquired wide circulation in
the form of a pamphlet at a chemical convention somewhat later, and it
dealt so clearly and ably with Avogadro’s principle, Dulong and Petit’s
law, and other points in connection with formulas that it led to a rapid
and almost universal reform among those who were using unsatisfactory
formulas.

At about this time also the dualistic formulas of Berzelius were
generally abandoned, and hydrogen came to be regarded as the
characteristic element of all acids. For instance, CaO.SO_{3}, called
“sulphate of lime,” came to be written CaSO_{4} and was called “calcium
sulphate,” and while it had been shown as early as 1815 by Davy that
“iodic acid,” I_{2}O_{5}, showed no acid reaction until it was combined
with water, the accumulation of similar facts led to the formulation of
sulphuric acid as H_{2}SO_{4} instead of SO_{3} or H_{2}O.SO_{3}, and
that of other “oxygen acids” in a similar way. As a necessary
consequence of this view of acids, the bases came to be regarded as
compounds of the “hydroxyl” group, OH. Therefore the formula for caustic
soda came to be written NaOH instead of Na_{2}O.H_{2}O, and so on.

_The Periodic System of the Elements._—The periodicity of the elements
in connection with their atomic weights was roughly grasped by Newlands
in England, who announced his “law of octaves” in 1863. This was at the
time when the atomic weights were being modified and their numerical
relations properly shown. The subject was worked out more fully by L.
Meyer in Germany a little later, but it was most clearly and elaborately
presented by the Russian chemist Mendeléeff in 1869.

In order that this subject may be explained to some extent Mendeléeff’s
table is given here, with the addition of the recently discovered
elements and some other modifications.

 ┌─────────┬────────────────┬───────────────────┬───────────────────┐
 │ Groups  │       I        │        II         │        III        │
 │    „    │    A       B   │    A         B    │    A         B    │
 ├─────────┼────────────────┼───────────────────┼───────────────────┤
 │ Typical │     R_{2}O     │        RO         │    R_{2}O_{3}     │
 │Compounds│                │                   │                   │
 │    „    │      RCl       │      RCl_{2}      │      RCl_{3}      │
 │    „    │   RH       —   │(RH_{2})      —    │    —     (RH_{3}) │
 ╞═════════╪════════════════╪═══════════════════╪═══════════════════╡
 │Series 1 │                │                   │                   │
 │         │                │                   │                   │
 ├─────────┼────────────────┼───────────────────┼───────────────────┤
 │    2    │ Lithium        │          Beryllium│           _Boron_ │
 │         │  6·94          │             9·1   │            11·0   │
 ├─────────┼────────────────┼───────────────────┼───────────────────┤
 │    3    │ Sodium         │          Magnesium│          Aluminium│
 │         │  23·00         │            24·32  │            27·1   │
 ├─────────┼────────────────┼───────────────────┼───────────────────┤
 │    4    │Potassium       │ Calcium           │Scandium           │
 │         │  39·10         │  40·07            │  44·1             │
 │    „    │    „           │    „              │    „              │
 │         │                │                   │                   │
 │    „    │    „           │    „              │    „              │
 │         │                │                   │                   │
 ├─────────┼────────────────┼───────────────────┼───────────────────┤
 │    5    │          Copper│            Zinc   │           Gallium │
 │         │          53·57 │            65·37  │            69·9   │
 ├─────────┼────────────────┼───────────────────┼───────────────────┤
 │    6    │Rubidium        │Strontium          │ Yttrium           │
 │         │  85·43         │  87·63            │  89·0             │
 │    „    │    „           │    „              │    „              │
 │         │                │                   │                   │
 │    „    │    „           │    „              │    „              │
 │         │                │                   │                   │
 ├─────────┼────────────────┼───────────────────┼───────────────────┤
 │    7    │          Silver│           Cadmium │           Indium  │
 │         │          107·88│           112·40  │            114·8  │
 ├─────────┼────────────────┼───────────────────┼───────────────────┤
 │         │                │                   │Lanthanum          │
 │    8    │ Cæsium         │ Barium            │139·0 to*          │
 │         │ 132·81         │ 137·87            │Lutecium           │
 │         │                │                   │  174.0            │
 │    „    │    „           │    „              │    „              │
 │         │                │                   │                   │
 │    „    │    „           │    „              │    „              │
 │         │                │                   │                   │
 ├─────────┼────────────────┼───────────────────┼───────────────────┤
 │    9    │           Gold │           Mercury │          Thallium │
 │         │          197·2 │            200·6  │            204·0  │
 ├─────────┼────────────────┼───────────────────┼───────────────────┤
 │   10    │   ——           │ Radium            │   ——              │
 │         │                │  226·4            │                   │
 └─────────┴────────────────┴───────────────────┴───────────────────┘

 ┌─────────┬────────────────────┬─────────────────────┐
 │ Groups  │         IV         │          V          │
 │    „    │    A          B    │   A          B      │
 ├─────────┼────────────────────┼─────────────────────┤
 │ Typical │       RO_{2}       │     R_{2}O_{5}      │
 │Compounds│                    │                     │
 │    „    │      RCl_{4}       │       RCl_{3}       │
 │    „    │    —      (RH_{4}) │   —        RH_{3}   │
 ╞═════════╪════════════════════╪═════════════════════╡
 │Series 1 │                    │                     │
 │         │                    │                     │
 ├─────────┼────────────────────┼─────────────────────┤
 │    2    │           _Carbon_ │           NITROGEN  │
 │         │             12·00  │            14·01    │
 ├─────────┼────────────────────┼─────────────────────┤
 │    3    │           _Silicon_│         _Phosphorus_│
 │         │             28·3   │            31·04    │
 ├─────────┼────────────────────┼─────────────────────┤
 │    4    │ Titanium           │Vanadium             │
 │         │   48·1             │  51·0               │
 │    „    │    „               │   „                 │
 │         │                    │                     │
 │    „    │    „               │   „                 │
 │         │                    │                     │
 ├─────────┼────────────────────┼─────────────────────┤
 │    5    │           Germanium│           Arsenic   │
 │         │             72·5   │            74·96    │
 ├─────────┼────────────────────┼─────────────────────┤
 │    6    │Zirconium           │Niobium              │
 │         │   90·6             │  93·5               │
 │    „    │    „               │   „                 │
 │         │                    │                     │
 │    „    │    „               │   „                 │
 │         │                    │                     │
 ├─────────┼────────────────────┼─────────────────────┤
 │    7    │           Tin 119·0│           Antimony  │
 │         │                    │            120·2    │
 ├─────────┼────────────────────┼─────────────────────┤
 │         │ (Cerium)           │                     │
 │    8    │  140·25            │Tantalum             │
 │         │(Lutecium)          │ 181·5               │
 │         │  174.0             │                     │
 │    „    │    „               │   „                 │
 │         │                    │                     │
 │    „    │    „               │   „                 │
 │         │                    │                     │
 ├─────────┼────────────────────┼─────────────────────┤
 │    9    │             Lead   │           Bismuth   │
 │         │            207·10  │            208·0    │
 ├─────────┼────────────────────┼─────────────────────┤
 │   10    │ Thorium            │   ——                │
 │         │  292·4             │                     │
 └─────────┴────────────────────┴─────────────────────┘

 ┌─────────┬─────────────────────┬───────────────────┬─────────────────┐
 │ Groups  │         VI          │        VII        │      VIII       │
 │    „    │    A          B     │    A         B    │    A        B   │
 ├─────────┼─────────────────────┼───────────────────┼─────────────────┤
 │ Typical │       RO_{3}        │    R_{2}O_{7}     │(RO_{4})     —   │
 │Compounds│                     │                   │                 │
 │    „    │       RCl_{2}       │    —        RCl   │    —        R   │
 │    „    │    —        RH_{2}  │    —        RH    │    —        R   │
 ╞═════════╪═════════════════════╪═══════════════════╪═════════════════╡
 │Series 1 │                     │          HYDROGEN │          HELIUM │
 │         │                     │            1·008  │           3·99  │
 ├─────────┼─────────────────────┼───────────────────┼─────────────────┤
 │    2    │             OXYGEN  │          FLUORINE │           NEON  │
 │         │             16·00   │            19·0   │           20·2  │
 ├─────────┼─────────────────────┼───────────────────┼─────────────────┤
 │    3    │           _Sulphur_ │          CHLORINE │           ARGON │
 │         │             32·07   │            35·46  │           39·88 │
 ├─────────┼─────────────────────┼───────────────────┼─────────────────┤
 │    4    │ Chromium            │Manganese          │  Iron           │
 │         │   52·0              │  54·93            │  55·84          │
 │    „    │    „                │    „              │ Cobalt          │
 │         │                     │                   │  58·97          │
 │    „    │    „                │    „              │ Nickel          │
 │         │                     │                   │  58·68          │
 ├─────────┼─────────────────────┼───────────────────┼─────────────────┤
 │    5    │           _Selenium_│          _Bromine_│          KRYPTON│
 │         │              79·2   │            79·92  │           82·92 │
 ├─────────┼─────────────────────┼───────────────────┼─────────────────┤
 │    6    │Molybdenum           │ —— 100            │Ruthenium        │
 │         │   96·0              │                   │  101·7          │
 │    „    │    „                │    „              │ Rhodium         │
 │         │                     │                   │  102·9          │
 │    „    │    „                │    „              │Palladium        │
 │         │                     │                   │  106·7          │
 ├─────────┼─────────────────────┼───────────────────┼─────────────────┤
 │    7    │           Tellurium │          _Iodine_ │           XENON │
 │         │             127·5   │           126·92  │           130·2 │
 ├─────────┼─────────────────────┼───────────────────┼─────────────────┤
 │         │                     │                   │                 │
 │    8    │ Tungsten            │ —— 188            │ Osmium          │
 │         │  184·0              │                   │  190·9          │
 │         │                     │                   │                 │
 │    „    │    „                │    „              │ Iridium         │
 │         │                     │                   │  193·1          │
 │    „    │    „                │    „              │Platinum         │
 │         │                     │                   │  195·2          │
 ├─────────┼─────────────────────┼───────────────────┼─────────────────┤
 │    9    │               ——    │             ——    │           NITON │
 │         │                     │                   │           222·4 │
 ├─────────┼─────────────────────┼───────────────────┼─────────────────┤
 │   10    │ Uranium             │                   │                 │
 │         │  238·5              │                   │                 │
 └─────────┴─────────────────────┴───────────────────┴─────────────────┘

 ┌────────────────────────────────────────────────────────────────┐
 │    *      Lanthanum,  Cerium,  Praseodymium, Neodymium,   ——,  │
 │Rare·Earth    139·0     140·25      140·6       144·3           │
 │ Metals:                                                        │
 │    „      Gadolinium, Terbium,  Dysprosium,   Holmium,  Erbium,│
 │              157·3     159·2       162·5       163·5     167·7 │
 └────────────────────────────────────────────────────────────────┘

 ┌─────────────────────────────────────────┐
 │    *      Samarium, Europeum,     ——,   │
 │Rare·Earth   150·4     152·0             │
 │ Metals:                                 │
 │    „      Thulium,  Ytterbium, Lutecium,│
 │             168·5     172·0      174·0  │
 └─────────────────────────────────────────┘

 NOTE.—Distinctions in printing: GASEOUS ELEMENTS. _Other non-metallic
    elements_, metallic elements. The heavy line encloses approximately
    the acid-forming elements.

In this table the elements arranged in the order of their atomic weights
fall into eight groups where the known oxides progress regularly, with
the exception of two or three elements, from R_{2}O in Group I to
R_{2}O_{7} in Group VII, while in Group VIII two oxides (of ruthenium
and osmium) are known which carry the progression to RO_{4}.

It was pointed out by Mendeléeff that, with the exception of series 1
and 2 at the top of the table, the alternate members of the groups show
particularly close relationships. These subordinate groups, marked A and
B, in most cases show remarkable analogies and gradations in their
properties, for example, in the alkali-metals from lithium to cæsium,
and in the halogens from fluorine to iodine. The two divisions of a
group do not usually show very close relations to each other, except in
their valency, and they even display, in several instances, opposite
gradations in chemical activity in the order of their atomic weights.
For instance, cæsium stands at the electro-positive end, while gold
stands at the electro-negative end of its subordinate group. The
difference between the two divisions is very great in Groups VI and VII,
but it is extreme in Group VIII, where heavy metals are on one side and
inactive gases on the other. Many authorities separate these gases into
a “Group O” by themselves at the left-hand side of the table, but this
does not change their relative positions, and the plan may be objected
to on the ground that many vacant places are thus left in the groups
VIII and O.

The periodic law has been useful in rectifying certain atomic weights.
At the outset Mendeléeff was obliged to change beryllium from 14·5
(assuming Be_{2}O_{3}) to 9 (assuming BeO), and later the atomic weights
of indium and uranium were changed to make them fit the system. All of
these changes have been confirmed by physical means.

Mendeléeff found a number of vacant places in his table, and was thus
able to render further service to chemical science by predicting the
properties of undiscovered elements, and his predictions were very
closely confirmed by the later discovery of scandium, gallium, and
germanium. The table indicates that there are still two undiscovered
elements below manganese and probably two more among the rare-earth
metals. The interesting observation has just recently been made by Soddy
that the products of radioactive disintegration appear to pass in a
symmetrical way through positions in the periodic system, giving off a
helium molecule at alternate transformations until the place of lead is
reached. It appears, therefore, that the five vacant places in the table
above bismuth are probably occupied by these evanescent elements, and it
is to be noticed that all of the elements that have been placed in this
region of high atomic weights are radioactive.

There are some inconsistencies in the periodic system. The increments in
the atomic weights are irregular, and there are three cases, argon and
potassium, cobalt and nickel, and tellurium and iodine, where a higher
atomic weight is placed before a lower one in order to bring these
elements into their undoubtedly proper places. There is a peculiarity
also in the heavy-metal division of Group VIII, where three similar
elements occur in each of three places, and where the usual periodicity
appears to be suspended, or nearly so, in comparison with most of the
other elements. However, there seems to be a still more remarkable case
of this kind in Group III, where fourteen metals of the rare earths have
been placed. They are astonishingly similar in their chemical
properties, hence it seems necessary to assume that periodicity is
suspended here throughout the wide range of atomic weights from 139 to
174, where no elements save these have been found.

Several other interesting features of the table may be pointed out. The
chlorides and hydrides, as indicated by the “typical compounds,” show a
regular progression in both directions towards Group IV. (Where the
type-formulas do not apply, as far as is known, to more than one or two
elements, they have been placed in parentheses in the table given here.)
It is a striking fact that the acid-forming elements occur together in a
definite part of the table, and that the gases and other non-metallic
elements, except the inactive gases of Group VIII, occur in the same
region.

_Atomic Numbers._—As the result of a spectroscopic study of the wave
lengths or frequencies of the X-rays produced when cathode rays strike
upon anticathodes composed of different elements, Moseley in 1914
discovered that whole numbers in a simple series can be attributed to
the atoms. These atomic numbers are: 1 for hydrogen, 2 for helium, 3 for
lithium, 4 for beryllium, and so on, in the order in which the elements
occur in Mendeléeff’s periodic table, and in the cases of argon and
potassium, cobalt and nickel, and tellurium and iodine, they follow the
correct chemical order, while the atomic weights do not. They appear to
indicate, therefore, an even more fundamental relation between the atoms
than that shown by the atomic weights.

These numbers are now available for every element up to lead, and they
are particularly interesting in indicating, on account of missing
numbers, the existence of two undiscovered elements in the manganese
group, and two more among the rare-earth metals, in confirmation of the
vacant places below lead in Mendeléeff’s table.

_The Isolation of Elements._—In the year 1818 about 53 elements were
recognized, and since that time about 30 more have been discovered, but
the elements already known comprised the more common ones, and nearly
all of those which have been commercially important. A few of them,
including beryllium, aluminium, silicon, magnesium, and fluorine, were
then known only in their compounds, as they had not yet been isolated in
the free condition.

Berzelius in 1823 prepared silicon, a non-metallic element resembling
carbon in many respects. This element has recently been prepared on a
rather large scale in electric furnaces at Niagara Falls, and has been
used for certain purposes in the form of castings.

Wöhler created much sensation in 1827 by isolating aluminium and finding
it to be a very light, strong and malleable metal, stable in the air,
and of a silver-white color. For a long time this metal was a
comparative rarity, being prepared by the reduction of aluminium
chloride with metallic sodium; but about 25 years ago Hall, an American,
devised a method of preparing it by electrolyzing aluminium oxide
dissolved in fused cryolite. This process reduced the cost of aluminium
to such an extent that it has now come into common use.

Wöhler and Bussy prepared beryllium in 1828, and Liebig and Bussy did
the same service for magnesium in 1830. The latter metal has come to be
of much practical importance, both as a very powerful reducing agent in
chemical operations, and as an ingredient of flash-light powders and of
mixtures used for fireworks. It is also used in making certain light
alloys.

After almost innumerable attempts to isolate fluorine, during a period
of nearly a century, this was finally accomplished in 1886 by Moissan in
France by the electrolysis of anhydrous hydrogen fluoride. The free
fluorine proved to be a gas of extraordinary chemical activity,
decomposing water at once with the formation of hydrogen fluoride and
ozonized oxygen. This fact explains the failure of many previous
attempts to prepare it in the presence of water.

_Early Discoveries of New Elements._—The remarkable activity of chemical
research at the beginning of our period is illustrated by the fact that
three new elements were discovered in 1817. In that year Berzelius had
discovered selenium, Arfvedson, working in Berzelius’s laboratory had
discovered the important alkali-metal lithium, and Stromeyer had
discovered cadmium.

In 1826 Ballard in France discovered bromine in the mother-liquor from
the crystallization of common salt from sea water. Bromine proved to be
an unusually interesting element, being the only non-metallic one that
is liquid at ordinary temperatures, and being strikingly intermediate in
its properties between chlorine and iodine. It has been obtained in
large quantities from brines, and is produced extensively in the United
States. The elementary substance and its compounds have found important
applications in chemical operations, while the bromides have been found
valuable in medicine and silver bromide is very extensively used in
photography.

In 1828 Berzelius discovered thorium. The oxide of this metal has
recently been employed extensively as the principal constituent of
incandescent gas-mantles, and the element has acquired particular
importance from the fact that, like uranium, it is radioactive,
decomposing spontaneously into other elements.

Vanadium had been encountered as early as 1801 by Del Rio, who named it
“erythronium,” but a little later it was thought to be identical with
chromium and was lost sight of for a while. In 1830, however, it was
re-discovered by, and received its present name from Sefström in Sweden.
Berzelius immediately made an extensive study of vanadium compounds, but
he gave them incorrect formulas and derived an incorrect atomic weight
for the element, because he mistook a lower oxide for the element
itself. Roscoe in England in 1867 isolated vanadium for the first time,
found the right atomic weight, and gave correct formulas to its
compounds. Vanadium is particularly interesting from the fact that it
displays several valencies in its compounds, many of which are highly
colored. It has found important use as an ingredient in very small
proportions in certain “special steels” to which it imparts a high
degree of resistance to rupture by repeated shocks.

Columbium was discovered early in the nineteenth century in the mineral
columbite from Connecticut by Hatchett, an Englishman, who did not,
however, obtain the pure oxide. It was afterwards obtained by Rose who
named it niobium. Both names for the element are in use, but the former
has priority. Attention was called to this fact by an article in the
Journal by Connell, an Englishman (=18=, 392, 1854).

_The Platinum Group of Metals._—In 1854 a new member of the platinum
group of metals, ruthenium, was discovered by Claus. Platinum had been
discovered about the middle of the eighteenth century, while its other
rarer associates, iridium, osmium, palladium, and rhodium, had been
recognized in the very early years of the nineteenth century. It was
during the latter period that platinum ware began to be employed to a
considerable extent in chemical operations, and this use was greatly
extended as time went on. The discovery was made by Phillips in 1831
that finely divided platinum by contact would bring about the
combination of sulphur dioxide with atmospheric oxygen, and this
application during the past 20 years has become enormously important in
the sulphuric acid industry, while other important applications of
platinum as a “catalytic agent” have also been made. Wolcott Gibbs and
Carey Lea have contributed perhaps more than any other recent chemists
to a knowledge of the platinum metals. Carey Lea (=38=, 81, 248, 1864)
dealt chiefly with the separation of the metals from each other, while
Gibbs’s work (=31=, 63, 1861; =34=, 341, 1862) included investigations
of many of the compounds.

It may be mentioned that while platinum and its associates were formerly
known only in the uncombined condition in nature, the arsenide
sperrylite, PtAs_{2}, was described by the late S. L. Penfield, and the
senior writer of this chapter, in articles published in the Journal
(=37=, 67, 71, 1889).

_Applications of the Spectroscope._—The discovery in certain mineral
waters of the rare alkali-metals rubidium and cæsium by Bunsen and
Kirchoff in 1861 was in consequence of the application of spectroscopy
by these same scientists a short time previously to the identification
of elements imparting colors to the flame. Since that time the
employment of the spectroscope for chemical purposes has been much
extended, as it has been used in the examination of light from electric
sparks and arcs, as well as from Geissler tube discharges and from
colored solutions.

The metals rubidium and cæsium are interesting in being closely
analogous to potassium and in standing at the extreme electro-positive
end of the series of known metals. It should be noticed here that
Johnson and Allen of our Sheffield Laboratory, having obtained a good
supply of rubidium and cæsium material from the lepidolite of Hebron,
Maine, made some important researches upon these elements, accounts of
which were published in the Journal (=34=, 367, 1862; =35=, 94, 1863).
They established the atomic weight of cæsium, thus correcting Bunsen’s
determination which was unsatisfactory on account of the small quantity
and impurity of his material. Pollucite, a mineral rich in cæsium, which
had been found in very small amount on the Island of Elba, has more
recently been obtained in large quantities—hundreds of pounds—at Paris,
Maine, and its vicinity. This American pollucite was first analyzed and
identified by the senior writer of this article (=41=, 213, 1891), and
later (=43=, 17, 1892 _et seq._) the results of many investigations on
cæsium and rubidium compounds, in which the junior writer played an
important part, carried out in Sheffield Laboratory, were published in
the Journal.

The application of the spectroscope led to the discovery of thallium in
1861 by Crookes of England, and to that of indium in 1863 by Reich and
Richter in Germany. Both of these metals are extremely rare, but they
are of considerable theoretical interest. Thallium is particularly
remarkable in showing resemblances in its different compounds to several
groups of metals.

The spectroscope was employed again in connection with the discovery of
gallium in 1875 by Boisbaudran. It is in the same periodic group as
thallium and indium, and it has a remarkably low melting point, just
above ordinary room-temperature. It has been among the rarest of the
rare elements, but within two or three years a source of it has been
found in the United States in certain residues from the refining of
commercial zinc. The recent issues of the Journal (=41=, 351, 1916;
=42=, 389, 1916) show that Browning and Uhler of Yale have availed
themselves of this new material in order to make important chemical and
physical researches upon this metal.

_Germanium._—The discovery of germanium in the mineral argyrodite in
1886 by Winkler revealed a curious metal which gives a white sulphide
that may be easily mistaken for sulphur and which is volatilized
completely when its hydrochloric acid solution is evaporated, so that it
is evasive in analytical operations. This element had been predicted
with much accuracy by Mendeléeff, and it is rather closely related to
tin.

A few years after the discovery of germanium, Penfield published in the
Journal (=46=, 107, 1893; =47=, 451, 1894) some analyses of argyrodite,
correcting the formula given by Winkler to the mineral; also he
described canfieldite, an analogous mineral from Bolivia, in which a
large part of the germanium was replaced by tin.

_The Rare Earths._—Before the year 1818 two rare earths, the oxides of
yttrium and cerium, were known in an impure condition. Since that time
about fourteen others have been discovered as associates of the first
two. The rare earths are peculiar from the fact that many of them are
always found mixed together in the minerals containing them, and also
from the circumstance that most of them are remarkably similar in their
chemical reactions and consequently exceedingly difficult to separate
from each other. In many cases multitudes of fractional precipitations
or crystallizations are needed to obtain pure salts of a number of these
metals. The solutions of the salts of several of these elements give
characteristic absorption bands when examined spectroscopically by the
use of transmitted light.

No important practical application has been found for any of these
earthy oxides, except that about one per cent of cerium oxide is mixed
with thorium oxide in incandescent gas-mantles in order to obtain
greatly increased luminosity.

_The Inactive Gases._—As long ago as 1785, Cavendish, that remarkable
Englishman who first weighed the world and first discovered the
composition of water, actually obtained a little argon in a pure
condition by sparking atmospheric nitrogen with oxygen converting it
into nitric acid (another discovery of his) and absorbing the excess of
oxygen. The volume of this residual gas as estimated by him corresponds
very closely to the volume of argon in the atmosphere, as now known.

It was more than a century later, in 1894, that Rayleigh and Ramsay
discovered argon in the air. Lord Rayleigh had found that atmospheric
nitrogen was about one-half per cent heavier than chemical nitrogen, a
fact which led to the investigation. It was only necessary to repeat
Cavendish’s experiment on a large scale, or to absorb oxygen with hot
copper and nitrogen with hot magnesium, in order to obtain argon. The
gas attracted much attention, both on account of having but a single
atom in its molecule, and particularly because it failed to enter into
chemical combination of any kind. This gas has been used of late for
filling the bulbs of incandescent electric lamps in cases where a gas
pressure without chemical action is desired.

In 1890 and 1891, Hillebrand published in the Journal (=40=, 384, 1890:
=42=, 390, 1891) a series of analyses of the mineral uraninite and
reported in some samples of the mineral as much as 2·5 per cent of an
inactive gas. Hillebrand examined the gas spectroscopically but, just
missing an important discovery, he detected only the spectrum lines of
nitrogen. Ramsay, in searching for argon in some sort of natural
combination, and doubtless remembering Hillebrand’s work, heated some
cleveite, a variety of uraninite, and obtained, not argon, but a new
gas. This gave a yellow spectrum-line corresponding to a line previously
observed in the light of the sun’s corona and attributed to an element
in the sun called helium. Helium, therefore, in 1895 had been found on
the earth. This gas is a constant constituent of uranium minerals, as it
is produced by the breaking down of radioactive elements. It has been
found in very small quantity in the atmosphere, and is the most
difficult of all known gases to liquefy, as its boiling point, as shown
by Onnes in 1908, is only 4° above the absolute zero. It has not yet
been solidified.

In 1898 Ramsay and Travers, by the use of ingenious methods of
fractional distillation and absorption by charcoal, obtained three other
much rarer inactive gases from the atmosphere which they called neon,
krypton and xenon.

The inactive gases are all colorless, and as they form no chemical
compounds they are characterized by their densities, which give their
atomic weights, by their boiling points, and by their characteristic
Geissler-tube spectra.

The gaseous radium emanation, or niton, belongs also to the inactive
group, and it was also collected and studied by Ramsay who was compelled
to work with only 0·0001 cc. of it, as the volume obtained by heating
radium salts is very small. It is an evanescent element, disappearing
within a few days on account of radioactive disintegration. Meanwhile it
glows brilliantly when liquefied and cooled to the temperature of liquid
air. It has an atomic weight of 222, four units below that of radium,
and the difference is considered as due to the loss by radium of an atom
of helium in passing into the emanation.

_The Radioactive Elements._—The discovery of radium in 1898 by Madame
Curie, and the study of that and other radioactive elements has produced
a profound effect upon chemical theory. It was found that the two
elements of the highest atomic weights, uranium and thorium, are always
spontaneously decomposing into other elements at a fixed rate of speed
which can be controlled by no artificial means, and that the elements
resulting from these decompositions likewise undergo spontaneous changes
into still other elements at greatly varying rates of speed, forming in
each case a remarkable series of temporary elements. These
transformations are accompanied by the emission at enormous velocities
of three kinds of rays, one variety of which has been shown to consist
of helium atoms. The greater number of the elements formed in these
transformations have not as yet been obtained in a pure condition, and
they are known only in connection with their radioactivity, volatility,
etc.; but radium and niton, two of these products, have been obtained in
a pure condition, so that their atomic weights and their places in the
periodic system have been fixed.

We owe much of our knowledge of the radioactive transformations to the
researches of Rutherford and of Soddy, and of their co-workers, but one
of the important products of the transformation of uranium, an element
which he called ionium, was characterized by Boltwood of Yale (=25=,
365, 1908).

Radium and niton, apart from their radioactive properties, resemble
barium and the inert gases of the atmosphere, respectively. The rates at
which their progenitors produce them, and the rates at which they
themselves decompose, bring about a state of equilibrium after a time.
Therefore a given amount of uranium, which decomposes exceedingly
slowly, can yield even after thousands of years only a very small
proportional quantity of undecomposed radium, one-half of which
disappears in about 2500 years, because the amount decomposed must
eventually be equal to the amount produced. The first conclusive
evidence that radium is a product of the decomposition of uranium was
given by Boltwood in the Journal (=18=, 97, 1904). He found that all
uranium minerals contain radium; and the amount of radium present is
always proportional to the amount of uranium, which shows the genetic
relation between the two.

In the case of niton, which is produced by radium, and is called also
the radium emanation, the rate of decay is rapid, so that if the gas is
expelled from radium by heating, equilibrium is reached after a few
days, with the accumulation of the largest possible amount of niton.

The conclusion has been reached by Rutherford and others that the final
product besides helium, in the radioactive transformations, is lead, or
at least an element or elements resembling lead to such a degree that no
separation of them by chemical means is possible. Atomic weight
determinations by Richards and others have shown that specimens of lead
found in radioactive minerals give distinctly different atomic weights
from that of ordinary lead. This fact has led to the view that possibly
the atoms of the elements are not all of the same weight, but vary
within certain limits—a view that is contrary to previous conclusions
derived from the uniformity in atomic weights obtained with material
from many different sources.

The results of the investigations upon radioactivity have led to
modified views in regard to the stability of the elements in general.
There has been little or no proof obtained that any artificial
transmutation of the elements is possible, but the spontaneous
transformation of the radioactive elements brings forward the
possibility that other elements are changing imperceptibly, and that a
state of evolution exists among them. All of the radioactive changes
that we know proceed from higher to lower atomic weights, and we are
entirely ignorant of the process by which uranium and thorium must have
been produced originally.

Since radioactive changes have been found to be accompanied by the
release of vast amounts of energy, compared with which the energy of
chemical reactions is trivial, a new aspect in regard to the structure
of atoms has arisen,—they must be complex in structure, the seats of
enormous energy.

The determination of the amount of radium in the earth’s crust has
indicated that the heat produced by it is amply sufficient to supply the
loss of heat due to radiation, and this source of heat is regarded by
many as the cause of volcanic action. The sun’s radiant heat also has
been supposed to be supplied by radioactive action, so that the older
views regarding the limitation of the age of the earth and the solar
system on account of loss of heat have been considerably modified by our
knowledge of radioactivity.


                         _Physical Chemistry._

The application of physical methods as aids to chemical science began in
early times, and some of these, such as the determinations of gas and
vapor densities, specific heats, and crystalline forms have been
mentioned already in this article. Within recent times physical
chemistry has greatly developed and a few of its important achievements
will now be described.

_Molecular Weight Determinations._—Gas and vapor densities in connection
with Avogadro’s principle, formed the only basis for molecular weight
determinations until comparatively recent times. The early methods of
Gay-Lussac and Dumas for vapor density were supplemented in 1868 by the
method of Hofmann, whereby vapors were measured under diminished
pressure over mercury. In 1878 Victor Meyer introduced a simpler method
depending upon the displacement of air or other gas by the vapor in a
heated tube. As refractory tubes, such as those of porcelain or even
iridium, could be used in this method, molecular weights at extremely
high temperatures were determined with interesting results. For
instance, it was found that iodine vapor, which shows the molecule I_{2}
at lower temperatures, gradually becomes monatomic with rise in
temperature, that sulphur vapor dissociates from S_{8} to S_{2} under
similar conditions, and that most of the metals, including silver, have
monatomic vapors.

In 1883 and later it was pointed out by Raoult that the molecular
weights of substances could be found from the freezing points of their
solutions, but this method was complicated from the fact that salts,
strong acids and strong bases behaved quite differently from other
substances in this respect, and allowances had to be made for the types
of substances used. The complication was afterwards explained by the
ionization theory of Arrhenius. Better apparatus for this method was
soon devised by Beckmann, who introduced also a method depending upon
the boiling points of solutions, and these two methods are still the
standard ones for determining molecular weights in solution. They are
very extensively employed by organic chemists.

It has been found that the majority of substances when dissolved have
the same molecular weight as in the gaseous condition, provided that
they can be volatilized at comparable temperatures. For instance,
sulphur in solution has the formula S_{8}, iodine is I_{2} and the
metals are monatomic.

_Van’t Hoff’s Law and Arrhenius’s Theory of Ions._—Modern views on
solutions date largely from 1886, when van’t Hoff called attention to
the relations existing between the osmotic pressure exerted by dissolved
substances and gas pressure.

Pfeffer, a botanist, was the first to measure osmotic pressure (1877).
Basing his conclusions chiefly upon Pfeffer’s determinations, van’t Hoff
formulated a new and highly important law, which may be stated as
follows: The osmotic pressure exerted by a substance in solution is
equal to the gas pressure that the substance would exert if it were a
gas at the same temperature and the same volume. Further investigations
have fully established the fact that molecules in dilute solution obey
the simple laws of gases.

It was pointed out by van’t Hoff that salts, strong acids and strong
bases showed marked exceptions to his law in exerting much greater
osmotic pressures than those calculated for them.

The next year in 1887, Arrhenius explained this abnormal behavior of
salts, strong acids and strong bases by assuming that they dissociate
spontaneously into ions when they dissolve, and that these more numerous
particles act like molecules in producing osmotic pressure. He showed
that these exceptional substances all conduct electricity in solution,
while those conforming with van’t Hoff’s law do not, and according to
his theory the ions become positively or negatively charged when they
are formed, and these charged ions conduct the current. For example a
molecule of sodium chloride was supposed to give the two ions Na^+ and
Cl^-, thus exerting twice as much osmotic pressure as a single molecule.

Determinations of osmotic pressure or related values, such as depression
of the freezing point and of electric conductivity, indicated that
ionization could not be regarded as complete in any case except in
exceedingly dilute solutions, and that the extent of ionization varied
with different substances. The fact that osmotic pressures and electric
conductivities gave closely agreeing results in regard to the extent of
ionization in various cases, is the strongest evidence in support of the
theory.

It was difficult at first for many chemists to believe that atoms, such
as those of sodium and chlorine, and groups such as NH_{4} and SO_{4}
could exist independently in solution, even though electrically charged.
However, the theory rapidly gained ground and is now accepted by nearly
every chemist as a satisfactory explanation of many facts.

During recent years, many investigations relating to osmotic pressure
and ionization have been carried out in the United States, but only the
work of Morse, A. A. Noyes, and the late H. C. Jones can be merely
alluded to here. It should be mentioned that the eminent author of the
ionic hypothesis gave the Silliman Memorial course of lectures at Yale
in 1911 on Theories of Solution.

_Colloidal Solutions._—Graham, an English chemist, in 1861 was the first
to make a distinction between substances forming true solutions, which
he called crystalloids, and those of a gummy nature resembling glue,
which in solution do not diffuse readily through parchment membranes, as
crystalloids do, and which he called colloids. The separation of
colloids by means of parchment was called dialysis, and this process has
come into extensive use in preparing pure colloidal solutions. Slow
diffusion is now regarded as characteristic of colloids rather than
their gummy condition.

Colloidal solutions occupy an intermediate position between true
solutions and suspensions, resembling one or the other according to the
kind of colloid and the fineness of division. By preparing filters with
pores of varying degrees of fineness, Bechold has been able to separate
colloids from each other in accordance with the size of their particles.
It has also been possible to prepare different solutions of a colloid
varying gradually from one in which the particles were undoubtedly in
suspension to one which had many of the properties of a true solution.

Beginning in 1889, Carey Lea described in the Journal (=37=, 476, 1889
_et seq._) a variety of methods for preparing colloidal solutions of the
metals, consisting in general of treating solutions of metallic salts
with mild reducing agents. His work on colloidal silver was particularly
extensive and interesting. Solutions of this kind have recently yielded
some extremely interesting results by means of the ultra-microscope, an
apparatus devised by Zsigmondy and Siedentopf. A very intense beam of
light is passed through the solution and observed at right angles with a
powerful microscope. Under these conditions, particles much too small to
be seen by other means, reveal their presence by reflected light. It has
been possible in a very dilute solution of known strength to count the
particles and thus to calculate their size. The smallest colloidal
particles measured in this way were of gold and were shown to have
approximately ten times the diameter, or 1000 times the volume,
attributed to ordinary molecules. It is of interest that the particles
appear in rapid motion corresponding to the well-known Brownian
movement.

The chemistry of colloids has now assumed such importance that it may be
considered as a separate branch of the science. It has its own technical
journal and deals largely with the chemistry of organic products. All
living matter is built up of colloids, and hæmoglobin, starch, proteins,
rubber and milk are examples of colloidal substances or solutions. Among
inorganic substances, many sulphides, silicic acid, and the amorphous
hydroxides, like ferric hydroxide, frequently act as colloids.

_Law of Mass Action._—Berthollet about the beginning of the last century
was the first chemist to study the effect of mass, or more correctly,
the concentration of substances on chemical action. His views summarized
by himself are as follows: “The chemical activity of a substance depends
upon the force of its affinity and upon the mass which is present in a
given volume.” The development of this idea, which is fundamentally
correct, was greatly hindered by the fact that Berthollet drew the
incorrect conclusion that the composition of chemical compounds depended
upon the masses of the substances combining to produce them, a
conclusion in direct contradiction to the law of definite proportions,
and since this view was soon disproved by Proust and others,
Berthollet’s law in its other applications received no immediate
attention. Mitchell, however, pointed out in the Journal (=16=, 234,
1829) the importance of Berthollet’s work, and Heinrich Rose in 1842
again called attention to the effect of mass, mentioning as one
illustration the effect of water and carbonic acid in decomposing the
very stable natural silicates. Somewhat later several other chemists
made important contributions to the question of the influence of
concentration upon chemical action, but it was the Norwegians, Guldberg
and Waage, who first formulated the law of mass action in 1867.

This law has been of enormous importance in chemical theory, since it
explains a great many facts upon a mathematical basis. It applies
particularly to equilibrium in reversible reactions, where it states
that the product of the concentrations on the one side of a simple
reversible equation bears a constant relation to the products of the
concentrations on the other side, provided that the temperature remains
constant. In cases of this kind where two gases or vapors react with two
solids, the latter if always in excess may be regarded as constant in
concentration, and the law takes on a simpler aspect in applying only to
the concentrations of the gaseous substances. For example, in the
reversible reaction

                 3Fe + 4H_{2}O ⇄ Fe_{3}O_{4} + 4H_{2},

which takes place at rather high temperatures, a definite mixture of
steam and hydrogen at a definite temperature will cause the reaction to
proceed with equal rapidity in both directions, thus maintaining a state
of equilibrium, provided that both iron and the oxide are present in
excess. If, however, the relative concentrations of the hydrogen and
steam are changed, or even if the temperature is changed, the reaction
will proceed faster in one direction than in the other until equilibrium
is again attained.

The principle of mass action also explains why it is sometimes possible
for a reversible reaction to become complete in either direction. For
instance, in connection with the reaction that has just been considered,
if steam is passed over heated iron and if hydrogen is passed over the
heated oxide, the gaseous product in each case is gradually carried
away, and the reaction continually proceeds faster in one direction than
in the other until it is complete, according to the equations

               3Fe + 4H_{2}O → 3Fe_{3}O_{4} + 4H_{2}, and

               Fe_{3}O_{4} + 4H_{2} → 3Fe + 4H_{2}O.

Many other well-known and important facts, both chemical and physical,
depend upon this law. It explains the circumstance that a vapor-pressure
is not dependent upon the amount of the liquid that is present; it also
explains the constant dissociation pressure of calcium carbonate at a
given temperature, irrespective of the amounts of carbonate and oxide
present; in connection with the ionic theory, it furnishes the reason
for the variable solubility of salts due to the presence of electrolytes
containing ions in common; and it elucidates Henry’s law which states
that the solubilities of gases are proportional to their pressures.

Ostwald, more than any other chemist, has been instrumental in making
general applications of this law, and he made particularly extensive use
of it in connection with analytical chemistry in a book upon this
subject which he published.

_The Phase Rule._—In 1876 Willard Gibbs of Yale published a paper in the
Proceedings of the Connecticut Academy of Science on the “Equilibrium of
Heterogeneous Substances,” and two years later he published an abstract
of the article in the Journal (=16=, 441, 1878). He had discovered a new
law of nature of momentous importance and wide application which is
called the “Phase-Rule” and is expressed by a very simple formula.

The application of this great discovery to chemical theory was delayed
for ten years, partly, perhaps, because it was not sufficiently brought
to the attention of chemists, but largely it appears because it was not
at first understood, since its presentation was entirely mathematical.

It was Rooseboom, a Dutch chemist, who first applied the phase-rule. It
soon attracted profound attention, and the name of Willard Gibbs
attained world-wide fame among chemists. When Nernst, who is perhaps the
most eminent physical chemist of the present time, was delivering the
Silliman Memorial Lectures at Yale a few years ago, he took occasion to
place a wreath on the grave of Willard Gibbs in recognition of his
achievements.

To understand the rule, it is necessary to define the three terms,
introduced by Gibbs, _phase_, _degrees of freedom_ and _component_.

By the first term, is meant the parts of any system of substances which
are mechanically separable. For instance, water in contact with its
vapor has two phases, while a solution of salt and water is composed of
but one. The degrees of freedom are the number of physical conditions,
including pressure, temperature and concentration, which can be varied
independently in a system without destroying a phase. The exact
definition of a component is not so simple, but in general, the
components of a system are the integral parts of which it is composed.
Any system made up of the compound H_{2}O, for instance, whether as ice,
water or vapor, contains but one component, while a solution of salt and
water contains two. Letting P, F, and C stand for the three terms, the
phase-rule is simply

                             F = C + 2 − P

that is, the number of degrees of freedom in a system in equilibrium
equals the number of components, plus two, minus the number of phases.
The rule can be easily understood by means of a simple illustration. In
a system composed of ice, water and water vapor, there are three phases
and one component and therefore

                           F = 1 + 2 − 3 = 0

Such a system has no degrees of freedom. This means that no physical
condition, pressure or temperature can be varied without destroying a
phase, so that such a system can only exist in equilibrium at one fixed
temperature, with a fixed value for its vapor-pressure.

[Illustration: J. William Gibbs]

For instance, if the system is heated above the fixed temperature, ice
disappears and if the pressure is raised, vapor is condensed. If this
same system of water alone contains but two phases, for instance, liquid
and vapor, F = 1 + 2 − 2 = 1, or there is one degree of freedom. In such
a system, one physical condition such as temperature can be varied
independently, but only one, without destroying a phase. For instance,
the temperature may be raised or lowered, but for every value of
temperature there is a corresponding value for the vapor-pressure. One
is a function of the other. If both values are varied independently, one
phase will disappear, either vapor condensing entirely to water or the
reverse. Finally if the system consists of one phase only, as water
vapor, F = 2, or the system is divariant, which means that at any given
temperature it is possible for vapor to exist at varying pressures.

The illustration which has been given relates to physical equilibrium,
but the rule is applicable to cases involving chemical changes as well.
In comparing the phase-rule with the law of mass action, it will be
noticed that both have to do with equilibrium. The great advantage of
the former is that it is entirely independent of the molecular condition
of the substances in the different phases. For instance, it makes no
difference so far as the application of the rule is concerned, whether a
substance in solution is dissociated, undissociated or combined with the
solvent. In any case, the solution constitutes one phase. On the other
hand, the rule is purely qualitative, giving information only as to
whether a given change in conditions is possible. The law of mass action
is a quantitative expression so that when the value of the constant is
once known, the change can be calculated which takes place in the entire
system if the concentration of one substance is varied. The law,
however, requires a knowledge of the molecular condition of the reacting
substances, which may be uncertain or unknown, and chiefly on this
account it has, like the phase-rule, often only a qualitative
significance.

The phase rule has served as a most valuable means of classifying
systems in equilibrium and as a guide in determining the possible
conditions under which such systems can exist. As illustrations of its
practical application, van’t Hoff used it as an underlying principle in
his investigations on the conditions under which salt deposits have been
formed in nature, and Rooseboom was able by its means to explain the
very complicated relations existing in the alloys of iron and carbon
which form the various grades of wrought iron, steel and cast iron.

_Thermochemistry._—This branch of chemistry has to do with heat evolved
or absorbed in chemical reactions. It is important chiefly because in
many cases it furnishes the only measure we have of the energy changes
involved in reactions. To a great extent, it dates from the discovery by
Hess in 1840 of a fundamental law which states that the heat evolved in
a reaction is the same whether it takes place in one or in several
stages. This law has made it possible to calculate the heat values of a
large number of reactions which cannot be determined by direct
experiment.

Thermochemistry has been developed by a comparatively few men who have
contributed a surprisingly large number of results. Favre and
Silbermann, beginning shortly after 1850, improved the apparatus for
calorimetric determinations, which is called the calorimeter, and
published many results. At about the same time Julius Thomsen, and in
1873 Berthelot, began their remarkable series of publications which
continued until recently. Thomsen’s investigations were published in
1882 in =4= volumes. It is probably safe to say that the greater part of
the data of thermochemistry was obtained by these two investigators. The
bomb calorimeter, an apparatus for determining heat values by direct
combustion, was developed by Berthelot. The recent work of Mixter at
Yale, published in the Journal, and of Richards at Harvard should be
mentioned particularly. Mixter’s work in this field began in 1901 (=12=,
347). Using an improved bomb calorimeter, he has developed a method of
determining the heats of formation of oxides by combustion with sodium
peroxide. By this same method as well as by direct combustion in oxygen,
he has obtained results which appear to equal or excel in accuracy any
which have ever been obtained in his field of work. Richards’s work has
consisted largely of improvements in apparatus. He developed the
so-called adiabatic calorimeter which practically eliminates one of the
chief errors in thermal work caused by the heating or cooling effect of
the surroundings. This modification is being generally adopted where
extremely accurate work is required.


                          _Organic Chemistry._

One hundred years ago qualitative tests for a few organic compounds were
known, the elements usually occurring in them were recognized, and some
of them had been analyzed quantitatively, but organic chemistry was far
less advanced than inorganic, and almost the whole of its enormous
development has taken place during our period.

Berzelius made a great advance in the subject by establishing the fact,
which had been doubted previously, that the elements in organic
compounds are combined in constant, definite proportions. In 1823 Liebig
brought to light the exceedingly important fact of isomerism by showing
that silver fulminate had the same percentage composition as silver
cyanate, a compound of very different properties. Isomeric compounds
with identical molecular weight as well as the same composition have
since been found in very many cases, and they have played a most
important part in determining the arrangements of atoms in molecules.
They have been found to be very numerous in many cases. For instance,
three pentanes with the formula C_{5}H_{12}are known, all that are
possible according to theory, and in each case the structure of the
molecule has been established. On theoretical grounds it has been
calculated that 802 isomeric compounds with the formula C_{13}H_{28} are
possible, while with more complex formulas the numbers of isomers may be
very much greater.

A particularly interesting case of isomerism was observed by Wöhler in
1828, when he found that ammonium cyanate changes spontaneously into
urea

                      (NH_{4}CNO → N_{2}H_{4}CO).

This was the first synthesis of an organic compound from inorganic
material, and it overthrew the prevailing view that vital forces were
essential in the formation of organic substances. A great many natural
organic compounds have been made artificially since that time, and some
of them, such as artificial alizarin, indigo, oil of wintergreen, and
vanillin, have more or less fully replaced the natural products. The
preparation of a vast number of compounds not known in nature, many of
which are of practical importance as medicines, dyes, explosives, etc.,
has been another great achievement of organic chemistry.

The development of our present formulas for organic compounds, by means
of which in many cases the relative positions of the atoms can be shown
with the greatest confidence, has been gradual. Formulas based on the
dualistic idea of Berzelius were used for some time, type-formulas, with
the employment of compound radicals, came later, the substitution of
atoms or groups of atoms for others in chemical reactions came to be
recognized, but one of the most important steps was the recognition of
the quadrivalence of carbon and the general application of valency to
atoms by Kekulé about 1858. This led directly to the use of modern
structural formulas which have been of the greatest value in the
theoretical interpretation of organic reactions. It was Kekulé also who
proposed the hexagonal ring-formula for benzene, C_{6}H_{6}, which led
to exceedingly important theoretical and practical developments. The
details of the formulas for many other rings and complex structures have
been established since that time, and there is no doubt that the
remarkable achievements in organic chemistry during the past sixty years
have been much facilitated by the use of these formulas.

Many important researches in organic chemistry have been carried out in
the United States, and the activity in this direction has greatly
increased in recent years. In this connection the large amount of work
of this kind accomplished in the Sheffield Laboratory, at present under
the guidance of Professor T. B. Johnson, should be mentioned.

It has happened that comparatively few publications on organic chemistry
have appeared in the Journal, but it may be stated that the preparation
of chloroform and its physiological effects were described by Guthrie
(=21=, 64, 1832). Unknown to him, it had been prepared by Souberain, a
French chemist, the previous year, but the former was the first to
describe its physiological action. Silliman gave a sample to Doctor Eli
Ives of the Yale Medical School, who used it to relieve a case of
asthma. This was the first use of chloroform in medical practice (=21=,
405, 1832). Guthrie also described in the Journal (=21=, 284, 1832) his
new process for converting potato starch into glucose, a method which is
essentially the same as that used to-day in converting cornstarch into
glucose. Lawrence Smith (=43=, 301, 1842 _et seq._), Horsford (=3=, 369,
1847 _et seq._), Sterry Hunt (=7=, 399, 1849), Carey Lea (=26=, 379,
1858 _et seq._), Remsen (=5=, 179, 1873 _et seq._), and others have
contributed articles on organic chemistry.


                       _Agricultural Chemistry._

Until near the middle of the nineteenth century, it was believed that
plants, like animals, used organic matter for food, and depended chiefly
upon the humus of the soil for their growth. This view was held even
long after it was known that plant leaves absorb carbon dioxide and give
off oxygen, and after the ashes of plants had been accurately analyzed.

This incorrect view was overthrown by the celebrated German chemist,
Liebig, who made many investigations upon the subject, and, properly
interpreting previous knowledge, published a book in 1840 upon the
application of chemistry to agriculture and physiology in which he
maintained that the nutritive materials of all green plants are
inorganic substances, namely, carbon dioxide, water, ammonia (nitrates),
sulphates, phosphates, silica, lime, magnesia, potash, iron, and
sometimes common salt. He drew the vastly important conclusion that the
effective fertilization of soils depends upon replenishing the inorganic
substances that have been exhausted by the crops.

The fundamental principles set forth by Liebig have been confirmed, and
it has been found that the fertilizing constituents most commonly
lacking in soils are nitrogen compounds, phosphates, and potassium
salts, so that these have formed the important constituents of
artificial fertilizers. Liebig himself found that humus is valuable in
soils, because it absorbs and retains the soluble salts.

The foundation established by Liebig in regard to artificial fertilizers
has led to an enormous application of these materials, much to the
advantage of the world’s food supply.

It was Liebig’s belief, in accordance with the prevailing views, that
decay and putrefaction as well as alcoholic and other fermentations were
spontaneous processes, and when the eminent French chemist, Pasteur, in
1857, explained fermentation as directly caused by yeast, an
epoch-making discovery which led to the explanation of decay and
putrefaction by bacterial action and to the germ-theory of disease, the
explanation was violently opposed by Liebig and other German chemists.
Pasteur’s view prevailed, however, and since that time it has been found
that various kinds of bacteria are responsible for the formation of
ammonia from nitrogenous organic matter and also for the change of
ammonia into the nitrates that are available as plant-food.

The long-debated question as to the availability of atmospheric nitrogen
for plant-food was settled in 1886 by the discovery of Hellriegel that
bacteria contained in nodules on the roots, especially of leguminous
plants, are capable of bringing nitrogen into combination and furnishing
it to the plants.

No more than an allusion can be made to agricultural experiment stations
where soils, fertilizers, foods and other products are examined, and
where other problems connected with agriculture are studied.

The late S. W. Johnson of Yale studied with Liebig and subsequently did
much service for agricultural chemistry in this country, by his
investigations, his teaching, and his writings. His book, “How Crops
Grow,” published in 1868, gave an excellent account of the principles of
agricultural chemistry. He did much to bring about the establishment of
agricultural experiment stations in this country, and for a long time he
was the director of the Connecticut Station.

In the Journal, as early as 1827, Amos Eaton (=12=, 370) published a
simple method for the mechanical analysis of soils to determine their
suitability for wheat-culture, and Hilgard, between 1872 and 1874,
described an elaborate study of soil-analysis. J. P. Norton, a Yale
professor, in 1847 (=3=, 322) published an investigation on the analysis
of the oat, which was awarded a prize of fifty sovereigns by a Scotch
agricultural society, while Johnson, Atwater, and others have
contributed articles on the analysis of various farm products.


                    _Industrial Acids and Alkalies._

One hundred years ago sulphuric acid was manufactured on a comparatively
very small scale in lead chambers. In 1818, an English manufacturer of
the acid introduced the modern feature of using pyrites in the place of
brimstone, while the Gay-Lussac tower in 1827 and the Glover tower in
1859 began to be applied as great improvements in the chamber process.
Within about twenty years the contact process, employing platinized
asbestos, has replaced the old chamber process to a large extent. It has
the advantage of producing the concentrated acid, or the fuming acid,
directly.

During our period the manufacture of sulphuric acid has increased
enormously. Very large quantities of it have been used in connection
with the Leblanc soda process in its rapid development. It came to be
employed extensively for absorbing ammonia in the illuminating-gas
industry, which was in its infancy one hundred years ago. New industries
such as the manufacture of “superphosphates” as artificial fertilizers,
the refining of petroleum, the manufacture of artificial dyestuffs and
many other modern chemical products have greatly increased the demand
for it, while its employment in the production of nitric and other
acids, and for many other purposes not already mentioned, has been very
great.

The manufacture of nitric acid has been greatly extended during our
period on account of its employment for producing explosives, artificial
dyestuffs, and for many other purposes. Chile saltpeter became available
for making it about 1852. This acid has been manufactured recently from
atmospheric nitrogen and oxygen by combining them by the aid of powerful
electric discharges. This process has been used chiefly in Norway where
water-power is abundant, as it requires a large expenditure of energy. A
still more recent method for the production of nitric acid depends upon
the oxidation of ammonia by air with the aid of a contact substance,
such as platinized asbestos.

The production of ammonia, which was very small a hundred years ago, has
been vastly increased in connection with the development of the
illuminating-gas industry and the employment of by-product coke ovens.
This substance is very extensively used in refrigerating machines and
also in a great many chemical operations, including the Solvay soda
process. Ammonium salts are of great importance also as fertilizers in
agriculture. The conversion of atmospheric nitrogen into ammonia on a
commercial scale is a recent achievement. It has been accomplished by
heating calcium carbide, an electric-furnace product made from lime and
coke, with nitrogen gas, thus producing calcium cyanamide, and then
treating this cyanamide with water under proper conditions. Another
method devised by Haber consists in directly combining nitrogen and
hydrogen gases under high pressure with the aid of a contact substance.

Leblanc’s method for obtaining sodium carbonate from sodium chloride by
first converting the latter into the sulphate by means of sulphuric acid
and then heating the sulphate with lime and coal in a furnace was
invented as early as 1791, but it was not rapidly developed and did not
gain a foothold in England until 1826 on account of a high duty on salt
up to that time. Afterwards the process flourished greatly in connection
with the sulphuric acid industry upon which it depended, and with the
bleaching-powder industry which utilized the hydrochloric acid
incidentally produced by it, and, of course, in connection with soap
manufacture and many other industries in which the soda itself was
employed.

About 1866 the Solvay process appeared as a rival to the Leblanc
process. This depends upon the precipitation of sodium bicarbonate from
salt solutions by means of carbon dioxide and ammonia, with the
subsequent recovery of the ammonia. It has displaced the older process
to a large extent, and it is carried on extensively in this country, for
instance, at Syracuse, New York.

Other processes for soda depend upon the electrolysis of sodium chloride
solutions. In this case caustic soda and chlorine are the direct
products, and the chlorine thus produced and liquefied by pressure in
steel cylinders, has become an important commercial article.

In earlier times wood-ashes were the source of potash and potassium
salts. Wurtz in the Journal (=10=, 326, 1850) suggested the availability
of New Jersey greensand as a source of potash and showed how this
mineral could be decomposed, but it does not appear that this mineral
has ever been utilized for the purpose. About 1861 the German
potash-salt deposits began to be developed, and these have since become
the chief source of this material. At present many efforts are being
made to obtain potassium compounds from other sources, such as brines,
cement-kiln dust, and feldspar and other minerals but thus far the
results have not satisfied the demand.


                             _Conclusion._

This account of chemical progress has given only a limited view of small
portions of the subject, because the amount of available material is so
vast in comparison with the space allowed for its presentation. Since
the Journal has published comparatively little organic chemistry, it was
decided to make room for a better presentation of other things by giving
only a brief discussion of this exceedingly active and important branch
of the science. For similar reasons industrial and metallurgical
chemistry, and other branches besides, in spite of their great growth
and importance, have been neglected, except for some incidental
references to them, and some account of a few of the more important
industrial chemicals.

It appears that we have much reason to be proud of the advances in
chemistry that have been made during the Journal’s period, and of the
part that the Journal has taken in connection with them, and there seems
to be no doubt that this progress has not diminished during more recent
times.

The present tendency of chemical research is evidently towards a still
greater development of organic chemistry, and an increased application
of physics and mathematics to chemical theory and practice.

The very great improvements that have been made in chemical education,
both in the number of students and the quality of instruction, during
the period under discussion, and particularly in rather recent times,
gives promise for excellent future progress.


                                _Note._

Footnote 153:

  It appears that the most accurate experimental demonstration ever made
  of this law was that of E. W. Morley, published in the Journal (=41=,
  220, 276, 1891). He showed that 2·0002 volumes of hydrogen combine
  with one volume of oxygen.




                                   XI
                    A CENTURY’S PROGRESS IN PHYSICS

                             By LEIGH PAGE


 _Dynamics._—At the beginning of the nineteenth century mechanics was
the only major branch of physical science which had attained any
considerable degree of development. Two centuries earlier, Galileo’s
experiments on the rate of fall of iron balls dropped from the top of
the Leaning Tower of Pisa, had marked the origin of dynamics. He had
easily disproved the prevalent idea that even under conditions where air
resistance is negligible heavy bodies would fall more rapidly than light
ones, and further experiments had led him to conclude that the increase
in velocity is proportional to the _time_ elapsed, and not to the
_distance_ traversed, as he had at first supposed. Less than a century
later Newton had formulated the laws of motion in the same words in
which they are given to-day. These laws of motion, coupled with his
discovery of the law of universal gravitation, had enabled him to
correlate at once the planetary notions which had proved so puzzling to
his predecessors. His success gave a tremendous stimulus to the
development and extension of the fundamental dynamical principles that
he had brought to light, which culminated in the work of the great
French mathematicians, Lagrange and Laplace, a little over a hundred
years ago.

Newton’s laws of motion, it must be remembered, apply only to a
particle, or to those bodies which can be treated as particles in the
problem under consideration. In his “Mécanique Analytique” Lagrange
extended these principles so as to make it possible to treat the motion
of a connected system by a method almost as simple as that contained in
the second law of motion. Instead of three scalar equations for each of
the innumerably large number of particles involved, he showed how to
reduce the ordinary dynamical equations to a number equal to that of the
degrees of freedom of the system. This is made possible by a combination
of d’Alembert’s principle, which eliminates the forces due to the
connections between the particles, and the principle of virtual work,
which confines the number of equations to the number of possible
independent displacements. The aim of Lagrange was to make dynamics into
a branch of analysis, and his success may be inferred from the fact that
not a single diagram or geometrical figure is to be found in his great
work.

_Celestial Mechanics._—Almost simultaneously with the publication of the
“Mécanique Analytique” appeared Laplace’s “Mécanique Celeste.” Laplace’s
avowed aim was to offer a complete solution of the great dynamical
problem involved in the solar system, taking into account, in addition
to the effect of the sun’s gravitational field, those perturbations in
the motion of each planet caused by the approach and recession of its
neighbors. So successful was his analysis of planetary motions that his
contemporaries believed that they were not far from a complete
explanation of the world on mechanical principles. Laplace himself was
undoubtedly convinced that nothing was needed beyond a knowledge of the
masses, positions, and initial velocities of every material particle in
the universe in order to completely predetermine all subsequent motion.

The greatest triumph of these dynamical methods was to come half a
century later. The planet Uranus, discovered in 1781 by the elder
Herschel, was at that time the farthest known planet from the sun. But
the orbit of Uranus was subject to some puzzling variations. After
sifting all the known causes of these disturbances, Leverrier in France
and Adams in England independently reached the conclusion that another
planet still more remote from the sun must be responsible, and computed
its orbit. Leverrier communicated to Galle of Berlin the results of his
calculations, and during the next few days the German astronomer
discovered Neptune within one degree of its predicted position!

[Illustration: H. A. Newton]

We shall mention but one other achievement of the methods of celestial
mechanics. Those visitors of the skies, the comets, which become so
prominent only to fade away and vanish perhaps forever, had interested
astronomers from the earliest times. Soon after the discovery of the law
of gravitation, Newton had worked out a method by which the elements of
a comet’s orbit can be computed from observations of its position. It
was found that the great majority of these bodies move in nearly
parabolic paths and only a few in ellipses. Of the latter the most
prominent is the brilliant comet first observed by Halley in 1681. It
has reappeared regularly at intervals of seventy-six years; the last
appearance in the spring of 1910 is no doubt well remembered by the
reader. Kant had considered comets to be formed by condensing solar
nebulæ, whereas Laplace had maintained that they originate in matter
which is scattered throughout stellar space and has no connection with
the solar system. A study of the distribution of inclinations of comet
orbits by H. A. Newton (=16=, 165, 1878) of New Haven substantiated
Laplace’s hypothesis, and led to the conclusion that the periodic comets
have been captured by the attraction of those planets near to which they
have passed. Of these comets a number have comparatively short periods,
and are found to have orbits which are in general only slightly inclined
to those of the planets, and are traversed in the same direction.
Moreover, the fact that the orbit of each of these comets comes very
close to that of Jupiter made it seem probable that they have been
attached to the solar system by the attraction of this planet. Further
confirmation of this hypothesis was furnished by H. A. Newton’s (=42=,
183 and 482, 1891) explanation of the small inclination of their orbits
and the scarcity of retrograde motions among them.

In 1833 occurred one of the greatest meteoric showers of history.
Olmstead (=26=, 132, 1834) and Twining (=26=, 320, 1834) of New Haven
noticed that these shooting stars traverse parallel paths, and were the
first to suggest that they must be moving in swarms in a permanent
orbit. From an examination of all accessible records, H. A. Newton
(=37=, 377, 1864; =38=, 53, 1864) was able to show that meteoric showers
are common in November, and of particular intensity at intervals of 33
or 34 years. He confidently predicted a great shower for Nov. 13th,
1866, which not only actually occurred but was followed by another a
year later, showing that the meteoric swarm extended so far as to
require two years to cross the earth’s orbit. H. A. Newton (=36=, 1,
1888) in America and Adams in England took up the study of meteoric
orbits with great interest, and the former concluded that these orbits
are in every sense similar to those of the periodic comets, implying
that a swarm of meteors originates in the disintegration of a comet. In
fact Schiaparelli actually identified the orbit of the Perseids, or
August meteors, with Tuttle’s comet of 1862, and shortly after the orbit
of the Leonids, or November meteors, was found to be the same as that of
Tempel’s comet.

_Electromagnetism._—During the eighteenth century much interest had been
manifested in the study of electrostatics and magnetism. Du Fay,
Cavendish, Michell and Coulomb abroad and Franklin in America had
subjected to experimental investigation many of the phenomena of one or
both of these sciences, and in the early years of the nineteenth century
Poisson developed to a remarkable extent the analytical consequences of
the law of force which experiment had revealed. Both Laplace and he made
much use of the function to which Green gave the name “potential” in
1828, and which is such a powerful aid in solving problems involving
magnetism or electricity at rest.

Meantime electric currents had been brought under the hand of the
experimenter by the discoveries of Galvani and Volta. Large numbers of
cells were connected in series, and interest seemed to lie largely in
producing brilliant sparks or fusing metals by means of a heavy current.
Hare (=3=, 105, 1821) of the University of Pennsylvania constructed a
battery consisting of two troughs of forty cells each, so arranged that
the coppers and zincs can be lowered simultaneously into the acid and
large currents obtained before polarization has a chance to interfere.
This “deflagrator” was used to ignite charcoal in the circuit, or melt
fine wires, and was for some time the most powerful arrangement of its
kind. That “galvanism” is something quite different from static
electricity was the opinion of many investigators; Hare considered the
heat developed to be the distinguishing mark of the electric current. He
says: “It is admitted that the action of the galvanic fluid is upon or
between atoms; while mechanical electricity when uncoerced, acts only
upon masses. This difference has not been explained unless by my
hypothesis, in which caloric, of which the influence is only exerted
between atoms, is supposed to be a principal agent in galvanism.”

Questioning minds were beginning to suspect that there must be some
connection between electricity and magnetism. For lightning had been
known to make magnets of steel knives and forks, and Franklin had
magnetized a sewing needle by the discharge from a Leyden jar. Finally
Oersted of Copenhagen undertook systematic investigation of the effect
of electricity on the magnetic needle. His researches were without
result until during the course of a series of lectures on “Electricity,
Galvanism, and Magnetism” delivered during the winter of 1819–20 it
occurred to him to investigate the action of an electric current on a
magnetic needle. At first he placed the wire bearing the current at
right angles to the needle, with, of course, no result; then it occurred
to him to place it parallel. A deflection was observed, for to his
surprise the needle insisted on turning until perpendicular to the wire.

Oersted’s discovery that an electric current exerts a couple on a
magnetic needle was followed a few months later by Ampère’s
demonstration before the French Academy that two currents flowing in the
same direction attract each other, while two in opposite directions
repel. The story goes that a critic attempted to belittle this discovery
by remarking that as it was known that two currents act on one and the
same magnet, it was obvious that they would act upon each other.
Whereupon Arago arose to defend his friend. Drawing two keys out of his
pocket he said, “Each of these keys attracts a magnet; do you believe
that they therefore attract each other?”

A few years later Ampère showed how to express quantitatively the force
between current elements, and indeed developed to a considerable degree
the equivalence between a closed circuit carrying a current and a
magnetic shell. So convincing was his analysis and so thorough his
discussion of the subject, that Maxwell said of this memoir half a
century later, “The whole, theory and experiment, seems as if it had
leaped, full grown and full armed, from the brain of the ‘Newton of
electricity.’ It is perfect in form and unassailable in accuracy; and it
is summed up in a formula from which all the phenomena may be deduced,
and which must always remain the cardinal formula of electrodynamics.”

Shortly afterwards the dependence of a current on the conductivity of
the wire used and the grouping of cells employed, was made clear by the
work of Ohm. Many of his results were obtained independently by Joseph
Henry (=19=, 400, 1831) of the Albany Academy, who described in 1831 a
powerful electromagnet in which a great many coils of wire insulated
with silk were wound around an iron core and connected in parallel with
a single cell. He remarks in this paper that with long wires, as in the
telegraph, many cells arranged in series should be used, whereas for
several short wires connected in parallel a single cell with large
plates is more efficient.

_Current Induction._—Impressed by the fact that electric charges have
the power of inducing other charges on neighboring conductors without
coming into contact with them, Faraday was engaged in investigating the
possibility of an analogous phenomenon in the case of electric currents.
His idea at first seems to have been that a current should induce
another current in any closed conducting circuit which happens to be in
its vicinity. Experiment readily showed the falsity of this conception,
but a brief deflection of the galvanometer in the secondary circuit was
noticed at the instant of making and breaking the current in the
primary. Further experiments showed that thrusting a permanent steel
magnet into a coil connected to a galvanometer caused the needle to
deflect. In fact Faraday’s report to the Royal Society on November 24th,
1831, contains a complete account of all experimental methods available
for inducing a current in a closed circuit.

While Faraday is entitled to credit for the discovery of current
induction by virtue of the priority of his publication, it must not pass
unnoticed that Henry obtained many of the same experimental results
independently and some even earlier. Henry was at this time instructor
in mathematics at the Albany Academy, and seven hours of teaching a day
made it well nigh impossible to carry on original research except during
the vacation month of August. As early as the summer of 1830 he had
wound 30 feet of copper wire around the armature of a horseshoe
electromagnet and connected it to a galvanometer. When the magnet was
excited, a momentary deflection was observed. “I was, however, much
surprised,” he says, “to see the needle suddenly deflected from a state
of rest to about 20° to the east, or in a contrary direction, when the
battery was withdrawn from the acid, and again deflected to the west
when it was re-immersed.” In addition a deflection was obtained by
detaching the armature from the magnet, or by bringing it again into
contact. Had the results of these experiments been published promptly,
America would have been entitled to credit for the most important
discovery of the greatest of England’s many great experimenters. But
Henry desired first to repeat his experiments on a larger scale, and
while new magnets were being constructed, the news of Faraday’s
discovery arrived. This occasioned hasty publication of the work already
done in an appendix to volume =22=, 1832, of the Journal.

At almost the same time Henry made another important discovery and this
time he was anticipated by no other investigator in making public his
results. In the paper already referred to be describes the phenomenon
known to-day as self-induction. “When a small battery is moderately
excited by diluted acid and its poles, which must be terminated by cups
of mercury, are connected by a copper wire not more than a foot in
length, no spark is perceived when the connection is either formed or
broken; but if a wire thirty or forty feet long be used, instead of the
short wire, though no spark will be perceptible when the connection is
made, yet when it is broken by drawing one end of the wire from its cup
of mercury a vivid spark is produced.... The effect appears somewhat
increased by coiling the wire into a helix; it seems to depend in some
measure on the length and thickness of the wire; I can account for these
phenomena only by supposing the long wire to become charged with
electricity which by its reaction on itself projects a spark when the
connection is broken.”

Soon after, Henry went to Princeton and there continued his experiments
in electromagnetism. No difficulty was experienced in inducing currents
of the third, fourth and fifth orders by using the first secondary as
primary for yet another secondary circuit, and so on (=38=, 209, 1840).
The directions of these currents of higher orders when the primary is
made or broken proved puzzling at first, but were satisfactorily
explained a year later (=41=, 117, 1841). In addition induced currents
were obtained from a Leyden jar discharge. Faraday failed to find any
screening effect of a conducting cylinder placed around the primary and
inside the secondary. Henry examined the matter, and found that the
screening effect exists only when the induced current is due to a make
or break of the primary circuit, and not when it is caused by motion of
the primary.

Henry’s work was mainly descriptive; it remained for Faraday to develop
a theory to account for the phenomena discovered and to prepare the way
for quantitative formulation of the laws of current induction. This he
did in his representation of a magnetic field by means of lines of
force; a conception which he found afterwards to be equally valuable
when applied to electrostatic problems. Every magnet and every current
gives rise to these closed curves; in the case of a magnet they thread
it from south pole to north, while a straight wire bearing a current is
surrounded by concentric rings. The connection between lines of force
and the induction of currents is contained in the rule that a current is
induced in a closed circuit only when a change takes place in the number
of lines of force passing through it. Furthermore the dependence of the
current strength on the conductivity of the wire employed has led to
recognition of the fact that it is the electromotive force and not the
current itself which is conditioned by the change in magnetic flux.

Great interest was attached to the utilization of the newly discovered
forces of electromagnetism. In 1831 Henry (=20=, 340, 1831) described a
reciprocating engine depending on magnetic attraction and repulsion, and
C. G. Page (=33=, 118, 1838; =49=, 131, 1845) devised many others. The
latter’s most important work, however, was the invention of the
Ruhmkorff coil. In 1836 (=31=, 137, 1837) he found the strongest shocks
to be obtained, from a secondary coil of many windings forming a
continuation of a primary of half the number of turns. His perfection of
the self-acting circuit breaker (=35=, 252, 1839) widened the usefulness
of the induction coil, and his substitution of a bundle of iron wires
for a solid iron core (=34=, 163, 1838) greatly increased its
efficiency.

_Conservation of Energy._—Perhaps the most important advance of the
nineteenth century has been the establishment of the principle of
conservation of energy. Despite the fact that the “principe de la
conservation des force vives” had been recognized by the French
mathematicians of the early part of the century, the application of this
principle even to purely mechanical problems was contested by some
scientists. Through the early numbers of the Journal runs a lively
controversy as to whether there is not a loss of power involved in
imparting momentum to the reciprocating parts of a steam engine only to
check the motion later on in the stroke. Finally Isaac Doolittle (=14=,
60, 1828), of the Bennington Iron Works, ends the discussion by the
pertinent remark: “If there be, as is contended by one of your
correspondents, a loss of more than one third of the power, in
transforming an alternating rectilinear movement into a continuous
circular one by means of a crank, I should like to be informed what
would be the effect if the proposition were reversed, as in the case of
the common saw mill, and in many other instances in practical
mechanics.”

A realization of the equivalence of heat and mechanical work did not
come until the middle of the century, in spite of the conclusive
experiments of the American Count Rumford and the English Davy before
the year 1800. So firmly enthroned was the caloric theory, according to
which heat is an indestructible fluid, that evidence against it was
given scant consideration. In fact the success of the analytical method
introduced by Fourier in 1822 for the solution of problems in conduction
of heat only added to the difficulties of the adherents of the kinetic
theory. But recognition of heat as a form of energy was on the way, and
when it came it made its appearance almost simultaneously in half a
dozen different places. Perhaps Robert Mayer of Heilbronn was the first
to state explicitly the new principle. His paper “On the Forces of
Inorganic Nature” was refused publication in Poggendorff’s Annalen, but
fared better at the hands of another editor. During the next few years
Joule determined the mechanical equivalent of heat experimentally by a
number of different methods, some of which had already been devised by
Carnot. Of those he used, the most familiar consists in churning up a
measured mass of water by means of paddles actuated by falling weights
and calculating the heat developed from the rise in temperature.
However, the work of the young Manchester brewer received little
attention from the members of the British Association before whom it was
reported until Kelvin showed them its significance and attracted their
interest to it. Meanwhile Helmholtz had completed a very thorough
disquisition on the conservation of energy not only in dynamics and heat
but in other departments of physics as well. His paper on “Die Erhaltung
der Kraft” was frowned upon by the members of the Physical Society of
Berlin before whom he read it, and received the same treatment as
Mayer’s from the editor of Poggendorff’s Annalen. Helmholtz’s “Kraft,”
like the “vis viva” of other writers, is the quantity which Young had
already christened energy. Not many years elapsed, however, until the
convictions of Mayer, Joule, Kelvin and Helmholtz became the most
clearly recognized of all physical principles. As early as 1850 Jeremiah
Day (=10=, 174, 1850), late president of Yale College, admitted the
improbability of constructing a machine capable of perpetual motion,
even though the “imponderable agents” of electricity, galvanism and
magnetism be utilized.

_Thermodynamics._—The importance of the principle of conservation of
energy lies in the fact that it unites under one rule such diverse
phenomena as gravitation, electromagnetism, heat and chemical action.
Another principle as universal in its scope, although depending upon the
coarseness of human observations for its validity rather than upon the
immutable laws of nature, was foreshadowed even before the first law of
thermodynamics, or principle of conservation of energy, was clearly
recognized. This second law was the consequence of efforts to improve
the efficiency of heat engines. In 1824 Carnot introduced the conception
of cyclic operations into the theory of such engines. Assuming the
impossibility of perpetual motion, he showed that no engine can have an
efficiency greater than that of a reversible engine. Finally Clausius
expressed concisely the principle toward which Carnot’s work had been
leading, when he asserted that “it is impossible for a self-acting
machine, unaided by any external agency, to convey heat from one body to
another at a higher temperature.” Kelvin’s formulation of the same law
states that “it is impossible, by means of inanimate material agency, to
derive mechanical effect from any portion of matter by cooling it below
the temperature of the coldest of the surrounding objects.”

The consequences of the second law were rapidly developed by Kelvin,
Clausius, Rankine, Barnard (=16=, 218, 1853, _et seq._) and others.
Kelvin introduced the thermodynamic scale of temperature, which he
showed to be independent of such properties of matter as condition the
size of the degree indicated by the mercury thermometer. This scale,
which is equivalent to that of the ideal gas thermometer, was used
subsequently by Rowland in his exhaustive determination of the
mechanical equivalent of heat by an improved form of Joule’s method. He
found different values for different ranges in temperature, showing that
the specific heat of water is by no means constant. Since then
electrical methods of measuring this important quantity have been used
to confirm the results of purely mechanical determinations.

The definition of a new quantity, entropy, was found necessary for a
mathematical formulation of the second law of thermodynamics. This
quantity, which acts as a measure of the unavailability of heat energy,
was given a new significance when Boltzmann showed its connection with
the probability of the thermodynamic state of the substance under
consideration. If two bodies have widely different temperatures, a large
amount of the heat energy of the system is available for conversion into
mechanical work. From the macroscopic point of view this is expressed by
saying that the entropy is small, or if the motions of the individual
molecules are taken into account, the probability of the state is low.
The interpretation of entropy as the logarithm of the thermodynamic
probability has thrown much light on the meaning of this rather abstruse
quantity. Gibbs’s “Elementary Principles in Statistical Mechanics”
treats in detail the fundamental assumptions involved in this point of
view, its limitations and its consequences. In his “Equilibrium of
Heterogeneous Substances”[154] he had already extended the principle of
thermal equilibrium to include substances which are no longer
homogeneous. The value of the chemical potential he introduced
determines whether one phase is to gain at the expense of another or
lose to it. It is unfortunate that the analytical rigor and austerity of
his reasoning combined with lack of mathematical training on the part of
the average chemist, delayed true appreciation of his work and full
utilization of the new field which he opened up.

_Liquefaction of Gases._—Meanwhile the problem of liquefying gases was
attracting much attention on the part of experimental physicists.
Faraday had succeeded in making liquid a number of substances which had
hitherto been known only in the gaseous state. His method consists in
evolving the gas from chemicals placed in one end of a bent tube, the
other end of which is immersed in a freezing mixture. The high pressure
caused by the production of the gas combined with the low temperature is
sufficient to bring about liquefaction in many cases. Failure with other
more permanent gases was unexplained until the researches of Andrews in
1863 showed that no amount of pressure will produce liquefaction unless
the temperature is below a certain critical value. The method of
reducing the temperature in use to-day depends on a fact discovered by
Kelvin and Joule in connection with the free expansion of a gas. These
investigators allowed the gas to escape through a porous plug from a
chamber in which the pressure was relatively high. With the single
exception of hydrogen, the effect of the sudden expansion is to cool the
gas, and even with it cooling is found to take place after the
temperature has been made sufficiently low. By this method all known
gases have been liquefied. Helium, with a boiling point of –269°C, or
only 4°C. above the absolute zero, was the last to be made a liquid,
finally yielding to the efforts of Kammerlingh Onnes in 1907. This
investigator[155] finds that at temperatures near the absolute zero the
electrical conductivity of certain substances undergoes a profound
modification. For example, a coil of lead shows a superconductivity so
great that a current once started in it persists for days after the
electromotive force has ceased to act.

_Electrodynamics._—Faraday’s representation of electric and magnetic
fields by lines of force had been of great value in predicting the
results of experiments in electromagnetism. But a more mathematical
formulation of the laws governing these phenomena was needed in order to
make possible quantitative development of the theory. This was supplied
by Maxwell in his epoch-making treatise on “Electricity and Magnetism.”
Starting with electrostatics and magnetism, he gives a complete account
of the mathematical methods which had been devised for the solution of
problems in these branches of the subject, and then turning to Ampère’s
work he shows how the Lagrangian equations of motion lead to Faraday’s
law if the single assumption is made that the magnetic energy of the
field is kinetic. In the treatment of open circuits Maxwell’s intuition
led to a great advance, the introduction of the displacement current.
Consider a charged condenser, the plates of which are suddenly connected
by a wire. A current will flow through the wire from the positively
charged plate to the negative, but in the gap between the two plates the
conduction current is missing. So convinced was Maxwell that currents
must always flow in _closed_ circuits, that he postulated an electrical
displacement in the medium between the plates of a charged condenser,
which disappears when the condenser is short-circuited. Thus even in the
so-called open circuit the current flows along a closed path.

Maxwell’s theory of the electromagnetic field is based essentially on
Faraday’s representation by lines of force of the strains and stresses
of a universal medium. So it is not surprising that he was led to a
consideration of the propagation of waves through this medium. The
introduction of the displacement current made the form of the
electrodynamic equations such as to yield a typical wave equation for
space free from electrical charges and currents. Moreover, the
disturbance was found to be transverse, and its velocity turned out to
be _identical with that of light_. The conclusion was irresistible. That
light could consist of anything but electromagnetic waves of extremely
short length was inconceivable. In fact so certain was Maxwell of this
deduction from theory that he felt it altogether unnecessary to resort
to the test of experiment. For the electromagnetic theory explained so
many of the details which had been revealed by experiments in light,
that no doubt of its validity could be entertained. Even dispersion
received ready elucidation on the assumption that the dispersing medium
is made up of vibrators having a natural period comparable with that of
the light passing through it.

[Illustration: James Clerk Maxwell]

Maxwell’s book was published in 1873. Fifteen years later, Hertz,[156]
at the instigation of Helmholtz, succeeded in detecting experimentally
the electromagnetic waves predicted by Maxwell’s theory. His oscillator
consisted of two sheets of metal in the same plane, to each of which was
attached a short wire terminating in a knob. The knobs were placed
within a short distance of each other, and connected to the terminals of
an induction coil. By reflection standing waves were formed, and the
positions of nodes and loops determined by a detector composed of a
movable loop of wire containing an air gap. Thus the wave length was
measured. Hertz calculated the frequency of his radiator from its
dimensions, and then computed the velocity of the disturbance. In spite
of an error in his calculations, later pointed out by Poincaré, he
obtained very nearly the velocity of light for waves traveling through
air, but a velocity considerably smaller for those propagated along
wires. Subsequent work by Lecher, Sarasin and de la Rive, and Trowbridge
and Duane (=49=, 297, 1895; =50=, 104, 1895) cleared up this
discrepancy, and showed the velocity to be in both cases identical with
that of light. The last-named investigators increased the size of the
oscillator until it was possible to measure the frequency by
photographing the spark in the secondary with a rotating mirror. The
positions of nodes and loops were obtained by means of a bolometer after
the secondary had been tuned to resonance with the vibrator. The
velocity thus found for electromagnetic waves along wires is within
one-tenth of one percent of the accepted value of the velocity of light.
Hertz’s later experiments showed that waves in air suffer refraction and
diffraction, and he succeeded in polarizing the radiation by passing it
through a grating constructed of parallel metallic wires.

In order to satisfy the law of action and reaction, it is found
necessary to attribute a quasi-momentum to electromagnetic waves. When a
train of such waves is absorbed, their momentum is transferred to the
absorbing body, while if they are reflected an impulse twice as great is
imparted. This consequence of theory, foreseen by Maxwell and developed
in detail by Poynting, Abraham and Larmor, has been verified by the
experiments of Lebedew, and Nichols and Hull.[157] The latter used a
delicate torsion balance from which was suspended a couple of silvered
glass vanes. In order to eliminate the effect of impulses imparted by
the molecules of the residual gas, such as Crookes had observed in his
radiometer, readings were made at many different pressures and the
ballistic rather than the static deflection recorded. After the pressure
produced by light from a carbon arc had been measured, the intensity of
the radiation was determined with a bolometer. Preliminary experiments
indicated the existence of a pressure of the order expected, and later
more careful measurements showed good quantitative agreement with
theory. This pressure had already found an important application in
Lebedew’s explanation of the solar repulsion of comet’s tails. These
tails are made up of enormous swarms of very minute particles, and as
the comet swings around the sun they suffer a repulsion due to the
pressure of the intense solar radiation which counteracts the sun’s
gravitational attraction. Hence the tail, instead of following after the
comet in its orbit, points in a direction away from the sun.

Some uncertainty existed as to whether a convection current produces a
magnetic field. A compass needle is deflected by a current from a
Daniell cell; is the same effect obtained when a conductor is charged
electrostatically and then whirled around the needle by means of an
insulating handle? The experimental difficulties involved in settling
this question are realized when the enormous difference between the
electrostatic and electromagnetic units of current is taken into
consideration. For a sphere one centimeter in radius, charged to a
potential of 20,000 volts, and revolving in a circle sixty times a
second, constitutes a current of little over a millionth of an ampere.

This problem was undertaken by Rowland (=15=, 30, 1878) in Helmholtz’s
laboratory at Berlin in 1876. A hard rubber disk coated on both sides
with gold was charged and rotated about a vertical axis at a rate of
sixty revolutions a second. On reversing the sign of the electrification
on the disk, the astatic needle hung above its center showed a
deflection of over five millimeters. The current was calculated in
electrostatic units from the charge on the disk and its rate of motion,
and in electromagnetic units from the magnetic deflection. The ratio of
these two quantities gave fair agreement with its theoretical value, the
velocity of light.

Although the result of this experiment was confirmed by Rowland and
Hutchinson in 1889, Crémieu was convinced by an investigation carried
out at Paris in 1900 that the Rowland effect did not exist. Consequently
further repetition of the experiment was desirable. So the following
year Adams (=12=, 155, 1901) arranged two rings of eight spheres each so
that they could be rotated about their common axis from fifty to sixty
times a second. One set of spheres was connected by brushes to the
positive pole of a battery of 20,000 volts, the other to the negative
pole. The deflection of a nearby magnetometer needle was observed when
the electrification of the two rings was reversed, and from the reading
so obtained the ratio of the electromagnetic to the electrostatic unit
of current computed. This quantity was found to differ from the velocity
of light by only a few percent. This experiment and the even more
exhaustive investigations carried out by Pender, both independently and
in collaboration with Crémieu, finally convinced the scientific world
that a convection current produces the same magnetic field as a
conduction current of the same magnitude.

In discussing the ponderomotive force experienced in a magnetic field by
a conductor through which a current is passing, Maxwell had said, “It
must be carefully remembered, that the mechanical force which urges a
conductor carrying a current across the lines of magnetic force, acts,
not on the electric current, but on the conductor which carries it.”
Hall (=19=, 200, 1880), one of Rowland’s students, questioned this
statement, and determined to put it to the test of experiment. Efforts
to find an increase in the resistance of a wire placed at right angles
to the lines of magnetic force were unsuccessful. So the current was
passed through a moderately broad strip of gold leaf and the effect of
the magnetic field on the equipotential lines investigated. The results
obtained confirmed Hall’s belief that the force exerted by the field
acts on the current itself, and is transmitted through it to the
conductor. Further investigation (=20=, 161, 1880) revealed the same
deflection of equipotential lines in thin strips of other metals,
although the effect was found to be reversed in iron.

During the closing years of the nineteenth century occurred three events
of far reaching importance. The electron was isolated, and its charge
and mass measured by J. J. Thomson in England; X-rays were discovered by
Röntgen in Germany; and the first indications of radioactivity were
found by Becquerel in France. The first two are certainly to be
attributed largely to the great advances which had been made in
obtaining high vacua, and the last two might not have occurred so soon
had it not been for the photographic plate.

_The Electron._—The atomic theory of electricity dates from the time of
Faraday. His experiments on electrolysis showed that each monovalent
atom or radical, whatever its nature, carries the same charge, each
bivalent ion a charge twice as great. Only a lack of knowledge of the
number of atoms in a gram of the dissociated salt prevented him from
calculating the value of the elementary charge. As the discharge of
electricity through gases at low pressures became a subject for
experimental investigation, another line of approach to the study of the
atom of electricity was opened up. As early as the seventies Hittorf and
Goldstein had observed that a shadow is cast by a screen placed in front
of the cathode of a Crookes tube. Varley suggested that the cathode rays
producing the shadow consist of “attenuated particles of matter,
projected from the negative pole by electricity.” The discovery that
these rays are deflected by a magnetic field led English physicists to
the conclusion that they must be composed of charged particles, and the
direction of the deflection was such as to require the charge to be
negative. Hertz contested this view on the ground that his experiments
showed the rays to be unaffected by an electrostatic field, and
suggested that they consist of etherial disturbances. Finally Perrin
succeeded in passing the rays into a metal cylinder which received from
them a negative charge, and Lenard showed how excessively minute these
negatively charged particles must be by actually passing them through a
thin sheet of aluminium in the wall of a vacuum tube, and detecting
their presence in the air outside. Conclusive information as to the
nature of the electron, as it was named by Johnstone Stoney, was
supplied by the classic experiments of J. J. Thomson.[158] First he
showed that Hertz’s failure to find a deflection when a stream of
electrons passes between the plates of a charged condenser was due to
the screening effect of the gaseous ions produced by the discharge. With
a much more highly evacuated tube he found no difficulty in obtaining a
deflection in an electrostatic field. By using crossed electric and
magnetic fields the deflection produced by one was just balanced by that
caused by the other, and from the field strengths employed both the
velocity of the particles and the ratio (_e_)/(_m_) of charge to mass
was calculated. The former was found to be about one-tenth the velocity
of light, but the most startling result of the experiment was that the
same value of (_e_)/(_m_) was obtained no matter what residual gas was
contained in the tube or of what metal the cathode was made.

To calculate _e_ and then _m_ other methods are necessary. C. T. R.
Wilson has shown that in supersaturated air, water drops form easily on
charged molecules, and that negative ions are more effective in causing
condensation than positive ones. By making use of the results of this
research Thomson has been able to measure the elementary charge. For
suppose a stream of negative ions to pass through supersaturated air. A
little drop forms on each charged particle, and the cloud of condensed
vapor settles to the bottom of the vessel. The charge carried and the
mass of water deposited can be measured directly. Stokes’ law for the
rate of fall of a minute particle through a gaseous medium enables the
average size of the drops to be computed from the observed rate of
descent of the cloud. Hence the number of drops formed and the charge
carried by each follows at once. H. A. Wilson improved the method by
noting the effect of an electric field upon the rate of fall of the
charged drops, and subsequent experiments undertaken by Millikan[159]
have been of such a character as to enable him to follow the motion of a
single drop. Instead of water, the latter uses oil drops less than one
ten-thousandth of a centimeter in diameter. A drop, after one or more
electrons have attached themselves to it, is actually _weighed_ in terms
of the charge on its surface by applying an upward electric force just
sufficient to balance the force of gravity. Then its weight is
independently obtained from the density of the oil and the radius of the
drop as determined by the rate of fall when the electric field is
absent. Comparison of these two expressions gives 4·774(10)^{–10}
electrostatic units for the elementary charge. Combining this result
with the value of (_e_)/(_m_) found by Thomson, the mass of the electron
comes out to be about one eighteen-hundredth that of an atom of the
lightest known element, hydrogen.

That the electron is a fundamental constituent of all matter is attested
by the fact that charge and mass are the same regardless of the source
or manner of production. Whether emitted by a heated metal, under the
action of ultra-violet light, from a radioactive substance, by a body
exposed to X-rays, as a result of friction, it is the same negatively
charged particle that constitutes the cathode ray of the discharge tube.
Moreover, it makes its effect felt indirectly in many other phenomena,
and from an investigation of some of these the ratio of charge to mass
can be determined independently. Of such perhaps the most interesting is
the Zeeman effect.

_Spectroscopy._—Early in the nineteenth century Fraunhofer had observed
that the solar spectrum is crossed by a large number of dark lines.
Their presence was unexplained until in 1859 Kirchhoff and Bunsen showed
“that a colored flame, the spectrum of which contains bright sharp
lines, so weakens rays of the color of these lines when they pass
through it, that dark lines appear in place of bright lines as soon as
there is placed behind the flame a light of sufficient intensity, in
which the lines are otherwise absent.” For intra-atomic oscillators must
have the natural frequency of the radiation which they emit, and
consequently resonance will take place when they are exposed to rays of
this frequency coming from an outside source, and selective absorption
ensue. By comparing the bright lines in the spectra of metallic vapors
made luminous by a gas flame with the dark lines in the sun’s spectrum
these investigators showed that many of the common terrestrial elements
exist in the sun. The interest in spectroscopy grew rapidly. The
excellent diffraction gratings made by Rutherfurd were succeeded by the
superior concave gratings of Rowland. In 1877 Draper (=14=, 89, 1877)
announced the discovery of the bright lines of oxygen in the solar
spectrum, but his interpretation of his photographs has not been
corroborated by the work of later investigators. Langley (=11=, 401,
1901), by the aid of his newly invented bolometer, succeeded in
detecting the emission of energy from the sun in the infra-red in
amounts far exceeding that contained in the visible spectrum. In 1842
Doppler drew attention to the fact that motion of the source should
cause a displacement of the spectral lines, the shift being to the blue
if the light is approaching and to the red if it is receding, and a few
years later Fizeau suggested the application of Doppler’s principle to
the measurement of the velocity of a star moving in the line of sight.
Thus the spectroscope has been able to supply one of the deficiencies of
the telescope, and the two together are sufficient to reveal all
components of stellar motion. When spectra formed by light from the
sun’s limb and from its center are compared, the same effect reveals the
rotation of the sun about its axis. (C. S. Hastings, =5=, 369, 1873; C.
A. Young, =12=, 321, 1876.)

_Further Evidence of the Electron._—In 1845 Faraday discovered a
rotation of the plane of polarization when light passes in the direction
of the lines of force through a piece of glass placed between the poles
of an electromagnet. Examination of the spectrum from a glowing vapor
situated between the poles of a magnet, however, failed to reveal any
effect of the field. The latter problem was attacked anew by Zeeman[160]
in 1896, and with the aid of the improved appliances of modern science
he succeeded in detecting a broadening of the lines. Later experiments
with more powerful apparatus resolved these broadening lines into
several components.

Lorentz[161] showed at once how the electron theory furnishes an
explanation of the Zeeman effect. He found that when the source is
viewed at right angles to the lines of magnetic force, a spectral line
should be split into three components. Of these he predicted that the
middle, or undisplaced component, would be found to be polarized at
right angles to the direction of the field, and the other components
parallel to the field. When the light proceeds from the source in a
direction parallel to the magnetic lines of force, two components only
should be formed, and these should be circularly polarized in opposite
senses. Moreover, from the separation of the components can be
calculated the ratio of charge to mass of the electronic vibrator which
is responsible for the emission of radiant energy. Zeeman’s experiments
confirmed Lorentz’s theory in every detail, and yielded a value of
(_e_)/(_m_) in substantial agreement with that obtained for cathode
rays. Subsequent research, however, has shown that in many cases more
components are found than the elementary theory calls for. Hale has
detected the Zeeman effect in light from sun spots, proving that these
blemishes on the sun’s face are vortices caused by whirling swarms of
electrified particles. Recently Stark and Lo Surdo have found a similar
splitting up of lines in the spectrum formed by light from canal rays
(rays of positively charged particles) passing through an intense
electric field. This phenomenon has as yet received no adequate
explanation.

On discovering that an electric current is capable of producing a
magnetic field, Ampère had suggested that the magnetic properties of
such substances as iron might be explained on the assumption of
molecular currents. The electron theory considers these currents to be
due to the revolution, inside the atom, of negatively charged particles
about an attracting nucleus. It occurred to Richardson that this motion
should give the atom the properties of a gyrostat. Hence if an iron bar
be rotated about its axis, the atoms should orient themselves so as to
make their axes more nearly parallel to the axis of rotation. Thus its
rotation should cause the bar to become a magnet. Barnett[162] has
tested this hypothesis, and has found the effect Richardson had
predicted. From the strength of the magnetization produced, the value of
(_e_)/(_m_) can be computed. Barnett finds a value somewhat smaller than
that for cathode rays, but of the right order of magnitude and sign.
Einstein and De Haas have detected the inverse of this effect, i. e.,
the rotation of an iron rod when it is suddenly magnetized.

_X-Rays._—In 1895, on developing a plate which had been lying near a
vacuum tube, Röntgen[163] was surprised to find distinct markings on it.
As the plate had never been exposed to light, it was necessary to
suppose the effect to be due to some new and unknown type of radiation.
Further investigation showed that this radiation originates at the
points where cathode rays impinge on the glass walls of the tube.
Besides being able to pass with ease through all but the most dense
material objects X-rays were found to have the power of ionizing gases
through which they pass and ejecting electrons from metal surfaces
against which they strike. The points at which these electrons are
produced are in turn the sources of secondary X-rays whose properties
are characteristic of the metal from which they come.

Röntgen’s discovery excited intense interest among laymen as well as in
scientific circles. Of the many X-ray photographs taken, those of Wright
(=1=, 235, 1896) of Yale were the first to be produced in this country.
His experiments were made immediately on receipt of the news of
Röntgen’s research, and resulted in the publication of a number of
photographs showing the translucency for these rays of paper, wood, and
even aluminium.

As X-rays are undeviated by electric or magnetic fields, Schuster, and
later Wiechert and Stokes, suggested that they might be electromagnetic
waves of the same nature as light, but much shorter and less regular.
The great objection to this hypothesis was the failure either to refract
or diffract these rays. In fact Bragg contended that they were not
etherial disturbances at all, but consisted of neutral particles moving
with very high velocities. Finally Laue[164] demonstrated their
undulatory nature by showing that diffraction took place under proper
conditions. Just as the distance between adjacent lines of a grating
must be comparable to the wave length of light for a spectrum to be
formed, a periodic structure with a grating space of their very much
shorter wave length is necessary to diffract X-rays. Such a structure is
altogether too fine to be made by human tools. Nature, however, has
already prepared it for man’s use. The distance between the atoms of a
crystal is just right to make it an excellent X-ray grating, and Laue
had no difficulty in obtaining diffraction patterns when Röntgen rays
were passed through a block of zincblende. The distance between adjacent
atoms of this cubic crystal can be computed at once from its density and
molecular weight, and then the wave length of the radiation calculated
from the deviation suffered. In this way X-rays are found to have a
length less than one thousandth as great as visible light. Further study
of this phenomenon, particularly by the two Braggs, father and son, has
revealed many of the structural details of more complicated crystals.

The most significant investigation in the field opened up by Laue’s
discovery is that undertaken by Moseley[165] only a couple of years
before he lost his life in the trenches at Gallipoli. Using many
different metals as anticathodes in a vacuum tube, he measured the
frequencies of the characteristic rays emitted. He found that if the
elements are arranged in order of increasing atomic weight, the square
roots of the characteristic frequencies form an arithmetical
progression. If to each element is assigned an integer, beginning with
one for hydrogen, two for helium, and so on, the square root of the
frequency of the characteristic radiation is found to be proportional to
this atomic number. Even though Uhler has shown recently that over wide
ranges Moseley’s law does not hold within the limits of experimental
error, there is undoubtedly much significance to be attached to this
simple relation.

_Radioactivity._—The year following the discovery of X-rays, Becquerel
found that a photographic plate is similarly affected by radiations from
uranium salts. Two years later the Curies separated from pitchblende the
very active elements polonium and radium. Passage of the rays from these
substances through electric and magnetic fields revealed the existence
of three types. The alpha rays have been shown by Rutherford and his
co-workers to be positively charged helium atoms; the beta rays are very
rapidly moving electrons; and the gamma rays are electromagnetic pulses
of the same nature as X-rays but somewhat shorter. In 1902 Rutherford
and Soddy advanced the theory of atomic disintegration, according to
which the emission of a ray is an indication of the breaking down of the
atom to a simpler form. Thus in the radioactive substances there is
going on before our eyes a continual transformation of one element into
another, a change, by the way, which appears to be in no slightest
degree either hastened or delayed by changes in temperature (H. L.
Bronson, =20=, 60, 1905) or external electrical condition of the
radioactive element. Uranium is the progenitor of a long line of
descendants, of which radium was supposed for some time to be the first
member. Boltwood (=25=, 365, 1908) of Yale, however, showed that the
slow growth of radium in uranium solutions is incompatible with this
assumption, and soon isolated an intermediate product which he named
ionium. Radium itself disintegrates into a gas known as radium
emanation, which in turn gives rise to a succession of other products.
Analyses by Boltwood (=23=, 77, 1907) of radioactive minerals from the
same locality show such a constant ratio between the amounts of uranium
and lead present that it is natural to conclude that lead is the end
product of the series. This hypothesis is confirmed by the fact that the
oldest rocks show relatively the greatest amounts of this element.

In addition to the Ionium-Radium series two others have been discovered.
Of these Boltwood’s (=25=, 269, 1908) investigations seem to indicate
that the one which starts with actinium is a collateral branch of the
radium series and comes from the same parent uranium. The other begins
with thorium and comprises ten members. As yet the end products of the
actinium and thorium series have not been identified, although there is
some reason for believing that an isotope of lead may be the final
member of the latter.

As the amount of a radioactive element which disintegrates in a given
time is proportional to the total mass present, an infinite time would
be required for the substance to be completely transformed. Hence the
life of such an element is measured by the half value period, or time
taken for half the initial mass to disintegrate. This time varies widely
for different radioactive substances, ranging from a small fraction of a
second for actinium A to five billion years for uranium. Boltwood’s
(=25=, 493, 1908) original determination of the life of radium from the
rate of its growth in a solution containing ionium gave 2000 years as
its result, although recent measurements by Miss Gleditsch (=41=, 112,
1916) agree more closely with the value 1760 years obtained by
Rutherford and Geiger from the number of alpha particles emitted.

Under the action of X-rays or the radiations from radioactive
substances, gases acquire a conductivity which has been attributed by
Thomson and Rutherford to the formation of ions. Zeleny has found that
ions of opposite sign have somewhat different mobilities in an electric
field, and experiments of Wellisch (=39=, 583, 1915) show that at low
pressures some of the negative ions are electrons. T. S. Taylor (=26=,
169, 1908 _et seq._) and Duane (=26=, 464, 1908) have investigated the
ionization produced by alpha particles, and Bumstead (=32=, 403, 1911
_et seq._) has studied the emission of electrons from metals which are
bombarded by these rays. The investigations of Franck and Hertz, and
McLennan and Henderson, show a significant relation between the ionizing
potential (energy which must be possessed by an electron in order to
produce an ion on colliding with an atom) and a quantity, to be
considered later in more detail, which has been introduced by Planck
into the theory of radiation.

_Methods of Science._—Scientific progress seems to follow a more or less
clearly defined path. Experimentation brings to light the hidden
processes of nature, and hypotheses are advanced to correlate the facts
discovered. As more and more phenomena are found to fit into the same
scheme, the hypotheses at first proposed tentatively, although often
only after extensive alterations, become firmly established as theories.
Finally there may appear a fundamental clash between two theories, each
of which in its respective domain seems to represent the only possible
manner in which a large group of phenomena can be correlated. The maze
becomes more perplexing at every step. At last a genius appears on the
scene, approaches the problem from a new and unsuspected point of view,
and the paradox vanishes. Such changes in point of view are the
milestones which mark the progress of science. That science is stagnant
whose only function is to collect, classify and correlate vast stores of
experimental data. The sign of vitality is the existence of clearly
defined and fundamental problems any possible solution of which seems
irreconcilable with the most basic truths of the science in question.
The greater the paradox grows, the more certain the advent of a new
point of view which will bring one step nearer the comprehensive picture
of nature which is the goal of natural philosophy.

_The Ether._—From the earliest times philosophers have been attracted by
the possibility of explaining physical phenomena in terms of an
all-pervading medium. So strong had this tendency become by the middle
of the nineteenth century that the English school of physicists were
attributing rigidity, density and nearly all the properties of material
media to the ether. In fact most physicists seemed to have forgotten
that no experiment had ever given _direct_ evidence of the existence of
such a medium. Not until the first decade of the twentieth century was
it realized that the experimental evidence actually pointed in quite the
opposite direction, and that a new point of view was needed in dealing
with those phenomena of light and electromagnetism which had been
previously described in terms of a universal medium. Some account of the
development of the ether theory and of the origin and growth of the
point of view which has its principal exemplification in the principle
of relativity is essential for an understanding of present tendencies in
formulating a philosophic basis for scientific thought.

In the time of Newton and for a century after there was much controversy
between the adherents of two irreconcilable theories of light. Hooke had
suggested that light is a wave motion traveling through a homogeneous
medium which fills all space, and Huygens had shown that the law of
refraction can be deduced at once from this hypothesis if it is assumed
that the velocity of light in a transparent body is less than that in
free ether. However, Newton, impressed by the fact that a ray obtained
by double refraction in Iceland spar differs from a ray of ordinary
light just as a rod of rectangular cross section differs from one of
circular cross section, and seeing no way of explaining this dissymmetry
in terms of a wave motion analogous to longitudinal sound waves, adhered
to the view that light consists of infinitesimal particles shot out from
the luminous body with enormous velocities. So great was his reputation
on account of his discoveries in other fields that this theory of light
held sway among his contemporaries and successors until the labors of
Young and Fresnel at the beginning of the nineteenth century definitely
established the undulatory theory. However, in spite of the fact that a
corpuscular theory of light made the assumption of an ether unnecessary
in so far as the simpler of the observed phenomena are concerned, even
Newton postulated the existence of such a medium, partly in order to
explain the more complicated results of experiments in light, and partly
in order to provide a vehicle for the propagation of gravitational
forces.

Now an ether, if it is to explain anything at all, must have at least
some of the simpler properties of material media. The most fundamental
of these, perhaps, is position in space. As a first approximation in
explaining optical phenomena on the earth’s surface, the earth might be
supposed to be at rest relative to the ether. But the establishment of
the Copernican system made the sun the center of the solar system and
gave the earth an orbital speed of eighteen miles a second. It may be
remarked parenthetically that the speed of a point on the equator due to
the earth’s diurnal rotation is quite insignificant compared to its
orbital velocity. Hence as a second approximation the sun might be
considered at rest relative to the ether and the earth as moving through
this unresisting medium.

The first indication of this motion lay in the discovery of aberration
by the British astronomer Bradley in 1728. Bradley noticed that stars
near the pole of the ecliptic describe small circles during the course
of a year, while those in the plane of the ecliptic vibrate back and
forth in straight lines, stars in intermediate positions describing
ellipses. The surprising thing, however, was that the time taken to
complete one of these small orbits is in all cases exactly a year.
Bradley concluded that the phenomenon is in some way dependent on the
earth’s motion around the sun, and he was not long in reaching the
correct explanation. For suppose the earth to be at rest. Then in
observing a star at the pole of the ecliptic it would be necessary to
keep the axis of the telescope exactly at right angles to the plane of
the earth’s orbit. However, as the earth is in motion, the telescope
must be pointed a little forward, just as in walking rapidly through the
rain an umbrella must be inclined forward so as to intercept the
raindrops which would otherwise fall on the spot to be occupied at the
end of the next step. The angle through which the telescope has to be
tilted is known as the angle of aberration, and the tangent of this
angle may easily be shown to be equal to the ratio of the velocity of
the earth to the velocity of light. Knowing the velocity of the earth,
the velocity of light can then be calculated. This method was one of the
first of obtaining the value of this important quantity.

More recently, terrestrial methods of great precision have been devised
for measuring the velocity of light. The most accurate of these is that
employed by the French physicist Foucault in 1862. A ray of light is
reflected by a rotating mirror to a fixed mirror placed at some
distance, which in turn reflects the ray back to the moving mirror. The
latter, however, has turned through a small angle during the time
elapsed since the first reflection, and consequently the direction of
the ray on returning to the source is not quite opposite to that in
which it had started out. This deviation in direction is determined from
the displacement of the image formed by the returning light, and from it
the velocity of light is calculated. In order to make the deflection
appreciable the distance between the two mirrors should be very great.
As originally arranged by Foucault, it was found impractical to make
this distance greater than twenty meters, and consequently the
displacement of the image was less than a millimeter. Such a small
deflection limited the accuracy of the experiment to one percent. In
1879, however, Michelson (=18=, 390, 1879), then a master in the United
States Navy, improved Foucault’s optical arrangements to such an extent
that he was able to use a distance of nearly seven hundred meters
between the two mirrors. With a rate of two hundred and fifty-seven
revolutions a second for the rotating mirror, the displacement obtained
was over thirteen centimeters. This experiment gave 299,910 kilometers a
second for the velocity of light, with a probable error of one part in
ten thousand. Later investigations by Newcomb and Michelson (=31=, 62,
1886) gave substantially the same result. So great has been the accuracy
of these terrestrial determinations that recent practice has been to
calculate from them and the angle of aberration the earth’s orbital
velocity, and hence the distance of the earth from the sun. This
indirect method of measuring the astronomical unit has a probable error
no greater than the best parallax methods of the astronomer. (J.
Lovering, =36=, 161, 1863.)

Aberration is a first order effect, i. e., it depends upon the first
power of the ratio of the velocity of the earth to the velocity of
light, and at first sight it seemed to prove conclusively that the earth
must be in motion relative to the luminiferous medium. Other questions
had to be settled, however, and one of these was whether or not light
coming from a star would be refracted differently when passing through
optical instruments from light which had a terrestial origin. Arago
subjected the matter to experiment, and concluded that in every respect
the light from a star behaved as if the earth were at rest and the star
actually occupied the position which it appears to occupy on account of
aberration. Finally optical experiments with terrestrial sources seemed
to be in no way affected by the motion of the earth through the ether.

In order to account for these facts Fresnel advanced the following
theory. To explain the refraction that takes place when light enters a
transparent body, it is necessary to assume that light waves travel more
slowly through matter than in free ether. Now the velocity of sound is
known to vary inversely with the square root of the density of the
material medium through which it passes. Hence it is natural to assume
that ether is condensed inside material objects to such an extent that
this same relation connects its density with the velocity of light
traveling through it. But when a lens or prism is set in motion, Fresnel
supposed it to carry along only the _excess_ ether which it contains,
ether of the normal density remaining behind. This assumption suffices
to explain Arago’s results, and yet fits in with the phenomenon of
aberration. It gives for light traveling in the direction of motion
through a moving material medium of index of refraction _n_ an absolute
velocity greater than that when the medium is at rest by an amount

                          (1 − (1/_n^2_))_v_,

which is only a fraction of the velocity _v_ which would have to be
added if convected matter carried along all the ether which resides
within it. This expression was tested directly, first by Fizeau in 1851,
and later by Michelson and Morley (=31=, 377, 1886) in this country. The
experiment consists in bifurcating a beam of light, passing one-half in
one direction and the other in the opposite direction through a stream
of running water. On reuniting the two rays the usual interference
fringes are produced. Reversing the direction of motion of the water
causes the fringes to shift, and from the amount of this shift the
velocity imparted to the light by the motion of the stream is computed.
The divergence between the experimental value of this quantity and that
calculated from Fresnel’s coefficient of entrainment was found by
Michelson and Morley to be less than one percent, which was about their
experimental error. Thus Fresnel’s expression for the velocity of light
in a moving medium is entirely confirmed by experiment. The derivation
of it accepted to-day, however, is very different from his original
deduction.

It has been noted that the phenomena of polarization led Newton to
reject the wave theory of light. The only type of wave known to him was
the longitudinal wave, in which the vibrations of the particles of the
medium are in the same direction as that of propagation of the wave, and
it was impossible to suppose that such a wave could have different
properties in different directions at right angles to the line in which
it is advancing. But in 1817 Young suggested that this inconsistency
between the wave theory and the facts of polarization could be removed
by supposing the vibrations constituting light to be executed at right
angles to the direction of propagation. Thus in ordinary light the
vibrations are to be conceived as taking place haphazard in all
directions in the plane perpendicular to the ray, while in plane
polarized light these vibrations are confined to a single direction.
This supposition explained so many of the puzzling results of
experiment, that it was accepted at once and led to the complete
vindication of the undulatory theory.

_Elastic Solid Theory._—Shortly afterwards Poisson succeeded in solving
the differential equation which determines the motion of a wave through
an elastic medium. His solution shows that such a medium is capable of
transmitting two types of wave—one longitudinal, the other transverse.
If κ denotes the volume elasticity, η the rigidity and ρ the density of
the medium, the velocities of the two waves are respectively

                      √((κ + (⁴⁄₃)η)/ρ) and √(η/ρ)

Now a solid has both compressibility and rigidity, and transmits in
general both types of wave. A fluid, on the other hand, on account of
its lack of rigidity, cannot support a transverse vibration. Hence it
was natural that Green, in searching for a dynamical explanation of the
ether, should have proposed in a paper read before the Cambridge
Philosophical Society in 1837 that the ether has the elastic properties
of a solid. One great difficulty presented itself; disturbances inside
an elastic solid must give rise to compressional as well as to
transverse waves. But no such thing as a compressional wave had been
found in the experimental study of light. Green attempted to overcome
this difficulty by attributing an infinite volume elasticity to the
ether. The expression above shows that longitudinal waves originating in
such an incompressible medium would be carried away with an infinite
velocity, and it may be shown that the energy associated with them would
be infinitesimal in amount. The next step was to calculate the
coefficients of transmission and reflection for light passing from one
material medium to another. Here the elastic solid theory is not
altogether successful. If the ether is supposed to have different
densities in the two media, as in Fresnel’s theory, but the same
rigidity, certain of these coefficients fail to give the values demanded
by experiment, while if the densities are assumed the same but the
rigidities different, other of the coefficients have discordant values.
In connection with the phenomena of double refraction even more serious
difficulties are encountered.

_Electromagnetic Theory._—It was beginning to be felt that an ether must
explain more than the phenomena of light, for Faraday’s conception of
electromagnetic action as carried on through the agency of a medium had
added greatly to its functions. Finally Maxwell’s demonstration that
electromagnetic waves are propagated with the velocity of light made the
theory of light into a subdivision of electrodynamics. Maxwell himself
did not apply electromagnetic theory to the explanation of reflection
and refraction. This deficiency, however, was remedied by Lorentz in
1875. The results obtained, as well as those for double refraction (J.
W. Gibbs, =23=, 262, 1882 _et seq._), and metallic reflection (L. P.
Wheeler, =32=, 85, 1911), provided a complete vindication of the
electromagnetic theory of light. This is all the more significant when
the extreme precision obtainable in optical experiments is taken into
account. For instance, Hastings (=35=, 60, 1888) has tested Huygens’
construction for double refraction in Iceland spar and found that “the
difference between a measured index of refraction ... at an angle of 30°
with the crystalline axis, and the index calculated from Huygens’ law
and the measured principal indices of refraction” is a matter of only
4–5 units in the sixth decimal place. Since Maxwell’s time the gamut of
electromagnetic waves has been steadily extended. The shortest Hertzian
waves merge almost imperceptibly into the longest heat waves of the
infra-red, and from there the known spectrum runs continuously through
the visible region to the short waves of the extreme ultra-violet
recently disclosed by Lyman. Here there is a short gap until soft X-rays
are reached, and finally the domain of radiation comes to an end with
gamma rays a billionth of a centimeter in length.

Maxwell’s ether was not a dynamical ether in the sense of Green’s
elastic solid medium. In spite of the fact that Maxwell was always
active in devising mechanical analogues to illustrate the phenomena of
electromagnetism, he was never enthusiastic over the speculations of the
advocates of a dynamical ether. The electrodynamic equations provided an
accurate representation of the electric and magnetic fields, and beyond
that he felt it was needless to go. That Gibbs (=23=, 475, 1882) held
the same view is made evident by the closing paragraphs of a paper in
which he shows that the electromagnetic theory of light accounts in
minutest detail for the intricate phenomena accompanying the passage of
light through circularly polarizing media. He says:


  “The laws of the propagation of light in plane waves, which have thus
  been derived from the single hypothesis that the disturbance by which
  light is transmitted consists of solenoidal electrical fluxes, ... are
  essentially those which are received as embodying the results of
  experiment. In no particular, so far as the writer is aware, do they
  conflict with the results of experiment, or require the aid of
  auxiliary and forced hypotheses to bring them into harmony therewith.

  In this respect the electromagnetic theory of light stands in marked
  contrast with that theory in which the properties of an elastic solid
  are attributed to the ether,—a contrast which was very distinct in
  Maxwell’s derivation of Fresnel’s laws from electrical principles, but
  becomes more striking as we follow the subject farther into its
  details, and take account of the want of absolute homogeneity in the
  medium, so as to embrace the phenomena of the dispersion of colors and
  circular and elliptical polarization.”


_Further Dynamical Theories._—Kelvin, however, was not satisfied with
this type of ether. To him dynamics was the foundation of all physical
phenomena, and nothing could be said to be explained until a mechanical
model was provided. So he returned to the elastic solid theory, and
developed the consequences of the assumption, already made use of by
Cauchy, that the ether has a negative volume elasticity of such a value
as to make the velocity of the compressional wave zero. In order to
prevent such an ether from collapsing it is necessary to assume that it
is rigidly attached at its boundaries and that cavities cannot be formed
at any point in its interior. Now Gibbs (=37=, 129, 1889) has pointed
out the remarkable fact that the equations describing the motion of
Kelvin’s quasi-labile ether are of exactly the same form as the
electromagnetic equations. Electric displacement is represented by an
actual displacement of the ether, magnetic intensity by a rotation.
Hence everything which can be explained by the electrodynamic equations
finds an analogue in terms of Kelvin’s ether. Still another type of
dynamic ether which fits the known facts was proposed by McCullagh and
perfected by Larmor. In this ether a rotational elasticity is premised,
such as would exist if each particle of the medium consisted of three
rigidly connected gyrostats with mutually perpendicular axes. In this
ether electrical displacements correspond to rotations, and magnetic
strains to etherial displacement.

_A New Point of View._—While the dynamical school was still dominant in
England, another point of view was developing on the continent.
Kirchhoff denied that it was the province of science to provide
mechanical explanations of the ether and electrodynamic phenomena such
as Kelvin conceived to be necessary in order to make these phenomena
intelligible. Kirchhoff’s contention was that the object of science is
purely descriptive,—phenomena must be observed, classified, and mutual
connections described by the fewest number of differential equations
possible. Mach expressed the same idea somewhat more concisely when he
asserted that the aim of science is “economy of thought.” For instance,
in the time of Newton, planetary motions could be described quite
satisfactorily by means of the three laws of Kepler. The motion of
falling bodies on the earth’s surface had been described with a fair
degree of accuracy by Galileo. The value of Newton’s law of gravitation,
however, lay in the fact that this great generalization made it possible
to describe these and many other types of motion by a single simple
formula, instead of leaving each to be governed by a number of separate
and apparently unrelated laws. The importance of such a generalization
is measured by the economy of thought which it introduces.

[Illustration: FIG. 1.      FIG. 2.      FIG. 3.]

_Electron Theory._—The electron theory was leading to a reversal of
Kelvin’s idea that dynamical principles must underlie electrodynamics.
Lorentz had shown that a rigorous solution of the electrodynamic
equations did away entirely with Maxwell’s displacement current, but
made the electromagnetic field at a point in space depend not upon the
distribution of charges and currents at the _same_ instant, but at a
time earlier sufficient to allow the effect to travel with the velocity
of light from the charges and currents producing the field to the point
at which the electric and magnetic intensities are to be found. The
position of a charge or current element at this earlier time he denoted
its “effective position.” The effective distribution, then, is that
actually _seen_ by an observer stationed at the point under
consideration at the instant for which the intensity of the
electromagnetic field is to be determined. This solution of the
electrodynamic equations led in turn to rigorous expressions for the
electric and magnetic intensities produced by a very small charged
particle, such as an electron. Fig. 1 shows the electrostatic field
produced by a charged particle at rest. The lines of force spread out
radially and uniformly in all directions. In fig. 2 the electron is
supposed to have a velocity _v_ horizontally to the right of an amount
smaller than, though comparable with, the velocity of light _c_. It is
seen that the lines of electric force still diverge radially from the
charge, but are crowded in the equatorial plane and spread apart in the
polar regions. The dissymmetry grows as the velocity increases until if
the velocity of light should be reached the field would be entirely
concentrated in a plane at right angles to the direction of motion. Now
it may be shown that fig. 2 is obtainable from fig. 1 by _reducing
dimensions in the direction of motion in the ratio of_

                   √(1 − β^2) : 1, where β ≡ _v_/_c_.

For a uniformly convected electric field differs from an electrostatic
field only in that the dimensions in the direction of motion are
contracted in this particular ratio. Fig. 3 represents the electric
field of a charged particle which has a uniform acceleration to the
right. Consider Faraday’s analogy between lines of force and stretched
elastic bands. The symmetry of the first two figures shows that in
neither of these cases would there be a resultant force on the charged
particle. But in the third figure it is obvious that a force to the left
is exerted on the charge by its own field. Calculation shows this force
to be proportional in magnitude to the acceleration. Let it be
postulated that the resultant force on a charged particle is always
zero. Then if _F_ is the applied force, the force on the particle due to
the reaction of its field will be — _m f_, where _f_ stands for the
acceleration and _m_ is a positive constant, and we have the fundamental
equation of dynamics

                           _F_ − _m_ _f_ = 0

Hence, instead of admitting Kelvin’s contention that all physical
phenomena must be given a mechanical explanation, it would seem more
logical to assert that electrodynamics actually underlies mechanics.

Calculation shows the electromagnetic mass _m_ to vary inversely with
the radius of the charged particle. Now Thomson’s experiments made it
possible to calculate the mass of an electron. Hence its radius can be
computed, and is found to be about 2(10)^{–13} part of a centimeter, or
one fifty-thousandth part of the radius of the atom. Since numbers so
small convey little meaning, consider the following illustration, due,
in part, to Kelvin. Imagine a single drop of water to be magnified until
it is as large as the earth. The individual atoms would then have the
size of baseballs. Now magnify one of these atoms until it is comparable
in size with St. Peter’s cathedral at Rome. The electrons within the
atom would appear as a few grains of sand scattered about the nave. This
separation between the constituent electrons of the atom,—so great in
comparison with their dimensions,—explains how alpha particles can be
shot by the billion through thin-walled glass tubing without leaving any
holes behind or impairing in the slightest degree the high vacuum within
the tube. The much smaller high speed beta particles pass through an
average of ten thousand atoms without even coming near enough to one of
the component electrons to detach it and form an ion.

_Michelson-Morley Experiment._—In 1881 Michelson (=22=, 120, 1881)
conceived an ingenious and bold method of measuring the orbital motion
of the earth through the luminiferous ether. As the experiment was one
involving considerable expense, Bell, the inventor of the telephone
receiver, was appealed to successfully for the funds necessary to carry
it through. Michelson’s experimental plan was as follows: A beam of
light traveling in the direction of the earth’s motion strikes an
unsilvered mirror _m_ at an angle of 45°. Part of the light passes
through, the rest being reflected at right angles to its original
direction. Each ray is returned by a mirror at a distance _l_ from _m_.
On meeting again, the ray whose path has been at right angles to the
direction of the earth’s motion passes on through the mirror, while the
other ray is reflected so as to bring the two in line and form
interference fringes. Now consider the effect of the earth’s motion on
the paths of the two rays. In fig. 4 the earth is supposed to be moving
to the right. The unsilvered mirror _m_ bifurcates a beam of light
coming from a source _a_. By the time the ray reflected from _m_ has
traveled to the mirror _b_ and back, _m_ will have moved forward to
_m’_; a distance 2β_l_, where the small quantity β is the ratio of the
earth’s velocity to the velocity of light. Hence the length of the path
traversed by this ray is approximately

                            2_l_(1 + ½β^2).

The other ray will reach the mirror _c_ after the latter has moved
forward a distance

                             β_l_/(1 − β^2)

and on returning find _m_ at _m’_. Hence its path has a length of
roughly 2_l_(1 + β^2). The difference in path of the two rays is β^2_l_
and consequently they should be a little out of phase on meeting at _d_.
By rotating the apparatus clockwise through 90° the directions of the
two rays relative to the earth’s motion are interchanged, and the
interference fringes would be expected to shift an amount corresponding
to a difference in path of 2β^2_l_. This quantity is of course
small,—β^2 is about one one hundred millionth,—but so sensitive are the
methods of interferometry that Michelson felt confident that he would be
able to detect the earth’s motion through the ether. The apparatus
consisted of a table which could be rotated about a vertical axis in
much the same way as a spectrometer table, and provided with arms a
meter long to carry the mirrors _b_ and _c_. With this length of arm the
interference fringes from sodium light should shift by an amount
corresponding to four hundredths of a wave length when the table is
rotated through a right angle. When the experiment was first performed
the apparatus was placed on a stone pier in the Physical Institute at
Berlin. So sensitive was the instrument to outside vibrations that even
after midnight it was found impossible to get consistent readings.
Finally a satisfactory foundation was constructed in the cellar of the
Astrophysical observatory at Potsdam. But what was the astonishment of
the experimenters to find that the expected shift of the interference
fringes did not exist!

[Illustration: FIG. 4.]

The extreme delicacy of the experiment made it desirable to confirm the
result by repeating it. This was done by Michelson and Morley (=34=,
333, 1887) in 1887. In place of a revolving table a massive slab of
stone floating on mercury was used to carry the apparatus. This slab was
kept in constant rotation, the observer following it around. Moreover,
the precision of the experiment was greatly increased by reflecting each
ray back and forth across the slab a number of times between leaving and
returning to the mirror _m_. The accuracy attained was such as to
justify Michelson in declaring that if the effect sought actually
existed it could not be so great as one-twentieth of its calculated
value. In 1905 Morley and Miller[166] repeated the experiment for the
second time and succeeded in increasing the sensitiveness of the
apparatus to a point such that a motion through the ether of one-tenth
of the earth’s orbital velocity could have been detected.

The displacement looked for in the Michelson-Morley experiment is known
as a second-order effect in that it depends upon the square of the ratio
of the velocity of the earth to that of light. Michelson at first
considered that the negative result obtained confirmed a theory proposed
by Stokes in which it was assumed that the ether inside and near its
surface partakes of the motion of the earth, while that at a distance is
practically quiescent. But there are many objections to Stokes’ theory,
one of which was brought out by an experiment of Michelson’s (=3=, 475,
1897) in which he attempted by an interference method to detect a
difference in the velocity of light at different levels above the
earth’s surface. The negative result obtained led him to conclude that
if Stokes’ theory were true the earth’s influence on the ether would
have to extend to a distance above its surface comparable with its
diameter. Meanwhile a more satisfactory explanation was forthcoming. It
has been pointed out that a uniformly convected electric field is
derivable from an electrostatic field by contracting dimensions in the
direction of motion in the ratio

                            √(1 − β^2) : 1.

Fitzgerald and Lorentz showed independently that if moving matter is
distorted in this same way the result obtained by Michelson would be
just that to be expected. For then the distance of the mirror _c_ from
_m_ would be

                              l√(1 − β^2)

instead of _l_, and the path of the ray moving parallel to the earth’s
orbit

                            2_l_(1 + ½β^2),

which is just that of the other ray. Of course when the apparatus is
rotated through 90°, the distance of this mirror from _m_ assumes its
normal value again, and the distance of the other mirror becomes
shortened. As all measurement consists in comparing the object to be
measured with a standard this contraction could never be detected by
experimental methods, for the measuring rod would contract in exactly
the same ratio as the body to be measured.

In computing its electromagnetic mass Abraham had assumed the electron
to be a uniformly charged rigid sphere which keeps its spherical form no
matter how great a velocity it may be given. He found that the mass
increases with the speed at very high velocities, becoming infinite as
the velocity of light is approached, and that its value depends upon the
direction of the applied force. After the Fitzgerald-Lorentz contraction
was seen to be necessary in order to explain Michelson’s result, Lorentz
calculated the electromagnetic mass of a charged sphere which is
deformed into an oblate spheroid when set in motion. For this type of
electron too, the mass approaches infinity for velocities as great as
that of light, and is different for different directions. If a force is
applied in the direction of motion the inertia to be overcome is a
little greater than when the force is applied at right angles to this
direction. Thus we have to distinguish between longitudinal and
transverse masses. But the masses of Lorentz’s electron are not the same
functions of its velocity as those of Abraham’s. Kaufmann and after him
Bucherer tested experimentally the relation between transverse mass and
velocity by observing the deflections produced by electric and magnetic
fields in the paths of high speed beta particles. The latter’s work was
such an ample confirmation of Lorentz’s formula that it may be
considered as proven that a moving electron at least suffers contraction
in the direction of motion in the ratio

                            √(1 − β^2) : 1.

The electromagnetic theory of light had proved so successful when
applied to bodies at rest that Lorentz was anxious to extend this theory
to the optics of moving media. His problem was to find a group of
homogeneous linear transformations that would leave the form of the
electrodynamic equations unchanged. The Michelson-Morley experiment had
shown that dimensions in the direction of motion must be contracted in
the moving system, those at right angles remaining unaltered. But
Lorentz soon found that it was also necessary to use a new unit of time
in the moving system, and as this time was found to depend upon the
_position_ of the point at which it is to be determined, he called it
the _local_ time. Lorentz’s transformation is just that of the principle
of relativity, but he did not succeed in expressing the electrodynamic
equations in terms of the new coördinates and time in exactly the same
form as for a system at rest, for the reason that he failed to endow
these new units with sufficient reality to justify him in using them
when it came to transforming the velocity term involved in an electric
current.

_Principle of Relativity._—In 1905 appeared in the Annalen der
Physik[167] a paper destined to alter entirely the point of view from
which problems in light and electromagnetic theory are to be approached.
The author was Albert Einstein, of Berne, Switzerland, a young man of
twenty-six who had already made a number of notable contributions to
theoretical physics.

The principle of relativity proposed by Einstein was by no means new to
students of dynamics. Newton’s first two laws of motion express very
clearly the fact that in mechanics all motion is relative. Force is
proportional to acceleration, and the relation between the two is the
same whether the motion under consideration is referred to fixed axes or
to axes moving with a constant velocity. But in connection with the
phenomena of light and electromagnetism the case seemed to be quite
different. There everything was referred to a fixed ether, and even
though Lorentz had found a set of transformations which left the
electrodymanic equations practically unchanged, he continued to think in
terms of an ether. So physicists were not a little startled when
Einstein postulated that no experiment, practical or ideal, could ever
distinguish between two systems in such a manner as to warrant the
assertion that one of them is at rest and the other in motion. All
motion is relative, and the laws governing physical, chemical and
biological phenomena are the same in terms of the units of one system as
in terms of those of any other.

Einstein next considers some very fundamental questions. What do we mean
when we say that two events, one at A and the other at a point B far
from A, occur at the same time? Obviously the expression has no
significance unless synchronous clocks are stationed at the two points.
But how is it to be determined whether or not these two clocks are
synchronous? If instantaneous communication could be established between
A and B the matter would be simple enough. Since no infinite velocity of
transmission is available, however, let a light wave be sent from A to B
and returned to A immediately upon its arrival. If the time indicated by
the clock at B when the signal is received is half way between that at
which it left A and the time at which it arrives on its return, then the
two clocks may be considered synchronous. Now if it desired to measure
the length of a bar which is moving parallel to the scale with which the
measurement is to be made, it is necessary to note the positions of the
two ends of the bar at the _same_ instant. So even the measurement of
the length of a moving body depends upon the condition of synchronism at
different points in space.

The principle of relativity requires that the velocity of light shall be
the same in one system as in another relative to which the first is in
motion. Hence the definition of synchronism makes it possible to obtain
a set of transformations connecting space and time measurement on one
system with those on another. This group of transformations is exactly
that which Lorentz had found would transform the electrodynamic
equations into themselves. But Einstein’s point of view brought out a
remarkable reciprocity which Lorentz had missed. If two parallel rods MN
and OP are in motion relative to each other in the direction of their
lengths, not only does OP appear shortened to an observer at rest with
respect to MN, but MN appears shorter than normal in the same ratio to
an observer who is moving along with the rod OP.

Einstein’s theory makes the velocity of light the maximum speed with
which a signal can be transmitted. This leads to his celebrated addition
theorem. Consider three observers A, B and C. Let B be moving relative
to A with a velocity of nine-tenths the velocity of light, and C in the
same direction with an equal velocity relative to B. In terms of
old-fashioned notions of time and space, the velocity of C relative to A
would be computed as one and eight-tenths the velocity of light. But the
relativity theory gives it as ninety-nine hundredths the velocity of
light. For the velocity of light can never be surpassed by that of any
material object. This deduction from theory is most strikingly confirmed
by the fact that although beta particles have been observed with
velocities as high as ninety-nine hundredths that of light, the velocity
of light is never quite equalled. It may be remarked in passing that the
principle of relativity requires that the masses of all material bodies
shall vary with the velocity in the same manner as Lorentz found to be
the case for the electromagnetic mass of the deformable electron. In
this connection Bumstead (=26=, 498, 1908) has devised an elegant method
of deducing the ratio of longitudinal to transverse mass.

The close connection between electrodynamics and the principle of
relativity is obvious from the fact that both lead to the same time and
space transformations. Furthermore L. Page (=37=, 169, 1914) has shown
that the electrodynamic equations can be derived exactly and in their
entirety from nothing more than the kinematics of relativity and the
assumption that every element of charge is a center of uniformly
diverging lines of force. Hence it may safely be asserted that no purely
electromagnetic phenomenon can ever come into contradiction with this
principle. The simplicity thus introduced into the solution of a certain
class of problems is enormous. As an example consider the question as to
whether a moving star is retarded by the reaction of its own radiation.
This purely electrodynamical problem is of such complexity that attempts
to solve it have led to some controversy among mathematical physicists.
The principle of relativity tells us without recourse to analysis that
no retardation can exist.

Throughout the nineteenth century the ether has played a fundamental
part in all important physical theories of light and electromagnetism.
But if it is not possible for experiment to detect even the state of
motion of the ether, why postulate the existence of such a medium? If it
does not possess the most fundamental characteristic of matter, how can
it possess such derived properties as density and elasticity,—properties
which any conceivable _mechanical_ medium must have in order to transmit
transverse vibrations? The relativist does not deny the existence of an
ether. To him the question has no more meaning than if he were asked to
express an opinion as to the reality of parallels of latitude on the
earth’s surface. As a convenient medium of expression in describing
certain phenomena the ether has justified much of the use which has been
made of it. But to attribute to it a degree of substantiality for which
there is no warrant in experiment, is to change it from an aid into an
obstacle to the progress of science. From the relativist point of view
the distinction is very sharp between those motions of charged particles
which are experimentally observable, and such geometrical conventions as
electromagnetic fields, or analytical symbols as electric and magnetic
intensities. These modes of representation have been and still are of
the greatest use and importance, but their value in scientific
description must not lead to lack of appreciation of their purely
speculative character.

Finally attention must be drawn to the fact that the discoveries of
inductive science, embodied in the great generalization we have just
been discussing, have led to a more intimate knowledge of the nature of
time and space than twenty centuries of introspection on the part of
professional philosophers. Minskowski, whose promise of greater
achievement was cut off by an untimely death, has shown that four
dimensional geometry makes possible the representation with beautiful
simplicity of the time and space relationships of this theory. The one
time and three space dimensions merge in such a manner as to form a
single whole with not a vestige of differentiation between these
fundamental quantities. Wilson and Lewis[168] have made this
representation familiar to American readers through their admirable
translation of Minskowski’s work into the notation of Gibbs’s vector
analysis.

Aberration, the Doppler effect, anomalous dispersion, —indeed all known
phenomena,—are found to be in accord with the principle of relativity.
It must be borne in mind, however, that this principle applies only to
systems moving relative to one another in straight lines with constant
velocities. That there is something absolute about rotation has been
recognized since Foucault performed his famous pendulum experiment in
1851. This experiment (C. S. Lyman, =12=, 251 and 398, 1851) consisted
in setting a pendulum composed of a heavy-brass ball suspended by a long
wire into oscillation in such a way as to avoid appreciable ellipticity
in its motion. Observation of the rate at which the ground rotates
relative to the plane of vibration of the pendulum furnished a method of
measuring the rotation of the earth about its axis _without reference to
celestial bodies_. The gyroscopic compass in use to-day provides yet
another terrestrial method of detecting this rotation.

_The Future of Physics._—At times during the history of physics it has
seemed as if the fundamental laws of this science had been so completely
formulated that nothing remained to future generations beyond the
routine of deducing to the full the consequences of these laws, and
increasing the precision of the methods used to measure the constants
appearing in them. That Laplace held this view has already been pointed
out, and Maxwell, in his introductory lecture at the opening of the
Cavendish laboratory in 1871, said, “This characteristic of modern
experiments—that they consist principally of measurements—is so
prominent, that the opinion seems to have gotten abroad that in a few
years all the great physical constants will have been approximately
estimated, and that the only occupation which will then be left to men
of science will be to carry on these measurements to another place of
decimals.” That he himself did not entertain this view is made evident
by a succeeding paragraph. “But we have no right to think thus of the
unsearchable riches of creation, or of the untried fertility of those
fresh minds into which these riches will continue to be poured. It may
possibly be true that, in some of those fields of discovery which lie
open to such rough observations as can be made without artificial
methods, the great explorers of former times have appropriated most of
what is valuable, and that the gleanings which remain are sought after
rather for their abstruseness than for their intrinsic worth. But the
history of science shows that even during that phase of her progress in
which she devotes herself to improving the accuracy of the numerical
measurement of quantities with which she has long been familiar, she is
preparing the materials for the subjugation of new regions, which would
have remained unknown if she had been contented with the rough methods
of her early pioneers....”

That Maxwell’s forecast of the prospects of his science was no
overestimate will be granted by those who have followed the progress of
physics during the last twenty years. Yet the work accomplished in the
past appears small compared to that which is left to the future. Many of
the unsolved problems are matters of fitting together puzzling details,
but there is at least one whose solution appears to demand a radical
modification in our fundamental physical conceptions. This is the
formulation of the laws which govern the motions of electrons and
positively charged particles inside the atom.

_Black Radiation._—The significance of the problem was first brought to
light through the study of black radiation. By a black body is meant one
whose distinguishing characteristic is that it emits and absorbs
radiation of all frequencies, and black radiation is that which will
exist in thermal equilibrium with such a body. The interest of this type
of radiation lies in the fact, demonstrated by Kirchhoff, that its
nature depends only upon the temperature of the black body with which it
is in equilibrium, and on none of this body’s physical or chemical
characteristics. Thus we may speak of the “temperature” of the radiation
itself, meaning by this the temperature of the material body with which
it would be in equilibrium.

The problem of black radiation is to find the distribution of energy
among the waves of different frequencies at any given temperature. The
first step toward a solution was made when Stefan showed experimentally,
and Boltzmann as a deduction from thermodynamics and electrodynamics,
that the total energy density summed up over all wave lengths varies
with the fourth power of the absolute temperature. If the energy density
is plotted as ordinate against the wave length as abscissa, the
experimental curve for any one temperature rises from the axis of
abscissas at the origin, reaches a maximum, and falls to zero again as
the wave length becomes infinitely great. Now Wien’s displacement law,
the second important step toward the determination of the form of this
curve, shows that as the temperature is raised the wave length to which
its highest point corresponds becomes shorter,—in fact this particular
wave length varies inversely with the absolute temperature. This
theoretical conclusion is entirely confirmed by experiment. (J. W.
Draper, =4=, 388, 1847.)

Farther than this general thermodynamical principles are unable to go.
Statistical mechanics, however, asserts that when a large number of like
elements are in thermal equilibrium, the average kinetic energy
associated with each degree of freedom is equal to a universal constant
multiplied by the absolute temperature. This “principle of
equi-partition of energy” has been applied in various ways to obtain a
radiation law. The most straightforward method is based on the
equilibrium which must ensue between radiation field and material
oscillators when the latter emit, on the average, as much energy as they
absorb. From whatever aspect the problem is treated, however, the
radiation law obtained from the application of the equi-partition
principle is the same. And while this law agrees well with the
experimental curve for long wave lengths, it shows an energy density
that becomes indefinitely great for extremely short waves, which is not
only at variance with the facts, but actually leads to an _infinite_
value of this quantity when integrated over the entire spectrum.

_The Energy Quantum._—Now the principle of equi-partition of energy
rests securely on most general dynamical principles. That these
dynamical laws are inexact to any such extent as the divergence between
theory and experiment would indicate, is inconceivable; that they are
_insufficient_ when applied to motions of electrons in such intense
fields as occur within the atom seems no longer open to doubt. In order
to obtain a radiation formula in accord with experiment Planck has found
it necessary to extend the atomic idea to energy, which he conceives to
exist in multiples of a fundamental quantum _h_ν, ν being the frequency
and _h_ Planck’s constant. That some such hypothesis of discontinuity is
essential in order to obtain any law that will even approximately fit
the experimental facts has been proved by Poincaré. But the precise spot
at which the quantum is introduced differs for every new derivation of
Planck’s law. As deduced most recently by Planck himself, the quantum
shows itself in connection with the emission of energy by the material
oscillators with which the radiation field is in equilibrium. These
oscillators are supposed to act quite normally in every respect except
emission; here the radiation demanded by the electrodynamic equations is
cast aside, and an oscillator is supposed to emit at once all its energy
after it has accumulated an amount equal to some integral multiple of
_h_ν. A form of the theory which does not contain this improbable
contradiction of the firmly established facts of electrodynamics
introduces the quantum into the specification of the energy of vibration
which is permitted to each oscillator. Here both emission and absorption
follow the classical theory, but the motion of an emitting and absorbing
linear oscillator of frequency ν is supposed to be stable only for those
amplitudes for which the energy of its oscillations is an integral
multiple of _h_ν. In order to maintain the energy at these particular
values, the oscillator may draw energy from, or deposit surplus energy
with, other degrees of freedom which partake neither in emission nor
absorption, but act merely as storehouses.

_Photoelectric Effect._—When investigating the production of
electromagnetic waves, Hertz had noticed that a spark passed more
readily between the terminals of his oscillator when the negative
electrode was illuminated by light from another spark. Further
investigation by Hallwachs, Elster and Geitel, and others showed that
this effect was due to the emission of electrons by a metal exposed to
the influence of ultra-violet light. Lenard discovered that the energy
with which a negatively charged particle is ejected is entirely
independent of the intensity of the light, and further investigation
showed it to depend only on the frequency. Einstein suggested that the
electrons appearing in this so-called photo-electric effect start from
within the metal with an initial energy _h_ν. In passing through the
surface a resistance is encountered, however, so he concluded that the
energy with which the fastest moving electrons appear outside the metal
should be equal to _h_ν less the work done in overcoming this
resistance. Recent experiments not only confirm this relation, but
provide a most satisfactory method of determining the value of _h_.
Millikan[169] finds it to be 6·57(10)^{–27} ergs sec., which gives the
quantum for yellow light a value sixty times as great as the heat energy
of a monatomic gas molecule at O°C. That this large amount of energy can
be transferred from the incident light to the ejected electron is quite
out of the question; it must come from within the atom. In this way some
indication is obtained of how vast intra-atomic energies must be.

_Structure of the Atom._—The generally accepted model of the atom is
that due chiefly to Rutherford.[170] He considers it to be constituted
of electrons revolving about a positive nucleus either singly or grouped
in concentric rings, in much the same manner as the planets revolve
around the sun. Experiments on the scattering of alpha rays, however,
show that the nucleus, while it must have a positive charge sufficient
to neutralize the charges of all the electrons moving around it, cannot
have a volume of an order of magnitude greater than that of the
electron. The number of unit charges residing on it, except in the case
of hydrogen, which is supposed to consist of a singly charged nucleus
and only one electron, is found to be approximately half the atomic
weight. Thus helium, with an atomic weight of about four, has a doubly
charged nucleus with two electrons revolving about it, and lithium a
triply charged nucleus and three electrons. The number of unit charges
on the nucleus is supposed to correspond with the atomic number used by
Moseley in interpreting the results of his experiment on the X-ray
spectra of the elements.

Now the electron which is revolving around the positive nucleus of a
hydrogen atom, must, according to electrodynamic laws, radiate energy.
This radiation will act as a resistance to its motion, causing its orbit
to become smaller and its frequency to increase. Hence luminous hydrogen
would be expected to give off a continuous spectrum. The very fine lines
actually found seem inexplicable on the classical dynamical and
electrodynamical theories. These lines, and those of many other spectra,
may even be grouped into series, and the relations between them
expressed in mathematical form. Formulæ have been proposed by Balmer,
Rydberg, Ritz and others, all of which contain a universal constant _N_
as well as certain parameters which must be varied by unity in passing
from one line of a series to the next.

In 1913 Bohr[171] proposed anatomic theory which brings to light a
remarkable numerical relationship between this quantity _N_ and Planck’s
constant _h_. He postulated that the electron in the hydrogen atom, for
instance, cannot revolve in a circle of any arbitrary radius, but is
confined to those orbits for which its kinetic energy is an integral
multiple of ½_hn_, _n_ being its orbital frequency. Now at times this
electron is supposed to jump from an outer to an inner orbit, when the
excess energy of the first orbit over the second is radiated away. But
the energy emitted is also taken to be equal to _h_ν, where ν is the
frequency of the radiation. Hence ν can be determined, and the
expression obtained for it is exactly that given long before by Balmer
as an empirical law. The most remarkable thing about it, however, is
that Bohr’s result contains a constant involving _h_ and the electronic
charge and mass which has precisely the value of the universal constant
_N_ of Balmer’s and Rydberg’s formulæ. In all, the theory accounts for
three series of hydrogen, and yields satisfactory results for helium
atoms which have lost an electron, or lithium atoms which have a double
positive charge. But for atoms which retain more than a single electron
it seems no longer to hold.

The three mentioned are only the most clearly defined of a growing group
of phenomena in which the quantum manifests itself. Its significance and
the alteration in our fundamental conceptions to which it seems to be
leading is for the future to make clear. That it presents the most
important and interesting problem as yet unsolved few physicists would
deny.

_American Physicists._—In attempting to cover the progress of physics
during the last hundred years in the space of a few pages, many
important developments of the subject have of necessity remained
untouched, and the treatment of many others has been entirely
inadequate. Among those appearing in the Journal of which no mention has
been made are LeConte’s (=25=, 62, 1858) discovery of the sensitive
flame and Rood’s (=46=, 173, 1893) invention of the flicker photometer.
However, enough has been recounted to indicate the preeminent position
in the history of physics in America occupied by four men: Joseph Henry,
of the Albany Academy, Princeton, and the Smithsonian Institution; Henry
Augustus Rowland, of Johns Hopkins University; Josiah Willard Gibbs, of
Yale; and Albert Abraham Michelson, of the United States Naval Academy,
Case School of Applied Science, Clark University, and the University of
Chicago. Of these, the last named has the distinction of being the only
American physicist to have received the Nobel prize, though there is
little doubt that the other three would have been similarly honored had
not their important work been published prior to the institution of this
award. All four occupy high places in the ranks of the world’s great men
of science, and the investigations carried out by them and their fellow
workers in America have given to their country a position in the annals
of physics which is by no means insignificant.


                  _The Journal’s Part in Meteorology._

The meteorological investigations published in the early numbers of the
Journal have played an important role in establishing a correct theory
of storms. Before the origin of the United States Signal Service in 1871
no systematic weather reports were issued by any governmental agency in
this country, and consequently the work of collecting as well as
interpreting meteorological data rested entirely in the hands of
interested individuals and institutions. The earliest important studies
of storms to appear in the Journal were contributed by Redfield of New
York, whose first paper (=20=, 17, 1831) treated in considerable detail
a violent storm which passed over Long Island, Connecticut and
Massachusetts in 1821. He concluded that “the direction of the wind at a
particular place, forms no part of the essential character of a storm,
but is only incidental to that particular portion ... of the track of
the storm which may chance to become the point of observation, ... the
direction of the wind being, in all cases, compounded of both the
rotative and progressive velocities of the storm.” A few years later,
analyses of twelve “gales and hurricanes of the Western Atlantic” (=31=,
115, 1837) led to the statement that the phenomena involved “are to be
ascribed mainly to the mechanical gravitation of the atmosphere, as
connected with the rotative and orbital movements of the earth’s
surface.” In this paper is emphasized the fact that the wind may blow in
diametrically opposite directions at points near the storm center.
“While one vessel has been lying-to in a heavy gale of wind, another,
not more than thirty leagues distant, has at the very same time been in
another gale equally heavy, and lying-to with the wind in quite an
opposite direction.” From an accompanying sketch showing wind
directions, the reader would infer that, at this time, Redfield believed
the motion of the air to be very nearly in circles about the storm
center. The same idea is conveyed by a later paper (=42=, 112, 1842).
Espy (=39=, 120, 1840) of Philadelphia, however, claimed that
observation showed rather that the wind blew inwards toward a central
point, if the storm were round in shape, or toward a central line, if it
were oblong. This view Redfield (=42=, 112, 1842) contested, and brought
forth much evidence to prove its falsity. A later statement (=1=, 1,
1846) of his own theory is as follows: “I have never been able to
conceive, that the wind in violent storms moves only in _circles_. On
the contrary, a vortical movement ... appears to be an essential element
of their violent and long-continued action, of their increased energy
towards the center or axis, and of the accompanying rain.... The
_degree_ of vorticular inclination in violent storms must be subject,
locally, to great variations; but it is not probable that, on an average
of the different sides, it ever comes near to forty-five degrees from
the tangent of a circle,—and that such average inclination ever exceeds
two points of the compass, may well be doubted.” A qualitative
explanation of the effect of the earth’s rotation on the direction of
the wind near the storm center had already been given by Tracy (=45=,
65, 1843), and this was followed some years later by Ferrel’s (=31=, 27,
1861) very thorough quantitative investigation of the dynamics of the
atmosphere.

A number of individuals kept systematic records of meteorological
observations, among whom was Loomis, whose storm analyses did much to
settle the merits of the rival theories of Redfield and Espy. In
studying the storm of 1836 (=40=, 34, 1841) he had drawn on the map
lines through those points in the track of the storm where the
barometer, at any given hour, is lowest. While this method revealed the
general direction in which the storm was progressing, it failed to give
much indication of its size or shape. In discussing the two tornadoes of
February, 1842, one of which had already been described in the Journal
(=43=, 278, 1842), he adopted a new and more illuminating graphical
method. Instead of connecting points of lowest pressure, he drew a curve
through all points where the barometer stood at its normal level, then
one through those points at which the pressure was ²⁄₁₀ of an inch below
normal, and so on. Temperature he treated in much the same way, and the
strength and direction of the wind were indicated by arrows. This
innovation gave to his storm analyses a significance which had been
entirely lacking in those of his predecessors, and led to the familiar
systems of isobars and isotherms in use on the daily charts issued by
the Weather Bureau at the present time. Loomis advocated careful
observations for one year at stations 50 miles apart all over the United
States, so that sufficient data might be obtained to settle once for all
the law of storms. His efforts, seconded by those of Henry, Bache,
Pierce, Abbe, and Lapham, led eventually to the establishment of the
Signal Service, and the publication of daily weather maps according to
the plan advocated thirty years before. These maps afforded a basis for
further analyses of storms, which he published in numerous
“Contributions to Meteorology” (=8=, 1, 1874, _et seq._) between 1874
and his death in 1890.

In addition to his work on storms, Loomis made a careful study of the
earth’s magnetism (=34=, 290, 1838 _et seq._), and of the aurora
borealis (=28=, 385, 1859 _et seq._). That a connection existed between
sunspots, aurora, and terrestrial magnetism was already recognized.
Loomis (=50=, 153, 1870 _et seq._), however, showed that the periodicity
of the aurora borealis, as well as of excessive disturbances in the
earth’s magnetic field, corresponds very closely with that of sunspots.


                                _Notes._

Footnote 154:

  J. W. Gibbs, Trans. Conn. Acad. Arts and Sci., =3=, 108 and 343.
  Abstract by the author, the Journal, =16=, 441, 1878.

Footnote 155:

  H. K. Onnes, Nature, =93=, 481, 1914.

Footnote 156:

  H. Hertz, Wied. Ann., =34=, 551, 1888 _et seq._

Footnote 157:

  E. F. Nichols and G. F. Hull, Phys. Rev., =13=, 307, 1901 _et seq._

Footnote 158:

  J. J. Thomson, Phil. Mag., =44=, 293, 1897.

Footnote 159:

  R. A. Millikan, Phys. Rev., =2=, 109, 1913.

Footnote 160:

  P. Zeeman, Phil. Mag., =43=, 226, 1897.

Footnote 161:

  H. A. Lorentz, Phil. Mag., =43=, 232, 1897.

Footnote 162:

  S. J. Barnett, Phys. Rev., =6=, 239, 1915, and =10=, 7, 1917.

Footnote 163:

  W. C. Röntgen, Wied. Ann., =64=, 1, 1898 _et seq._

Footnote 164:

  W. Friedrich, P. Knipping, and M. Laue, Ann. d. Phys., =41=, 971,
  1913.

Footnote 165:

  H. G. J. Moseley, Phil. Mag., =26=, 1024, 1913, and =27=, 703, 1914.

Footnote 166:

  E. W. Morley and D. C. Miller, Phil. Mag., =9=, 680, 1905.

Footnote 167:

  =17=, 891, 1905.

Footnote 168:

  E. B. Wilson and G. N. Lewis, Proc. Am. Acad., of Arts and Sci., =48=,
  389, 1912.

Footnote 169:

  R. A. Millikan, Phys. Rev., =7=, 355, 1916.

Footnote 170:

  E. Rutherford, Phil. Mag., =21=, 669, 1911.

Footnote 171:

  N. Bohr, Phil. Mag., 26, =1=, 1913 _et seq._




                                  XII
                    A CENTURY OF ZOOLOGY IN AMERICA

                            By WESLEY K. COE


 This article is intended as a brief survey of the development of
zoology in America, and no attempt is made to give a general history of
the science. There are numerous accounts in several languages of
zoological history in general, among them being W. A. Locy’s “Biology
and its Makers.” Brief outlines of the history of zoology may be found
in many zoological and biological text-books.

For the history of American zoology the reader is referred to Packard’s
report on “A Century’s Progress in American Zoology,” published in the
American Naturalist, (10, 591, 1876), to Packard’s “History of Zoology,”
published in volume 1 of the Standard Natural History (pp. lxii to
lxxii, 1885); to G. B. Goode’s “Beginnings of Natural History in
America,”[172] and “Beginnings of American Science,”[173] and to H. S.
Pratt’s Manual of the Common Invertebrate Animals (pp. 1–9), 1916. In
Binney’s “Terrestrial Air-breathing Mollusks of the United States”
(1851) is a chapter on the rise of scientific zoology in the United
States which well describes the zoological conditions in the early part
of the century, while numerous monographs and papers give the history of
the investigations on the various groups of animals or on special fields
of study.

Brief biographical sketches of the most distinguished of our older
Naturalists—Wilson, Audubon, Agassiz, Wyman, Gray, Dana, Baird, Marsh,
Cope, Goode and Brooks are given in “Leading American Men of Science,”
edited by David Starr Jordan, 1910. More extensive biographies have been
published separately, and the activities of a number of the more
prominent American zoologists have been recorded in the Biographical
Memoirs of the National Academy of Sciences.

The developmental history of zoology in America falls naturally into
four fairly well marked periods, namely:—1, _Period of descriptive
natural history_, previous to 1847, embracing the early studies on the
classification and habits of animals, characteristic of the zoological
work previous to the arrival of Louis Agassiz in America. 2, _Period of
morphology and embryology_, 1847–1870, during which the influence of
Agassiz directed the zoological studies toward problems concerning the
relationships of animals as indicated by their structure and
developmental history. 3, _Period of evolution_, 1870–1890, when the
principle of natural selection received general recognition and the
zoological studies were largely devoted to the applications of the
theory to all groups of animals. 4, _Period of experimental biology_,
since 1890, during which time have occurred the remarkable advances in
our knowledge of the nature of organisms through the application of
experimental methods in the various branches of the modern science of
biology.


                      _American Zoology in 1818._

At the beginning of the century which this volume commemorates, the
accumulated biological knowledge of the world consisted mainly of what
is to-day called descriptive natural history. The zoological treatises
of the time were devoted to the names, distinguishing characters and
habits of the species of animals and plants known to the naturalists of
Europe either as native species or as the results of explorations in
other parts of the world. This required little more than a superficial
knowledge of their general anatomical structures.

The naturalists of those days had no conception of the life within the
cell which we now know to form the basis of all the activities of
animals and plants, nor had they even the necessary means of studying
such life. The compound microscope, so necessary for the study of even
the largest of the cells of the body, was not adapted to such use until
1835, although the instrument was invented in the seventeenth century.
With the perfection of the microscope came a period of enthusiastic
study of microscopic organisms and microscopic structures of higher
animals and plants. It was not until twenty years after the founding of
the Journal that the cell theory of structure and function in all
organisms was established by the discoveries of Schleiden and Schwann.

The beginning of the nineteenth century saw great zoological activity in
Europe, and particularly in France. Buffon’s great work on the Natural
History of Animals had recently been completed, Cuvier had only one year
before published his classic work in comparative anatomy, “Le Regne
Animal,” and Lamarck’s “Philosophie Zoologique” had then aroused a new
interest in classification and comparative anatomy from an evolutionary
standpoint. E. Geoffroy St.-Hilaire was at the same time supporting an
evolutionary theory based on embryonic influences resulting in sudden
modifications of adult structure. These epoch-making discoveries and
theories gained a considerable following in France, Germany and England,
but seem to have had little influence on the zoological work of the
following half century in America.

The science of zoology as understood to-day is commonly said to have
been founded by Linnæus by the publication of the modern system of
classification in the tenth edition of his “Systema Naturæ” in 1758. The
influence of Linnæus aroused an interest in biological studies
throughout Europe and stimulated new investigations in all groups of
organisms. Such studies as related to animals naturally followed first
the classification and relationship of species, that is, systematic
zoology, and then led gradually into the development of the different
branches of the subject, as morphology, comparative anatomy, physiology,
and embryology, which eventually were recognized as almost independent
sciences.

Of these sciences systematic zoology, which has come to mean the
classification, structure, relationship, distribution and habits, or
natural history, is the pioneer in any region. Thus we find in our new
country at the time of the founding of the Journal in 1818, only sixty
years after the publication of Linnæus’ great work, the beginning of
American zoology taking the form of the collection and description of
our native animals.

It is true that many of our more conspicuous and easily collected
animals were described long before the opening of the nineteenth
century, but this is to be credited mainly to the work of European
naturalists who had made expeditions to this country for the purpose of
studying and collecting. These collections were then taken to Europe and
the results published there. We thus find in the 12th edition of Linnæus
descriptions of over 500 American species, about half of which were
birds. As an illustration of the extent to which some of these works
covered the field even in those early days may be mentioned a monograph
in two quarto volumes with many beautifully colored plates on the
“Natural History of the rarer Lepidopterous Insects of Georgia.” This
was published in London in 1797 by J. E. Smith from the notes and
drawings of John Abbot, one of the keenest naturalists of any period.

During the early years of the nineteenth century, however, economic
conditions in our country became such as to give opportunity for
scientific thought. Educated men then formed themselves into societies
for the discussion of scientific matters. This naturally led to the
establishment of publications whereby the papers presented to the
societies could be published and made available to the advancement of
science generally. The most influential of these was the Journal of the
Philadelphia Academy of Natural Science, which was established in 1817,
and was devoted largely to zoological papers. The Annals of the New York
Lyceum of Natural History date from 1823, and the Journal of the Boston
Society of Natural History from 1834. The Transactions of the American
Philosophical Society in Philadelphia and the Memoirs of the American
Academy of Arts and Sciences in Boston also published many zoological
articles.

In these publications and in the Journal, which was founded in 1818,
appear the descriptions of newly discovered animal species, with
observations on their habits.

The number of investigators in this field in the first quarter of the
nineteenth century was but few, and most of these were compelled to take
for the work such time as they could spare from their various
occupations.

Gradually the workers became more numerous until about the middle of the
century zoology was taught in all the larger colleges. The science
thereby developed into a profession.

For some years the studies remained largely of a systematic nature, and
embraced all groups of animals, but long before the close of the century
the attention of the majority of the ever increasing group of zoologists
was directed into more promising channels for research and there came
the development of the sciences of comparative anatomy, physiology,
embryology, experimental zoology, cytology, genetics, and the like,
while the systematists became specialists in the various animal groups.

But the work in systematic zoology remains incomplete and many native
species are still undescribed or imperfectly classified. It is perhaps
fortunate that a few faithful systematists remain at their tasks and
tend to keep the experimentalists from the disaster which might
otherwise result from the confusion of the species under investigation.


       _Period of Descriptive Natural History.—Previous to 1847._

Of the few American naturalists whose writings were published toward the
end of the eighteenth century and at the beginning of the nineteenth the
names of William Bartram (1739–1823), Benjamin Barton (1766–1815),
Samuel Mitchill (1764–1831), William Peck (1763–1822), and Thomas
Jefferson (1743–1826), require special mention. Bartram’s entertaining
volume describing his travels through the Carolinas, Georgia and
Florida, published in 1793, contains a most interesting account of the
birds and other animals which he found.

Barton wrote many charming essays on the natural history of animals, but
was more particularly interested in botany. Mitchill’s most important
works include a history of the fishes of New York (1814), and additions
to an edition of Bewick’s General History of Quadrupeds. The latter,
published in 1804, contains descriptions and figures of some American
species and is the first American work on mammals.

Peck has the distinction of writing the first paper on systematic
zoology published in America. This was a description of new species of
fishes and was printed in 1794. He is also well known for his work on
insects and fungi.

Jefferson in 1781 published an interesting book describing the natural
history of Virginia, and during his presidency was of inestimable
service to zoology through his support of scientific expeditions to the
western portions of the country.

Previous to Agassiz’s introduction of laboratory methods of study in
comparative anatomy and embryology in 1847, American naturalists
generally confined their attention to the study of the classification
and habits of the multitude of undescribed animals and plants of the
region.

Such studies were naturally begun on the larger and more generally
interesting animals such as the birds and mammals, and although many of
these were fairly well described as to species before the opening of the
nineteenth century, little was known of their habits. The natural
history of our eastern birds first became well known through the
accurate illustrations and exquisitely written descriptions of Alexander
Wilson (in 1808–1813). Bonaparte’s continuation of Wilson’s work was
published in four folio volumes beginning in 1826.

In 1828 appeared the first of Audubon’s magnificent folio illustrations
of our birds. These were published in England, with later editions of
smaller plates in America. Nuttall’s Manual of the Ornithology of the
United States appeared in 1832–1834.

The second work on American mammals appeared in the second American
edition of Guthrie’s Geography, published in 1815. The author is
supposed to have been George Ord, although his name does not appear. In
1825 Harlan published his “Fauna Americana: Descriptions of the
Mammiferous Animals inhabiting North America.” This was largely a
compilation from European writers, particularly from Demarest’s
Mammalogie, and had little value.

In 1826 Amos Eaton published a small “Zoological Text-book comprising
Cuvier’s four grand divisions of Animals: also Shaw’s improved Linnean
genera, arranged according to the classes and orders of Cuvier and
Latreille. Short descriptions of some of the most common species are
given for students’ exercises. Prepared for Rensselaer school and the
popular class room.” “Four hundred and sixty-one genera are described in
this text-book. They embrace every known species of the Animal Kingdom.”
This is a compilation from European sources with a few American species
of various groups included. On the other hand, Godman’s Natural History,
in three volumes (1826–1828), was an illustrated and creditable work.
Such was also the case with Sir John Richardson’s Fauna Boreali
Americana of which the volume on quadrupeds was published in England in
1829. The other volumes on birds, fishes and insects appeared between
1827 and 1836. Audubon and Bachman’s beautifully illustrated “Quadrupeds
of North America” was issued between 1841 and 1850.

About 1840 several of the states inaugurated natural history surveys and
published catalogues of the local faunas. The reports on the animals of
Massachusetts and New York are the most complete zoological monographs
published in America up to that time. This is particularly true of
DeKay’s Natural History of New York published between 1842 and 1844 in
beautifully illustrated quarto volumes.

The leader in the systematic studies in the early part of the century
was Thomas Say, who published descriptions of a large number of new
species of animals, particularly reptiles, mollusks, crustacea and
insects. Say’s conchology, printed in 1816 in Nicholson’s Cyclopedia, is
the first American work of its kind. This was reprinted in 1819 under
the title “Land and Fresh-water Shells of the United States.” In
1824–1828 appeared the three volumes of Say’s American Entomology.

The prominent position held by Say in the zoological work of this period
is illustrated by the following paragraph from Eaton’s Zoological
Text-book (1826, p. 133): “At present but a small proportion of American
Animals, excepting those of large size, have been sought out ... And
though Mr. Say is doing much; without assistance, his life must be
protracted to a very advanced period to afford him time to complete the
work. But if every student will contribute his mite, by sending Mr. Say
duplicates of all undescribed species, we shall probably be in
possession of a system, very nearly complete, in a few years.” How
different is the attitude of the zoologist of to-day who sees the goal
much further away after a century’s progress through the industry of
hundreds of investigators.

During the period of Say’s most active work he is reported to have
“slept in the hall of the Philadelphia Academy of Natural Sciences,
where he made his bed beneath the skeleton of a horse and fed himself on
bread and milk.”

Next to Say, the most active zoologist of the early part of the century
was Charles Alexander Lesueur, who described and beautifully illustrated
many new species of fishes, reptiles, and marine invertebrates. A memoir
by George Ord, published in this Journal (=8=, 189, 1849), gives a full
list of Lesueur’s papers.

One of the most prolific writers of the period was Constantine
Rafinesque, a man of great brilliancy but one whose imagination so often
dominated his observations that many of his descriptions of plants and
animals are wholly unreliable.

_United States Exploring Expedition._—In 1838 a fortunate circumstance
occurred which eventually brought American systematic zoology into the
front ranks of the science. This opportunity was offered by the United
States Exploring Expedition under the command of Admiral Wilkes. With
James D. Dana as naturalist, the expedition visited Madeira, Cape Verde
Islands, eastern and western coasts of South America, Polynesia, Samoa,
Australia, New Zealand, Fiji, Hawaiian Islands, west coast of United
States, Philippines, Singapore, Cape of Good Hope, etc.

Of the extensive collections made on this four-years’ cruise, Dana had
devoted particular attention to the study of the corals and allied
animals (Zoophytes) and to the crustacea. In 1846 the report on the
Zoophytes was published in elegant folio form with colored plates. Six
years later the first volume of the report on Crustacea appeared, with a
second volume after two additional years (1854). These reports describe
and beautifully illustrate hundreds of new species, and include the
first comprehensive studies of the animals forming well-known corals.
They remain as the most conspicuous monuments in American invertebrate
zoology. Unfortunately the very limited edition makes them accessible in
only a few large libraries. The other, equally magnificent, volumes
include: Mollusca and Shells, by A. A. Gould, 1856; Herpetology, by
Charles Girard, 1858; Mammalogy and Ornithology, by John Cassin, 1858.

_Principal investigators._—Of the many writers on animals at this period
of descriptive natural history, the following were prominent in their
special fields of study:

Ayres, Lesueur, Mitchill, Storer, Linsley, Wyman, DeKay, Smith,
Kirtland, Rafinesque and Haldeman described the fishes.

Green, Barton, Harlan, Le Conte, Say, and especially Holbrook, studied
the reptiles and amphibia. Holbrook’s great monograph of the reptiles
(North American Herpetology) was published between 1834 and 1845.

Wilson, Audubon, Nuttall, Cooper, DeKay, Brewer, Ord, Baird, Gould,
Bachman, Linsley and Fox were among the numerous writers on birds.

Godman, Ord, Richardson, Audubon, Bachman, DeKay, Linsley and Harlan
published accounts of mammals.

On the invertebrates an important general work entitled “Invertebrata of
Massachusetts; Mollusca, Crustacea, Annelida and Radiata” was published
by A. A. Gould in 1841, which contains all the New England species of
these groups known to that date.

Lea, Totten, Adams, Barnes, Gould, Binney, Conrad, Hildreth, Haldeman,
were the principal writers on mollusks. The crustacea were studied by
Say, Gould, Haldeman, Dana; the insects by Say, Melsheimer, Peck,
Harris, Kirby, Herrick; the spiders by Hentz; the worms by Lee; the
coelenterates and echinoderms by Say, Mantell and others.

The history of entomology in the United States previous to 1846 is given
by John G. Morris in the Journal (=1=, =17=, 1846). In this article F.
V. Melsheimer is stated to be the father of American Entomology, while
Say was the most prolific writer. Say’s entomological papers, edited by
J. L. Le Conte, were completely reprinted with their colored
illustrations in 1859. The first economic treatise is that by Harris on
Insects Injurious to Vegetation; printed in 1841. This has had many
editions.


        _Zoology in the American Journal of Science, 1818–1846._

The establishment of the Journal gave a further impetus to the
scientific activities of Americans in furnishing a convenient means for
publishing the results of their work. In the first volume of the
Journal, for example, are two zoological articles by Say and a dozen
short articles on various topics by Rafinesque, the latter being curious
combinations of facts and fancy. Most of the zoological papers appearing
in its first series of 50 volumes are characteristic of an undeveloped
science in an undeveloped country. They deal, naturally, with
observational studies on the structure and classification of species
discovered in a virgin field, with notes on habits and life histories.

Many of the papers are purely systematic and include the first
descriptions of numerous species of our mollusks, crustacea, insects,
vertebrates and other groups. Of these, the writings of C. B. Adams,
Barnes, A. A. Gould and Totten on mollusks, of J. D. Dana on corals and
crustacea, of Harris on insects, of Harlan on reptiles, and of Jeffries
Wyman and D. Humphreys Storer on fishes are representative and
important.

The progress of zoology in America during the first twenty-eight years
of the Journal’s existence, that is, up to the year 1846, is thus
summarized by Professor Silliman in the preface to vol. 50 (page ix),
1847:


  “Our zoology has been more fully investigated than our mineralogy and
  botany; but neither department is in danger of being exhausted. The
  interesting travels of Lewis and Clark have recently brought to our
  knowledge several plants and animals before unknown. Foreign
  naturalists are frequently visiting our territory; and, for the most
  part, convey to Europe the fruits of their researches, while but a
  small part of our own is examined and described by Americans:
  certainly this is little to our credit and still less to our
  advantage. Honorable exceptions to the truth of this remark are
  furnished by the exertions of some gentlemen in our principal cities,
  and in various other parts of the Union.”


During these 28 years the Journal had been of great service to zoology
not only in the publication of the results of investigations but also in
the review of important zoological publications in Europe as well as in
America. There were also the reports of meetings of scientific
societies. In fact all matters of zoological interest were brought to
the attention of the Journal’s readers.


                   _The Influence of Louis Agassiz._

At the time of the founding of the Journal and for nearly thirty years
thereafter descriptive natural history constituted practically the
entire work of American zoologists. In this respect American science was
far behind that in Europe and particularly in France. It was not until
the fortunate circumstances which brought the Swiss naturalist, Louis
Agassiz, to our country in 1846 that the modern conceptions of
biological science were established in America.

Agassiz was then 39 years of age and had already absorbed the spirit of
generalization in comparative anatomy which dominated the work of the
great leaders in Europe, and particularly in Paris. The influence of
Leuckart, Tiedemann, Braun, Cuvier and Von Humboldt directed Agassiz’s
great ability to similar investigations, and he was rapidly coming into
prominence in the study of modern and fossil fishes when the opportunity
to continue his research in America was presented. On arriving on our
shores the young zoologist was so inspired with the opportunities for
his studies in the new country that he decided to remain.

Bringing with him the broad conceptions of his distinguished European
masters, he naturally founded a similar school of zoology in America. It
is from this beginning that the present science of zoology with its many
branches has developed.

It must be remembered in this connection that the great service which
Agassiz rendered to American zoology consisted mainly in making
available to students in America the ideals and methods of European
zoologists. This he was eminently fitted to do both because of his
European training and because of his natural ability as an inspiring
leader.

The times in America, moreover, were fully ripe for the advent of
European culture. There were already in existence natural history
societies in many of our cities and college communities. These societies
not only held meetings for the discussion of biological topics, but
established museums open to the public, and to which the public was
invited to contribute both funds and specimens. This led to a wide
popular interest in natural history. It was therefore comparatively easy
for such a man as Agassiz to develop this favorable public attitude into
genuine enthusiasm.

The American Journal of Science announces the expected visit of Agassiz
as a most promising event for American Zoology (=1=, 451, 1846): “His
devotion, ability, and zeal—his high and deserved reputation and ... his
amiable and conciliating character, will, without doubt, secure for him
the cordial cooperation of our naturalists ... nor do we entertain a
doubt that we shall be liberally repaid by his able review and
exploration of our country.” We of to-day can realize how abundantly
this prophecy was fulfilled.

In the succeeding volume (=2=, 440, 1846) occurs the record of Agassiz’s
arrival. “We learn with pleasure that he will spend several years among
us, in order thoroughly to understand our natural history.”

Immediately on reaching Boston, Agassiz began the publication of
articles on our fauna, and the following year he was appointed to a
professorship at Harvard. The Journal says (=4=, 449, 1847): “Every
scientific man in America will be rejoiced to hear so unexpected a piece
of good news.” The next year the Journal (5, 139, 1848) records
Agassiz’s lecture courses at New York and Charleston, his popularity
with all classes of the people and the gift of a silver case containing
$250 in half eagles from the students of the College of Physicians and
Surgeons.

The service of Agassiz to American zoology, therefore, consisted not
only in the publication of the results of his researches and his
philosophical considerations therefrom, but also, and perhaps in even
greater degree, in the popularization of science. In the latter
direction were his inspiring lectures before popular audiences and the
early publication of a zoological text-book. This book, published in
1848, was entitled “Principles of Zoology, touching the Structure,
Development, Distribution and Natural arrangement of the races of
Animals, living and extinct, with numerous illustrations.” It was
written with the cooperation of Augustus A. Gould. The review of this
book in the Journal (=6=, 151, 1848) indicates clearly the broad modern
principles underlying the new era which was beginning for American
zoology.


  “A work emanating from so high a source as the Principles of Zoology,
  hardly requires commendation to give it currency. The public have
  become acquainted with the eminent abilities of Prof. Agassiz through
  his lectures, and are aware of his vast learning, wide reach of mind,
  and popular mode of illustrating scientific subjects ... The volume is
  prepared for the student in zoological science; it is simple and
  elementary in style, full in its illustrations, comprehensive in its
  range, yet well considered and brought into the narrow compass
  requisite for the purpose intended.”


The titles of its chapters will show how little it differs in general
subject matter from the most recent text-book in biology. Chapter I, The
Sphere and fundamental principles of Zoology; II, General Properties of
Organized Bodies; III, Organs and Functions of Animal Life; IV, Of
Intelligence and Instinct; V, Of Motion (apparatus and modes); VI, Of
Nutrition; VII, Of the Blood and Circulation; VIII, Of Respiration; IX,
Of the Secretions; X, Embryology (Egg and its Development); XI, Peculiar
Modes of Reproduction; XII, Metamorphoses of Animals; XIII, Geographical
Distribution of Animals; XIV, Geological Succession of Animals, or their
Distribution in Time.

A moment’s consideration of the fact that all these topics are
excellently treated will show how great had been the progress of zoology
in the first half of the nineteenth century. The sixty years that have
elapsed since the publication of this book have served principally to
develop these separate lines of biology into special fields of science
without reorganization of the essential principles here recognized. This
remained for many years the standard zoological and physiological
text-book, and was republished in several editions here and in England.
Another popular book is entitled “Methods of Study in Natural History”
(1864).

More than 400 books and papers were written by Agassiz, over a third of
which were published before he came to America. They cover both
zoological and geological topics, including systematic papers on living
and fossil groups of animals, but most important of all are his
philosophical essays on the general principles of biology.

One of Agassiz’s greatest services to zoology was the publication of his
“Bibliographia Zoologiæ et Geologiæ” by the Ray Society, beginning with
1848. The publication of the Lowell lectures in Comparative Embryology
in 1849 gave wide audience to the general principles now recognized in
the biogenetic law of ancestral reminiscence. As stated in the Journal
(=8=, 157, 1849), the “object of the Lectures is to demonstrate that a
natural method of classifying the animal kingdom may be attained by a
comparison of the changes which are passed through by different animals
in the course of their development from the egg to the perfect state;
the change they undergo being considered as a scale to appreciate the
relative position of the species.” These “principles of classification”
are fully elucidated in a separate pamphlet, and are discussed at length
in the Journal (=11=, 122, 1851).

One of the most interesting of Agassiz’s numerous philosophical essays,
originally contributed to the Journal (9, 369, 1850), discusses the
“Natural Relations between Animals and the elements in which they live.”
Another philosophical paper contributed to the Journal discusses the
“Primitive diversity and number of Animals in Geological times” (=17=,
309, 1854). Of his systematic papers, those on the fishes of the
Tennessee river, describing many new species, were published in the
Journal (=17=, 297, 353, 1854).

[Illustration: Ls Agassiz]

Agassiz’s beautifully illustrated “Contributions to the Natural History
of the United States” cover many subjects in morphology and embryology,
which are treated with such thoroughness and breadth of view as to give
them a place among the zoological classics. The Essay on Classification,
the North American Testudinata, the Embryology of the turtle, and the
Acalephs are the special topics. These are summarized and discussed at
length in the Journal (=25=, 126, 202, 321, 342, 1858; =30=, 142, 1860;
=31=, 295, 1861).

The volume on the “Journey in Brazil” (1868) in joint authorship with
Mrs. Agassiz is a fascinating narrative of exploration.

The conceptions which Agassiz held as to the most essential aim of
zoological study are well illustrated in his autobiographical sketch,
where he writes:[174]


  “I did not then know how much more important it is to the naturalist
  to understand the structure of a few animals, than to command the
  whole field of scientific nomenclature. Since I have become a teacher,
  and have watched the progress of students, I have seen that they all
  begin in the same way; but how many have grown old in the pursuit,
  without ever rising to any higher conception of the study of nature,
  spending their life in the determination of species, and in extending
  scientific terminology!”


It is not surprising, then, that under such influence the older
systematic studies should be replaced in large measure by those of a
morphological and embryological nature.

The personal influence of Agassiz is still felt in the lives of even the
younger zoologists of the present day. For the investigators of the
present generation are for the most part indebted to one or another of
Agassiz’s pupils for their guidance in zoological studies. These pupils
include his son Alexander Agassiz, Allen, Brooks, Clarke, Fewkes, Goode,
Hyatt, Jordan, Lyman, Morse, Packard, Scudder, Verrill, Wilder, and
others—leaders in zoological work during the last third of the
nineteenth century. Through such men as these the inspiration of Agassiz
has been handed on in turn to their pupils and from them to the younger
generation of zoologists.

The essential difference between the work of Agassiz and that of the
American zoologists who preceded him was in his power of broad
generalizations. To him the organism meant a living witness of some
great natural law, in the interpretation of which zoology was engaged.
The organism in its structure, in its development, in its habits
furnished links in the chain of evidence which, when completed, would
reveal the meaning of nature. Of all Agassiz’s pupils, probably William
K. Brooks most fittingly perpetuated his master’s ideals.


           _Period of Morphology and Embryology, 1847–1870._

The new aspect of zoology which came as a result of the influence of
Agassiz characterized the zoological work of the fifties and sixties,
that is, until the significance of the natural selection theory of
Darwin and Wallace became generally appreciated.

The work in these years and well into the seventies was largely
influenced by the morphological, embryological and systematic studies of
Louis Agassiz and his school. The structure, development, and homologies
of animals as indicating their relationship and position in the scheme
of classification was prominent in the work of this period. The
adaptations of animals to their environment and the application of the
biogenetic law to the various groups of animals were also favorite
subjects of study.

The most successful investigators in this period on the different groups
of animals include:—Louis Agassiz on the natural history and embryology
of coelenterates and turtles; A. Agassiz, embryology of echinoderms and
worms; H. J. Clark, embryology of turtles and systematic papers on
sponges and coelenterates; E. Desor, echinoderms and embryology of
worms; C. Girard, embryology, worms, and reptiles; J. Leidy, protozoa,
coelenterates, worms, anatomy of mollusks; W. O. Ayres and T. Lyman,
natural history of echinoderms; McCrady, development of acalephs; W.
Stimpson, marine invertebrates; A. E. Verrill, coelenterates,
echinoderms, worms; A. Hyatt, evolutionary theories, bryozoa and
mollusks; Pourtales, deep sea fauna; C. B. Adams, A. and W. G. Binney,
Brooks, Carpenter, Conrad, Dall, Jay, Lea, S. Smith, Tryon, mollusks; E.
S. Morse, brachiopods, mollusks; J. D. Dana, coelenterates and
Crustacea; Kirtland, Loew, Edwards, Hagen, Melsheimer, Packard, Riley,
Scudder, Walsh, insects; Gill, Holbrook, Storer, fishes; Cope,
evolutionary theories, fishes and amphibia; Baird, reptiles and birds;
J. A. Allen, amphibia, reptiles and birds; Brewer, Cassin, Coues,
Lawrence, birds; Audubon, Bachman, Baird, Cope, Wilder, mammals.

The progress of ornithology in the United States previous to 1876 is
well described in a paper by J. A. Allen in the American Naturalist
(=10=, 536, 1876). A sketch of the early history of conchology is given
by A. W. Tryon in the Journal (=33=, 13, 1862).

Jeffries Wyman was the most prominent comparative anatomist of this
period. His work includes classic papers on the anatomy and embryology
of fishes, amphibia, and reptiles.


        _Zoology in the American Journal of Science, 1846–1870._

The fifty volumes of the second series of the Journal, including the
years 1846 to 1870, cover approximately this period of morphology and
embryology. During this period the Journal occupied a very important
place in zoological circles, for J. D. Dana was for most of this period
the editor-in-chief, while Louis Agassiz and Asa Gray were connected
with it as associate editors. Moreover, in 1864 one of the most
promising of Agassiz’s pupils, Addison E. Verrill, was called to Yale as
professor of zoology and was made an associate editor in 1869.

In the Journal, therefore, may be found, in its original articles,
together with its reports of meetings and addresses and its reviews of
literature, a fairly complete account of the zoological activity of the
period. The most important zoological researches, both in Europe and
America, were reviewed in the bibliographic notices.

The most important series of zoological articles are by Dana himself. As
his work on the zoophytes and crustacea of the U. S. Exploring
Expedition continued, he published from time to time general summaries
of his conclusions regarding the relationships of the various groups.
Included among these papers are philosophical essays on general
biological principles which must have had much influence on the
biological studies of the time, and which form a basis for many of our
present concepts.

The importance of these papers warrants the list being given in full.
The titles are here in many cases abbreviated and the subjects
consolidated.


  General views on Classification, =1=, 286, 1846.

  Zoophytes, =2=, 64, 187, 1846; =3=, 1, 160, 337, 1847.

  Genus Astraea, =9=, 295, 1850.

  Conspectus crustaceorum, =8=, 276, 424, 1849; =9=, 129, 1850; =11=,
  268, 1851.

  Genera of Gammaracea, =8=, 135, 1849; of Cyclopacea, =1=, 225, 1846.

  Markings of Carapax of Crabs, =11=, 95, 1851.

  Classification of Crustacea, =11=, 223, 425; =12=, 121, 238, 1851;
  =13=, 119; =14=, 297, 1852; =22=, 14, 1856.

  Geographical distribution of Crustacea, =18=, 314, 1854; =19=, 6;
  =20=, 168, 349, 1855.

  Alternation of Generations in Plants and Radiata, =10=, 341, 1850.

  Parthenogenesis, =24=, 399, 1857.

  On Species, =24=, 305, 1857.

  Classification of Mammals, =35=, 65, 1863; =37=, 157, 1864.

  Cephalization, =22=, 14, 1856; 36, =1=, 321, 440, 1863; =37=, 10, 157,
  184, 1864; =41=, 163, 1866; =12=, 245, 1876.

  Homologies of insectean and crustacean types, =36=, 233, 1863; =47=,
  325, 1894.

  Origin of life, =41=, 389, 1866.

  Relations of death to life in nature, =34=, 316, 1862.


Of the above, the articles on cephalization as a fundamental principle
in the development of the system of animal life have attracted much
attention. The evidence from comparative anatomy, paleontology, and
embryology alike supports the view that advance in the ontogenetic as
well as in the phylogenetic stages is correlated with the unequal growth
of the cephalic region as compared with the rest of the body. Dana shows
that this principle holds good for all groups of animals. His homologies
of the limbs of arthropods and vertebrates, however, do not accord with
more modern views.

Other papers on the same and allied topics were published by Dana in
other periodicals. His most conspicuous zoological works, however, are
his reports on the Zoophytes and Crustacea of the United States
Exploring Expedition, 1837–1842. The former consists of 741 quarto pages
and 61 folio plates, describing over 200 new species, while the
Crustacea report, in two volumes, has 1620 pages and 96 folio plates,
with descriptions of about 500 new species. Each of these remains to-day
as the most important contribution to the classification of the
respective groups. The relationships of the species, genera and families
were recognized with such remarkable judgment that Dana’s admirable
system of classification has remained the basis for all subsequent work.

Dana’s critical reviews (=25=, 202, 321, 1858) of Agassiz’s
“Contribution to the Natural History of the United States” are among the
most interesting of his philosophical discussions concerning the
relationships of animals as revealed by their structure, their
embryology, and their geological history.

The remaining zoological articles in this series cover nearly the whole
range of systematic zoology. Especially important are the articles by
Verrill on coelenterates, echinoderms, worms and other invertebrates.

In the years following the publication of Darwin’s Origin of Species in
1859 occur many articles on the theory of natural selection. Some of the
writers attack the theory, while others give it more or less
enthusiastic support.

Experimental methods in solving biological problems were little used at
this time, although a few articles of this nature appear in the Journal.
Of these, a paper by W. C. Minor (35, 35, 1863) on natural and
artificial fission in some annelids has considerable interest to-day.


                        _Exploring Expeditions._

Of the important zoological expeditions the following may be selected as
showing their influence on American Zoology:

The North Pacific Expedition, with William Stimpson as zoologist,
returned in 1856 with much new information concerning the marine life of
the coasts of Alaska and Japan and many new species of invertebrates.

In 1867–1869 the United States Coast Survey extended its explorations to
include the deep sea marine life off the southeastern coasts and Gulf of
Mexico under the leadership of Pourtales and Agassiz.

The Challenger explorations (1872–1876) added greatly to the knowledge
of marine life off the American coast as well as in other parts of the
world.

The explorations of the United States Fish Commission succeeded those of
the Coast Survey in the collection of marine life off our coasts and in
our fresh waters. These have continued since 1872 and have yielded most
important results from both the scientific and economic standpoints.

Under the charge of Alexander Agassiz the Coast Survey Steamer “Blake,”
in 1877 to 1880, was engaged in dredging operations in three cruises to
various parts of the Atlantic. The U. S. Fish Commission Steamer
“Albatross,” also in charge of Agassiz, made three expeditions in the
tropical and other parts of the Pacific in the years from 1891 to 1905.
The study of these collections has added greatly to our knowledge of
systematic zoology and geographical distribution. The reports on some of
the groups are still in course of preparation.


                   _Period of Evolution, 1870–1890._

The time from 1870 to 1890 may be appropriately called the period of
evolution, for although it commences eleven years after the publication
of the Origin of Species, the importance of the natural selection theory
was but slowly receiving general recognition. The hesitation in
accepting this theory was due in no small degree to the opposition of
Louis Agassiz. After the acceptance of evolution, although morphological
and embryological studies continued as before, they were prosecuted with
reference to their bearing on evolutionary problems.

Following closely the methods which had produced so much progress during
the life of Agassiz, the field of zoology was now occupied by a new
generation, among whom the pupils of Agassiz were the most prominent.

[Illustration: Thomas H. Huxley]

The teaching of biology at this time was also strongly influenced by
Huxley, whose methods of conducting laboratory classes for elementary
students were adopted in most of our large schools and colleges. This
placed biology on the same plane with chemistry as a means for training
in laboratory methods and discipline, with the added advantage that the
subject of biology is much more intimately connected with the student’s
everyday life and affairs.

This increasing demand for instruction in biology and the consequent
necessity for more teachers brought an increasing number of
investigators into this field.

Conspicuous in this period was the work of E. D. Cope, best known as a
paleontologist, but whose work on the classification of the various
groups of vertebrates stands preeminent, and whose philosophical essays
on evolution had much influence on the evolutionary thought of the time.
He was a staunch supporter of the Lamarckian doctrine. Alpheus Hyatt
also maintained this theory, and brought together a great accumulation
of facts in its support. He thereby contributed largely to our knowledge
of comparative anatomy and embryology. A. S. Packard, whose publications
cover a wide range of topics, was best known for his text-books of
zoology and his manuals on insects.

W. K. Brooks was a leading morphologist and embryologist. S. F. Baird,
for many years the head of the United States Fish Commission, was the
foremost authority on fish and fisheries and is also noted for his work
on reptiles, birds and mammals. The man of greatest influence, although
by no means the greatest investigator, was C. O. Whitman. It is to him
that we owe the inception of the Marine Biological Laboratory, the most
potent influence in American zoology to-day; the organization of the
American Morphological Society, the forerunner of the present American
Society of Zoologists; and the establishment of the Journal of
Morphology. G. B. Goode was distinguished for his work on fishes and for
his writings on the history of science.

E. L. Mark, C. S. Minot, and Alexander Agassiz were acknowledged leaders
in their special fields of research—Mark in invertebrate morphology and
embryology, and Minot in vertebrate embryology, while Alexander Agassiz
made many important discoveries in the systematic zoology and embryology
of marine animals, and to him we owe in large measure our knowledge of
the life in the oceans of nearly all parts of the world.

The knowledge of the representatives of the different divisions of the
American fauna had now become sufficient to allow the publication of
monographs on the various classes, orders and families. At this time
also particular attention was given to the marine invertebrates of all
groups.

Of the many investigators working on the various groups of animals at
this time only a few may be mentioned. The protozoa were studied by
Leidy, Clark, Ryder, Stokes; the sponges by Clark, Hyatt; the
coelenterates by A. Agassiz, S. F. Clarke, Verrill; the echinoderms by
A. Agassiz, Brooks, Kingsley, Fewkes, Lyman, Verrill; the various groups
of worms by Benedict, Eisen, Silliman, Verrill, Webster, Whitman; the
mollusks by A. and W. G. Binney, Tryon, Conrad, Dall, Sanderson Smith,
Stearns, Verrill; the Brachiopods by Dall and Morse; the Bryozoa by
Hyatt; the crustacea by S. I. Smith, Harger, Hagen, Packard, Kingsley,
Faxon, Herrick; the insects by Packard, Horn, Scudder, C. H. Fernald,
Williston, Norton, Walsh, Fitch, J. B. Smith, Comstock, Howard, Riley
and many others; spiders by Emerton, Marx, McCook; tunicates by Packard
and Verrill; fishes by Baird, Bean, Cope, Gilbert, Gill, Goode, Jordan,
Putnam; amphibians and reptiles by Cope; birds by Baird, Brewer, Coues,
Elliott, Henshaw, Allen, Merriam, Brewster, Ridgway; and the mammals by
Allen, Baird, Cope, Coues, Elliott, Merriam, Wilder.

Interest in the evolutionary theory continued to increase and eventually
developed into the morphological and embryological studies which reached
their culmination between 1885 and 1890 under the guidance of Whitman,
Mark, Minot, Brooks, Kingsley, E. B. Wilson and other famous zoologists
of the time. In these years the Journal of Morphology was established
and the American Morphological Society was formed.

The morphological, embryological and paleontological evidences of
evolution as indicated by homologies, developmental stages and
adaptations were the most absorbing subjects of zoological research and
discussion.

[Illustration: A. E. Verrill March 1904]


        _Zoology in the American Journal of Science, 1870–1918._

The third series of the Journal (1870–1895), likewise including fifty
volumes, embraces this period of zoological activity in morphological
and embryological studies, culminating with the inception of the modern
experimental methods.

In this period also occurred the greatest progress in marine systematic
zoology, due to the explorations of the United States Fish Commission
off the Atlantic Coast. The Journal had an important share in the
zoological development of this period also, for A. E. Verrill, who was
now an associate editor, was in charge of the collections of marine
invertebrates. Consequently most of the discoveries in this field were
published in the Journal in numerous original contributions by Verrill
and his associates. The explorations of the U. S. Fish Commission
Steamer “Albatross” are described from year to year by Verrill, with
descriptions of the new species of invertebrates discovered.

The numerous original contributions by Verrill on subjects of general
zoological interest as well as on those of a systematic nature give this
third series of the Journal much zoological importance. Verrill’s papers
cover almost the whole field of descriptive zoology, but are mainly
devoted to marine invertebrates. Those which were originally contributed
to the Journal or summarized by him in his literature reviews include
the following topics:


  Sponges, =16=, 406, 1878.

  Coelenterates, 37, 450, 1864; =44=, 125, 1867; =45=, 411, 186; =46=,
  143, 1868; =47=, 282, 1869; =48=, 116, 419, 1869; =49=, 370, 1870;
  =3=, 187, 432, 1872; =6=, 68, 1873; =21=, 508, 1881; =6=, 493, 1898;
  =7=, 41, 143, 205, 375, 1899; =13=, 75, 1902.

  Echinoderms, =44=, 125, 1867; =45=, 417, 1868; =49=, 93, 101, 1870;
  =2=, 430, 1871; =11=, 416, 1876; =49=, 127, 199, 1895; =28=, 59, 1909;
  =35=, 477, 1913; =37=, 483, 1914; =38=, 107, 1914; =39=, 684, 1915.

  Worms, =50=, 223, 1870; =3=, 126, 1872.

  Mollusks, =49=, 217, 1870; =50=, 405, 1870; 3, 209, 281, 1872; =5=,
  465, 1873; =7=, 136, 158, 1874; =9=, 123, 177, 1875; 10, 213, 1875;
  =12=, 236, 1876; =14=, 425, 1877; =19=, 284, 1880; =20=, 250, 251,
  1880; =2=, 74, 91, 1896; =3=, 51, 79, 162, 355, 1897.

  Crustacea, =44=, 126, 1867; =48=, 244, 430, 1869; =25=, 119, 534,
  1908.

  Ascidians, =1=, 54, 93, 211, 288, 443, 1871; =20=, 251, 1880.

  Dredging operations and marine fauna, =49=, 129, 1870; =2=, 357, 1871;
  =5=, 1, 98, 1873; =6=, 435, 1873; =7=, 38, 131, 405, 409, 498, 608,
  1874; =9=, 411, 1875; =10=, 36, 196, 1875; =16=, 207, 371, 1878; =17=,
  239, 258, 309, 472, 1879; =18=, 52, 468, 1879; =19=, 137, 187; =20=,
  390, 1880; =22=, 292, 1881; =23=, 135, 216, 309, 406, 1882; =24=, 360,
  477, 1882; =28=, 213, 378, 1884; =29=, 149, 1885.

  Miscellaneous, =39=, 221, 1865; =41=, 249, 268, 1866; =44=, 126, 1867;
  =48=, 92, 1869; =3=, 386, 1872; =7=, 134, 1847; =10=, 364, 1875; =16=,
  323, 1878; =20=, 251, 1880; =3=, 132, 135, 1897; =9=, 313, 1900; =12=,
  88, 1901; =13=, 327, 1902; =14=, 72, 1902; =15=, 332, 1903; =24=, 179,
  1907; =29=, 561, 1910.


S. I. Smith describes the metamorphosis of the Crustacea (=3=, 401,
1872; =6=, 67, 1873), species of crustacea (=3=, 373, 1872; =7=, 601,
1874; =9=, 476, 1875), and dredging operations in Lake Superior (=2=,
373, 448, 1871). In this series occurs also a series of papers on
comparative anatomy and embryology from the Chesapeake Zoological
Laboratory in charge of W. K. Brooks. In the 39th and 40th volumes of
the third series (1890) occur several papers on evolutionary topics by
John T. Gulick (=39=, 21; =40=, 1, 437) which have attracted much
attention.

Before the end of this period, however, the Journal was relieved from
the necessity of publishing zoological articles by the establishment of
several periodicals devoted especially to the various fields of zoology.
We find, therefore, but few exclusively zoological papers after 1885,
although articles of a general biological interest and the reviews of
zoological books continue.

In the fourth series of the Journal, beginning in 1896, occur also a
number of articles on systematic zoology by Verrill and others and
several papers having a general biological interest. Brief reviews of a
small number of zoological books are still continued, but at the present
day the Journal, which played so important a part in the early
development of American zoology, has been given over to the geological
and physical sciences in harmony with the modern demand for
specialization.


             _Period of Experimental Biology, since 1890._

Zoological studies remained in large measure observational and
comparative until about 1890 when the experimental methods of Roux,
Driesch and others came into prominence. Interest then turned from the
accumulation of facts to an analysis of the underlying principles of
biological phenomena. The question now was not so much what the organism
does as how it does what is observed, and this question could be
answered only by the experimental control of the conditions. These
experimental studies met with such remarkable success that in a few
years the older morphological studies were largely abandoned, the
Morphological Society changed its name to the Society of Zoologists, and
in 1904 the Journal of Experimental Zoology was established. The
experimental methods were applied to all branches of biological science,
and while it must be freely admitted that little progress has been made
toward an understanding of the ultimate causes which underlie biological
phenomena, a great advance has been made in the elucidation of the
general principles involved.

Experimental embryology, histology, regeneration, comparative
physiology, neurology, cytology, and heredity have in recent years
successfully adopted an experimental aspect and have made significant
progress thereby. Biology has now taken its place beside chemistry and
physics as an experimental science.

The latest great advance in biology has been in the field of heredity.
The rediscovery of the Mendelian principles of heredity in 1900 brought
to light the most important generalization in biology in recent times.
The new science of genetics is essentially the experimental study of
heredity.

We are at the moment in the midst of an effort to establish in biology a
few relatively simple laws by using for the purpose the vast
accumulations of observational data gathered in past years, supplemented
by such experimental data as have been provided by these more recent
investigations. Such hypotheses as have been formulated are for the most
part only tentatively held, for their validity is generally incapable of
a critical test. But wherever such tests have been possible, the laws of
mathematics, physics and chemistry are found applicable to biological
phenomena.

The number of investigators has now become so great and their activities
so prolific that the list and synopses of the zoological publications
each year cover upwards of 1000 to 1500 pages in the International
Catalogue of Scientific Literature.

_American Leadership._—During the first half of the century the progress
of zoology in America remained distinctly behind that of Europe. At the
beginning of the century the science was farthest developed by the
French and English, although Linnæus was a Swede and took his degree in
Holland. Under the influence of Von Baer and his monumental treatise on
embryology (Ueber Entwicklungsgeschichte der Thiere, 1828), and
supported later by the great physiologist, Johannes Müller, whose
“Physiologie des Menschen” (1846) forms the basis of modern physiology,
the German school forged rapidly ahead and eventually assumed the
leadership in zoology, as in several other branches of science.

In the latter half of the century the influence of the German
universities dominated in a large measure the zoological investigations
in America. The reason for this is partly due to the fact that many of
our young zoologists, after finishing their college course, completed
their preparation for research by a year or more at a German university.
The more mature zoologists, too, looked forward with keen anticipation
to spending their summer vacations and sabbatical years in research in a
German laboratory or at the famous Naples station in which the German
influence was dominant.

With the rise of experimental biology since 1890, however, the American
zoologists have shown so high a degree of originality in devising
experiments, so much skill in performing them, and such keenness in
analyzing the results, that they have assumed the world leadership in
several of the special fields into which the science of zoology is now
divided.


                       _Biological Periodicals._

Perhaps in no better way can the progress of biology in America be
illustrated than by a brief survey of the origin and development of the
more important biological journals. For it will be seen that these
publications have become more numerous and more specialized as the
science has advanced in specialization.

The early publications—which as is well known, treated mainly of the
birds, mammals and other vertebrates, and of insects, crustacea and
shells—consisted mainly of separate books or pamphlets, published by
private subscription. After the establishment of the so-called Academies
of Science, or of Arts and Sciences, toward the end of the eighteenth
and in the first quarter of the nineteenth century, the reports of the
meetings began to be published as periodical Journals, supported by the
academies. In these publications, and in the Journal which was founded
at the same time, appear papers on all branches of science, including
zoology. As soon as zoology in America assumed its modern aspects
through the influence of Louis Agassiz and his followers the earliest
strictly zoological journals were established.

It should be noted, however, that the journals of the scientific and
natural history societies were more or less fully devoted to zoological
topics according to the nature of the activities of the members and
correspondents. After the establishment of the Museum of Comparative
Zoology by Louis Agassiz came the founding in 1863 of its Bulletin and
later its Memoirs. These publications have continued to the present day
as a standard of excellence for the reports of zoological
investigations. In connection with the systematic work on mollusks, the
American Journal of Conchology was established in 1865. The American
Naturalist was founded in 1867 by four of Louis Agassiz’s pupils, Hyatt,
Morse, Packard and Putnam. It was later edited by Cope as a leading
periodical for the publication of biological papers, particularly those
relating to evolution, and is at present devoted to evolutionary topics.
It is now in the 52d volume of its new series.

With the awakened interest in comparative anatomy and embryology came
the need for an American journal which should supply a means of
publication for the reports of researches accomplished by the increasing
number of workers in these fields. This need was fully met by the
establishment of the Journal of Morphology in 1887. This publication,
now in its 30th volume, has equalled the best European journals in the
character of its papers. A few years later (1891) came the Journal of
Comparative Neurology for the publication of investigations relating to
the morphology and physiology of the nervous system and to nervous and
allied phenomena in all groups of organisms. Twenty-eight volumes of
this journal have been completed. The Zoological Bulletin was started
under the auspices of the Marine Biological Laboratory in 1897 for the
publication of papers of a less extensive nature and which could be more
promptly issued than those in the Journal of Morphology where elaborate
plates were required. After two years the scope of the Bulletin was
enlarged to include botanical and physiological subjects. The name was
correspondingly changed to the Biological Bulletin. Of this important
periodical 33 volumes have been issued.

For the publication of papers on human and comparative anatomy and
embryology, the American Journal of Anatomy was established in 1901, and
is now in its twenty-third volume.

Meanwhile the trend of zoological interest was toward topics connected
with the ultimate nature of biological phenomena. The meaning of these
phenomena could be determined only by the experimental method.
Researches in this field became more prominent and the adequate
publication of the numerous papers required the establishment of a new
journal in 1904. This was named the Journal of Experimental Zoology. It
immediately took its place in the front rank of American zoological
periodicals. Twenty-four volumes have been published.

In spite of the constantly increasing number of journals, the science
grew faster than the means of publication. So crowded did the American
journals become that long delays often resulted before the results of an
investigation could be issued. This condition was met in part by the
sending of many papers to be published in European journals (a necessity
most discreditable to American zoology) and in part by the establishment
of additional means of publication. Of the latter the Anatomical Record,
now in its fourteenth volume, was begun in 1906 for the prompt
publication of briefer papers on vertebrate anatomy, embryology and
histology and for preliminary reports and notes on technique.

During the past few years has come a great advance in the experimental
breeding of plants and animals. Problems in heredity and evolution have
taken on a new interest since the importance and validity of Mendel’s
discovery have been recognized. To meet this development of biology the
journal Genetics was begun in 1916 for the publication of technical
papers, while the Journal of Heredity, modified from the American
Breeders Magazine, is devoted to popular articles on animal and plant
breeding, and Eugenics.

On the whole, the science of zoology is now assuming a closer relation
to practical affairs. Entomology, for example, is now represented by the
Journal of Economic Entomology, of which 10 volumes have been issued
since 1907. The Journal of Animal Behavior covers another practical
field of research. The Proceedings of the Society for Experimental
Biology and Medicine, starting in 1903, the American Journal of
Physiology, and several other publications cover the physiological
field. The Journal of Parasitology, established 1914, now in its fourth
volume, is devoted to the interests of medical zoology. The Auk, now in
the 34th volume of its new series (42d of old series), is the official
organ of the American Ornithologists Union and is devoted to the
dissemination of knowledge concerning bird life. The Annals of the
Entomological Society of America, established in 1908, and now in its
10th volume, is one of several important entomological journals. The
Nautilus, of which 28 volumes have been issued, is one of the more
successful journals devoted to conchology. This list might be extended
to include numerous other periodicals of importance, both technical and
popular, which have been of great service in the various fields of
biology.

In addition to these are the many volumes of systematic papers in the
Proceedings of the United States National Museum, the practical reports
in the Bulletin of the United States Fish Commission, the vast
literature issued yearly by the various divisions of the United States
Department of Agriculture, Public Health Service and other Governmental
departments, while the list of publications by scientific societies,
museums, and other institutes is constantly increasing and covers all
fields of biological research.

At the present time facilities for the publication of research on any
branch of zoology are as a rule entirely adequate. For this highly
satisfactory condition the science is indebted to the support given five
of its most important journals by the Wistar Institute of Anatomy and
Biology.


                       _Biological Associations._

An important light on the history of biology in America can be thrown by
a glance at the rise and development of societies or associations for
the report and discussion of papers relating to that branch of science.
In the first half of the nineteenth century natural history societies
were formed in most cities and centers of learning. These were very
important factors in the promotion of scientific research as well as in
the diffusion of popular knowledge of living things. The aims and
activities of twenty-nine such scientific societies, many of which were
devoted especially to natural history, are described in one of the early
volumes of the Journal (=10=, 369, 1826). The Connecticut Academy of
Arts and Sciences, dating from 1799, the Philadelphia Academy of Natural
Sciences from 1812, and the New York Lyceum of Natural History (in 1876
name changed to New York Academy of Sciences) from 1817 are among the
oldest of those which still exist.

Of national institutions the American Philosophical Society was founded
in 1743, the American Academy of Arts and Sciences in 1780, and the
National Academy of Sciences in 1863.

The American Association for the Advancement of Science, with its
thousands of members, now has separate sections for each of the special
branches of science. This great association was organized in 1848, as
the successor of the Association of American Geologists and Naturalists.
This was itself a revival of the American Geological Society which first
met at Yale in 1819. Its meetings have given a great support to the
scientific work of the country.

The American Society of Naturalists was founded in 1883. The original
plan of the society was for the discussion of methods of investigation,
administration and instruction in the natural sciences, but its program
is now entirely devoted to discussions and papers of a broad biological
interest. It also arranges for an annual dinner of the several
biological societies and an address on some general biological topic.

In 1890, toward the end of the period in which morphological studies
were being emphasized, the professional zoologists of the eastern states
founded the American Morphological Society. This association held annual
meetings during the Christmas holidays for the presentation of
zoological papers. This name became less appropriate after a few years
because of the gradual decrease in the proportion of morphological
investigations owing to the greater attention being directed to problems
in experimental zoology and physiology. Consequently the name was
changed to the American Society of Zoologists. To be eligible for
membership in this society a person must be an active investigator in
some branch of zoology, as indicated by the published results.

The American Association of Anatomists includes in its membership
investigators and teachers in comparative anatomy, embryology, and
histology as well as in human anatomy. Many professional zoologists and
experimental biologists present their papers before this society, or at
the meetings of the American Physiological Society. The Entomological
Society of America and the American Association of Economic
Entomologists are large and active societies.

These national societies have been of great service in fostering a high
standard of zoological research. A still more important service, though
generally less conspicuous, is rendered by the journal clubs in
connection with all the larger zoological laboratories, and by local
scientific societies which are now maintained in all the larger centers
of learning throughout the country. There are also specific societies
for some of the different fields of biological work.


                         _Biological Stations._

No insignificant factor in the development of biological science has
been the establishment of biological stations where investigators,
teachers and students meet in the Summer vacation for special studies,
discussions and research. The most successful of these laboratories have
been located on the seashore and here the study of marine life in Summer
supplements the work of the school or university biological courses. The
famous Naples Station was founded in 1870, and was shortly after
followed by several others. Similar biological stations are now
supported on almost every coast in Europe and in several inland
localities.

The first such American school was established by Louis Agassiz at the
island of Penikese on the coast of Massachusetts in 1873, succeeding his
private laboratory at Nahant. During that Summer more than forty
students gained enthusiasm for the work of future years. Unfortunately
the laboratory so auspiciously started was of brief duration, for the
death of Agassiz occurred in December of the same year, and the
laboratory was discontinued at the end of the following Summer. Shortly
afterward Alexander Agassiz equipped a small private laboratory at
Newport, Rhode Island, and W. K. Brooks established the Chesapeake Bay
Zoological Laboratory.

At this time the United States Fish Commission was engaged under the
direction of Spencer F. Baird in a survey of the marine life of the
waters off the Eastern Coast. Between 1881 and 1886 the Commission
established the splendidly equipped biological station at Woods Hole,
Massachusetts. Both here and at the Fish Commission Laboratory at
Beaufort, North Carolina, much work in general zoology as well as in
economic problems is accomplished. These laboratories are designed
particularly for specialists engaged in researches connected with the
work of the Fish Commission.

A need was soon felt for a marine laboratory along broader lines, and
one available to the students and teachers of the schools and colleges.
To meet these requirements the Woods Hole Marine Biological Laboratory
was started in 1887, as the successor to an earlier laboratory at
Annisquam, and has since become a great Summer congress for biologists
from all parts of the country. It is safe to say that no other
institution has been of equal service in securing for biology the high
plane it now occupies in American science. The leading spirit in the
establishment of this laboratory and its director for many years was
Charles O. Whitman.

Successful marine laboratories are located also at Cold Spring Harbor,
Long Island; at Harpswell, Maine; and at Bermuda. The Carnegie
Institution maintains a laboratory at Tortugas Island, Florida, for the
investigation of tropical marine life.

On the Pacific Coast marine laboratories are located at Pacific Grove
and at La Jolla, California, and at Friday Harbor, Washington. Several
other biological laboratories are open each Summer on our coasts, as
well as a number of fresh-water laboratories on the interior lakes.
There are also several mountain laboratories. The influence of these
laboratories on American biology is immeasurable.


                       _Natural History Museums._

Museums of Natural History or “Cabinets of Natural Curios” as they were
sometimes called, were established in the first half of the nineteenth
century in connection with the various natural history societies. These
were of much service in stimulating the collection of zoological
“specimens” and in arousing a popular interest in natural history.

The zoological museum of earlier days consisted of rows on rows of
systematically arranged specimens, each carefully labelled with
scientific name, locality, date of collection and donor—much like the
pages of a catalogue. All this has now been changed; the bottles of
specimens have been relegated to the storeroom, and the great plate
glass cases of the modern museum represent individual studies in the
various fields of modern zoological research, or individual chapters in
the latest biological text-books. Often the talent of the artist and the
skill of the taxidermist are cunningly combined to produce most
realistic bits of nature.

The United States National Museum, the American Museum of Natural
History, the Field Columbian Museum and the Museum of Comparative
Zoology are among the finest museums of the world, while many of the
states, cities, and universities maintain public museums as a part of
their educational systems.


                   _Systematic Zoology and Taxonomy._

The work in systematic zoology is now mainly carried on by specialists
in relatively small groups of animals. This is necessitated both by the
increasingly large number of species known to science and by the
completeness and exactness with which species must now be defined. The
majority of systematic workers are now connected with museums where the
large collections furnish material for comparative studies.

Prominent in this field is the United States National Museum, the
publications of which are mainly taxonomic and zoogeographic, and cover
every group of organism. The adequacy of this great museum for such
studies may be illustrated by the collection of mammals. This museum has
the types of 1135 of the 2138 forms (including species and subspecies)
of North American mammals recognized in Miller’s list,[175] and less
than 200 forms lack representatives among the 120,000 specimens of
mammals. Systematic monographs of several of the orders of mammals have
been published.

Systematic study of the birds has brought the number of species and
subspecies known to inhabit North and Middle America to above 3000. The
most comprehensive systematic treatise is the still incomplete report of
Ridgeway[176] of which seven large volumes have already been issued.

On the reptiles, the most complete monograph is that by Cope[177]
entitled “The Crocodilians, Lizards and Snakes of North America.”

The Amphibia have also been studied by Cope, whose report on the
Batrachia of North America[178] is the standard taxonomic work.

The most comprehensive systematic work on fishes is the “Descriptive
Catalogue of the Fishes of North and Middle America” by Jordan and
Evermann.[179]

The invertebrate groups have been in part similarly monographed by the
members of the U. S. National Museum staff and others, and further
studies are in progress. Other taxonomic monographs published by this
museum include the various groups of animals from many different parts
of the world.

A number of the larger State, municipal, and university museums publish
bulletins on special groups represented in their collections as well as
articles of general zoological interest.

Expeditions, subsidized by museum and private funds, are from time to
time sent to various parts of the world and their results are often
published in sumptuous manner.

The total number of living species of animals is unknown, but
considering that about a quarter of a million new species have been
described during the past thirty years, it is probable that several
million species are in existence to-day. More than half a million have
been described. These are probably but a small fraction of the number
that have existed in past geological ages.

Thus, in spite of all the work that has been done in systematic zoology
and as the number of known species continues to increase, there still
remain many groups of animals, some of which are by no means rare or
minute, in which probably only a small proportion of the species are as
yet capable of identification.

It is only since the publication of Ward and Whipple’s “Fresh-water
Biology” within the past year that the amateur zoologist could hope to
find even the names of all the organisms which may be collected from a
single pool of water. And in many cases he will still meet with
disappointment, for many of our protozoa and other fresh-water organisms
have not yet been described as species.

During the past few years there has been a tendency on the part of some
of our biologists engaged in experimental work to disparage the studies
of the systematists. It must be granted, however, that both lines of
work are essential to the sound development of zoological science, for
experimental investigations in which the accurate diagnosis of species
is ignored always result in confusion.

_Ecology._—The marvelous modifications in structure and instincts by
which the various animals are adapted to their surroundings now forms a
special topic in biological research and one of the most fascinating.
The adaptations in habitat, time, behavior, appearance and even in
structure are found capable of a certain individual modification when
studied experimentally.

_Zoogeography._—Closely associated with systematic zoology, and indeed a
part of the subject in its broader sense, is the study of the
geographical distribution of animal species and larger groups.

_Paleontology._—The geological succession of organisms embraces a field
where zoologist and geologist meet. The wonderful progress made by
American investigators is well described in the preceding chapters on
Historical Geology and Vertebrate Paleontology.


                              _Biometry._

Since Darwin’s theory of evolution postulated the origin of new species
by means of natural selection, it was obviously necessary in order to
apply a critical test to determine the precise limits of a species. It
was, therefore, proposed to subject a given species to a strict
examination by the application of statistical methods to determine the
range of variation of its members and the extent to which the species
intergrades with others. Other problems, particularly those concerning
heredity, were treated in similar manner. This branch of biological
science was particularly developed by the English School, led by Sir
Francis Galton, followed by Karl Pearson and William Bateson.

In America the methods of biometry have been utilized extensively by
Charles B. Davenport, Raymond Pearl, H. S. Jennings and others in the
solution of problems in genetics and evolution. Their work shows the
great value of critical statistical analysis in the interpretation of
biological data. A thorough training in mathematics is now found to be
hardly less important for the biologist than is a knowledge of physics
and chemistry, for the science of biometry has become one of the most
important adjuncts to the study of genetics.


                 _Comparative Anatomy and Embryology._

_Comparative Anatomy._—Upon the foundations laid down by Cuvier a
century ago the present elaborate structure of comparative anatomy of
animals, both vertebrate and invertebrate, has been developed. Vast as
is the present accumulation of facts and theories many important
problems still await their solution. Jeffries Wyman was long a leader in
this field, where many workers are now engaged.

_Embryology._—The embryological studies, so brilliantly begun by Von
Baer early in the nineteenth century, are still in progress. They have
now been extended to the groups more difficult of investigation and into
the earliest stages of fertilization and implantation in the mammals.
Artificial cultural methods have yielded important results. Louis and
Alexander Agassiz, Mark, Minot, Brooks, Whitman, Conklin and E. B.
Wilson have taken prominent parts in this work.

In the early nineties embryological studies were directed to the
arrangement of cells in the dividing egg, and there was much discussion
of “cell lineage” in development. Valuable as were these studies they
threw comparatively little light on the general problems of evolution.

_Experimental Embryology._—A more fertile field, developed at the same
period and a little later, was found in experimental embryology. The
discoveries made by Driesch and others in shaking apart the cells of the
dividing egg or by destroying one or more of these cells gave a new
insight into the potency of cells for compensatory and regenerative
processes. These studies attracted many able investigators, who made
still further advance by subjecting the germ cells, developing eggs,
embryos, and developing organs to a great variety of artificial
conditions.

_Artificial Parthenogenesis._—Another question concerns the nature of
the process of fertilization and the agencies which cause the fertilized
egg to develop into an embryo. In 1899 Jacques Loeb succeeded in causing
development in unfertilized sea-urchin eggs by subjecting them to
concentrated sea water for a period and then returning them to their
normal environment. To this promising field of experimental work came
many of the foremost biologists both in America and Europe. It was soon
found that the eggs of most groups of animals except the higher
vertebrates could be made to develop into more or less perfect embryos
and larval forms by treatment with a great variety of chemical
substances, by increased temperature, by mechanical stimuli and by other
means. This artificial parthenogenesis, as it is called, has also been
successful in plants (_Fucus_), and recently Loeb has reared several
frogs to sexual maturity by merely puncturing with a sharp needle the
eggs from which they were derived. Loeb, then, maintains that “the egg
is the future embryo and animal; and that the spermatozoon, aside from
its activating effect, only transmits Mendelian characters to the
egg.”[180]

Further experimental analyses of the nature of the fertilization
mechanism have recently been made by Morgan, Conklin, F. R. Lillie, and
others.

_Germinal Localization._—The question as to whether the egg contains
localized organ-forming substances has been studied experimentally
particularly by means of the centrifuge. The results indicate that
neither of the older opposing theories of “performation” or “epigenesis”
is applicable to all eggs, but that in certain organisms the eggs
possess a well marked differentiation while in others each part of the
egg is essentially, although probably not absolutely, equipotential.

_The Germplasm Cycle._—Since Weismann’s postulation of the independence
of soma and germplasm in 1885 many attempts have been made to trace the
path of the hereditary substance from one generation to the next. A
recent book by Hegner[181] summarizes the success attained in various
groups of animals.


                              _Cytology._

Another important field of investigation which has attracted many
workers is that which pertains to the life of the cell—the science of
cytology. Although the celltheory was established as early as 1839,
little advance was made in this subject in America before 1880. Since
that time, however, Americans have been so successful in cytological
discoveries that they are now among the world’s leaders in this field.

These studies have been followed along both descriptive and experimental
lines. The most prominent of the early workers in this field are E. L.
Mark and E. B. Wilson. Mark’s description of the maturation,
fecundation, and segmentation of the egg is the most accurate and
complete of the early cytological studies. Wilson’s discoveries
concerning the details of fertilization and his “Atlas of Fertilization
and Karyokinesis,” published in 1895, have now become classic. Wilson,
too, has published the only American text-book on cytology,[182] and has
more recently taken the lead in studies concerning the relation between
the chromosomes and sex. Besides Wilson, Montgomery, Mark, McClung,
Morgan, Miss Stevens, Conklin and their associates and students have now
furnished conclusive evidence that the sex of an organism is determined
by, or associated with, the nuclear constitution of the fertilized egg.
This constitution is moreover shown to be dependent upon the chromosomes
received from the germ cells.

This explanation is in strict accordance with the results of
experimental breeding. It is also quite in harmony with the Mendelian
law of inheritance, and in fact forms one of the strongest supports for
the view that all Mendelian factors are resident in the chromosomes.
Recent work has also discovered the mechanism which governs the
complicated conditions of sex which occur in those animals which exhibit
alternating sexual and parthenogenetic generations. These remarkable
processes are in all cases found to depend upon a definite distribution
of the chromosomes.

Other recent experimental work has shown that while the sex is thus
normally determined in the fertilized egg, it is in some animals not
irrevocably fixed, and the normal effect of the sex chromosomes may be
inhibited by abnormal conditions in the developing embryo, as is
demonstrated by the recent work of Lillie and others.

The cytological basis for Mendelian inheritance has been very
extensively studied by Morgan and his pupils in connection with their
work on inheritance in the common fruit fly _Drosophila_. The evidence
supports Weismann’s earlier hypothesis that the chromosomes are the
bearers of the heritable factors, and that these are arranged in a
series in the different chromosomes. This theory is shown to be in such
strict accord with both the cytological studies and the results of
experimental breeding that Morgan has ventured to indicate definite
points in particular chromosomes as the loci of definite heritable
factors, or genes.

Confirmation of this view is furnished by the behavior of the so-called
sex-linked characters, the genes for which are situated in the same
chromosome as that which carries the sex factor. Many ingenious breeding
experiments indicate further that all the hereditary characters in
_Drosophila_ are borne in four great linkage groups corresponding with
the four pairs of chromosomes which the cells of this fly possess.


                       _Comparative Physiology._

None of the experimental fields has been of greater importance in
zoological progress than that which concerns the functions of the
various organs. Without this companion science morphology and
comparative anatomy would have become unintelligible. American
investigators, among whom G. H. Parker stands prominent, have taken a
leading part in this field also.

_Neurology._—The physiological analysis of the components of the nervous
system, both in vertebrates and invertebrates, is another important
branch of experimental biology. The 28 volumes of the Journal of
Comparative Neurology attest the large influence that American
investigators have had in the development of this science.

_Regeneration._—Experimental studies on the powers of regeneration in
plants and animals have been made from the earliest times. During the
past few years, however, there has been made a concerted attempt to
analyze the factors which determine the amount and rate of regeneration.
Much progress has been made toward the postulation of definite laws
applicable to the regenerative processes of the parts of each organism.
The critical analyses of Morgan, Loeb and Child have been particularly
stimulating.

_Tissue Culture._—Another line of experimental work which has been
developed within the past few years by Harrison, Carrell, and others is
the culture of body tissues in artificial media. These experiments have
included the cultivation in tubes or on glass slides of the various
tissues of numerous species of animals. They have yielded much
information regarding the structure, growth and multiplication of cells,
the formation of tissues, and the healing of wounds.

_Transplantation and Grafting._—Closely associated experiments consist
in the transplantation of organs or other portions of the body to
abnormal positions, to the bodies of other animals of the same species
or of other species. In this way much has been learned about the
potentiality of organs for self-differentiation, for regulation, for
regeneration and for compensatory adaptations. The experiments have
shown, further, the independence of soma and germplasm and have revealed
the nature of certain organs whose functions were previously obscure.

_Tropisms and Instincts._—Another field of experimental biology concerns
the analysis of behavior of organisms in response to various forms of
stimuli. These studies are being prosecuted on all groups of organisms,
including the larval stages of many animals, and are yielding most
remarkable results. The success in this field of research is largely due
to stimulating influence of Jacques Loeb, Parker, Jennings, and their
co-workers.

_Biological Chemistry._—Still another experimental field which has
developed into one of the most important of the biological sciences
relates to the fundamental chemical and physical changes which underlie
all organic phenomena. A knowledge of both physiological and physical
chemistry is to-day essential for all advanced biological work. The
peculiar nature of life itself, of growth, disease, old-age,
degeneration, death and dissolution are presumably only manifestations
of chemical and physical laws. The ultimate goal of all experimental
biology, therefore, will be reached only when the basic physico-chemical
properties of life are understood. At that time only will the perennial
controversy between vitalism and mechanism be ended.


                          _Economic Zoology._

A moment’s reflection will show that economic biology is the most
essential of all sciences to the human welfare and progress. For man’s
relation to his environment is such that the penalty for ignorance or
neglect of the biological principles involved in the struggle for
existence quickly overwhelms him with a horde of parasites or other
enemies.

It is only by the intelligent application of biological knowledge that
our food supplies, our forests, our domesticated animals and our bodies
can be protected from the ever ravenous organisms which surround us.

The losses to food supplies and other products by insects alone amounts
to 100 millions of dollars a month in the United States. And the
parasites cause losses in sickness and premature deaths each year of
many millions more. Then there are the destructive rodents and other
animals which add largely to our burdens of support. These enemies next
to wars and fungi are the most destructive agencies on earth. Could they
but be eliminated man’s struggle against opposing forces would be in
large measure overcome. The results of recent work in economic zoology,
both in regard to the destruction of enemies and protection of useful
mammals, birds and fishes, furnish a bright outlook for the future.

_Protozoology._—Partly as an experimental field for the solution of
general biological problems and partly because of its practical
applications the study of protozoa has now developed into a special
science.

The results of the investigations of Calkins, Woodruff, Jennings and
others have greatly supplemented our understanding of the signification
of such important biological phenomena as reproduction, sexual
differentiation, conjugation, tropisms, and metabolism.

From an economic standpoint the protozoa have recently been shown to be
of the greatest importance because of the human and animal diseases for
which they are responsible.

_Parasitology._—The animal parasites of man, domesticated animals and
plants include numerous species of protozoa, worms, and insects.
Together with the bacteria and a few higher fungi they cause all
communicable diseases. When we consider that not only our health but
also our entire food supply is dependent upon the elimination of these
organisms we must admit that parasitology is the most important
economically of all the sciences.

The reports of the investigations of Stiles and his associates in the
Hygienic Laboratory and of Ransom and his staff in the Bureau of Animal
Industry are widely distributed by the federal government. The
systematic studies so ably begun by Joseph Leidy in the middle of the
last century have been continued by Ward, Linton, Pratt, Curtis and
others on the parasites of many groups of animals.

_Economic Entomology._—Another extremely important biological science,
the practical applications of which are second only to those of
parasitology in importance, is entomology. In the last few years
economic entomology has exceeded any of the other branches of biology in
the number of its investigators. The American Association of Economic
Entomologists has a membership of about five hundred. The work of most
of these is supported by appropriations from the State and federal
governments, and the results of their investigations are widely
published.

It is now well known that some of the protozoon parasites are conveyed
from man to man only through the bites of insects. The local eradication
of several of our most fatal diseases has recently been brought about by
the application of measures to destroy such insects. This is the
greatest triumph of economic zoology.

_Economic Ichthyology._—The U. S. Fish Commission has for many years
been actively engaged in investigations on the food fishes, including
methods for increasing the food supply by suitable protection and
artificial propagation. The work includes also edible and otherwise
useful mollusks and crustacea. Their marine and fresh-water laboratories
have also been of great service to general biological science.

_Economic Ornithology and Mammalogy._—In addition to the local bird
clubs and the American Ornithologists Union for the study and
preservation of bird and mammal life, the Bureau of Biological Survey
has for some years conducted investigations on the economic importance
of the various species. The publications of this Bureau are of great
value both in determining the economic status of our birds and mammals,
and also in recommending means for the protection of the beneficial
species and the destruction of the injurious. Several of the States
issue similar publications.


                              _Genetics._

One of the most interesting chapters in biology relates to the
development of the modern science of heredity, or genetics.

Previous to the year 1900, when the Mendelian principle of inheritance
was re-discovered, the relative importance of heredity and of
environment in the development of an organism was little understood. It
is true that Weismann had insisted on the independence of soma and
germplasm some years earlier (1883), but the body of the individual was
still generally considered the key to its inheritance.

The recognition of the general application of Mendel’s discovery gave a
great impetus to experimental breeding both in plants and animals. While
heretofore it had been necessary to depend upon the somatic characters
as evidence of the hereditary constitution of an individual, it now
became possible, knowing the hereditary constitution of the parents of
any pair of individuals, to predict with almost mathematical certainty
the characters of their possible offspring.

In general, the laws of possible chance combinations of any group of
characters determine the probability of any particular offspring
possessing one or many of those characters. The physical basis for such
Mendelian inheritance is evidently the chance combinations of
chromosomes which result from the processes of maturation and union of
the germ cells.

Certain limitations to the law are met with because the relatively small
number of chromosomes involves linkage of genes, because of the
occasional interchange of groups of genes between homologous
chromosomes, and because the relative activity or potency of any
particular gene may differ in different races, and, finally, because the
normal activity of any given gene may be modified or inhibited by the
action of other genes. It is by no means certain, however, that all
inheritance is Mendelian, for there still remains much evidence that the
hereditary basis of certain characters may be resident in the cytoplasm,
rather than in the chromosomes. A recent book by Morgan, Sturtevant,
Müller and Bridges (1915), entitled “the mechanism of Mendelian
heredity” gives the cytological explanation of Mendelian inheritance.

Americans have from the first taken a leading part in this field of
research and have been quick to recognize its practical applications to
the improvement of breeds in both animals and plants. This prominent
position is largely due to the experimental work of Castle, Davenport,
Morgan, Jennings, Pearl, and their co-workers on animals and that of
East, Emerson, Davis, Hayes and Shull on plants.

The geneticist now realizes that the appearance of the body (phenotype)
gives but little clue to the inheritance (genotype). That two white
flowers produce only purple offspring, or two white fowls only deeply
colored chickens, or that a pair of guinea pigs, one of which is black
and the other white, have only gray agouti offspring, while other
apparently similar white flowers or white animals produce offspring like
themselves, is now readily comprehensible and mathematically
predictable.

The most important application of our newly acquired knowledge of
inheritance is in the improvement of the human race. The wonderful
opportunity in this direction must be apparent to all. The welfare of
humanity depends upon the immediate adoption of eugenic principles. The
Eugenics Record Office has secured many of the essential data.

With the destruction of the world’s best germ plasm at a rate never
equalled before, the outlook for the future race would be appalling were
it not for the hope that with the advent of a righteous peace will come
a realization of the necessity of applying these new biological
discoveries to improving the races of men. That the discoveries have
been made too late in the world’s history to be of such use to humanity
must not be thought possible.


                              _Evolution._

Previous to the publication of Darwin’s “Origin of Species” in 1859,
American zoologists were generally inclined toward special creation, in
spite of the evidences for evolution which had been presented by Erasmus
Darwin, Buffon, Lamarck, and Geoffroy St.-Hilaire. This attitude of mind
continued for some years after the publication of the natural selection
theory of Darwin and Wallace. This was in part due to the powerful
influence of Louis Agassiz and others who bitterly opposed the Darwinian
theory. The influence of Asa Gray in gaining a general acceptance for
this theory is explained in the following chapter.

A modified Lamarckian doctrine was widely accepted in the last quarter
of the century, due largely to the influence of Cope, Hyatt and Packard.
The inheritance of “acquired characters” demanded by this theory seems
incompatible with the discoveries of recent times, so that “to-day the
theory has few followers amongst trained investigators, but it still has
a popular vogue that is wide-spread and vociferous.”[183]

The origin of new varieties and species by accidental and fortuitous
modifications (mutations) of the germplasm is now the most widely
accepted theory of evolution.

Some of the most important discoveries regarding the origin of new forms
have been recently made by Morgan and his pupils. From a stock of the
common fruit fly (_Drosophila ampelophila_) more than 125 new types have
arisen within six years. Each of these types breeds true. “Each has
arisen independently and suddenly. Every part of the body has been
affected by one or another of these mutations.” To arrange these
mutations arbitrarily into graded series would give the impression of an
evolutionary series, but this is directly contrary to the known facts
concerning their origin, for each mutation “originated independently
from the wild type.” “Evolution has taken place by the incorporation
into the race of those mutations that are beneficial to the life and
reproduction of the individual.” This evolutionary process is usually
accompanied by the elimination of those forms which have remained stable
or which have developed adverse mutations.

A question that is being vigorously debated at this time concerns the
possible effects of selection on the hereditary factors. Are the genes
fixed both qualitatively and quantitatively or does a given gene vary in
potency under different conditions and in different individuals? In the
former case selection can only separate the existing genes into separate
pure strains. But if the gene be quantitatively variable, then selection
will result in the establishment of new types.

Castle has long stoutly maintained the effect of such selection, and his
forces have recently been augmented by Jennings. The experimental work
now in process will doubtless yield a decisive answer.


                             _Conclusion._

A comparison of the simple descriptive natural history of a century ago
with the foregoing manifold developments of modern biology will indicate
the wonderful progress which has occurred during this period. The path
has led from the crude methods of the almost unaided eye and hand to the
applications of the most delicate experimental apparatus. For the
marvelous success which zoology has attained has been possible only by
the skillful use of scalpel, microscope, microtome and other mechanical
devices and by the refined methods of the chemist and physicist.

The central truth to which all these discoveries consistently point is
the unity and harmony of all biological phenomena, and indeed of all
nature. No longer does the zoologist find any demarcated line separating
his field of research from that of the botanist or the chemist or even
of the physicist, for all the natural sciences obviously deal with
closely associated phenomena. The aim of the future will be both to
complete fields of study already marked out and to derive a
comprehensive explanation of the general principles involved.


                                _Notes._

Footnote 172:

  Proc. Biol. Soc. Washington, =3=, 35, 1886.

Footnote 173:

  Ibid., =4=, 9, 1888. Both of these papers are reprinted in Ann. Rept.
  Smithsonian Inst., 1897, U. S. Nat. Mus., Pt. 2, pp. 357–466, 1901.

Footnote 174:

  Louis Agassiz: his Life and Correspondence, by Elizabeth Carey
  Agassiz, p. 145, 1885.

Footnote 175:

  List of North American Land Mammals in the United States National
  Museum, 1911. Bull. 79, U. S. Nat. Mus., 1912.

Footnote 176:

  Birds of North and Middle America, Bull. 50, parts I-VII, U. S. Nat.
  Mus., 1901–1916.

Footnote 177:

  Report U. S. Nat. Mus. for 1898, pp. 153–1270, 1900.

Footnote 178:

  Bull. 34, U. S. Nat. Mus., 1889.

Footnote 179:

  Bull. 47, parts I-IV, U. S. Nat. Mus., 1896–1900.

Footnote 180:

  J. Loeb, The Organism as a Whole, p. 126, 1916.

Footnote 181:

  The Germ-cell Cycle in Animals, 1914.

Footnote 182:

  The Cell in Development and Inheritance, 1896; second edition, 1900.

Footnote 183:

  Morgan, T. H. A critique of the theory of evolution, p. 32, 1916.




                                  XIII
                  THE DEVELOPMENT OF BOTANY SINCE 1818

                          By GEORGE L. GOODALE


  “_Our Botany, it is true, has been extensively and successfully
  investigated, but this field is still rich, and rewards every new
  research with some interesting discovery._”


Such are the words with which the sagacious and far-sighted founder of
the American Journal of Science and Arts, in his general introduction to
the first volume, alludes to the study of plants. It is plain that the
editor, embarking on this new enterprise, appreciated the attractions of
this inviting field and sympathetically recognized the good work which
was being done in it. It is not surprising, therefore, to find that he
welcomed to the pages of his initial number contributions to botany.

_Early Botanical Works._—The collections of dried and living North
American plants, which had been carried from time to time to botanists
in Europe, had been eagerly studied, and the results had been published
in accessible treatises. Besides these general treatises, there had been
issued certain works, wholly devoted to the American Flora. Among these
latter may be mentioned Pursh’s “Flora” (1814) and Nuttall’s “Genera”
(1818). There were also a few works which were rather popular in their
character, such as Amos Eaton’s “Manual of Botany for North America”
(1817), and Bigelow’s “Collection of the Plants of Boston and environs”
(1814). These handbooks were convenient, and possessed the charm of not
being exhaustive; consequently a botanist, whether professional or
amateur, was stimulated to feel that he had a good chance of enriching
the list of species and adding to the next edition.


              _The Early Years of Botany in the Journal._

At that time, the botanists had no journal in this country devoted to
their science. Here and there they found opportunity for publishing
their discoveries in some medical periodical or in a local newspaper.
Hence American botanists availed themselves of the welcome extended by
Silliman to botanical contributors to place their results on record in a
magazine devoted to science in its wide sense. Specialization and
subdivision of science had not then begun to dissociate allied subjects,
and, consequently, botanists felt that they would be at home in this
journal conducted by a chemist. Botanists responded promptly to this
invitation with interesting contributions.

It is well to remember that the appliances at the command of naturalists
at the date when the Journal began its service, were imperfect and
inadequate. The botanist did not possess a convenient achromatic
microscope, and he was not in possession of the chemical aids now deemed
necessary in even the simplest research. Hence, attention was given
almost wholly to such matters as the forms of plants and the more
obvious phenomena of plant-life. In view of the poverty of instrumental
aids in research, the results attained must be regarded as surprising.

In the very first volume of the Journal, bearing the date of 1818, there
are descriptions of four new genera and of four new species of plants;
certainly a large share to give to systematic botany. Besides these
articles, there are some instructive notes concerning a few plants,
which up to that time had been imperfectly understood. There are four
Floral Calendars which give details in regard to the blossoming and the
fruiting of plants in limited districts, a botanical subject of some
importance but likely to become tedious in the long run. Just here, the
skill of the editor in limiting undesirable contributions is shown by
his tactful remark designed to soothe the feelings of a prolix writer
whose too long list of plants in a floral calendar he had editorially
cut down to reasonable limits. The editor remarks, “such extended
observations are desirable, but it may not always be convenient to
insert very voluminous details of daily floral occurrence.” It is
convenient to consider by themselves some of the botanical contributions
published in the first series of volumes of the Journal during a period
of twenty years, the period before Asa Gray became actively and
constantly associated with the Journal.

In systematic and geographical botany one finds communications from
Douglass and Torrey (=4=, 56, 1822) on the plants of what was then the
Northwest; Lewis C. Beck (=10=, 257, 1826; =11=, 167, 1826; =14=, 112,
1828) contributed valuable papers on the botany of Illinois and
Missouri; there is a literal translation by Dr. Ruschenberger (=19=, 63,
299, 1831; =20=, 248, 1831; =23=, 78, 250, 1833) of a very long list of
the plants of Chili; Wolle and Huebener (=37=, 310, 1839) gave an
annotated catalogue of botanical specimens collected in Pennsylvania;
Tuckerman (=45=, 27, 1843) presented communications in regard to
numerous species which he had examined critically; Darlington (=41=,
365, 1841) published his lecture on grasses; Asa Gray (=40=, 1, 1841)
gave an instructive account of European herbaria visited by him, and he
contributed also a charming account (=42=, 1, 1842) of a botanical
journey to the mountains of North Carolina. The most extensive series of
botanical communication at this time was the Caricography by Professor
Dewey of Williams College, presented in many numbers of the Journal; the
first of these in =7=, pp. 264–278, 1824. There were also descriptions
of certain new genera, and species, and critical studies in synonyms.

Cryptogamic botany is represented in the first series of volumes of the
Journal by L. C. Beck’s (=15=, 287, 1829) study of ferns and mosses, by
Bailey’s (=35=, 113, 1839) histology of the vascular system of ferns, by
Fries’ Systema mycologicum (=12=, 235, 1829), and by De Schweinitz (=9=,
397, 1825) and Halsey, who had in hand a cryptogamic manual. There are
two important papers by Alexander Braun, translated by Dr. George
Engelmann, one on the Equisetaceæ of North America (=46=, 81, 1844) and
the other on the Characeæ (=46=, 92, 1844).

Vegetable paleontology had begun to attract attention in many places in
this country, and therefore the translated contributions by Brongniart
on fossil plants were given space in the Journal. Plant-physiology
received a good share of attention either in short notices or in longer
articles. Such titles appear as, the respiration of plants, the
circulation of sap, the excrementitious matter thrown off by plants, the
effects of certain gases and poisons on plants, and the relations of
plants to different colored light. One of the most important of the
notes is that in which is described the discovery by Robert Brown (=19=,
393, 1831) of the constant movement of minute particles suspended in a
liquid, first detected by him in the fovilla of pollen grains, and now
known as the Brownian (or Brunonian) movement. The heading under which
this note appears is of interest, “The motion of living particles in all
kinds of matter.”

One side of botany touches agriculture and economics. That side was
represented even in the first volume of the Journal by a study of “the
comparative quantity of nutritious matter which may be obtained from an
acre of land when cultivated with potatoes or wheat.” Succeeding volumes
in this series likewise present phases which are of special interest
regarded from the point of view of economics; for example, those which
treat of rotation of crops and of enriching the soil. Probably the
economic paper which may be regarded as the most important, in fact
epoch-making, is the full account of the invention by Appert of a method
for preserving food indefinitely (=13=, 163, 1828). We all know that
Appert’s process has revolutionized the preservation of foods, and in
its modern modification underlies the vast industry of canned fruits,
vegetables and so on. There are suggestions, also, as to the utilization
of new foods, or of old foods in a new way, which resemble the
suggestions made in these days of food conservation. For example, it is
shown that flour can be made from leguminous seeds by steaming and
subsequent drying, and pulverizing. There are excellent hints as to the
best ways of preparing and using potatoes, and also for preserving them
underground, where they will remain good for a year or two. It is shown
that potato flour can be made into excellent bread. Another method of
making bread, namely from wood, is described, but it does not seem quite
so practicable. There are interesting notes on the sugar-beet as a
source of sugar, and here appears one of the earliest accounts of the
Assam tea-plant, which was destined to revolutionize the tea industry
throughout the world. Cordage and textile fibers of bark and of wood
should be utilized in the manufacture of paper. In fact one comes upon
many such surprises in economic botany as the earlier volumes of the
Journal are carefully examined.

Early numbers of the Journal present with sufficient fullness accounts
of the remarkable discovery by Daguerre and others of a process for
taking pictures by light, on a silver plate or upon paper (=37=, 374,
1839; =38=, 97, 1840, etc.). Before many years passed, the Journal had
occasion to show that these novel photographic delineations could be
made useful in the investigation of problems in botany. In the pages of
the Journal it would be easily possible to trace the development of this
art in its relations to natural history. Silliman possessed great
sagacity in selecting for his enterprise all the novelties which
promised to be of service in the advancement of science. In 1825 (=9=,
263) the Journal republished from the Edinburgh Journal of Science an
essay by Dr. (afterwards Sir) William Jackson Hooker, on American
Botany. In this essay the author states that “the various scientific
Journals” which “are published in America, contain many memoirs upon the
indigenous plants. Among the first of these in point of value, and we
think also the first with regard to time, we must name Silliman’s
Journal of Science.” The author enumerates some of the contributors to
the Journal and the titles of their papers.

It has been a useful practice of the Journal, almost from the first, to
transfer to its pages memoirs which would otherwise be likely to escape
the notice of the majority of American botanists. The book notices and
the longer book reviews covered so wide a field that they placed the
readers of the Journal in touch with nearly all of the current botanical
literature both here and abroad. These critical notices did much towards
the symmetrical development of botany in the United States. And as we
shall now see, the Journal notices and reviews in the hands of Asa Gray
continued to be one of the most important factors in the advancement of
American botany.


                      _Asa Gray and the Journal._

In 1834 there appears in the Journal (=25=, 346) a “Sketch of the
Mineralogy of a portion of Jefferson and St. Lawrence Counties, New
York, by J. B. Crawe of Watertown and A. Gray of Utica, New York.” This
appears to be the first mention in the Journal of the name of Dr. Asa
Gray, who, shortly after that date, became thoroughly identified with
its botanical interests. In the early part of his career both before and
immediately after graduating in medicine, Gray gave much attention to
the different branches of natural history in its wide sense. He not only
studied but taught “chemistry, geology, mineralogy, and botany,” the
latter branch being the one to which he devoted most of his attention.
Among his early guides in the pursuit of botany may be mentioned Dr.
Hadley, “who had learned some botany from Dr. Ives of New Haven,” and
Dr. Lewis C. Beck of Albany, author of Botany of the United States North
of Virginia. At that period he made the acquaintance of Dr. John Torrey
of New York, with whom he later became associated in most important
descriptive work. During the years between his graduation in medicine
and 1842, the year when he came to Harvard College, his activities were
diverse and intense; so that his preparation for his distinguished
career was very broad and thorough. His first visit to Europe, in 1838,
brought him into personal relations with a large number of the botanists
of Great Britain and the Continent. This extensive acquaintance, added
to his broad training, enabled him even from the outset to exert a
profound influence upon the progress of his favorite science. He made
the Journal tributary to this development. His name first appears as
associate editor in 1853, but there are articles in the Journal from his
pen which bear an earlier date. The first of these early botanical
papers is the following: “A Translation of a memoir entitled ‘Beiträge
zur Lehre von der Befruchtung der Pflanzen,’ (contributions to the
doctrine of the impregnation of plants, by A. J. C. Corda:) with
prefatory remarks on the progress of discovery relative to vegetable
fecundation; by Asa Gray, M. D.” (=31=, 308, 1837). Dr. Gray says that
he made the translation from the German for his own private use, but
thinking that it might be interesting to the Lyceum, he brought it
before the Society, with “a cursory account of the progress of discovery
respecting the fecundation of flowering plants, for the purpose of
rendering the memoir more generally intelligible to those who are not
particularly conversant with the present state of botanical science.”
The translation occupies six pages of the Journal, while the prefatory
remarks fill nine pages. The prefatory remarks constitute an exhaustive
essay on the subject, embodied in attractive and perfectly clear
language. The translator shows complete familiarity with the matter in
hand and gives an adequate account of all the work done on the subject
up to the date of M. Corda’s paper. A second important paper by him near
this period is his review of “A Natural System of Botany: or a
systematic view of the Organization, Natural Affinities, and
Geographical Distribution of the whole Vegetable Kingdom; together with
the use of the more important species in Medicine, the Arts, and rural
and domestic economy, by John Lindley. Second edition, with numerous
additions and corrections, and a complete list of genera and their
synonyms. London: 1836” (=32=, 292, 1837). A very brief notice of this
work in the first part of the volume for 1837 closes with the words, “A
more extended notice of the work may be expected in the ensuing number
of the Journal.” The extended notice proved to be a critical study of
the work, signed by the initials A. G. which later became so familiar to
readers of the Journal. Citation of a few of its sentences will indicate
the strong and quiet manner in which Dr. Gray, even at the outset, wrote
his notices of books. In speaking of the second edition of Professor
Lindley’s work, he says:

[Illustration: Sincerely yours Asa Gray]


  “It is not necessary to state that a treatise of this kind was greatly
  needed, or to allude to the peculiar qualifications of the learned and
  industrious author for the accomplishment of the task, or the high
  estimation in which the work is held in Europe. But we may properly
  offer our testimony respecting the great and favorable influence which
  it has exerted upon the progress of botanical science in the United
  States. Great as the merits of the work undoubtedly are, we must
  nevertheless be excused from adopting the terms of extravagant and
  sometimes equivocal eulogy employed by a popular author, who gravely
  informs his readers that no book, since printed Bibles were first sold
  in Paris by Dr. Faustus, ever excited so much surprise and wonder as
  did Dr. Torrey’s edition of Lindley’s Introduction to the Natural
  System of Botany. Now we can hardly believe that either the author or
  the American editor of the work referred to was ever in danger, as was
  honest Dr. Faustus, of being burned for witchcraft, neither do we find
  anything in its pages calculated to produce such astonishing effects,
  except, perhaps, upon the minds of those botanists, if such they may
  be called, who had never dreamed of any important changes in the
  science since the appearance of good Dr. Turton’s translation of the
  Species Plantarum, and who speak of Jussieu as a writer who has
  greatly improved the natural orders of Linnæus.”


In the Journal for 1840 there is a large group of unsigned book reviews
under the heading, “Brief notices of recent Botanical works, especially
those most interesting to the student of North American Botany.” The
first of these short reviews deals with the second section of Part VII
of De Candolle’s “Prodromus.” In 1847 the consideration of the
“Prodromus” is resumed by the same author and the initials of A. G. are
appended. This indicates that Dr. Gray was probably the writer of some
of the unsigned book reviews which had appeared in the Journal between
1837 and 1840. Doubtless Silliman availed himself of the assistance of
his associates, Eli Ives and others, in New Haven, in the examination of
current botanical literature, and it is extremely probable that he early
secured help from young Dr. Gray, who had shown himself to be a keen
critic as well as a pleasing writer. The notices of botanical works from
1840 bear marks of having been from the same hand. They cover an
extremely wide range of subjects. While they are good-tempered they are
critical, and they had much to do with the development of botany, in
this country, along safe lines.

_Gray as Editor._—Gray’s name as associate editor of the Journal appears
in 1853. He had been a welcome contributor, as we have seen, for many
years. His influence upon the progress of botany in the United States
was largely due to his connection with the Journal. His reviews extended
over a very wide range, and supplemented to a remarkable degree his
other educational work. It must be permitted to allude here to his
sagacity as a writer of educational treatises. In his first elementary
text-book, published in 1836, he expressed wholly original views in
regard to certain phases of structure and function in plants, which
became generally adopted at a later date. His Manual of Botany was
constructed, and subsequent editions were kept, on a plan which made no
appeal to those who wanted to work on lines of least resistance; in fact
he had no patience with those who desired merely to ascertain the name
of a plant. In the Journal he emphasizes the desirability of learning
all the affinities of the plant under consideration. At a later period,
when entirely new chapters had been opened in the life of plants, he
sought by his contributions in the Journal to interest students in this
wider outlook.

Professor C. S. Sargent has selected with good judgment some of the more
important scientific papers by Professor Gray and has republished them
in a convenient form.[184] Many of these papers were contributed to the
Journal in the form of reviews. These reviews touch nearly every branch
of the science of botany. As Sargent justly says, “Many of the reviews
are filled with original and suggestive observations, and taken
together, furnish the best account of the development of botanical
literature during the last fifty years that has yet been written.” In
these longer reviews in the Journal, Gray was wont to take a book under
review as affording an opportunity to illustrate some important subject,
and many of the reviews are crowded with his expositions. For example,
in his examination of vonMohl’s “Vegetable Cell” (=15=, 451, 1853) he
takes up the whole subject of microscopic structure, so far as it was
then understood, and he points out the probable errors of some of Mohl’s
contemporaries, showing what and how great were Mohl’s own contributions
to histology. Such a review is a landmark in the science. The physiology
of the cell and the nutrition of the plant were favorite topics with
Professor Gray, and he brought much of his knowledge in regard to them
into such a review as that of Boussingault (=25=, 120, 1858) on the
“Influence of nitrates on the production of vegetable matter.”

As a systematic botanist, Gray was naturally much interested in the
vexed question of nomenclature of plants. One of his most important
communications to the Journal is his review, in the volume for 1883
(=26=, 417), of DeCandolle’s work on the subject. He deals with this
strictly technical matter much as he did in a contribution to the
Journal which he made in 1868 (=46=, 63). In both of these papers he
states with clearness the general features of the code of nomenclature.
He says explicitly that the code does not make, but rather declares, the
common law of botanists. The treatment of the subject at his hands would
rightly impress a general reader as showing a strong desire to have
common sense applied to doubtful cases, instead of insisting on
inflexible rules. For this reason, his rule of practice was not always
acceptable to those who were anxious to secure conformity to arbitrary
rules at whatever cost. As he said in a paper published in the Journal
in 1847 (=3=, 302), “The difficulty of a reform increases with its
necessity. It is much easier to state the evils than to relieve them;
and the well-meant endeavors that have recently been made to this end,
are, some of them, likely, if adopted, to make confusion worse
confounded.” This feeling led him to be very conservative in the matter
of reform in nomenclature.

This subject of botanical nomenclature illustrates a method frequently
employed by Professor Gray to elucidate a difficult matter. He would
find in the treatise under review a text, or texts, on which he would
build a treatise of his own, and in this way he made clear his own views
relative to most of the important phases of botany. When he faced
controverted matters, his attitude still remained judicial. While he was
tolerant of opinions which clashed with his own, he was always severe
upon charlatanism and impatient of inaccuracy. The pages of the Journal
contain many severe criticisms at his hands, but an unprejudiced person
would say that the severity is merited.

Sometimes, however, instead of reviewing a book or an address, he would
follow the custom inaugurated early in the history of the Journal, of
making copious extracts, and thus give to its readers an opportunity of
examining materials which otherwise might not fall in their way.

Gray’s contributions to the Journal comprise more than one thousand
titles, without counting the memorial notices and the shorter obituary
notes. In these notices he sums up in a few well-chosen words the
contributions made to botany by his contemporaries. Even in the few
instances in which he felt obliged to note with disapproval some of the
work, he expressed himself with personal friendliness. The necrology, as
it appeared from month to month, was a labor of love. All of the longer
memorial notices are what it is the fashion now-a-days to call
appreciations, and these are so happily phrased that it would seem as if
the writer in many a case asked himself, “Would my friend, about whom I
am now writing, make any change in this sketch?”

_Gray on Darwinism._—In October, 1859, Darwin’s epoch-making work, “The
Origin of Species,” was published. An early copy was sent to the editor
of the Journal, Professor James D. Dana. This arrived in New Haven on
December 21, but it was preceded by a personal letter which is of so
much interest that it is here transcribed in full. It should be added
that Dana was at this time in Europe where he was spending a year in the
search for health after a serious nervous breakdown. In his absence the
book was noticed by Gray as stated below. The letter is, as follows:


                                            Down, Bromley, Kent.
                                                        Nov. 11th, 1859.

  My dear Sir,

  I have sent you a copy of my Book (as yet only an abstract) on the
  Origin of Species. I know too well that the conclusion, at which I
  have arrived, will horrify you, but you will, I believe and hope, give
  me credit for at least an honest search after the truth. I hope that
  you will read my Book, straight through; otherwise from the great
  condensation it will be unintelligible. Do not, I pray, think me so
  presumptuous as to hope to convert you; but if you can spare time to
  read it with care, and will then do what is far more important, keep
  the subject under my point of view for some little time occasionally
  before your mind, I have hopes that you will agree that more can be
  said in favour of the mutability of species, than is at first
  apparent. It took me many long years before I wholly gave up the
  common view of the separate creation of each species. Believe me, with
  sincere respect and with cordial thanks for the many acts of
  scientific kindness which I have received from you,

                                                     My dear Sir,
                                                 Yours very sincerely,
                                                         CHARLES DARWIN.


In March, 1860 (=29=, 153), Gray published in the Journal an elaborate
and cautious review of Darwin’s work. He alluded to the absence of the
chief editor of the Journal in the following words:


  “The duty of reviewing this volume in the American Journal of Science
  would naturally devolve upon the principal editor whose wide
  observation and profound knowledge of various departments of natural
  history, as well as of geology, particularly qualify him for the task.
  But he has been obliged to lay aside his pen to seek in distant lands
  the entire repose from scientific labor so essential to the
  restoration of his health, a consummation devoutly to be wished and
  confidently to be expected. Interested as Mr. Dana would be in this
  volume, he could not be expected to accept its doctrine. Views so
  idealistic as those upon which his ‘Thoughts upon Species’ are
  grounded, will not harmonize readily with a doctrine so thoroughly
  naturalistic as that of Mr. Darwin.... Between the doctrines of this
  volume and those of the great naturalist whose name adorns the title
  page of this Journal [Mr. Agassiz] the widest divergence appears.”


Gray then proceeds to contrast the two views of Darwin and Agassiz, “for
this contrast brings out most prominently and sets in strongest light
and shade the main features of the theory of the origination of species
by means of Natural Selection.” He then states both sides with great
fairness, and proceeds:


  “Who shall decide between such extreme views so ably maintained on
  either hand, and say how much truth there may be in each. The present
  reviewer has not the presumption to undertake such a task. Having no
  prepossession in favor of naturalistic theories, but struck with the
  eminent ability of Mr. Darwin’s work, and charmed with its fairness,
  our humbler duty will be performed if, laying aside prejudice as much
  as we can, we shall succeed in giving a fair account of its method and
  argument, offering by the way a few suggestions such as might occur to
  any naturalist of an inquiring mind. An editorial character for this
  article must in justice be disclaimed. The plural pronoun is employed
  not to give editorial weight, but to avoid even the appearance of
  egotism and also the circumlocution which attends a rigorous adherence
  to the impersonal style.”


In this review he moves slowly and thoughtfully, but not timidly, over
the new paths. There is no clear indication in the review that he has
yet made up his mind as to the validity of Darwin’s hypothesis. But, in
a second article appearing in the Journal for September of the same year
(=30=, 226), under the title “Discussion between two readers of Darwin’s
treatise on the origin of species upon its natural theology” Gray
plainly begins to incline to take a very favorable view of the Darwinian
theory, and makes use of the following ingenious illustration to show
that it is not inconsistent with theistic design. A few paragraphs here
quoted show the felicity of his style in a controverted matter:


  “Recall a woman of a past generation and show her a web of cloth; ask
  her how it was made, and she will say that the wool or cotton was
  carded, spun, and woven by hand. When you tell her it was not made by
  manual labor, that probably no hands have touched the materials
  throughout the process, it is possible that she might at first regard
  your statement as tantamount to the assertion that the cloth was made
  without design. If she did, she would not credit your statement. If
  you patiently explained to her the theory of carding-machines,
  spinning-jennies, and power-looms, would her reception of your
  explanation weaken her conviction that the cloth was the result of
  design? It is certain that she would believe in design as firmly as
  before, and that this belief would be attended by a higher conception
  and reverent admiration of a wisdom, skill, and power greatly beyond
  anything she had previously conceived possible.”


By this review Gray disarmed hostility to such an extent that some
persons who had been antagonistic to Darwinism accepted it with only
slight reservation. It may be fairly claimed that the Journal bore a
leading part in influencing the views of naturalists in America in
regard to the Darwinian theory.

Dr. Gray soon put the Darwinian hypothesis to a severe test. In the
Journal for 1840 he had called attention to the remarkable similarity
which exists between the flora of Japan and a part of the temperate
portion of North America. The first notice of this subject by him occurs
in a short review of Dr. Zuccarini’s “Flora Japonica,” a work based on
material furnished by Dr. Siebold, who had long lived in Japan. In this
review (=39=, 175, 1840), he enumerates certain plants common to the two
regions, and says, “It is interesting to remark how many of our
characteristic genera are reproduced in Japan, not to speak of striking
analogous forms.” In a subsequent paper (=28=, 187, 1859), he recurs to
this subject, and, after alluding to geological data furnished by J. D.
Dana, he says:


  “I cannot resist the conclusion that the extant vegetable kingdom has
  a long and eventful history, and that the explanation of apparent
  anomalies in the geographical distribution of species may be found in
  the various and prolonged climatic or other vicissitudes to which they
  have been subject in earlier times; that the occurrence of certain
  species, formerly supposed to be peculiar to North America, in a
  remote or antipodal region, affords in itself no presumption that they
  were originated there, and that interchange of plants between eastern
  North America and eastern Asia is explicable upon the most natural and
  generally received hypothesis (or at least offers no greater
  difficulty than does the arctic flora, the general homogeneousness of
  which round the world has always been thought compatible with local
  origin of the species) and is perhaps not more extensive than might be
  expected under the circumstances. That the interchange has mainly
  taken place in high northern latitudes, and that the isothermal lines
  have in earlier times turned northward on our eastern and southward on
  our northwest coast, as they do now, are points which go far towards
  explaining why eastern North America, rather than Oregon and
  California, has been mainly concerned in this interchange, and why the
  temperate interchange, even with Europe, has principally taken place
  through Asia.”


[Illustration: From “Life and Letters of Charles Darwin” by Francis
Darwin.]

This paper was communicated in 1859, on the eve of the publication of
Darwin’s “Origin of Species.” At a later date he applied the Darwinian
theory to the possible solution of the problem, and came to the
conclusion that the two floras had a common origin in the Arctic zone,
during the Tertiary period, or the Cretaceous which preceded it, and the
descendants had made their way down different lines toward the south,
the species varying under different climatic conditions, and thus
exhibiting similarity but not absolute identity of form. Before the
American Association for the Advancement of Science, in his Presidential
address, in 1872, he used the following language:


  “According to these views, as regards plants at least, the adaptation
  to successive times and changed conditions has been maintained, not by
  absolute renewals, but by gradual modifications. I, for one, cannot
  doubt that the present existing species are the lineal successors of
  those that garnished the earth in the old time before them, and that
  they were as well adapted to their surroundings then, as those which
  flourish and bloom around us are to their conditions now. Order and
  exquisite adaptation did not wait for man’s coming, nor were they ever
  stereotyped. Organic Nature—by which I mean the system and totality of
  living things, and their adaptation to each other and to the
  world—with all its apparent and indeed real stability, should be
  likened, not to the ocean, which varies only by tidal oscillations
  from a fixed level to which it is always returning, but rather to a
  river, so vast that we can neither discern its shores nor reach its
  sources, whose onward flow is not less actual because too slow to be
  observed by the ephemeræ which hover over its surface, or are borne
  upon its bosom.”


Gray’s active interest in the Journal continued until the very end of
his life. There were many critical notices from his pen in 1887. His
last contribution to its pages was the botanical necrology, which
appeared posthumously in volume =35=, of the third series (1888). His
connection with the Journal covered, therefore, a period of more than a
half a century of its life.[185]

The changes that were wrought in botany by the application of Darwinism
were far reaching. Attempts were promptly made to reconstruct the system
of botanical classification on the basis of descent. The more successful
of these endeavors met with welcome, and now form the groundwork of
arrangement of families, genera, and species, in the Herbaria in this
country, in the manuals of descriptive botany, and in the text-books of
higher grade. This overturn did not take place until after Gray’s death,
although he foresaw that the revolution was impending.

One of the most obvious changes was that which gave a high degree of
prominence in American school treatises to the study of the lower
instead of the higher or flowering plants, these latter being treated
merely as members in a long series, and with scant consideration. But of
late years, there has been a renewed popular interest in the phænogamia,
leading to a more thorough investigation of local floras, and also to
the examination of the relations of plants to their surroundings. The
results of a large part of this technical work are published in strictly
botanical periodicals and now-a-days seldom find a place in the pages of
a general journal of science.


            _Cryptogamic Botany in the Journal since 1846._

In glancing rapidly at the First Series it has been seen that a fair
share of attention was early paid by the Journal to the flowerless
plants. So far as the means and methods of the time permitted, the
ferns, mosses, lichens, and the larger algæ and fungi of America were
studied assiduously and important results were published, chiefly on the
side of systematic botany.

The Second Series comprises the years between 1846 and 1871. In this
series one finds that the range of cryptogamic botany is much widened.
Besides interesting book notices relative to these plants, there are a
good many papers on the larger fungi, on the algæ, and mosses. Here are
contributions by Curtis, by Ravenel, by Bailey, and by Sullivant. The
lichens are treated of in detail by Tuckerman, and there are some
excellent translations by Dr. Engelmann of papers by Alexander Braun.
Some of the destructive fungi are considered, as might well be the case
in the period of the potato famine. It is in these years that one first
finds the name of Daniel Cady Eaton, who later had so much to do with
developing an interest in the subject of ferns in this country. He was a
frequent contributor of critical notices.

Cryptogamic Botany, as it is now understood, is a comparatively modern
branch of science. The appliances and the methods for investigating the
more obscure groups, and especially for revealing the successive stages
of their development, were unsatisfactory until the latter half of the
last century. Gray recognized this condition of affairs, and appreciated
the importance of the new methods and the better appliances. Therefore
he viewed with satisfaction the pursuit of these studies abroad by one
of his students and assistants, William G. Farlow. Dr. Farlow carried to
his studies under DeBary and others unusual powers of observation and
great industry. He speedily became an accomplished investigator in
cryptogamic botany and enriched the science by notable discoveries, one
of which to-day bears his name in botanical literature. On his return to
the United States, Farlow entered at once upon a successful career as an
inspiring teacher and a fruitful investigator. He became a frequent
contributor to the Journal, keeping its readers in touch with the more
important additions to cryptogamic botany. He had wisely chosen to deal
with the whole field, and consequently he has been able to preserve a
better perspective than is kept by the extreme specialist. The greater
number of cryptogamic botanists in this country have been under
Professor Farlow’s instruction.


          _Systematic and Geographical Botany of Late Years._

The usefulness of the Journal in descriptive systematic botany of
phanerogams is shown not only by its acceptance of the leading features
of DeCandolle’s Phytography, where very exact methods are inculcated,
but by the very numerous contributions by Sereno Watson and others at
the Harvard University Herbarium, as well as from private systematists.
It is in the pages of the Journal that one finds the record of much of
the critical work of Tuckerman and of Engelmann, in interesting
Phanerogamia. Of late years the Journal has had the privilege, of
publishing a good deal of the careful work of Theo Holm, in the
difficult groups of Cyperaceæ, and also his admirable studies in the
morphology and the anatomy of certain interesting plants of higher
orders.

Attention was called, in passing, to Gray’s deep interest in
geographical botany. In this important branch, besides his
contributions, one finds, among many others, such papers as LeConte’s
“Flora of the Coast Islands of California in Relation to Recent Changes
of Physical Geography” (=34=, 457, 1887), and Sargent’s “Forests of
Central Nevada” (=17=, 417, 1879). Examination reveals a surprising
number of communications which bear indirectly upon this subject.


                       _Paleontological Botany._

When the Journal began its career, the subject of fossil plants was very
obscure. Brongniart’s papers, especially the Journal translations,
enabled the students in America to undertake the investigation of such
fossils and the results were to a considerable extent published in the
Journal. Since the subject belongs as much to geology as to botany, it
finds its appropriate home in the pages of the Journal. The recent
papers on this topic show how great has been the advance in methods and
results since the early days of the Journal’s century. Under the care of
George E. Wieland, the communications and the bibliographical notices of
paleontological treatises show the progress which he and others are
making in this attractive field.


               _Economic Botany, Plant Physiology, etc._

At the outset, the Journal, as we have seen, devoted much attention to
certain phases of economic botany, and, even down to the present, it has
maintained its hold upon the subject. The correspondence of Jerome
Nicklès from 1853 to 1867 brought before its readers a vast number of
valuable items which would not in any other way have been known to them.
And the Journal dealt wisely with the scientific side of agriculture,
under the hands of S. W. Johnson and J. H. Gilbert, and others, placing
it on its proper basis. This work was supplemented by Norton’s
remarkable work in the chemistry of certain plants, the oat, for
example, and certain plant-products. In fact it might be possible to
construct from the pages of the Journal a fair synopsis of the important
principles of agronomy.

Physiology has been represented not only by the studies which had been
inaugurated and stimulated by the Darwinian theory, such as the
cross-fertilization and the close-fertilization of plants,
plant-movements, and the like, but there have been a good many special
communications, such as Dandeno on toxicity, Plowman on electrical
relations, and ionization, and W. P. Wilson on respiration.

There are many broad philosophical questions which have found an
appropriate home in the Journal, such as “The Plant-individual in its
relation to the species” (Alexander Braun, =19=, 297, 1855; =20=, 181,
1855), and “The analogy between the mode of reproduction in plants and
the alternation of generations observed in some radiata” (J. D. Dana,
=10=, 341, 1850). Akin to these are many of the reflections which one
finds scattered throughout the pages of the Journal, frequently in minor
book notices. As might be expected, some attention has been paid to the
very special branch of botany which is strictly called medical. For
example, early in its history, the Journal published a long treatise by
Dr. William Tully (=2=, 45, 1820), on the ergot of rye. This is
considered from a structural as well as from a medical point of view and
is decidedly ahead of the time in which it was written. There are a few
references to vegetable poisons, and there is a fascinating account of
the effect of the common white ash on the activities of the rattlesnake.
In short it may be said that the editor did much towards making the
Journal readable as well as strictly scientific.

The list of reviewers who have been permitted to use the pages of the
Journal for notices of botanical and allied books in recent years is
pretty long. One finds the initials of Wesley R. Coe, George P. Clinton,
Arthur L. Dean, Alexander W. Evans, William G. Farlow, George L.
Goodale, Arthur H. Graves, Herbert E. Gregory, Lafayette B. Mendel, Leo
F. Rettger, Benjamin L. Robinson, George R. Wieland, and others.

At the present time, in the biological sciences, as in every department
of thought, there is great specialization, and each specialty demands
its own private organ of publication. Naturally this has led to a
falling off in the botanical communications to the Journal, but it
cannot be forgotten that the history of North American Botany has been
largely recorded in its pages.


                                _Notes._

Footnote 184:

  Scientific Papers of Asa Gray. Selected by Charles Sprague Sargent.
  Two volumes, Boston, 1889 (see notice in vol. 38, 419, 1889).

Footnote 185:

  A notice of Gray’s life and works is given by his life-long friend, J.
  D. Dana, in the Journal in 1888 (=35=, 181–203).

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                          TRANSCRIBER’S NOTES


 1. Typos fixed; non-standard spelling and dialect retained.
 2. Used numbers for footnotes.
 3. Enclosed italics font in _underscores_.
 4. Enclosed bold or blackletter font in =equals=.
 5. The caret (^) serves as a superscript indicator, applicable to
      individual characters (like 2^d) and even entire phrases (like
      1^{st}).
 6. Subscripts are shown using an underscore (_) with curly braces { },
      as in H_{2}O.