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                             AËRIAL NAVIGATION

                            A POPULAR TREATISE
                      ON THE GROWTH OF AIR CRAFT AND
                        ON AËRONAUTICAL METEOROLOGY

                                    BY

                  ALBERT FRANCIS ZAHM, A.M., M.E., PH.D.

      SECRETARY OF THE AËRO CLUB OF WASHINGTON; GOVERNOR OF THE AËRO
    CLUB OF AMERICA; GENERAL SECRETARY OF THE INTERNATIONAL CONFERENCES
              ON AËRIAL NAVIGATION IN 1893 AND 1907; OFFICIAL
           AMERICAN DELEGATE TO THE AËRONAUTIC CONGRESS OF 1900;
               FORMERLY LECTURER ON MECHANICS IN THE UNITED
                 STATES BUREAU OF STANDARDS, AND PROFESSOR
                  OF MECHANICS IN THE CATHOLIC UNIVERSITY
                                OF AMERICA

                              [Illustration]

                            NEW YORK AND LONDON
                          D. APPLETON AND COMPANY
                                   1911

                            COPYRIGHT, 1911, BY
                          D. APPLETON AND COMPANY

          _Published September, 1911_

                  Printed in the United States of America




                                PREFACE


The purpose of this work is to portray in popular terms the
substantial progress of aëronautics from its earliest beginning to
the present time. Beyond the introductory account, little note is
taken of experiments, however picturesque or clever, which constitute
no advance in the art, or lead to no useful result. At times some
minutiæ are presented to complete the story of an important series of
achievements; but the unproductive efforts of impractical zealots,
however prominent or widely known in their day, receive scant, if any,
attention. Failures and tragedies where introduced, are described for
the lessons involved rather than for any curious interest investing
them. The griefs and grotesque follies of aëronautic imbeciles form a
long story, but a futile and unprofitable one, of slight concern in the
evolutionary history of a veritable science.

A general history of aërial locomotion would naturally be divided
into four parts, treating respectively of passive balloons, power
balloons, passive flyers, and power flyers; but in this work a separate
treatment has not been allotted to passive flyers because of their too
backward state of development. Passive gliders which maneuver in the
air merely by virtue of gravitational force, or acquired momentum, are
familiar enough; but the much more interesting passive flyers of human
construction, adapted to rise without motive power considerably beyond
their initial level, or to soar far aloft, and sail long distances by
virtue of favorable winds, are still in their infancy. It may be hoped,
however, that the vulture’s art which now is well nigh overlooked,
because of the triumphant advance of dynamic flight, will soon receive
such attention that future treatises may relate human achievements
in soaring that shall rival the dexterous and marvelous feats of
the condor and albatross, even as the majestic sweep of the dynamic
aëroplane now rivals the powerful rowing flight of the strongest birds
of prey.

Following the story of the evolution of air ships, a brief account
of the medium they navigate has been added. In particular, the
circumstances which affect the density and motion of the air have been
studied; for the density of the air determines the static lift of air
ships; the density and speed of impact of the air together determine
the dynamic lift and the resistance to progression; while the velocity
of the air current conditions the possible speed of travel in any
direction. It is important, therefore, that the aëronautical student
should have some acquaintance with the general properties of the air
which affect its density, and some knowledge of the generation and
prevalence both of the great currents of the atmosphere, and of the
local winds and invisible turmoils which so nearly concern the safety
and effective progress of the aërial navigator.

The French units of measurement have been freely used, as well as the
English. This seems advisable because the official rules and records
of international aëronautic events are partly expressed in the metric
system. Moreover, the navigation of a universal medium seems to call
for such universal standards. Indeed a peculiar mission of world travel
is to eliminate provincialism, and to promote universalism of thought,
of sentiment, and of custom.

In order to lighten the book for the popular reader, some interesting
historical facts and much important quantitative data are placed in the
Appendices, where they may be available to the technical or special
student.

It is a pleasant duty to acknowledge here my obligations to the U.
S. Signal Corps, the Smithsonian Institution, and the U. S. Weather
Bureau, for much assistance in collecting the materials for this work.
Dr. W. J. Humphreys, of the U. S. Weather Bureau, has very kindly read
the manuscript for the chapters on the atmosphere.

My thanks are due also to the _Scientific American_ and to
_Aëronautics_ for the use of photographs for the illustrations, as also
to the manufacturers of various aircraft, and to Mr. W. J. Hammer, Mr.
Carl Dientsbach, and Mr. A. S. Levino.

                                                          A. F. ZAHM.

    COSMOS CLUB
  WASHINGTON, D. C.,
    January, 1911.




                               CONTENTS


  CHAPTER                                                           PAGE
                             INTRODUCTION

  INTRODUCTION                                                         3


                                PART I

                         GROWTH OF AËROSTATION

     I.—EARLY HISTORY OF PASSIVE BALLOONS                             29

    II.—PRACTICAL DEVELOPMENT OF PASSIVE BALLOONS                     54

   III.—EARLY HISTORY OF POWER BALLOONS                               78

    IV.—INTRODUCTION OF GASOLINE-DRIVEN DIRIGIBLES                   101

     V.—PRACTICAL DEVELOPMENT OF NON-RIGID DIRIGIBLES                115

    VI.—DEVELOPMENT OF RIGID DIRIGIBLES                              145


                                PART II

                          GROWTH OF AVIATION

   VII.—MODEL FLYING MACHINES                                        173

  VIII.—NINETEENTH CENTURY MAN-FLYERS                                202

    IX.—AËROPLANES OF ADEQUATE STABILITY AND POWER                   235

     X.—ADVENT OF PUBLIC FLYING                                      256

    XI.—STRENUOUS COMPETITIVE FLYING                                 283

   XII.—FORCING THE ART                                              307


                               PART III

                        AËRONAUTIC METEOROLOGY

  XIII.—GENERAL PROPERTIES OF FREE AIR                               347

   XIV.—GENERAL DISTRIBUTION OF HEAT AND PRESSURE                    363

    XV.—PERMANENT AND PERIODIC WINDS                                 376

   XVI.—CYCLONES, TORNADOES, WATERSPOUTS                             394

  XVII.—THUNDERSTORMS, WIND GUSTS                                    422


                              APPENDICES

     I.—STRESS IN A VACUUM BALLOON                                   443

    II.—AËRONAUTIC LETTERS OF BENJAMIN FRANKLIN                      446

   III.—SUCCESSFUL MILITARY DIRIGIBLE BALLOONS                       456

    IV.—THE RELATIONS OF WEIGHT, SPEED, AND POWER OF FLYERS          478

     V.—CURTISS’ HYDRO-AËROPLANE EXPERIMENTS                         481

  INDEX                                                              487




                            LIST OF PLATES


                                                                  FACING
                                                                    PAGE

  PLATE I                                                             66
          Glaisher and Coxwell.
          Parseval Kite Balloon.

  PLATE II                                                            98
          Haenlein’s Gas-driven Dirigible.
          Wölfert’s Benzine-driven Dirigible.
          Santos-Dumont’s Dirigible, _No. 16_.

  PLATE III                                                          116
          The _Lebaudy_.
          _La Patrie._
          Lebaudy’s _Morning Post_.

  PLATE IV                                                           124
          _La Ville de Paris._
          _Colonel Renard._

  PLATE V                                                            128
          _Zodiac III._
          _Zodiac IV._

  PLATE VI                                                           130
          _La Belgique._
          Italian Military Dirigible _No. I bis_.

  PLATE VII                                                          132
          _Clément-Bayard I._
          _Clément-Bayard II._

  PLATE VIII                                                         138
          _U. S. Signal Corps Dirigible I._
          _Gross II._

  PLATE IX                                                           140
          _Parseval I._
          _Parseval II._

  PLATE X                                                            146
          _Gross III._
          Zeppelin Airship Structure.

  PLATE XI                                                           160
          Zeppelin Dirigible Resting on the Water.
          Zeppelin Dirigible over Zürich.

  PLATE XII                                                          182
          Henson’s Aëroplane.
          Ader’s Aëroplane.

  PLATE XIII                                                         186
          Stringfellow’s Aëroplane (Front).
          Stringfellow’s Aëroplane (Side).

  PLATE XIV                                                          192
          Phillips’s Tethered Aëroplane.
          Phillips’s Aëroplane.

  PLATE XV                                                           194
          Langley’s Steam Model.
          Langley’s Gasoline Model.
          Langley’s Two Surface Gasoline Model.

  PLATE XVI                                                          212
          Lilienthal’s Monoplane Glider.
          Lilienthal’s Biplane Glider.
          Pilcher’s Monoplane Glider.

  PLATE XVII                                                         218
          Chanute’s Five-Deck Glider.
          Herring in Chanute Biplane.
          Herring’s Compressed-air Biplane.

  PLATE XVIII                                                        226
          Maxim’s Aëroplane.
          Langley’s Large Aëroplane.

  PLATE XIX                                                          246
          First Wright Glider.
          Second Wright Glider.

  PLATE XX                                                           248
          First Wright Aëroplane (Rear).
          First Wright Aëroplane (Side).

  PLATE XXI                                                          252
          Montgomery’s Aëroplane.

  PLATE XXII                                                         258
          Santos-Dumont’s Biplane.
          Santos-Dumont’s _Demoiselle_.

  PLATE XXIII                                                        260
          Farman Biplane, 1908.
          Farman Biplane, 1909.
          Harmon in Farman Biplane.

  PLATE XXIV                                                         264
          The _Red Wing_.
          Curtiss Biplane.
          Curtiss Biplane with Pontoons.

  PLATE XXV                                                          268
          Blériot Flying Over Toury-Artenay Circuit.
          Blériot Monoplane _No. VIII_.
          Blériot Monoplane _No. IX_.

  PLATE XXVI                                                         272
          Wright Biplane of 1908.
          Standard Wright Biplane of 1910.
          Wright Racing Biplane of 1910.

  PLATE XXVII                                                        286
          _Blériot XI_ With Moisant Aviator on Mexican Border.
          _Blériot XII._

  PLATE XXVIII                                                       288
          _Antoinette_ Monoplane of 1909.
          _Antoinette_ Monoplane of 1910.

  PLATE XXIX                                                         302
          Esnault-Pélterie Monoplane, Early Pattern.
          Esnault-Pélterie Monoplane of 1910.

  PLATE XXX                                                          304
          Grade Monoplane.
          Cody Biplane.

  PLATE XXXI                                                         332
          Fabre Hydro-aëroplane.
          Paulhan Hydro-aëroplane.
          Moisant Metal Monoplane.

  PLATE XXXII                                                        482
          Curtiss Starting from the Water.
          Curtiss Biplane for Land and Water.
          Curtiss Triplane Risen from the Water.




                     LIST OF ILLUSTRATIONS IN TEXT


  FIG.                                                              PAGE

   1.—Da Vinci’s designs for human flying-gear                         9

   2.—A possible air-scout                                            12

   3.—Blanchard’s flying-machine                                      17

   4.—Lana’s proposed vacuum balloon                                  24

   5.—Montgolfier’s experimental balloon                              34

   6.—Charles’ first hydrogen balloon                                 36

   7.—Montgolfier’s passenger balloon                                 39

   8.—Charles’ passenger balloon                                      43

   9.—La Flesselle                                                    50

  10.—_The Great Balloon of Nassau_                                   55

  11.—Car of Nadar’s balloon                                          61

  12.—Diagram of a modern spherical balloon with ripping panel        75

  13.—Blanchard’s dirigible balloon, 1784                             80

  14.—Robert Brothers’ dirigible, 1784                                82

  15.—General Meusnier’s proposed dirigible, 1784                     85

  16.—Rufus Porter’s dirigible, 1820                                  87

  17.—Jullien’s model dirigible, 1850                                 88

  18.—Giffard’s steam dirigible, 1852                                 89

  19.—Dupuy de Lome’s dirigible, 1872                                 92

  20.—Renard’s dirigible, _La France_, 1884                           94

  21.—_La Ville de Paris_                                            121

  22.—_Le Petit Journal_, Zodiac type                                128

  23.—_Clément-Bayard II_, 1910                                      133

  24.—_Morning Post_ dirigible, 1910                                 135

  25.—Route of British military dirigibles from France to England,
        1900                                                         137

  26.—Da Vinci’s helicopter                                          175

  27.—Da Vinci’s parachute                                           176

  28.—Veranzio’s parachute                                           178

  29.—Lenormand’s parachute, 1784                                    179

  30.—Paper traveling parachute                                      181

  31.—Wenham’s aëroplane, 1866                                       185

  32.—Penaud’s aëroplane toy, 1871                                   187

  33.—Tatin’s aëroplane model, 1879                                  188

  34.—Hargrave’s model screw monoplane, 1891                         190

  35.—Hargrave’s kite                                                191

  36.—Launoy and Bienvenu’s helicopter, 1784                         198

  37.—Forlanini’s helicopter, 1878                                   200

  38.—Le Bris’ aëroplane, 1855                                       204

  39.—Mouillard’s aëroplane                                          208

  40.—Blériot’s Toury-Artenay aëroplane circuit, 1908                269

  41.—Map of the “Circuit de l’Est”                                  330

  42.—Diagram of Curtiss hydro-aëroplane                             333

  43.—The Etrich monoplane of 1910                                   336

  44.—Summer and winter average vertical temperature gradients       369

  45.—General circulation of the atmosphere                          378

  46.—Normal Wind direction and velocity for January and February
        (Köppen)                                                     381

  47.—Normal Wind direction and velocity for July and August
        (Köppen)                                                     383

  48.—Trade and counter-trade winds                                  384

  49.—Velocity diagram in horizontal section of a cyclone            398

  50.—Funnel-like cloud sometimes observed in a tornado              409

  51.—Vertical section of the St. Louis, Mo., tornado of May 27,
        1896                                                         411

  52.—Horizontal section of St. Louis tornado of May 27, 1896        412

  53.—Vertical section of short tornado                              414

  54.—Vertical section of a tall tornado                             415

  55.—Vertical section of a hail tornado                             417

  56.—Universal anemograph                                           428

  57.—Records of wind variation in horizontal and vertical
        direction                                                    429

  58.—Records of Wind speed obtained by Langley                      433




                             INTRODUCTION




                             INTRODUCTION

                          FANCY AND FOLK-LORE

    Of silver wings he took a shining pair,
      Fringed with gold, unwearied, nimble, swift;
    With these he parts the winds, the clouds, the air,
      And over seas and earth himself doth lift.
    Thus clad he cuts the spheres and circles fair,
      And the pure skies with sacred feathers clift;
    On Lebanon at first his feet he set
      And shook his wings with rosy may-dews wet.
                                   TASSO, CANTO I, XIV.


How beautiful! May we hope ever to journey thus, on wings actuated by
human power? It is an old question, once dear to the philosopher and
fool alike, but now important mainly to the fool. Or say more kindly it
is the affair of untechnical inventors—the amateur, the rustic, the man
of chimerical dreams. For the wise aëronaut now numbers that project
among the roseate illusions of his youth.[1]

Ovid relates a story, doubtless credible in his day, of a clever
craftsman who with his son flew bravely aloft, the very first time they
put on wings. Daedalus, a Greek architect, having fled from Athens for
murder, went with his son Icarus to the island of Crete, where he built
the celebrated labyrinth for Minos, the king. He offended that monarch
and was cast into prison. In order to escape he made wings for himself
and his son, with which they flew far over the sea. But Icarus, in his
elation, soared too near the sun, ruined his wings, fell into the sea
and was drowned. For proof of this we have the Icarian Sea, named after
the unfortunate boy. Also we have Ovid’s charming poem:

    In tedious exile now too long detain’d
    Daedalus languish’d for his native land;
    The sea foreclosed his flight, yet thus he said;
    “Though earth and water in subjection laid,
    O cruel Minos, thy dominion be,
    We’ll go through air; for sure the air is free.”
    Then to new arts his cunning thought applies,
    And to improve the work of nature tries.
    A row of quills, in gradual order placed,
    Rise by degrees in length from first to last;
    As on a cliff the ascending thicket grows;
    Or different reeds the rural pipe compose:
    Along the middle runs a twine of flax,
    The bottom stems are join’d by plaint wax;
    Thus, well compact, a hollow bending brings
    The fine composure into real wings.
        His boy, young Icarus, that near him stood,
    Unthinking of his fate, with smiles pursued
    The floating feathers, which the moving air
    Bore loosely from the ground, and wafted here and there:
    Or with the wax impertinently play’d,
    And with his childish tricks the great design delay’d.
        The final masterstroke at last imposed,
    And now, the great machine completely closed;
    Fitting his pinions on, a flight he tries,
    And hung self-balanced in the beaten skies.
    Then thus instructs his child: “My boy, take care
    To wing your course along the middle air:
    If low, the surges wet your flagging plumes;
    If high, the sun the melting wax consumes.
    Steer between both: nor to the northern skies,
    Nor South Orion, turn your giddy eyes,
    But follow me; let me before you lay
    Rules for the flight, and mark the pathless way.”
    Thus teaching, with a fond concern, his son,
    He took the untried wings, and fix’d them on:
    But fix’d with trembling hands; and, as he speaks,
    The tears roll gently down his aged cheeks;
    Then kiss’d, and in his arms embraced him fast,
    But knew not this embrace must be the last;
    And mounting upward, as he wings his flight,
    Back on his charge he turns his aching sight;
    As parent birds, when first their callow care
    Leave the high nest to tempt the liquid air;
    Then cheers him on, and oft, with fatal art,
    Reminds the stripling to perform his part.
    These, as the angler at the silent brook,
    Or mountain shepherd leaning on his crook,
    Or gaping ploughman, from the vale descries,
    They stare, and view them with religious eyes,
    And straight conclude them gods; since none but they
    Through their own azure skies could find a way.
    Now Delos, Paros, on the left are seen,
    And Samos, favour’d by Jove’s haughty queen;
    Upon the right, the isle Lebynthos named,
    And fair Calymne for its honey famed.
    When now the boy, whose childish thoughts aspire
    To loftier aims, and make him ramble higher,
    Grown wild and wanton, more embolden’d flies
    Far from his guide, and scars among the skies:
    The softening wax, that felt a nearer sun,
    Dissolved apace, and soon began to run:
    The youth in vain his melting pinion shakes,
    His feathers gone, no longer air he takes:
    “Oh! father, father!” as he strove to cry,
    Down to the sea he tumbled from on high,
    And found his fate; yet still subsists by Fame,
    Among those waters that retain his name.
    The Father, now no more a father, cries:
    “Ho, Icarus! where are you?” as he flies;
    “Where shall I seek my boy?” he cries again,
    And saw his feathers scatter’d on the main;
    Then cursed his art; and funeral rites conferr’d
    Naming the country from the youth interr’d.

How tender and apprehensive that gentleman’s farewell, compared with
the modern vogue in like circumstances! Of the two Americans at Berlin
who fell four thousand feet in a balloon, it is not recorded that they
either kissed or wept.[2] But some Teutonic Ovid may yet adorn the tale
with quaint embellishments.

Taking more serious note of Daedalus, it will be observed that he
has had few imitators. It is because he never really flew, and no
one else can fly, in such manner. That is to say, no man can achieve
practical flight on wings actuated by his own muscular power. It may be
physically possible for an athlete putting forth herculean energy for
a few seconds to sustain himself on wings of enormous spread; but in
every lightest zephyr he would be as helpless as a thistle seed.

The actual area of wing required for a man of given weight and power
may be roughly estimated; at least its lower limit of size can be
determined. Lord Rayleigh,[3] on purely theoretical ground, has
computed that a man operating a screw propeller 280 feet in diameter,
moving without frictional loss, could sustain his weight for a period
of eight hours a day at a comfortable rate of work. But that estimate
does not include the weight of the propeller. By exerting ten times his
normal power the man could support his weight with a 28-foot propeller.

The physical basis of the computation is the same for every type of
flyer, whether bird, man, or machine. Its weight must be sustained by
hurling the air downward. The humming bird in its aërial pause, the bee
floating beside a blossom, rests on a down-driven column of air. The
home-gliding eagle at dusk may encounter a medium in stillest repose,
but he leaves behind him a down-flowing wake, viewless, maybe, but none
the less real. In all cases the downward impulse per second given to
the air must equal the weight supported by its reaction. If the wings
be very extensive a proportionate mass of air may be struck down, and
yield support with so much the less exertion.

Horizontal flight promises little more than direct screw lift, with the
feeble energy of the human muscle. The best modern aëroplanes carry
less than 100 pounds per horse power, while an average man must weigh,
with a light machine, not less than 200 pounds, and must therefore
exert upwards of two horse power during flight. Such an output of
energy would exhaust a powerful athlete in a few seconds. Hence from
every point of view it appears that Daedalean flight, which still has
its devotees in some form, was and always will be utterly impracticable.

Ruskin finds another objection to the disciples of the winged arm.
In his disquisition on the equilibrium of angels he complains that
those of the traditional two-wing type are devoid of gravitational
balance. Such creatures vex the imagination with apprehensions for
their stability; hence they cannot be entirely beautiful. The centroid
of an angel is in the small of its back, whereas the center of wing
support is well forward; therefore the horizontal poise is absurd and
unæsthetic. The scientific artist, consequently, views with pain the
picture of a fair lady floating level through space supported only at
her front end.

Milton adroitly forestalls this censure. In the conception of his
glorious Raphael, he provides consummately for uniform and adequate
support:

        Six wings he wore, to shade
    His lineaments divine; the pair that clad
    Each shoulder broad, came mantling o’er his breast
    With regal ornament; the middle pair
    Girt like a starry zone his waist, and round
    Skirted his loins and thighs with downy gold,
    And colors dipped in Heaven; the third his feet
    Shadowed from either heel with feathered mail,
    Sky-tinctured grain. Like Maia’s son he stood,
    And shook his plumes, that heavenly fragrance filled
    The circuit wide.

Leonardo da Vinci, who was a gifted engineer as well as an artist,
devised a flying gear for man which shows some dynamic improvement over
the mechanism of the old-time angels, flying gods, and hobgoblins. As
shown in the accompanying sketch, it provided for gravitational balance
by use of an expanding tail projecting well to the rear. Moreover, the
propulsion was to employ both arms and legs. This design is considered
very remarkable for the time in which it was produced, probably a few
years before the discovery of America; and yet it is but one of Da
Vinci’s quaint aëronautical inventions, as will appear later.

A less futile scheme of aviation may be to saddle the birds. If one
eagle can float a child, a few may possibly carry a man. They are
physically able; they are inexpensive; they are unwearied, nimble,
swift. Some harness, some tuition may be required; but these come
to the industrious. Apparently, such locomotion is a sport worth
developing; a royal art, if you please; for who would not course the
sky in a purple palanquin borne by imperial eagles?

Kai Kaoos, the King of Persia, is credited with a voyage of this kind,
as described in the _Shah-Nemeh_, or _King-Book_, written in the tenth
century:

  “To the king it became a matter of great concern how he might
  be enabled to ascend the heavens, without wings; and for that
  purpose he consulted the astrologers, who presently suggested a
  way in which his desires might be successfully accomplished.

[Illustration: FIG. 1.—DA VINCI’S DESIGNS FOR HUMAN FLYING-GEAR.]

  “They contrived to rob an eagle’s nest of its young, which they
  reared with great care, supplying them with invigorating food.

  “A frame of aloes-wood was then prepared, and at each of the
  four corners was fixed perpendicularly a javelin surmounted
  on the point with the flesh of a goat. At each corner again
  one of the eagles was bound, and in the middle the king was
  seated with a goblet of wine before him. As soon as the eagles
  became hungry they endeavored to get at the goat’s flesh upon
  the javelins, and by flapping their wings, and flying upwards
  they quickly raised the throne from the ground. Hunger still
  pressing on them, and still being distant from their prey,
  they ascended higher and higher in the clouds, conveying the
  astonished king far beyond his own country. But after a long
  and fruitless exertion, their strength failed them, and, unable
  to keep their way, the whole fabric came tumbling down from the
  sky, and fell upon a dreary solitude in the Kingdom of Chin,
  where Kai Kaoos was left a prey to hunger, alone, and in utter
  despair.”

One might prefer a single bird, which could be ridden bareback by a man
or woman of common equestrian skill. The early philosophers, therefore,
sought with some care for such a creature. The following is related by
Bishop Wilkins:

  “Cardan and Scaliger doe unanimously affirm, that there is
  a bird amongst the Indians of so great a bignesse, that his
  beak is often used to make a sheath or scabbard for a sword.
  And Acosta tells us of a fowl in Peru called Condores, which
  will of themselves kill and eat up a whole calf at a time. Nor
  is there any reason why any other body may not be supported
  and carried in the air, though it should as much exceed the
  quantity of these fowls as they do the quantity of a flie.
  Marcus Polus mentions a fowl in Madagascar which he cals a
  Ruck, the feathers of whose wings are 12 paces, or threescore
  foot long, which can with as much ease scoop up an elephant as
  our kites do a mouse. If this relation was anything credible,
  it might serve as an abundant proof for the present quaere.”

As the roc has proved a myth, one questions whether a saddle bird
may not be evolved by judicious breeding. But opposed to this is the
square-cube law of the Greek geometer, by which a learned geologist
demonstrated that nature has reached the limit of her resources in the
production of large flyers, the ostrich, for example, being too bulky
to navigate at all. As a last resource, then, the human dwarf may
breed his weight downward to accommodate the bird. Assuredly, the most
powerful flyer can carry the lightest human dwarf without difficulty.

Such aërial cavalry has been projected occasionally, and if fairly
developed might have interesting employment. Its military value, to
say nothing of its civil uses, would be considerable. An aërial scout
that could hide in a tree top, or small cloud, then flit home with full
intelligence of the enemy, would be effective and unique. In aggressive
warfare it would serve the plan of that ingenious Englishman who
proposes to repel a German invasion by dispatching birds to peck holes
in the enemy’s war balloons. But here the dwarf might be omitted, if
the birds were taught to have a definite interest in attacking aërial
cruisers with their beaks, or with steel-armed spurs like those of the
Spanish fighting cock, or with talons treated chemically to strike
fire. Sparrows with sulphur-pointed toes could easily annihilate an
aërial squadron at all combustible.

Recurring to the geologist, it may be added that, having discovered the
major limit of feathered navigators, he concluded, as a corollary, that
human flight is forever impossible. That was in the latter eighties.
In 1901 a versatile astronomer adduced the same law to prove that an
aëroplane could not be made to carry a man. Presently, learning that
this had been achieved, he proved, in a second mellifluous paper, that
an aëroplane could not carry, several men.[4] Having erred twice, he
wrote a final article announcing that a flyer is fatuous, anyhow,
because she cannot repair her engines in the sky!

[Illustration: FIG. 2.—A POSSIBLE AIR-SCOUT.]

Of the numerous daring and industrious inventors who, during remote
generations, have launched themselves in the air on some species of
rigid or vibrant wings, a few were men of considerable equipment in
philosophy, or mechanics, and enjoyed a sufficient measure of success
to deserve passing notice; though it seems that no man before the
middle of the eighteenth century made a permanent contribution to the
real art of mechanical flight, if we except the ingenious suggestive
devices of Leonardo da Vinci. However skilfully their flying apparatus
may have been planned, or operated, the results were lost to the world,
due to inaccurate or inadequate description. Such inventors were J. B.
Dante, in the fifteenth century, and the Marquis de Bacqueville, in the
seventeenth. Each of these made one, or more, considerable flights, if
we may credit the unwavering testimony of their contemporaries; but
neither has left a sketch of his device, nor a school of followers to
continue his spectacular practice.

Jean-Baptiste Dante, a shrewd observer and profound mathematician, who
flourished toward the end of the fifteenth century, a contemporary of
Da Vinci and Columbus, is reported by the historians of that day to
have sailed successfully through the air on nonvibrant wings designed
by himself after a careful study of the great soaring birds. Perching
above a steep crag on the shore of Lake Trasimene, he set his wings
to the wind at a nice angle, as one sets the sails of a vessel; then,
lifted by the swelling breeze, he rose grandly aloft and floated far
over the waters. Again and again he repeated the experiment, until
the fame thereof secured for him a request to make the demonstration
at the marriage fêtes of the illustrious general, Barthelmi Alviano.
He accepted the invitation, and, starting from the top of the highest
tower in the city of Perugia, he sailed over the public square,
and balanced himself for a long time in space, amid the shouts and
acclamations of the multitude, attracted to Perugia by the novelty of
his performance. But, sad to relate, the very first time he performed
these wonderful maneuvers above the solid ground instead of the lake,
one of the levers used to alter the impact angle of his wings gave way,
disturbing his aërial poise, and causing him to pitch down upon Notre
Dame church, breaking one of his legs. After this he taught mathematics
at Venice, where he died of fever at the age of forty years.

In 1742, the Marquis de Bacqueville, at the age of sixty-two years,
announced that on a certain day he would fly from his house on the
Seine, traverse the river, and land in the Garden of the Tuileries. A
great multitude assembled, crowding both shores and the two bridges.
At the appointed moment the Marquis appeared with his pinions, and
launched himself from the terrace. He sailed forth in majestic and
serene poise, on graceful wings not unlike those of the traditional
angels. He was gliding directly toward the Tuileries, and he enjoyed a
happy cruise quite to the middle of the river. Then something happened;
his movements became fitful and uncertain; he plunged downward and
broke his leg on a laundry boat. The reason for his stopping there can
only be surmised, for he had nothing to report. He did not quite fulfil
his program, but he flew nine hundred feet delightfully, and he landed
without getting wet.

Commentators have marveled as to the nature of the mechanism used by
Dante and by De Bacqueville. Historians have strongly attested the
fact of the flights, but have overlooked the means. The inventors must
have employed aërial gliders of some kind, for adequate motive power
was not available before the end of the nineteenth century. Even as
an experiment in gliding, or soaring, the achievement of Dante was
most daring and wonderful, eclipsing the best performances up to the
twentieth century. It is strange that in that period of science the
survivor of such an experience, and a college professor, should not
have left to the world a careful account of such an extraordinary
performance. The alleged flights, however, were unquestionably
feasible, even in that remote period, for the construction of an
aërial glider is a simple task not beyond the capacity of craftsmen
in the fifteenth century A.D., or even the fifteenth century
B.C., directed by a skilful designer.

Besides the wing-armed scheme of flight credited to Daedalus, and
contemplated by Da Vinci, various other plans were evolved in
succeeding years. Aërial chariots and flying machines were devised for
the more advantageous use of muscular energy. In all these, of course,
the passenger could be both power plant and captain of the ship.

One of the earliest authenticated devices of this kind was the
invention of Blanchard, described by him in the _Journal de Paris_,
August 28, 1781, nearly two years before the invention of the hot-air
balloon, of which he became later an enthusiastic votary. As his device
is but one of a large number that appeared before the close of the
nineteenth century, and the advent of light motors, the reader who
wishes fuller acquaintance with man-driven airships may be referred
to Mr. Chanute’s book, entitled _Progress in Flying-Machines_, which
describes a large variety of such inventions, and discusses the merit
and weakness of each.

Blanchard prefaces the description of his machine by answering some
criticisms of his project, apparently ventured by his neighbors. “They
object to me,” he writes, “that flying is not the business of man, but
rather of the feathered birds. I reply that feathers are not at all
necessary to the bird for flight; any fabric suffices. The fly, the
butterfly, the bat, etc., fly without feathers and with fanlike wings
of material resembling horn. It is, then, neither the material nor
the form that causes flight, but the volume and the celerity of the
movement, which should be as lively as possible.

“They object, moreover, that a man is too heavy to lift himself alone
with wings, much less in a vessel which of itself presents enormous
weight. I reply that my ship is extremely light; as to the man’s
weight, I pray that attention be given to that which M. de Buffon says
in his _Histoire Naturelle_, on the subject of the condor; this bird,
though of enormous weight, easily lifts a two-year-old heifer weighing
at least a hundred pounds, the whole with wings of about thirty to
thirty-six feet expanse.”

He then describes the vessel as a little ship four feet long by two
feet wide, having on either side two posts, each supporting a wing ten
feet long, the whole forming a parasol twenty feet in diameter. The
construction was illustrated by an engraver, who had seen the vessel
and was convinced of its practicability. In conclusion, the inventor
writes that people shall see him cleave the air with more speed than
the crow, and that without losing his breath, being protected by a
pointed mask of peculiar construction. But, as he failed to make good
his promises, he was subjected to ridicule, as well as praise, by the
local press, one of the caricatures portraying him in the act of making
an ascension before a concourse of bulging-eyed savants and long-eared
jackasses, wearing spectacles to accentuate the appearance of wisdom
and solemnity.

The scientific coterie of Paris were apparently impatient of the
attention shown Blanchard by the press and people. Accordingly, in May,
1782, the distinguished astronomer, De Laland, of the French Academy,
administered a mild rebuke to the editors of the _Paris Journal_.
“Gentlemen,” he wrote, “you have given so much time to air ships and
divination rods that one might eventually think that you believe in
these follies, or that the scientists who coöperate with your journal
have nothing to say to dispel these absurd pretensions. Permit me,
therefore, gentlemen, to occupy some lines in your journal to assure
your readers that if the savants are silent it is only because of their
contempt.

[Illustration: FIG. 3.—BLANCHARD’S FLYING-MACHINE.]

“It has been demonstrated to be impossible for a man in any manner
whatever to raise himself, or even to sustain himself, in the air. M.
Coulomb, of the Academy of Sciences, at one of our meetings a year ago,
read a paper in which he showed clearly, by calculating the power of
a man, determined by experiments, that he would require wings two or
three thousand feet long moved three feet per second; hence no one but
an ignoramus would make an attempt of this kind.”

Not many months after this lofty deliverance, Blanchard took De Lalande
up in a balloon—“the dead borne by the dumb.”

Coulomb’s calculation that a man’s pinions should be half a mile long
must have been discouraging to those inventors who believed in him;
for, granting that such wings could lift a man, who could lift the
wings? And at that date the steam engine was only beginning to develop;
the petroleum engine was hardly thought of. No wonder that people
turned eagerly to the balloon when it finally appeared.

There has been some controversy as to what person first clearly
conceived a feasible design for a balloon. The conception was
certainly not new to the world in 1783, when Joseph Montgolfier made
his classical experiment. Indeed, prior to that date three distinct
principles of aërial flotation had been entertained by natural
philosophers; first, that a boat could be so formed of heavy material
as to ride on the upper surface of the atmosphere, as a metallic vessel
floats on the water; second, that a closed hull, comprising a partial,
or complete, vacuum, could be made light enough to rise; third, that
a bag could be made buoyant by filling it with material lighter than
air. Of course, it is now clear to men versed in mathematics that only
the light-gas principle is mechanically applicable. But the vacuum
principle still has adherents among inventors who are too “practical”
to understand, or trust, exact computation; and the first principle,
though now discarded by everyone, was plausible enough, even to
accomplished scientific men, before the experiments of Torricelli, and
his invention of the barometer, made in 1643. It may, therefore, be
interesting to notice some of the proposed, or reported, air ships
based upon these various principles. The following is from _Mendoza,
Viridario, libri III, probl. 47_:

  “Any brass vessel full of air, which otherwise would sink, is
  sustained on the surface of the water, though naturally of
  much greater specific gravity; consequently a wooden ship, or
  one of any other material, placed on the summit of an aërial
  superficies and filled with elementary fire, will be sustained
  in that position till the gravity of the vessel becomes greater
  than the sustaining power of the fire it contains.”

This is a clear scientific exposition of a plan for navigating the
atmosphere on its upper surface, assuming a distinct upper surface
to exist. In commenting on this passage, the Jesuit Schottus, in his
_Magia Universalis_, uses an expression which indicates his belief that
a vessel can be made to _float in the air_ by filling it with ether, or
the element of fire. He says:

  “In such terms has this matter been treated by Mendoza (died
  1626); nor is there any improbability involved in his view,
  whether the element of fire be placed above the air, or, what
  is still more credible, the ether—that is, the purest air.
  Although any wood, iron, copper, lead, and such like metals are
  weightier than an equal volume of water, and for that reason
  will sink in water when placed there alone, yet if fabricated
  into hollow shapes, and filled with our impure and heavy air,
  they swim upon waters, and are adapted to the construction of
  ships, and are sustained by water without danger of immersion;
  thus, although these bodies are of greater specific gravity
  than our air, nevertheless, when shaped into a boat and filled
  with that very light material, they can _float in the air_,
  and are suitable material for the construction of small ships,
  because the entire work composed of the little ship and the
  ether can be made lighter than an equal volume of our impure
  air, even in the highest region.”

As Roger Bacon proposed a similar device in 1542, Mendoza’s was not
entirely new and may not have been original. Bacon, describing his
aërial vessel, says: “It must be a large, hollow globe of copper, or
other suitable metal, wrought extremely thin, in order to have it
as light as possible. It must then be filled with ‘ethereal air or
liquid fire,’ and then be launched from some elevated point into the
atmosphere, where it will float like a vessel on water.”

In the year 1646 another learned Jesuit published a book, _Ars Magna
Lucis et Umbræ in Mundo_, in which he relates an episode indicating
that one of his order had made use of a hot-air balloon to intimidate
some ignorant pagans. The following demonstration, if reported by a
modern missionary, would be accepted as a matter of course; why, then,
should we gravely question the story, since it describes an achievement
quite possible at the time, assuming that the necessary materials were
available? And even assuming the report to be fictitious, still it is a
scientific description of a practicable hot-air balloon, presented and
credited by a learned scholar and accomplished mathematician more than
a century before the balloon was publicly exhibited by the illustrious
Frenchmen. He writes:

  “I know that many of our fathers have been rescued from the
  most imminent dangers amongst the barbarians of India by such
  inventions. These were cast into prison, and whilst they
  continued ignorant of any means of effecting their liberation,
  some one, more cunning than the rest, invented an extraordinary
  machine, and then threatened the barbarians, unless they
  liberated his companions, that they would behold in a short
  time some extraordinary portents, and experience the visible
  anger of the Gods. The barbarians laughed at the threat. He
  then had constructed a dragon of the most volatile paper, and
  in this he enclosed a mixture of sulphur, pitch, wax, and so
  artistically prepared all his materials, that, when ignited, it
  would illumine the machine, and exhibit the following legend
  in their vernacular idiom, _The Anger of God_. The body being
  formed and the ingredients prepared, he then affixed a long
  tail, and committed the machine to the heavens, and, favored
  by the wind, it soared aloft towards the clouds. The spectacle
  of the dragon so brilliantly lit was terrific. The barbarians,
  beholding the unusual motion of the apparition, were smitten
  with the greatest astonishment, and now, remembering the
  threatened anger of Deity and the words of the father, they
  were in fear of expiating the punishment he had prognosticated
  for them. Therefore, without delay, they threw open the gates,
  they suffered their prisoners to go forth in peace and enjoy
  their freedom. In the meantime the fire seized on the machine
  and set it in a blaze, and with an explosion, which was
  interpreted as an expiring declaration of satisfaction, it,
  apparently of its own accord, vanished from sight, as if it
  had accomplished its supernatural mission. Thus the fathers,
  through the apprehension which this natural manifestation
  inspired, obtained that which could not be purchased with a
  large amount of gold.”

Perhaps the reader will permit another anecdote, not entirely for its
scientific value, but because he may like to compare the attitude of
people toward aërial navigation in the dark ages with the attitude of
his neighbors at the opening of the twentieth century. In two histories
by Jef le Ministre and De Colonia, of the town of Lyons, the following
account is given:

  “Toward the end of Charlemagne’s reign, persons who lived
  near Mount Pilate in Switzerland, knowing by what means
  pretended sorcerers traveled through the air, resolved to try
  the experiment, and compelled some poor people to ascend in an
  aërostal. This descended in the town of Lyons, where they were
  immediately hurried to prison, and the mob desired their death
  as sorcerers. The judges condemned them to be burned; but the
  Bishop Agobard suspended the execution, and sent for them to
  his palace, that he might question them. They answered: ‘Qu’ils
  sont du pays meme, que des personnes de consideration les ont
  forcés de se laisser conduire, leur promettent qu’ils verroient
  des chose merveilleuses; et qu’ils sont veritablement descendu
  par l’air.’ Agobard, though he could not believe this fact,
  gave credence to their innocence, and allowed them to escape.
  On this occasion he wrote a work on the superstition of the
  time, in which he demonstrated the impossibility of rising in
  the air; that it is an error to believe in the power of magic;
  and that it has its existence in the credulity solely of the
  people.”

One of the first men to make an aërial model like a fire balloon was
the celebrated Brazilian, Bartholomeo-Lourenco de Gusmao, who in his
day was nicknamed the “flying man,” and who is reported to have made
a remarkable experiment in aërial locomotion at Lisbon. The following
account of it is found in a manuscript of Ferreira:

  “Gusmao made his experiment on August 8, 1709, in the court of
  the Palace of the Indies, before his majesty and a large and
  distinguished audience, with a globe which lifted itself softly
  to the height of the hall of the Ambassadors, then descended in
  like manner. It was borne up by certain materials which burned
  and which the inventor himself had ignited.”

All the details of this description, which was written a generation
or more before the Montgolfier experiment, suggest at once a hot-air
balloon. But a note printed in 1774 and cited by Cavallo explains that
the globes must have been transported by gas. It is certain that early
in 1709 Gusmao applied to the King for a patent and sole right to some
such invention, desiring an injunction and severe penalty against
all infringements. The application sets forth a machine capable of
journeying through the air faster than over land or sea, competent
to carry messages five or six hundred miles a day to troops, or the
most distant countries, and even adequate to explore regions about the
poles. Quite a modern promoter Señor Gusmao. The King in reply issued
the following decree:

  “Agreeably to the advice of my council, I order the pain of
  death against the transgressor. And in order to encourage the
  suppliant to apply himself with zeal toward improving the
  machine which is capable of producing the effects mentioned by
  him, I also grant him the first Professorship of Mathematics in
  my University of Coimbra, and the first vacancy in my College
  of Barcelona, with the annual pension of 600,000 reis during
  his life.”

The “patent” seemed liberal enough, and yet Gusmao never resumed
his aërial experiments. He was accused of magic, and may have
feared persecution on that account; accordingly he engaged in naval
construction till 1724, when he left Portugal.

The first vacuum balloon was proposed by the Jesuit father, Francis
Lana, and described in his book _Podromo dell’Arte Maestra Brecia_,
which appeared in 1670. Though not a practical project like Gusmao’s,
it was very ingenious, and marks an interesting phase in the evolution
of the fundamental idea of the air ship, or “balloon” as it was called
by the inventor, who then coined the word now in common use. Lana
proposed to use four copper spheres each 25 feet in diameter and
1/225 inches in wall thickness, quite well exhausted of air, to give
ascensional force which he computed at 1,200 pounds aggregate for the
four spheres. From these he would suspend the passengers in a boat
having a mast and sail to propel the ship in time of favorable wind.
Having computed the buoyancy according to well-known physical laws, he
could see no possible objection to his project “unless,” he writes,
“it be that God would never permit this invention to be practically
applied, in order to prevent the consequences that would ensue
therefrom in the civil and political government of men.”

[Illustration: FIG. 4.—LANA’S PROPOSED VACUUM BALLOON.]

Of recent years inventors having less delicate scruples about
embarrassing Providence, have revived Lana’s project with
improvements. It has been proposed to replace the sail by a
motor-driven propeller, and to ensure the hull against collapse from
the prodigious external air pressure—a ton per square foot—by ample
internal bracing. Even within the past twelve months this scheme has
been soberly advocated by several technical journals and by the author
of an elaborate book on aërial warfare. To a mathematician this is
amusing, when not too pathetic; for it can be rigorously proved that
no vacuum balloon of present day material, whatever its design, can
possibly resist crushing if made light enough to float.

In 1887 Walter Wellman described in the _Associated Press_ a steel
vacuum balloon 144 feet in diameter and 654 feet long in which a
Chicago doctor proposed to carry passengers to the North Pole, at
incredible speed, if they would furnish him $130,000 to meet the
expenses of construction. “Here is a most excellent opportunity,” wrote
Wellman, “for all who would like to win fame by being one of the party
which shall set foot upon that icy _ignis fatuus_ of many nations and
two centuries.” Two decades later Mr. Wellman organized, after his own
ideas, an aërial expedition to the North Pole; but he no longer favored
starting from Chicago in a vacuum balloon with a party of stockholders.

It may be added that the inventor of the great steel vacuum balloon,
after organizing the Trans-Continental Aërial Navigation Company, and
failing to raise all of the $130,000, sought aid from the national
government. Here was an interesting situation; a doctor ignorant
of mechanics, with the plans for a mammoth and impossible balloon,
appealing for aid to a congress, supremely shy of air ships, even
though recommended by its ablest military advisers. But in this case
there was a capable lobby. The bill for this physically impossible
balloon actually passed the House, and was finally defeated only by
the timely effort of a few scientific men who, by easy calculation,
proved the absurdity of the invention. As the reader may like to see a
mathematical proof of the impossibility of a vacuum balloon, since such
projects arise frequently, the argument is given in Appendix I.




                                PART I

                         GROWTH OF AËROSTATION




                               CHAPTER I

                   EARLY HISTORY OF PASSIVE BALLOONS

    Oh, that I could as smoke arise,
    That rolls its black wreathes through the air;
    Mix with the clouds, that o’er the skies
    Show their light forms, and disappear:
    Or like the dust be tossed
    By every sportive wind till all be lost!
                                           —ÆSCHYLUS.


If desire is sometimes the mother of invention, doubtless the wish to
“mix with the clouds,” or “as smoke arise,” suggested to man his first
means of aërial locomotion. Indeed this is openly avowed by Joseph
Montgolfier. “Smoke rises in the chimney; why not encage this smoke,
and have an available force.” But before describing his fundamental
experiments of 1783, let us notice the less conspicuous ones,
though not less philosophical, of his immediate predecessors in the
development of aëronautic science.

It has been seen, that many years before 1783, inventors had clearly
conceived the true principle of the balloon, and would be glad to
avail themselves of an element of sufficiently low specific gravity
for aërial flotation. The desired opportunity came when, in 1766,
Henry Cavendish published his experiments, proving that hydrogen is
many times lighter than air. Immediately after this, Dr. Black, the
famous chemist and natural philosopher of Edinburgh, conceived the
idea that a thin light vessel filled with hydrogen should be able to
float and rise in the atmosphere, ideas that he conveyed to his friends
and expressed in his lectures a year or two after the appearance of
Cavendish’s publication. But he contented himself with merely pointing
the way to an obviously practicable invention, leaving, as a university
professor should, the development of the scientific idea to inventors
and constructive engineers.

Intermediate between Dr. Black, the pure scientist, and the Montgolfier
brothers manufacturers, came Tiberius Cavallo, an Italian philosopher
living in England, who made the first small hydrogen balloons. In
a note presented to the Royal Society of London, June 20, 1782, he
relates experiments that seem to entitle him to all the credit of
inventing the balloon except success on a practical scale. He made
hydrogen soap bubbles which rose beautifully in the air, an experiment
that has been repeated throughout the world in every chemical
laboratory since his day. He made a variety of gum bubbles and varnish
bubbles inflated with hydrogen; but curiously enough these failed
to rise, though it is known that such bubbles can be made to float
handsomely.[5] He inflated carefully prepared gold-beater skin and
failed, though gold-beater skin balloons, both large and small, are now
a marketable commodity. Finally he constructed paper balloons which he
tried to float by use of hydrogen, but without success, though a year
later the Montgolfier brothers easily made paper bags arise with hot
air, and Professor Charles ascended in a large silk balloon inflated
with hydrogen.

The cause of Cavallo’s interesting failures reveals itself in his own
account of one of his pioneer experiments. In his _History and Practice
of Aërostation_, he relates that he constructed, of fine Chinese paper,
a cylindrical balloon having short conical ends and a calculated
buoyancy of twenty-five grains, when properly inflated with hydrogen.
This bag, carefully deflated of air by compression between the hands,
he suspended above a large bottle connected with it by a glass tube,
and supplied with materials for generating hydrogen; in this case a
mixture of dilute sulphuric acid and iron filings. When the hydrogen
was evolving quite rapidly, he expected to see the paper sac expand
and fill out with proportionate speed; but to his surprise it remained
perfectly flat, while the room filled with the strong and disagreeable
odor of the “inflaminable air.” He then realized that the carefully
made sac of paper, which could be so easily inflated with air, was very
permeable to hydrogen, allowing it to escape instantly, as through
porous cloth, or netting.

Cavallo desisted when the goal was within reach. His plans were
practicable, but he abandoned them too readily. Why did he not varnish
his balloon when it leaked? He could thus so easily have inaugurated
the art of aërial navigation. But after salting the bird’s tail he let
it escape.

Various accounts have been given of the steps by which the Montgolfiers
were led to their invention of the balloon. They are said to have
studied and discussed projects for aërial locomotion a decade before
hitting upon their first successful device; at one time filling a paper
bag with smoke ineffectually; again with steam, and again trying, but
in vain, to employ hydrogen. The following apparently reliable account
is given by a friend of the Montgolfiers, Baron Gernando, in his
biographical notice of Joseph Montgolfier, having obtained the story
from the inventor himself.

Joseph Montgolfier found himself at Abignon, and it was at the time
when the combined armies held the siege of Gibraltar. Alone, in the
chimney corner, dreaming, as usual, he was contemplating a sort of cut
that represented the work of the siege; he grew impatient observing
that one could not reach the body of the place either by land or
sea. “But could not one arrive there through the air? Smoke rises in
the chimney; why not store this smoke in such a manner as to form an
available force?” His mind calculated instantly the weight of a given
surface of paper, or taffeta; he constructed without delay his little
balloon, and saw it rise from the floor, to the great surprise of his
hostess, and with a peculiar joy. He wrote on the spot, to his brother
then at Annonay: “Prepare immediately a supply of taffeta and cordage,
and you shall see the most astonishing thing in the world.”

A quainter story is told by Brisson in his _Dictionary of Physics_. He
says: “I can only repeat what the citizen Montgolfier himself told me,
when he came to Paris to announce his discovery; that the citizeness
Montgolfier having placed a skirt on an open-wicker basket, such as
women use to dry linen, the skirt was lifted to the ceiling. It is from
this fact that the citizens Montgolfier started.”

Whatever the preliminaries, the Montgolfier brothers finally made the
experiment of holding a paper bag over a fire fed with wet straw and
wool. It is doubtful whether they purposed to fill it with smoke, or
with hot air or an electrical cloud. They knew that a cloud of some
kind rises from such a fire, and they wanted to harness it. Their
first balloon took fire and went up as smoke. But they were rich
paper manufacturers, and soon had another balloon of 700 cubic feet
capacity. This rose from the fire to a height of 1,000 feet, carrying
no fuel with it. Thus two practical[6] men had made fire lift a paper
sac; let the Academy explain how. The baby Aërostation was born.

How fortuitous the primal steps of science! Galvanism from the twitch
of a frog’s leg; aërostation from the puff of a petticoat! There had
been no year in thirty centuries when people could not easily have
built a hot-air balloon. All the materials were available; only a
little thought was wanting. A simple sketch sent to a Roman tailor,
or tent-maker, could have furnished a woven bag competent to lift
passengers from the heart of the Coliseum, to the wonder and delight
of a hundred thousand spectators. Yet the genius that could design the
Coliseum, or cover its vast enclosure with canvas, failed to think of
the magic bag that would have enhanced so much the ingenious shows of
a show-loving people. That device was an inspiration destined to a
common Frenchman at no uncommon period of science. The hydrogen balloon
arrived in the natural and logical order of scientific progression;
but the hot-air bag might have presented itself at any time since the
birth of weaving. It was a happy thought, like the ophthalmoscope,
or jack-knife—quaint modern creations of constant use or comfort to
mankind.

The public inauguration of aëronautics occurred on June 5, 1783, at
Annonay, the home of the Montgolfier family, 36 miles from Lyons.
The states of Vivarais being assembled at that place, were invited
to witness the ascension. The Deputies and many spectators found in
the public square an enormous bag which, with its frame, weighed 300
pounds, and would inflate to a ball 35 feet in diameter. When told
that this huge mass would rise to the clouds they were astonished and
incredulous. The Montgolfiers, however, lit a fire beneath and let the
bag speak for itself. It gradually distended, assuming a beautiful
form, and struggling to free itself from the men who were holding it.
At a given signal it was released; it ascended rapidly, and in ten
minutes attained a height of 6,000 feet. It drifted a mile and a half
and sank gently to the ground.

[Illustration: FIG. 5.—MONTGOLFIER’S EXPERIMENTAL BALLOON.]

When the French Academy learned of this event they desired to have
an ascension in Paris, and at once started a public subscription to
defray the expense of constructing and inflating a balloon. They
placed the work in charge of the physicist Charles, after inviting the
Montgolfiers to Paris, and finding they could not come immediately.
Charles proved more than a substitute; he became a fertile inventor and
a rival in the new field. Aided by the skill of the Robert brothers, he
made a silk globe varnished with dissolved rubber, and filled it with
hydrogen, which is many times lighter than hot air. The operation of
filling occupied three days, consuming 500 pounds of sulphuric acid and
half a ton of iron. The globe was 13 feet in diameter, and designated
a “balloon,” or big ball. This had next to be moved from the place of
filling, in the Place des Victoires, to the Champ de Mars, two miles
distant, in order to have space enough to accommodate the increasing
crowd of spectators. Accordingly, on the 26th it was conveyed thither,
in the dead of night, preceded by lighted torches, surrounded by a
cortege, and escorted by foot and horse guards. Impressive and weird,
indeed, was this nocturnal caravan of troops and towering globe
advancing slowly through the dark and silent streets. The astonished
cab drivers knelt humbly, hat in hand, while the procession passed.

The ascent of this, the first hydrogen balloon, was a popular and
a memorable event. The field was lined with troops. The curious
spectators had thronged every thoroughfare and darkened every housetop.
It was an all day festival, inaugurating a peculiarly French science,
with French animation. The booming of cannon announced to all Paris
the impending flight of the balloon. At five o’clock, in the presence
of 50,000 spectators, and in a shower of rain, the balloon rose more
than half a mile and entered the clouds. The people overwhelmed with
surprise and enthusiasm, stood gazing upward, despite the rain,
observing every maneuver till the vessel had ascended and faded from
view.

[Illustration: FIG. 6.—CHARLES’ FIRST HYDROGEN BALLOON.]

The landing of this little balloon did not leave it in a condition to
exhibit proudly to future generations. After drifting three quarters
of an hour, it fell in a field near Gonesse, a village fifteen miles
from the place of ascension, apparently ruptured from overdistention.
The villagers flocked about it with curiosity and trepidation, ignorant
of its nature, whether of bird kind or monster; and doubtful of its
origin, whether natural or satanic. They fell upon it with flails and
pitchforks. When struck it smelt strongly of sulphur, indicating a
diabolic source. They finally hitched it to the tail of a horse which
galloping away in terror, badly damaged it. Whether this destruction
was wrought through fear or rustic hilarity, it induced the government
of France to issue a notice to the public explaining the innocuous
nature of a simple balloon.

In the meantime Joseph Montgolfier, having reached Paris, had
constructed a waterproof linen balloon 46 feet in diameter and
ornamented in oil colors, which was to be publicly launched at
Versailles. On September 19, 1783, the king and queen, the court and a
vast throng of people of every rank and age, assembled to witness the
ascension. Montgolfier explained to them every detail, and finally lit
the fire, about one o’clock. The great bag gradually expanded, rounding
out in eleven minutes to a beautiful globular form, tugging upward with
a force of seven hundred pounds. Beneath was suspended a wicker cage
containing the first aërial passengers—a sheep, a rooster and a duck.
The vessel rose majestically above the applauding multitude to a height
of fourteen hundred feet, and drifted some two miles in eight minutes,
descending gradually in the wood at Vaucresson. The animals were tipped
out on landing; but, when found by two game-keepers, they were none the
worse for their strange journey. The sheep was grazing and the cock
crowing, says one report, while another relates that the sheep had
trampled on the rooster and lamed him.

Stephen Montgolfier now wishing to send up human passengers, made a
balloon of 100,000 cubic feet capacity. It was shaped like a full lemon
pointing upward, with a cylindrical neck below, 16 feet in diameter.
Around this neck was a wicker balcony three feet wide, to carry the
aëronauts, bundles of straw for fuel, pails of water and sponges to
extinguish incipient conflagrations, here and there in the balloon,
during a journey. Through stokeholes in the side of the neck sheaves
of straw could be forked to the grate suspended centrally below by
radial chains. During inflation the base of the balloon rested on a
platform, and its top was supported by a rope stretched between two
poles. The vessel when completed, in a garden of the Faubourg St.
Antoine, was 85 feet high by 48 feet across, and weighed 1,600 pounds.
About its zone, painted in oil, were elegant decorations; portraits,
cyphers of the king’s name, fleur-de-lis, with fancy borders below and
above; while higher still, on the arching dome of the bag, were all the
signs of the celestial zodiac.

The handsome vessel was now ready; but what daring captain should
navigate her? King Louis proposed two prisoners who were under sentence
of death, and had to be killed somehow. But the brave Pilâtre de
Rozier protested indignantly: “Eh quoi! de vils criminels auraient
les premiers la gloire de senlever dans les airs! Non, non, cela ne
sera point.” He stirred up the city, and finally prevailed, through
the entreaties of the Marquis d’Arlandes, who secured from the king
permission to accompany his friend.

After some days of preliminary practice in maneuvering the tethered
balloon, these gentlemen were ready for an aërial voyage. On November
21, 1783, the balloon was inflated in the garden of La Muette palace,
and stocked with enough straw for an hour’s journey. When all was ready
Pilâtre de Rozier and the Marquis d’Arlandes stepped with eager courage
into the gallery taking opposite sides to ensure proper balance. At two
o’clock they rose splendidly, amid the acclamations of a vast throng
of spectators, and at the height of 280 feet, removing their hats,
saluted the surprised multitude. Encountering a south blowing wind,
they drifted five miles in some twenty minutes, and landed safely in a
field. The apparatus was soon assembled on a cart and returned to the
Faubourg St. Antoine, where it was originally constructed. The details
of this first human voyage in a balloon are very interesting and well
told in a letter written by the Marquis d’Arlande to a member of the
French Academy.

[Illustration: FIG. 7.—MONTGOLFIER’S PASSENGER BALLOON.]

“At this time M. Pilâtre said: ‘You do nothing, and we shall not
mount.’ ‘Pardon me,’ I replied. I threw a truss of straw upon the
fire, stirring it a little at the same time, and then quickly turned
my face back again; but I could no longer see La Muette. Astonished,
I gave a look to the direction of the river.... M. Pilâtre then said,
‘See, there is the river, and observe that we descend.’ ‘Well, then,
my friend, let us increase the fire;’ and we worked away. But instead
of crossing the river, as our direction seemed to indicate, which
carried us over the house of the Invalides, we passed along the island
of Cygnes, reëntered over the principal bed of the river, and advanced
up it as far as the gate de la Conference. I said to my intrepid
companion: ‘See, there is the river &c.’ I stirred the fire, and took
with the fork a truss of straw, which from being too tight, did not
take fire very easily. I lifted it and shook it in the middle of the
flame. The next moment I felt as if I were lifted up from under the
arms, and said to my companion, ‘Now we mount, &c.’ At the same time
I heard a noise toward the top of the machine, as if it were going to
burst; I looked, but did not see anything. However, as I was looking
up, I felt a shock, which was the only one I experienced. The direction
of the motion was from the upper part downwards. I said then: ‘What
are you doing? Are you dancing?’ ‘I don’t stir,’ said he. ‘So much the
better,’ I replied, ‘it is then a new current, which, I hope, will push
us over the river.’ In fact, I turned myself in order to see where we
were, and I found myself between l’École Militaire and les Invalides,
beyond which place we had already gone about 2,500 feet. M. Pilâtre
said at the same time: ‘We are on the plain.’ ‘Yes,’ said I, ‘and
we advance.’ ‘Work on,’ said he. I then heard another noise in the
machine, which appeared to be the effect of a rope breaking. This fresh
admonition made me examine attentively the interior of our habitation.
I saw that the part of the machine which was turned toward the south
was full of round holes, many of which were of a considerable size. I
then said: ‘We must descend,’ and at the same time I took the sponge
and easily extinguished the fire, which was round some holes that I
could reach; but leaning on the lower part of the linen, to observe
whether it adhered firmly to the surrounding circle, I found that the
linen was easily separated from it, on which I repeated that it was
necessary to descend. My companion said: ‘We are over Paris.’ ‘Never
mind that,’ said I, ‘but look if there appears any danger for you on
your side—are you safe?’ He said: ‘Yes.’ I examined my side, and found
that there was no danger to apprehend. Farther, I wetted with a sponge
those cords which were within my reach. They all resisted, except two,
which gave way. I then said: ‘We may pass over Paris.’ In doing this,
we approached the tops of houses very sensibly; we increased the fire,
and rose with the greatest ease. I looked below me, and perfectly
discovered the Mission Étranger. It seemed as if we were going toward
Saint-Sulpice, which I could perceive through the aperture of our
machine. On rising a current of air made us leave this direction, and
carried us toward the south. I saw on my left a sort of forest, which
I took to be the Luxembourg; we passed over the Boulevard, and then I
said: ‘Let us now descend.’ The fire was nearly extinguished; but the
intrepid M. Pilâtre, who never loses his presence of mind, and who
went forward, imagining that we were going against the mills that are
between Petite Gentilly and the Boulevard, admonished me. I threw a
bundle of straw on the fire, and shaking it in order to inflame it more
easily, we rose, and a new current carried us a little toward our left.
M. Rozier said again: ‘Take care of the mills’; but as I was looking
through the aperture of the machine, I could observe more accurately
that we could not meet with them, and said: ‘We are there.’ The moment
after, I observed that we went over a piece of water, which I took
for the river, but after landing, I recollected that it was the piece
of water, &c. The moment we touched the ground, I raised myself up to
the gallery and perceived the upper part of the machine to press very
gently on my head, I pushed it back, and jumped out of the gallery, and
on turning toward the machine, expected to find it distended, but was
surprised to find it perfectly emptied and quite flattened, &c.”

While the foregoing experiment was in progress, plans were matured for
the construction of a hydrogen balloon large enough to support two
passengers and remain aloft many hours, without the need of carrying
dangerous fuel. This type of balloon, called a _Charlière_, after its
inventor, was destined largely to supersede the hot-air type, known
as the _Montgolfière_, and indeed, to replace it entirely for free
voyages of considerable endurance and for most power voyages. The
construction after the plan of Professor Charles was delegated to two
very intelligent mechanics, the Robert brothers who also had succeeded
in dissolving caoutchouc, and thus producing a very superior balloon
varnish. The project was first announced in the _Journal de Paris_ of
the 19th of November 1783. As usual in those days of public enthusiasm,
a subscription was opened to defray the expenses of the experiment,
estimated to cost about ten thousand francs.

[Illustration: FIG. 8.—CHARLES’ PASSENGER BALLOON.]

This balloon was a truly scientific creation, which advanced
aërostation from tottering infancy almost to full prime. The bag was
a sphere 27½ feet in diameter made of gores of varnished silk. A net
covered the upper half and was fastened to a horizontal hoop girding
the middle of the globe, and called the “equator.” From the equator
depended ropes which supported, just below the spherical bag, a wicker
boat measuring eight feet by four, covered with painted linen and
beautifully ornamented. The balloon had at the bottom a silk neck 7
inches in diameter, to admit the gas during inflation, and at the top,
a valve which could be opened by means of a cord in the boat to let
out gas during a voyage, so as to lower the balloon, or to relieve
excessive pressure. In the boat were carried sand ballast to regulate
the height of ascension, a barometer to measure the elevation, anchor
and rope for landing, a thermometer, notebook, provisions, and all the
paraphernalia of a scientific voyage. Barring the fancy boat, this is
almost a description of a good modern balloon.

The inflation and ascension occurred in the Garden of the Tuileries,
where the limp bag was initially suspended from a rope stretched
between two trees. For three days and nights the hydrogen, drawn from
twenty barrels containing iron and dilute sulphuric acid, poured upward
through the silken neck into the distending globe, which swelled in
volume to 1,400 cubic feet. Finally on a beautiful day, the first of
December 1783, the Tuileries and all the neighborhood were crowded with
spectators. A numerous guard of soldiers, stationed about the apparatus
and grounds, preserved order. The fashion and nobility of Paris were
there, in ample splendor, attracted by the novelty and importance
of the experiment, and the fame of the inventor. Shortly before two
o’clock Professor Charles presented to his friend, Montgolfier, a pilot
balloon six feet in diameter, saying, “It is your prerogative to blaze
the way through the sky.” The pilot balloon was released, showing to
everyone the direction of the aërial currents. Charles and Roberts
stepped into the boat, seated themselves, and quickly rose into the
sky. The multitude gazed in silent wonder. Presently they observed two
pennants waving high above them, though the navigators were scarcely
visible; whereupon they burst forth into wild enthusiasm and thunderous
applause.

Immediately a cavalcade set out in hot pursuit of the venturesome
sailors. It was the first chase after an air ship, and a most vigorous
one. The balloon drifting northwestward at a speed of fifteen miles
an hour, crossed the Seine, passed over several towns and villages,
to the great astonishment of the inhabitants, and landed in a field
near Nesle. Here it was securely held by friendly peasants, to await
the advent of the official witnesses. Presently these arrived, drew
up a certificate of descent and signed it. The Duke de Chartres, and
the Duke de Fitz-James, who had followed less swiftly, now rode up
and signed the formal document, to the great gratification of the
aëronauts. The aërial journey had been a most delightful one, lasting
about two hours and covering nearly thirty miles.

After receiving the felicitations of his friends, Charles determined
to reascend, in order to obtain further scientific observations. Owing
to leakage and loss of buoyancy, he must now leave behind his pleasant
companion. He had proposed replacing with earth, or stones, a part
of Mr. Robert’s weight, but, finding none at hand, he signaled the
peasants to let go, whereupon he rose with unusual speed. The remainder
of this first and very remarkable scientific voyage is well told by the
navigator himself:

  “In twenty minutes I was 1,500 fathoms high; out of sight of
  all terrestrial objects. I had taken the necessary precautions
  against the explosion of the globe, and prepared to make the
  observations which I had promised myself. In order to observe
  the barometer and thermometer, placed at the end of the car,
  without altering the center of gravity, I knelt down in the
  middle, stretching forward my body and one leg, holding my
  watch in my left hand, and my pen and the string of the valve
  in my right, waiting for the event. The globe, which, at my
  setting out, was rather flaccid, swelled insensibly. The air
  escaped in great quantities at the silken tube. I drew the
  valve from time to time, to give it two vents; and I continued
  to ascend, still losing air, which issued out hissing, and
  became visible, like a warm vapor in a cold atmosphere. The
  reason of this phenomenon is obvious. On earth, the thermometer
  was 47°, or 15° above freezing point; after ten minutes’ ascent
  it was only 21°, or 11° below. The inflammable air had not
  had time to recover the equilibrium of its temperature. Its
  elastic equilibrium being quicker than that of the heat, there
  must escape a greater quantity than that which the external
  dilatation of the air could determine by its least pressure.
  For myself, though exposed to the open air, I passed in ten
  minutes from the warmth of spring to the cold of winter; a
  sharp dry cold, but not too much to be borne. I declare that,
  in the first moment, I felt nothing disagreeable in the sudden
  change. When the barometer ceased to fall, I marked exactly
  18 inches 10 lines (20-01 in. English), the mercury suffering
  no sensible oscillation. From this I deduce a height of 1,524
  fathoms (3,100 yards), or thereabouts, till I can be more exact
  in my calculation. In a few minutes more, my fingers were
  benumbed by the cold, so that I could not hold my pen. I was
  now stationary as to the rising and falling, and moved only in
  an horizontal direction. I rose up in the middle of the car
  to contemplate the scene around me. At my setting out the sun
  was set on the valleys; he soon rose for me alone, who was the
  only luminous body in the horizon, and all the rest of nature
  in shade; he, however, presently disappeared, and I had the
  pleasure of seeing him set twice in the same day. I beheld,
  for a few seconds, the circumambient air and the vapors rising
  from the valleys and rivers. The clouds seemed to rise from the
  earth and collect one upon the other, still preserving their
  usual form, only their color was gray and monotonous from the
  want of light in the atmosphere. The moon alone enlightened
  them, and showed me that I was tacking about twice; and I
  observed certain currents that brought me back again. I had
  several sensible deviations; and observed, with surprise, the
  effects of the wind, and saw the streamers of my banners point
  upwards. This phenomenon was not the effect of the ascent or
  descent, for then I moved horizontally. At that instant I
  conceived, perhaps a little too hastily, the idea of being able
  to steer one’s course. In the midst of my transport I felt a
  violent pain in my right ear and jaw, which I ascribed to the
  dilatation of the air, in the cellular construction of those
  organs, as much as to the cold of the external air. I was in a
  waistcoat and bareheaded. I immediately put on a woolen cap,
  yet the pain did not go off but as I gradually descended. For
  seven or eight minutes I had ceased to ascend; the condensation
  of the internal inflammable air rather made me descend. I now
  recollected my promise to return in half an hour, and, pulling
  the string of the valve, I came down. The globe was now so much
  emptied, that it appeared only a half globe. I perceived a
  fine ploughed field near the wood of Tour du Lay, and hastened
  my descent. When I was between twenty or thirty fathoms from
  the earth I threw out hastily two or three pounds of ballast,
  and became for a moment stationary, till I descended gently
  in the field, about a league from the place whence I set out.
  The frequent deviations and turnings about make me imagine
  that the voyage was near three leagues, and I was gone about
  thirty-three minutes. Such is the certainty of the combinations
  of our aërostatic machine, that I might have kept in the air at
  least for twenty-four hours longer.”

Further interesting details of the first balloon experiments at Paris
are furnished by Dr. Benjamin Franklin, then American Minister to
France, in his letters written to Sir Joseph Banks, President of
the Royal Society of London, and presented in Appendix II of this
book. These quaint and substantial stories are well worth perusal
as the expressions of a great diplomat and philosopher who, in the
midst of social and political activities, found time for scientific
correspondence with his friends in both hemispheres.

Aërial navigation was now become a practical art which should advance
rapidly in popularity, in both Europe and America. Very soon ascensions
were made everywhere, for private amusement and for public exhibitions.
Not a few were made for scientific, for military and for topographical
purposes; thus giving the art a utilitarian as well as a sporting
feature. It will be interesting to note some of the more conspicuous
ascensions, voyages and improvements made in passive balloons
subsequently to the invention of _Montgolfières_ and _Charlières_.

The largest hot-air balloon ever constructed, _La Flesselle_, was
launched from the suburbs of the city of Lyons on January 19, 1784,
just two months after the ascent of the first human passengers. It was
also one of the most troublesome to assemble and keep in repair. Day by
day, for more than a week, the balloon was inflated for the purpose of
attaching the ropes to support the great gallery. But the wind blew
dreadfully at times; rain and snow fell on the machine; frost and ice
covered the huge bag; many rents ensued, demanding frequent repairs.
On one occasion, when fed too freely with flame from straw sprinkled
with alcohol, the monstrous ship rose so vigorously as to drag fifty
men with it some distance along the ground. Finally on the 19th of
January, when the weather moderated, the operators built small fires
under the scaffold below the balloon, and thawed away the ice from
the drenched and frozen bag. Then they stocked its gallery with straw
and pitchforks, with fire extinguishers, and other provisions for the
journey. The inflation beginning about noon, occupied but seventeen
minutes. The balloon swelled out rapidly, with the roaring flames
ascending inside, and at last stood forth huge and majestic before
the admiring multitude—a towering thing of magic growth, 100 feet in
diameter by 130 feet high.

The ascension of this gigantic vessel was immensely spectacular; but
it was also most adventurous and foolhardy. The great bag, which at
best was made of poor materials, was in bad repair after its frequent
inflations. But of the six passengers in the gallery not one could be
induced to remain behind to lessen the risk to the others. Their pilot,
M. de Rozier, remonstrated with them; the proprietor M. C. Flesselle
wished them to cast lots; but no one would abandon the journey. So,
with fear and reluctance, the pilot ordered the mooring ropes to be
cut. Just as the ascent began, a seventh passenger, M. Fontaine, sprang
into the gallery and sailed aloft with the others. By vigorous stoking
the aërial sailors urged their fiery vessel upward three thousand feet,
whence, apparently without fear, they waved their hats to the vast
throng below.

[Illustration: FIG. 9.—LA FLESSELLE.]

The spectators were now in a frenzy of excitement. For more than a week
they had vacillated between hope and disappointment; but now they saw
the huge ship soaring into the sky, perhaps on her way to destruction.
They heard the blast of martial music and the booming of mortars. Then
the accumulated emotion of the multitude burst forth. Exclamations
of joy, shrieks of fear, thunders of applause resounded above the
sea of people. Finally the balloon began to burst, a dangerous rent
running vertically along her side. The machine descended with great
rapidity, to the alarm of everyone. It is reported that not fewer than
sixty thousand people ran to the place of landing, with the greatest
apprehension for the lives of the travelers. But the adventurous men
stepped forth from the gallery, after a fifteen minutes’ voyage,
without hurt of any kind, save an insignificant scratch borne by Joseph
Montgolfier, who on this occasion made his first and last ascension.
This was also the first and last ascension of that gigantic fire
balloon; for although it furnished a world of delirious emotion and
excitement, the trouble of inflating the vessel was too great to be
repeated.

The crossing of the English Channel by balloon had been contemplated
many months by various adventurous spirits; and at length, on a fine
day, the seventh of January, 1785, this feat was attempted by two
intrepid men, the French aëronaut, M. Blanchard, and an American
physician, Dr. Jeffries, who had graduated at Harvard in 1763, and
was practicing medicine in England. Starting from the perpendicular
cliff at Dover Castle, at one o’clock, they sailed in the direction of
Calais, having with them only thirty pounds of sand ballast. This was
too little for so long a voyage; but it would doubtless carry them a
few miles, in the favorable breeze then blowing. To their surprise,
the atmosphere seemed to grow lighter as they advanced over the water,
letting them sink too freely. As they approached mid-channel they
were compelled to discharge all their ballast in order to maintain
their level. But the balloon still descended, seemingly attracted by
the water. Then they ejected a parcel of books to gain a moment’s
relief. When three-fourths across the Channel they sighted the French
Coast, which now they yearned to see at closer range; for the balloon
was contracting and sinking rapidly. They threw out from the boat
everything available, wings, anchors, cords, provisions; yet they saw
the vessel persistently approaching the sea. Finally they cast off part
of their clothing, fastened themselves to the cords suspended from
the balloon-ring, and prepared to cut away the boat. But presently
approaching the coast near Calais, they began to rise; then ascended
rapidly, soaring in a magnificent arch above the high grounds. At
last they descended gradually above the forest of Guines, seized the
branches of a tree to stop their flight, and at three o’clock were
happily landed. It was a thrilling voyage of two hours, and made a
profound impression at the time. As a mark of appreciation the King
presented Blanchard a sum of 12,000 francs and a pension of 1,200
francs per year. The people erected a monument on the place of landing
to commemorate this extraordinary voyage.

This splendid achievement incited two Frenchmen to attempt a counter
voyage which ended disastrously. On June 15, 1785, Pilâtre de Rozier
and M. Romain set out from Boulogne on a voyage from France to
England, in a compound balloon composed of a hydrogen balloon forty
feet in diameter, below which was suspended a fire balloon ten feet
in diameter. They hoped by judicious stoking of the lower balloon to
obviate the sinking tendency suffered by Blanchard and Jeffries. But
the smaller globe proved a fatal auxiliary. Scarcely a quarter of an
hour after launching, the whole apparatus was aflame at an altitude of
3,000 feet, and presently fell in charred and hideous fragments upon
the seashore. M. Romain still showed some signs of life, but Pilâtre
de Rozier was completely dead and all his bones were broken. They were
the first martyrs in the cause of the new science. Poor De Rozier
knew on starting that his apparatus was in bad condition, but he had
received for the purpose a sum of money from a distinguished patron,
and therefore felt obliged in honor to attempt the voyage. He was
twenty-eight years old and engaged to be married to a young lady in the
convent at Boulogne, who eight days after the catastrophe which robbed
her of her fiancé, died brokenhearted and in convulsions.




                              CHAPTER II

               PRACTICAL DEVELOPMENT OF PASSIVE BALLOONS


The next important advance in practical ballooning was made by the
substitution of coal gas for hydrogen. This was England’s contribution
to an art which previously had not greatly flourished west of the
Channel. It was a contribution following the natural growth of science;
for in 1814 coal gas began generally to be used for lighting London,
and seven years later for inflating balloons. This valuable innovation
was made by the famous aëronaut, Charles Green, on the occasion of his
first ascension, made July 19, 1821, the coronation day of George IV.
The new method largely superseded the old, extending throughout the
world with the spread of gas lighting; and it gave a powerful stimulus
to aëronautics by rendering inflation cheap and convenient. Mr. Green
himself made 526 ascensions during his life, or at the rate of one
cruise a month for nearly forty-four years. In due time, every country
had its professional aëronauts, and finally its amateurs, who, forming
themselves into aëro clubs, devoted themselves to racing in free
balloons, inflated quite usually from a city gas supply.

In 1836 Mr. Robert Holland organized an expedition designed to test the
utmost capabilities of the balloon of his day, particularly in points
of endurance and control. Engaging as pilot the first aëronaut of the
age, Mr. Charles Green, and employing the largest gas balloon that ever
had been constructed, stocked with provisions enough to last three
men a fortnight, he invited a third person, Mr. Monck Mason, to join
them on a cruise from London to wherever the wind would take them, but
preferably to land near Paris, as the balloon was to be delivered there
after the voyage.

[Illustration: FIG. 10.—THE GREAT BALLOON OF NASSAU.]

The vessel selected for that famous cruise was _The Great Balloon of
Nassau_, then recently built by Mr. Green and representing all that his
skill and experience could devise. It was of pear shape, formed of
the finest crimson and white silk, “spun, wove and dyed expressly for
the purpose,” and comprising when distended a volume of 85,000 cubic
feet. From its stout balloon-ring six feet in diameter was suspended a
wicker car measuring nine feet long by four wide, having a seat across
either end, and a cushioned bottom to serve as a bed, if such should be
needed. Across the middle of the car was a plank supporting a windlass
for raising or lowering the guide-rope, that is a heavy rope which
could be trailed over land, or water, to keep the balloon at a nearly
constant level without expenditure of ballast, and to check its speed
on landing. This valuable device invented by Mr. Green in 1820, was
now to receive adequate trial, which, indeed, formed one of the chief
purposes of the cruise. Other paraphernalia of the voyage were food
and drink, warm clothing, lamps, trumpets, telescopes, barometers, a
quicklime coffee-heater, a grapnel and cable, and a ton of sand ballast
in bags.

The voyage proved well worthy of the elaborate preparations. At
one-thirty o’clock on November 7th, the three navigators arose
from London, in presence of a mighty multitude, and drifted in a
southeasterly direction traversing the cultivated plains of Kent, and
in two hours passed the environs of Canterbury. Here they dropped
a parachute with a letter for the Mayor, which he duly received.
Continuing their journey they floated leisurely above the tree tops,
talking to the inhabitants of the country, startling the fleet-winged
quail, terrifying a colony of rooks, and finally reaching Dover at
sundown, where they again dropped a letter for the Mayor of the city,
which also was duly delivered.

Without a moment’s pause they drifted over the Channel into the
gathering darkness. Before them rose a huge wall of vapor and black
clouds standing on the bosom of the sea; behind them the twinkling
lights and the music of breakers rolling on a hospitable shore.
Presently they were immersed in a region of absolute silence and
impenetrable darkness. At times this deep stratum would slowly
dissolve, revealing a glimpse of the dusky ocean and a passing ship;
then some huge wreath of vapor would involve them in bottomless gloom,
without perspective, without apparent motion, without a sound to cheer
or mark their dubious course. Now to avoid the risk of settling too
near the sea, as Blanchard and Jeffries had done, they were preparing
to let down the guide-rope with floating ballast attached, when
suddenly they emerged from the pall of darkness, and were greeted by
the glittering lights of Calais, and the gentle sound of waters dashing
upon the beach. They had crossed the Channel in one hour, and were
soaring serenely three thousand feet above the ocean, not having to
lower the guide-rope to preserve their elevation.

Now came the preparations for a night voyage over an obscurely defined
land route. A simple rope one thousand feet long without ballast was
allowed to trail beneath them. A lamp was lit. Coffee was heated by the
slacking of quicklime. An ample store of viands and wine was spread on
the board in the middle of the car. The strenuous period of thought and
labor was past, and now three hungry men sat leisurely at dinner, after
a fast of twelve long hours. However sparing of bones and bottles,
which later might serve as ballast, they were not economical of food
and wine that evening. For the present they had only to live and be
happy as bachelors. Muffled in soft garments, well fed, abundantly
served with divine beverages, hot or cold; what finer picture of
masculine comfort and delight?

They were now floating tranquilly in the vast solitude of heaven, over
a teeming continent mantled in night and mystery. Far along earth’s
sable surface gleam the scattered fires of many villages; and above
it the lovelier fires of a moonless sky. Unseen, unsuspected, they
survey kingdoms and cities, trailing their long rope serpent-like
over woodland, field and quiet homestead. Now on the horizon before
them looms a greater fire, like a distant conflagration, widening as
they approach. Gradually it expands into a model city, shooting out
long lines of illuminated streets; here the public squares, markets
and theatres; there the rumbling iron mills with blazing furnaces.
They are above Liege at her festive hour, murmuring with animation
and busy life. Again they drift into the dark regions of slumber,
lapped in silence and deep tranquillity, where the lights of men are
extinguished, and the stars, redoubling their lustre, gleam whitest
silver in heaven’s jetty dome. Midnight involves the world; an abyss
of darkness enfolds it; their solitary lamp seems to melt its way
through solid space of blackest marble. For hours they undulate over
the rolling hills, rising and falling a thousand cubits, held always to
earth by the trailing rope. At times they are so near as to trace the
landscape dimly; here a white tract covered lightly with snow, here a
dark valley or forest, here a tortuous river, probably the Rhine, with
its multitudinous thunder of waters. But in all that weird and obscure
wandering no joyous note of human or animal life ascends ere dawn to
cheer their solitary course in the sky.

At last the paling of the morning star, and a faint tingeing of the
eastern cumuli, announce the expected day. With sudden bound the
great ship mounts aloft twelve thousand feet, into the glory of the
blazing sun, new risen among clouds of amber and purple. Far below,
twilight and mist still mantle the half-awakened world, presenting a
stupendous panorama, vast as an empire. Presently down they plunge into
the vaporous and obscure atmosphere, drifting carelessly, but soon
reascending into the splendor of morning. Thus after making the sun
rise three times and set twice, they float contentedly along the misty
landscape, marveling what region lies below them, whether a barren
wilderness, or the abode of civilized life, with human comforts and a
ready means of transportation. A hot breakfast would be very welcome
now; for they had accidentally dropped the lime pot and had spent the
latter half of the night without warm beverage in a region where oil
and water had frozen.

At length through the clearing vapor they perceive the country well
tilled and populous; a good place to land to shorten their route to
Paris, and avoid the wide plains of Poland or Russia. They raise the
guide-rope, lower the cable and anchor, open the valve, and descend
in a grassy field near Weilburg, in the Duchy of Nassau. It is now
seven-thirty o’clock, just eighteen hours since starting; and they
have traveled five hundred miles, the longest aërial voyage thus
far recorded. Very soon they are surrounded by a wondering crowd of
pipe-puffing, shaggy-headed, German peasants, by whose willing aid they
finally deflate the balloon, pack it in the bottom of the car, and
mount it on a one-horse cart for Weilburg. Thence the aëronauts, after
a week of festivities in their honor, and distinguished attentions from
the highest officials of the town, embarked with their balloon for
Paris. This famous craft now bore its permanent title; for a few days
previously the lovely daughter of the Baron de Bibra, with seven other
young ladies and Mr. Green, had stood within the air-inflated vessel,
poured a generous libation of wine, and christened the hardy cruiser
_The Great Balloon of Nassau_.

It was in truth a great balloon in various ways; in solidity and
strength, in workmanship, in completeness of appointment, in endurance
and control. Having accomplished that long journey without a sign
of weakness or defect, it was still in prime condition, proudly
heading for the farthest verge of Europe. It had not, of course, the
instrumental equipment of a modern balloon; but it did possess the
elements essential for a long and hard cruise. Since the day of its
launching many additions have been added to the art, but these, for
the most part, are special adjuncts. The more important features of a
good balloon are practically the same to-day as when they were first
introduced by Professor Charles and sturdy old Mr. Green.

A still more elaborate and colossal air ship was the _Geant_,
constructed in 1863, for A. Nadar of Paris. It was made of a double
layer of white silk, had a volume of 215,000 cubic feet and a buoyancy
of 4½ tons. The car was a wicker cabin 13 feet wide by 7 feet high,
with a wicker balcony round the top so that the roof could be used
as an observation deck—a delightful place to loll in the starlight,
or watch the morning sun “flatter the mountain tops with sovereign
eye.” The closed car comprised two main rooms with a hallway between
them, one containing the captain’s bed and baggage, the other having
three superposed berths for passengers. Minor divisions of the car
were reserved for provisions, a lavatory, photography and a printing
press, the latter to be used for the dissemination of news from the
sky, as the navigators floated from state to state. A compensator
balloon of 3,500 cubic feet, just below the main bag and connected
with it, received the escaping gas during expansion with increase of
temperature or altitude, and gave it back on contraction. In fact
as well as in name, Nadar’s vessel was a giant. Curiously enough, he
called it the “last balloon,” for he expected to realize enough money
by exhibiting it, to inaugurate successful flying by means of the
helicopter, and thus banish ballooning from the world of futile effort
to the domain of bygone dreams and chimæras.

[Illustration: FIG. 11.—CAR OF NADAR’S BALLOON.]

The first ascension, made on Sunday, October 4, 1863, was one of
magnificent promise. In the midst of a vast holiday throng on the Champ
de Mars, the great globe towered aloft nearly two hundred feet, held to
earth by one hundred men and twice as many sand bags. In the car were
fifteen notable passengers including one lady, the fair young Princess
de la Tour d’Auvergne, in morning toilet and a pretty hat. “Lachez
tout!” shouts Captain Nadar, the effervescent photographer of Paris.
Away they soar, heading for St. Petersburg, with provisions enough to
sail beyond the polar sea.

The captain was now in supreme control, with the key to the victual
and liquor room in his pocket, and his twelve commandments duly signed
by all aboard. They had pledged themselves not to gamble, not to carry
inflammable materials, not to smoke unduly, not to throw bottles
overboard, not to quit the balloon without permission, but to descend
if so ordered, etc. They had sailed at five o’clock in the evening and
all was going merrily. But presently trouble came. The valve rope gave
way, the vessel was sailing in the dark, and the Godards declared she
was drifting to sea, whereas she was drifting in quite the opposite
direction. To be on the safe side they threw out the anchors by
permission of the commander. One anchor broke, but the other took hold
and checked the balloon in spite of the strong wind blowing. At last
after three violent bumps on the ground they landed near Meaux at nine
o’clock in the evening, one passenger sustaining a broken knee, the
others various bruises. It was a grand adventure and all were pleased.

Two weeks later a second voyage was begun in similar style, and again
from the Champ de Mars, this time in the presence of the King of
France and the young King George of Greece; but now Nadar took along,
not the Princess with the pretty hat, but Madame Nadar, his wife. To
entertain the crowd before starting, thirty-two persons were first sent
aloft 300 feet and drawn back to earth. Finally at five o’clock Sunday
evening, October 18th, a party of nine passengers soared proudly
northward, well provisioned as before, and eager for a long voyage.
They disappeared in the gathering night, leaving their friends much
concerned for their safety and ultimate destination. At half past eight
they were over Compiegne, seventy-eight miles away, drifting near the
ground to say “All goes well” and have the good tidings transmitted
to Paris. At nine they crossed the Belgian frontier; at midnight they
were over Holland; at sunrise they skirted the Zuyder Zee and entered
Hanover; at eight they were coursing headlong toward Nienburg and the
North Sea in the current of a swift west wind.

They were now in great peril. If they went to sea they might all be
drowned; if they came to earth at such horizontal speed they should
be terribly pounded. Choosing the latter evil, they opened the valve
and threw down the grappling irons. “To the ropes,” shouted the Godard
brothers. Assembling on deck all clung to the suspension ropes to
mitigate the shock of landing. Nadar put his arm about his wife to
protect her. The anchors snatching a tree, uprooted and dragged it
along; then caught and tore off the roof of a house; threshed into
a telegraph line pulling down the wires and poles; struck into some
firmer obstacle and broke off completely, leaving the huge monster
to sweep unchecked in the violent ground current. Owing to trouble
with the valve, the gas could not be liberated quickly; the great
vessel again and again plunged to earth and rebounded high in air,
its ponderous basket crashing through heavy timber, and breaking
down whatever opposed its course. For nine miles they pounded over
the plain by Nienburg toward the sea, dashing into pools, bogs and
thickets, their limbs sprained or broken, their bodies bruised, their
faces splashed with mud. Presently through loss of gas the rebounding
ceased, the basket dragged along the earth squeezing some of the
passengers beneath it, and dumping others out on the ground, leaving
them behind. Those remaining tried to assist Madam Nadar to land, but
they were tumbled out and she was caught under the basket from which
she was extricated with much difficulty, when the balloon was finally
halted. Thus their memorable voyage of seventeen hours, covering 750
miles, had a terrific, though not fatal ending. One had a broken femur,
another a dislocated thigh, others numerous scratches and contusions.
But no complaint was uttered; for the afflictions were regarded as
natural concomitants to such interesting sport. After some days tender
nursing by the Germans, and solicitous inquiries from the King of
Hanover, they returned to Paris; some indeed on their backs, but for
all that, none the less admired by their countrymen, as survivors of a
marvelous adventure.

Another valiant English leader in aërostation was James Glaisher,
member of the British Association for the Advancement of Science.
As one of a committee of twelve appointed by that body in 1861, to
explore the higher strata of the atmosphere by means of the balloon,
he volunteered his services as an observer, when no other capable man
could offer to do so. With a professional aëronaut, Mr. Coxwell, and a
new balloon specially constructed for the work, cubing 90,000 feet, he
made eleven ascensions for the society, four from Wolverhampton, seven
from Woolwich. Incidentally he made seventeen other ascents of various
altitude; not at the expense of the committee, but as a scientific
passenger in public balloon ascents advertised beforehand.

The objects of the enterprise were first to study the physical
conditions of the atmosphere; secondly to study the effect of the
higher regions upon the passengers themselves, and some pigeons,
which they carried along; thirdly to make some observations in
acoustics and magnetism, particularly to determine the period of
oscillation of a magnet at various altitudes. The specific study of
the atmosphere itself was to comprise observations at all altitudes,
of the temperature of the air, its pressure, and percentage of
moisture; observations of the velocity and direction of the wind,
the constitution of the clouds, their height, density and depth, the
constitution and electrical properties of the air. They were also to
collect samples of the air at different elevations, which later might
be examined in the laboratory. Thus the voyages were systematically
planned for scientific research, and were the first thorough attempts
in England, though similar efforts had been made previously in France.
It may be added that Glaisher’s observations were the most important
made during the first century of aëronautics, and may be found fully
detailed by that hardy investigator himself in the British Association
Reports for 1862-66.

Mr. Glaisher’s most interesting voyage of that memorable series
occurred on September 5, 1862. Starting from Wolverhampton at three
minutes after one o’clock, they soared swiftly upward, passing through
a cloud eleven hundred feet thick and emerging in a glorious field
of sunlight with an amethystine sky above and a boundless sea of
vapor beneath; a sea of rolling hills and mountain chains, with great
snow-white masses steaming up from their surface. They had left the
noisy bustle of earth in the comfortable temperature of 59°; in three
quarters of an hour, they were five miles aloft in a deadly silent
atmosphere, two degrees below zero, and approaching one third its usual
density, the balloon neck white with hoar frost, the men gasping for
breath. Here the observations became increasingly interesting but
immensely more difficult. They are graphically told in the following
extract from Mr. Glaisher’s classical report:

  “I asked Mr. Coxwell to help me to read the instruments, as I
  experienced a difficulty in seeing. In consequence, however,
  of the rotatory motion of the balloon, which had continued
  without ceasing since the earth had been left, the valve-line
  had become twisted, and he had to leave the car and mount into
  the ring above to adjust it. At this time I looked at the
  barometer, and found it to be 10 inches, still decreasing
  fast; its true reading therefore, was 9¾ inches, implying a
  height of 29,000 feet. Shortly afterwards I laid my arm upon
  the table, possessed of its full vigor, and on being desirous
  of using it, I found it powerless; it must have lost its power
  momentarily. I tried to move the other arm, and found it
  powerless also. I then tried to shake myself, and succeeded
  in shaking my body. I seemed to have no limbs. I then looked
  at the barometer; whilst doing so my head fell on my left
  shoulder. I struggled and shook my body again, but could not
  move my arms. I got my head upright, but for an instant only,
  when it fell on my right shoulder, and then I fell backwards,
  my back resting against the side of the car, and my head on
  its edge; in this position my eyes were directed towards Mr.
  Coxwell in the ring. When I shook my body I seemed to have full
  power over the muscles of the back and considerable power over
  those of the neck, but none over either my arms or my legs; in
  fact I seemed to have none. As in the case of the arms, all
  muscular power was lost in an instant from my back and neck. I
  dimly saw Mr. Coxwell in the ring and endeavored to speak, but
  could not; when in an instant intense black darkness came, the
  optic nerve finally lost power suddenly. I was still conscious,
  with as active a brain as at the present moment whilst writing
  this. I thought I had been seized with asphyxia, and that I
  should experience no more, as death would come, unless we
  speedily descended; other thoughts were actively entering my
  mind, when I suddenly became unconscious as in going to sleep.
  I cannot tell anything of the sense of hearing; the perfect
  stillness and silence of the regions six miles from the earth
  (and at this time we were between six and seven miles high) is
  such that no sound reaches the ear.

PLATE I.

[Illustration: GLAISHER AND COXWELL.]

[Illustration: PARSEVAL KITE BALLOON.]

  “My last observation was made at 1 h. and 54 m., at 29,000
  feet. I suppose two or three minutes fully were occupied
  between my eyes becoming insensible to seeing fine divisions,
  and 1 h. 54 m., and then that two or three minutes more passed
  till I was insensible; therefore I think this took place at
  about 1 h. 56 m. or 1 h. and 57 m. Whilst powerless I heard
  the words, ‘temperature’ and ‘observation,’ and I knew Mr.
  Coxwell was in the car speaking to me, and endeavoring to
  arouse me, therefore consciousness and hearing had returned. I
  then heard him speak more emphatically, but I could not see,
  speak or move. I heard him again say, ‘Do try—now do.’ Then I
  saw the instruments dimly, then Mr. Coxwell, and very shortly
  saw clearly. I rose in my seat and looked round, as though
  waking from sleep, though not refreshed by sleep, and said to
  Mr. Coxwell, ‘I have been insensible;’ he said, ‘You have;
  and I, too, very nearly.’ I then drew up my legs, which had
  been extended before me, and took a pencil in my hand to begin
  observations. Mr. Coxwell told me he had lost the use of his
  hands, which were black, and I poured brandy on them.

  “I resumed my observations at 2 h. 7 m., recording the
  barometer reading at 11.53 inches, and temperature −2°. I
  suppose three or four minutes were occupied from the time of my
  hearing the words ‘temperature’ and ‘observation’ till I began
  to observe; if so, then returning consciousness came at 2 h.
  and 4 m., and this gives seven minutes for total insensibility.
  I found the water in the vessel supplying the wet-bulb
  thermometer, which I had by frequent disturbances kept from
  freezing, was one solid mass of ice; and it did not all melt
  until after we had been on the ground some time.

  “Mr. Coxwell told me that whilst in the ring he felt it
  piercingly cold; that hoar-frost was all round the neck of the
  balloon. On attempting to leave the ring he found his hands
  frozen, and he had to place his arms on the ring and drop
  down; that he thought for a moment I had laid back to rest
  myself; that he spoke to me without eliciting a reply; that
  he then noticed my legs projected and my arms hung down by my
  side; that my countenance was serene and placid, without the
  earnestness and anxiety he had noticed before going into the
  ring, and then it struck him I was insensible. He wished to
  approach me, but could not, and he felt insensibility coming
  over himself; that he became anxious to open the valve, but in
  consequence of having lost the use of his hands he could not,
  and ultimately did so by seizing the cord with his teeth and
  dipping his head two or three times until the balloon took a
  decided turn downwards. This act is quite characteristic of
  Mr. Coxwell. I have never yet seen him without a ready means
  of meeting every difficulty, as it has arisen, with a cool
  self-possession that has always left my mind perfectly easy,
  and given me every confidence in his judgment in the management
  of so large a balloon.

  “No inconvenience followed the insensibility; and when we
  dropped it was in a country where no conveyance of any kind
  could be obtained, so that I had to walk between seven or eight
  miles.

  “The descent was at first very rapid; we passed downwards three
  miles in nine minutes; the balloon’s career was then checked,
  and we finally descended in the center of a large grass-field
  belonging to Mr. Kersall, at Cold Weston, seven-and-a-half
  miles from Ludlow.

  “I have already said that my last observation was made at
  a height of 29,000 feet; at this time (1 h. 45 m.) we were
  ascending at the rate of 1,000 feet per minute; and when I
  resumed observations we were descending at the rate of 2,000
  feet per minute. These two positions must be connected, taking
  into account the interval of time between, viz. 13 minutes,
  and on those considerations the balloon must have attained
  the altitude of 36,000 or 37,000 feet. Again, a very delicate
  minimum thermometer read—12, and this would give a height of
  37,000 feet. Mr. Coxwell, on coming from the ring, noticed that
  the center of the aneroid barometer, its blue hand, and a rope
  attached to the car, were all in the same straight line, and
  this gave a reading of 7 inches, and leads to the same result.
  Therefore these independent means all lead to about the same
  elevation, viz. fully SEVEN MILES.

  “In this ascent six pigeons were taken up. One was thrown out
  at the height of three miles, when it extended its wings and
  dropped as a piece of paper; a second, at four and five miles,
  and it fell downward as a stone. A fourth was thrown out at
  four miles on descending. It flew in a circle, and shortly
  alighted on the top of the balloon. The two remaining pigeons
  were brought down to the ground. One was found to be dead, and
  the other, a ‘carrier,’ was still living, but would not leave
  the hand when I attempted to throw it off, till after a quarter
  of an hour it began to peck a piece of ribbon which encircled
  its neck, and was then jerked off the finger, and flew with
  some vigor toward Wolverhampton. One of the pigeons returned to
  Wolverhampton on Sunday the 7th, and it is the only one that
  has been heard of.”

This was the loftiest ascent ever made up to that time; and thus
Glaisher, or rather Coxwell, who was in the ring above him, could be
called the “highest man” of the first century of aëronautics. Their
greatest elevation, however, is now generally estimated at much less
than seven miles, and probably below six miles, due allowance being
made for inaccuracies of estimate made by Mr. Glaisher. His results,
nevertheless, were considered valuable, revealing as they did, that the
balloon may be used safely up to the neighborhood of five miles; that
the temperature of the atmosphere does not, as previously supposed,
decline one degree for each 300 feet of ascent, but often declines
more rapidly, and sometimes even increases with the elevation for
considerable stretches; that the moisture percentage is extremely
slight at an altitude beyond five miles; that at all elevations
attainable by man the dry- and wet-bulb thermometers can be used
effectively, etc.

A still loftier ascent was made by Professor Berson of Germany,
aided by the respiration of oxygen. On July 31, 1901, accompanied by
Dr. Süring, he ascended from Berlin in the balloon _Preussen_ to an
elevation of 10,800 meters, which at present constitutes the world’s
record for altitude. The balloon had a capacity of 300,000 cubic feet,
and left the ground two thirds filled with hydrogen, and carrying 8,000
pounds of ballast in the form of sand bags attached to the sides of the
basket, so that they could be cut loose with the slightest physical
effort.

The _Preussen_ was one of the largest passive balloons ever
constructed. In cubic capacity it was comparable with the colossal
_Montgolfière_, _La Flesselle_, already described, and the huge free
balloon _Le Geant_, constructed by Nadar in 1863. But all were
eclipsed by the great balloon of Henri Giffard. This latter measured
450,000 cubic feet, and even to-day ranks as the largest captive
balloon ever constructed. It was a familiar object at the Paris
Exposition of 1878, where it was installed by the famous inventor
Henri Giffard, to give sightseers a bird’s-eye view of Paris. It could
take up forty persons at one time, or eight more than once ascended in
Nadar’s _Geant_.

No serious attempt has been made to surpass the altitude flight of
Professor Berson and Dr. Süring; for though it is easily possible to
carry human beings to a greater height than seven miles, the results
seem hardly to justify the cost. To ascend very much higher would
require an enormous and costly balloon, and to ensure the comfort
of the passenger might require an air-tight car, or armor supplied
continuously with fresh air, or oxygen. Such a suit, or car, however,
can be made very light, since its pressure must naturally be internal;
and it would admit of an extremely rapid change of elevation without
discomfort to the passenger. A steel bottle weighing fifty pounds,
and filled with compressed air, or oxygen, would supply a passenger
several hours, and allow him to breathe under normal pressure. The
total weight of a bottle and air-tight car, or suit, need not exceed
the weight of a man. Moreover, the ballast could be largely dispensed
with, thus admitting of a very rapid ascent from the earth. A celluloid
car would have the advantage of transparency, though it might become
too brittle at very low temperatures. A suit, or car, with glass
portholes would serve in lieu of a celluloid car for transparency. The
usual balloon and basket, carrying a steel bottle, furnishing air at
normal pressure to a man in a rubberized silk suit is a sufficiently
simple and practicable device; the air entering the suit near his
mouth and leaving below through a check valve regulated to maintain the
desired internal pressure. An air-tight silk fabric capable of enduring
safely a tensile stress of 150 pounds per running inch would answer the
purposes. But at present there seems to be no incentive to attempt a
balloon trip exceeding the heights already attained, unless it be that
of notoriety or sentiment.

The French meteorologists have devised a much simpler and cheaper
method of exploring the upper atmosphere, by use of small balloons
carrying recording instruments. An ordinary silk or gold-beater
skin balloon, partly inflated, ascends to a great height with the
instruments, drifts away losing gas, and on landing is found by some
one who returns it according to written directions accompanying the
craft. Another method, introduced by Professor Assman, is to employ
closed rubber balloons which at great altitudes burst by the expansion
of the hydrogen within them, and allow the instruments to descend
in parachutes softly to the ground. Instrument-carrying balloons of
the above type are called “sounding balloons,” or _balloons sondes_,
whereas if they carry no instruments, but merely show the course of the
wind, they may be called “pilot balloons.” Such sounding balloons have
been used to explore the temperature of the atmosphere to an altitude
of 18 miles.

In the preceding pages some extended balloon voyages have been
described. These were considered very long in their day, but in recent
years have been surpassed frequently, first by the professional
aëronauts, then by the amateurs and members of various aëronautic
clubs practicing aërostation as a sport, and stimulated by attractive
prizes. But the man who achieved the longest balloon flight during the
first century of the art, seems to have been Mr. John Wise, America’s
foremost pioneer balloonist.

Mr. Wise was a rare composite of showman, scientist, sport and
dare-devil, who during the four decades succeeding his first ascension
at Philadelphia in 1835, made no fewer than 440 voyages. At first the
aërial art captivated him by the beauty and sublimity of the natural
panoramas witnessed from on high; then he amused himself by dropping
things from the basket and hearing them whistle through space; and
finally he coquetted with the balloon itself, in various ways to
observe the result. On one occasion the neck was choked and the
valve could not be operated, so that when the hydrogen expanded with
increasing altitude, it overstretched the cover and started a rent in
the side of the bag. The balloon descended rapidly, but landed without
injurious shock.

The audacious aëronaut then decided to make an ascension and
deliberately burst the balloon, by confining the gas in it and throwing
out ballast. But first he tried the experiment on a dog, taking him up
4,000 feet, dropping him in a small collapsed balloon and watching him
settle slowly to earth. Then rising to an altitude of 13,000 feet he
stood debating whether to follow the example of the dog. The balloon
quickly ended the question by exploding at the top. The hydrogen rushed
out with a tempestuous sound, and the great vessel sank swiftly with a
moaning noise of the wind in her rigging. In a few seconds the bag was
empty and collapsed on the top of the net thus forming an effective
parachute. After an exciting fall of more than two miles, Mr. Wise
landed on a farm, with a lively thump, which overturned the basket, and
threw him sprawling on the ground. It was fine sport; he decided at
once to advertise a repetition of it, and thus was led by degrees to
the invention of the ripping panel.[7]

Mr. Wise firmly believed that a steady wind from west to east prevails
at a height of two miles. He wished to use this for long voyages, and
even contemplated crossing the Atlantic; for he trusted his varnish to
hold hydrogen a fortnight if need be. Accordingly in 1873 the New York
_Daily Graphic_ paid the cost of a balloon to carry him and two others
on that hazardous voyage. The bag had a capacity of 400,000 cubic feet,
but was too frail in construction to receive Mr. Wise’s approval, and
actually burst during inflation when slightly more than three fourths
full. Fortunately, perhaps, for Mr. Wise, he never had an opportunity
to attempt the trans-Atlantic voyage; but on one occasion he enjoyed a
memorable cruise in the great west wind which so took his fancy. Rising
from St. Louis on June 23, 1859, he sailed northeastwardly for twenty
hours, and landed at Henderson, N. Y., having traversed a distance of
809 miles, measured directly. But in attempting another long voyage
with two companions, in September, 1879, he passed over Lake Michigan,
where all were drowned.

In recent years Mr. Wise’s long voyage has been exceeded several
times. In 1897 M. Godard sailed from Leipsic to Wilna, a distance of
1,032 miles in 24½ hours; but this was not an official flight nor in a
direct course as the crow flies. In October, 1900, M. Balsan voyaged
from Vincennes, France, to Rodom, Russia, a distance of 843 miles in
27 hours and 25 minutes, and De la Vaulx starting from the same point
landed at Korosticheff, Russia, having traversed 1,193 miles in 35¾
hours. This latter is the longest balloon flight thus far recorded. A
close second to this record was made by A. R. Hawley in his spherical
balloon _America_, aided by Augustus Post, in the Gordon Bennett
International Balloon Race of 1910. Sailing from St. Louis, October
17th, they drifted 1,172.9 miles from their starting point, and landed
in a great forest at Peribonka River, North Lake Chilogoma, Canada,
where they were lost for several days.

[Illustration: FIG. 12.—DIAGRAM OF A MODERN SPHERICAL BALLOON WITH
RIPPING PANEL.]

Quite as eventful was the ocean voyage of Walter Wellman, who left
Atlantic City October 15, 1910, for Europe in a motor balloon with a
drag rope, or equilibrator, voyaged with favorable wind to a point
140 miles northeast of Nantucket Island, then was driven by adverse
wind toward Bermuda, and finally rescued by a passing steamer, after
69 hours in the air and a journey of about one thousand miles. A full
account of this strange voyage is given in the New York _Times_ of
October 19, 1910, and in the _Scientific American_ of subsequent date.

The recent advances in aërostation, though not radically changing the
balloon itself, contribute much to its usefulness and convenience.
Improvements have occurred in the means of inflation and deflation,
in devices for making topographical and meteorological observations,
as also for transmitting and receiving signals. Hydrogen shipped in
steel tubes is now available for easy and rapid inflation, the process
of obtaining it on a large scale making it practically as cheap as
illuminating gas. The ripping panel, invented in 1844 by America’s
foremost pioneer aëronaut, John Wise, is a simple and an excellent
practical device. This is a long patch running longitudinally above the
equator[8] of the balloon, feebly sewed to the envelope, and having a
cord, called the “ripping cord,” extending down to the car along the
outside or inside of the bag, so that the pilot on coming to earth
can let out the gas quickly by tearing a rent in the balloon, thus
flattening it promptly on the earth’s surface, so as to avoid dragging
and bumping if any wind prevails. During an ascension the rise or fall
of the vessel may be instantly noted on the dial of the statoscope,
the temperature, pressure and moisture of the atmosphere may be read
on recording instruments, messages may be sent by telegraph and
telephone either by wire or through space, and sky or landscape may
be photographed if there be sufficient light. The bag itself has been
improved by making it of special fabrics formed of several layers of
silk, or cotton, with thin layers of rubber vulcanized between them
to render the cloth impermeable, also the bag, when not designed to
cleave the wind, is usually given a spherical form which is the figure
of greatest volume for a given surface, the figure originally used by
the inventor of the gas balloon; but when designed to be tethered in
a wind, it is given a longish shape and a tail so that it may ride
the wind like a kite. This type of balloon, though first proposed by
Douglass Archibald about 1845, was first made a practical invention by
Captain von Sigsfeld and Major von Parseval. In a certain sense it is a
tethered motor-balloon, just as a kite is a tethered aëroplane.




                              CHAPTER III

                    EARLY HISTORY OF POWER BALLOONS


Directly after the first launching of human passengers in a crude
aërostat, numerous schemes for controlling the course of a balloon were
evolved. Apparently mere flotation afforded less contentment to the
early pioneer aëronauts than to the free balloonists of the present
hour. Many were eager to apply propelling mechanism to their gas bags,
expecting thus to achieve practical locomotion through the air, even a
generation before the advent of practical steam navigation. Magnificent
dreams they had, indeed, but none the less futile. Few suspected the
enormous power required to propel swift balloons of the very best shape
and size; still fewer realized the impossibility of driving spherical
bags at a practicable velocity.

On the other hand, it must be said, to the credit of that era of
investigators, that certain noted scientists, after computing the power
required to drive a balloon at high speed, promptly recognized the
inadequacy to that task, of any motors then available. In conjunction
with favorable aërial currents something might be effected; that they
fully grasped; for they knew that the wind frequently has different
directions at different levels. They believed, therefore, that by
causing the craft to rise or fall to a suitable stratum, by use of
various then known devices, it could be made to travel in any direction
at the will of the pilot. Likewise they deemed that the rise and fall
of a balloon, due to change of buoyancy, could be used to propel it, if
sails attached to the vessel were set obliquely to the motion, so as to
receive fair pressure; or if the balloon were made flat, or longish, so
as to glide horizontally, like a kite or parachute.

Several devices for changing the altitude of the balloon were proposed
or tried. If the vessel were a _Montgolfière_, the mere increase or
lessening of the fire would promptly cause it to rise or fall. If a gas
bag were employed it could be sent up or down by casting out ballast
or opening the valve; or again, as proposed by Pilâtre de Roziere, by
having a _Montgolfière_ underneath the gas balloon, and lifting or
depressing the whole by altering the intensity of the flame. Finally,
an air balloon within a gas balloon was proposed by the Roberts, and a
gas balloon within an air balloon was proposed by General Meusnier, in
either of which combinations, a change of level could be effected by
pumping air into, or letting it escape from, the air bag. All of these
devices can be effected and practically operated by a competent balloon
maker and pilot; and yet they have not enabled man to realize his dream
of navigating the air in all directions without motive power.

The first attempts at balloon propulsion could not be seriously
regarded by trained engineers, even at the inception of aëronautics;
but still, as infantile steps in the new art, they may deserve passing
notice.

Blanchard, on March 2, 1784, made the first real effort to steer a
balloon, using for that purpose a spherical gas bag and car provided
with aërial oars and a rudder. As he was about to ascend, however,
from the Champs de Mars, a young officer with drawn sword persisted in
accompanying the pilot, thus compelling Blanchard to leave his wings
on earth to allow sufficient buoyancy for himself and his obtrusive
guest. His first trial was, therefore, frustrated; but subsequent ones
made with that inadequate contrivance also proved futile under the best
circumstances; for the scheme was evidently puerile, though tried by
various grown-up men besides M. Blanchard.

[Illustration: FIG. 13.—BLANCHARD’S DIRIGIBLE BALLOON, 1784.]

A no less simple and quaint device for propulsion was that of the
two physicists, the Abbé Miolan and Janinet. The balloon was a
_Montgolfière_ with a large hole in one side, through which the hot air
was to escape with such strong reaction as to drive the bag forward, on
the principle of a lawn sprinkler, or of Newton’s reaction wagon. The
projectors failed, however, to make an ascent, and the crowd becoming
furious destroyed the balloon.

A more reasonable plan for practical navigation was devised and tried
by the Robert brothers. A melon-shaped balloon, fifty-two feet long by
thirty-two feet in diameter, was made of silk and inflated with pure
hydrogen. Beneath was suspended a longish car of light wood covered
with sky-blue silk. This elegant ship was to be rowed through heaven by
means of six silken oars actuated by sturdy sailors. A silken rudder
should guide her at pleasure when the winds were asleep, or softly
playing in the placid sky. She was a fairy bark, indeed, a soaring
castle lovely to behold.

After a preliminary trial, accompanied by their patron, the Duke de
Chartres, they were ready for a substantial journey. On September 19,
1784, the vessel was inflated and taken to the Garden of the Tuileries,
in front of the palace, where its cords were held by Marshall Richelieu
and three other noblemen. At eleven forty-five the two Roberts and
their brother-in-law arose and drifted beyond the horizon on a seven
hours’ cruise. Before coming to earth, they plied the oars vigorously,
and described a curve of one kilometer radius, thus deviating 22° from
the feeble wind then prevailing. In a lighter wind they could deviate
still more. They considered, therefore, that the experiment was a
complete success. They had constructed the first elongated balloon,
and had “solved the problem of aërial navigation.” In very happy mood,
therefore, they landed at dusk among the delighted inhabitants of
Artois, where they were graciously met and hospitably entertained by
the Prince de Ghistelles-Richbourg.

[Illustration: FIG. 14.—ROBERT BROTHERS’ DIRIGIBLE, 1784.]

The Robert brothers were the first to employ in practice an air bag
inside a gas bag. This was held within the balloon by ropes and
connected with the outer atmosphere by a tube, the idea being to
regulate the internal pressure of the balloon by introducing air into,
or withdrawing it from, the smaller bag. But during an ascension with
their patron, the Duke de Chartres, they entered a violent eddy which
tore away the oars and rudder, at the same time agitating the balloon
so violently that the internal air bag broke its sustaining cords and
fell upon the bottom of the gas bag, thus throttling the connection
with the external atmosphere. The vessel rose swiftly and the gas
expanded dangerously near to the bursting pressure. At a height of
16,000 feet the Duke de Chartres, perceiving the imminent danger of
an explosion of the envelope, drew his sword and cut a rent ten feet
long in its lower part. A part of the gas immediately rushed forth,
and the balloon sank rapidly, but after the discharge of the ballast,
landed safely without further mishap. The Duke acted wisely enough,
but he was afterwards ridiculed for his apparent lack of courage. If
he had possessed more bravery and less caution he might have allowed
the balloon to burst and descend as a parachute, thus anticipating the
spectacular performance of John Wise, in 1838.

Simultaneously other inventors were evolving designs of no less
importance in the ultimate perfection of the dirigible. In a letter
written to Benjamin Franklin on May 24, 1784, Francis Hopkinson of
Philadelphia proposed to build a balloon of spindle shape and to drive
it by means of a wheel-like propeller at the stern, consisting of vanes
set at an angle to the line of progression, like the common smokejack.
This proposed craft, the harbinger of the modern screw-driven motor
balloon, far antedated the screw-driven boat and the submarine torpedo
which it most resembles.[9]

While Blanchard and other aëronauts were paddling their globose bags
in search of favorable winds, vainly hoping thereby to direct their
course in the air, General Meusnier of the French army, and member of
the Academy of Sciences, made a systematic study of the requirements
for practical air navigation. After some research on forms suitable
for aëronautic hulls, he designed a power balloon having a pointed
car suspended from a bag of goose-egg form, this latter embodying his
idea of the best shape for a balloon that must cleave the air swiftly
and resist deformation. The propulsion was to be effected by means of
three coaxial screw propellers, supported on the rigging between car
and bag, and actuated by eighty men, for lack of a light artificial
motor. He thus hoped to obtain a moderate velocity which, combined with
skillfully selected air currents, would enable the ship to reach her
destination in ordinary weather.

[Illustration: FIG. 15.—GEN. MEUSNIER’S PROPOSED DIRIGIBLE, 1784.]

General Meusnier introduced important special features in the design of
dirigibles for preserving their form and poise. He insisted that the
bag and boat should be so rigidly connected that one could not swerve
from alignment and relative position with the other. He also emphasized
the necessity of preserving the vessel from deformation during flight,
in order to diminish its resistance. To that end he proposed to provide
the hull with a double envelope, the inner one thin and light but
impermeable to hydrogen; the outer one strong and air-tight; the space
between the two envelopes to be pumped full of air under pressure
sufficient to preserve the form of the bag when beating its way swiftly
against a buffeting wind. This was an important invention which in
later years was adopted in many of the most powerful motor balloons—for
all, indeed, except those of the rigid type. He also proposed the
use of stabilizing planes to control the poise of the vessel, thus
anticipating the Lebaudy brothers by more than a century. Like the
Robert brothers he proposed to raise or lower the vessel in search of
suitable currents, by altering the quantity of air in the space between
the inner and outer envelope, by use of hand bellows.

Apparently General Meusnier and his colleagues were endowed with
constructive genius sufficient to have developed a practical motor
balloon, had they been able to secure a light engine. Lacking this the
early aëronauts could do little more than describe their projects, and
await the growth of the collateral arts and sciences. Accordingly no
substantial advance in motor balloons beyond Meusnier’s designs was
effected till after the middle of the nineteenth century; and until
then the art of aëronautics remained in the hands of showmen. Hundreds
of projects, indeed, were advanced, some exciting considerable interest
and expectation, but nevertheless of such paltry value as hardly to
deserve comment. One notable exception to these was the invention of
Porter in America.

In 1820 Rufus Porter, a Yankee inventor, and later the original
founder of the _Scientific American_, patented an air ship of very
promising appearance for that early day. Its hull was a long, finely
tapering symmetrical spindle, suspending a car of similar shape by
means of cords, which were vertical at its middle but more and more
slanting toward its ends. Midway between the hull and car was a large
screw propeller actuated by a steam engine in the car. A model of
this dirigible exhibited in Boston and New York, some years later, is
reported to have carried its own power, at fair speed, and to have
obeyed its helm satisfactorily.

[Illustration: FIG. 16.—RUFUS PORTER’S DIRIGIBLE, 1820.]

The inventor, being too poor to develop his air ship alone, did
little with the patent during its life; but in 1850 he organized
a stock company to realize the needed funds. From the sale of 300
five-dollar shares he expected to raise $1,500, and with this sum
build an “aëroport,” 150 feet long, capable of carrying five persons
sixty miles an hour, the whole to be completed in six weeks. Once
this was in operation he would easily command funds sufficient to
build a full-sized vessel adapted to regular passenger service. For,
after careful calculation, he reported that: “It appears certain that
a safe and durable aërial ship (or aëroport) capable of carrying 150
passengers at a speed of ninety miles an hour, with more perfect safety
than either steamboat or railroad cars, may be constructed for $15,000,
and that the expense of running it would not exceed $25 per day.”

The language and project seem very modern, even at the present
time, and might well be copied now by a promoter of that identical
project. But it must be observed that the most successful European
experimenters, after spending hundreds of thousands of dollars on giant
air ships, have not yet attained one half the speed contemplated by
that ambitious and chimerical Yankee. The picture was handsome and
alluring, none the less. It may even be said to excel in outward design
any of the air-ship plans produced in either hemisphere before the
middle of the nineteenth century.

In 1850 a clockmaker and skillful workman, Jullien by name, exhibited
in the Hippodrome, at Paris, a torpedo-shaped model balloon of
gold-beater’s skin, provided with a screw propeller at either side
of its bow, and a double rudder at its stern. It measured 23 feet in
length and weighed 1,100 grammes complete. The propellers were actuated
by spring power, and proved able to drive the tiny vessel against a
moderate wind. The most suitable form for the bag was determined by
towing models through water.

[Illustration: FIG. 17.—JULLIEN’S MODEL DIRIGIBLE, 1850.]

Aërodynamically considered, this tiny motor balloon was by far the best
in design of any that appeared during the first century of aëronautics.
It may be regarded as the harbinger of the swiftest modern French
balloons. It was also an inspiration to Henri Giffard who assisted
Jullien in constructing his clever model, and shortly afterwards built
the first dirigible ever driven by a heat engine.

The illustrious Henri Giffard was perhaps the first aëronautical
engineer adequately endowed and circumstanced to realize, on a
practical scale, General Meusnier’s well pondered and truly scientific
plans for a motor balloon. He had studied in the college of Bourbon,
and had worked in the railroad shops of the Paris and St. Germain
railway. He had further equipped himself by making free balloon
ascensions, under the auspices of Eugene Godard, for the purpose of
studying the atmosphere; and by building light engines, one of which
weighed 100 pounds, and developed three horse power. Finally in 1851 he
patented an air ship, consisting of an elongated bag and car, propelled
by a screw driven by a steam engine. He had not the means to build such
a vessel, but he had the genius and training necessary to construct it,
and at the same time enough enthusiasm and persuasive power to induce
his friends, David and Sciama, to loan him the requisite funds.

[Illustration: FIG. 18.—GIFFARD’S STEAM DIRIGIBLE, 1852.]

Giffard’s first dirigible was successful in both design and operation.
It consisted of a spindle-shaped bag covered with a net whose cords
were drawn down and attached to a horizontal pole, from which the car
and motor were suspended, and at the end of which was a triangular
sail serving as a rudder. To guard against fire, the furnace of the
vertical coke-burning boiler was shielded by wire gauze, like a miner’s
lamp, and the draft, taken from its top through a downward pointing
smoke pipe, was ejected below the car by force of exhaust steam, from
the engine, thus obviating, as Giffard asserted, all danger from the
use of fire near an inflammable gas. The car hung twenty feet below
the suspension pole, and carried a three horse-power engine driving a
three-blade propeller 11 feet in diameter, making 110 turns a minute.
The motor complete, including the engine and boiler without supplies,
weighed 110 pounds per horse power. The bag measured 143 feet long, 39
feet in diameter, and 75,000 cubic feet in volume. Giffard reports of
his first voyage, made from the Hippodrome in Paris at five fifteen
o’clock, September 23, 1852, that although he could not sail directly
against the strong wind then blowing, he could attain a speed of six
to ten feet per second relatively to the air, and he could easily
guide the vessel by turning her rudder. He continued his journey till
nightfall, then made a good landing, near Trappes, and by ten o’clock
was back in Paris.

This vessel was but a prelude to mightier projects. After some further
experience with dirigibles of moderate size, Giffard designed a
colossal air ship calculated for a speed of forty-four miles an hour.
Its hull was to be of torpedo shape, measuring 2,000 feet in length,
100 feet in diameter, and 7,000,000 cubic feet in volume. It was a
most audacious project, one worthy of the genius and energy of that
illustrious engineer, the most original and daring inventor known in
the aëronautical world during the nineteenth century.

Stimulated by this huge enterprise, Giffard’s first step was to pay his
debts and make a fortune. He soon acquired a hundred thousand francs
from the sale of small high-speed engines of his own construction, and
with this, settled his account with David and Sciama. Next he realized
several million francs from his world-famous injector, a device by
which steam flowing from a boiler is made to drive in feed-water
against the same pressure.

He now made definite plans to build a motor balloon of one and a half
million cubic feet capacity, driven by a condensing engine drawing
steam from two boilers, one fired with oil, the other with gas from
the balloon, so as to keep the vessel from rising with loss of weight.
His designs were complete, and everything was provided for. He had
deposited a million francs in the Bank of Paris to defray the estimated
cost. But, in the words of Tissandier,[10] “above the human will and
foresight are the fatal laws of destiny to which the strongest must
submit.” The great inventor was visited with a painful affliction
of the eyes; his sight waned, unfitting him for work; he became
disconsolate, pined away with pain and grief, and in 1882 ended his
life by taking chloroform.

Giffard was succeeded in France, first by Dupuy de Lome; then by
Gaston Tissandier, well-meaning projectors of steerable balloons, but
too cautious to effect an important advance in the art. The first of
these gentlemen, an eminent marine engineer, in 1872, completed a gas
balloon for the French government, resembling the one designed by
General Meusnier in 1784, and like that also driven by muscular power
actuating a screw, and kept rigidly inflated by use of an internal
balloon, or ballonet. The car was suspended from the bag by a close
fitting cover instead of a net, in order to lessen the resistance, and
it was kept in alignment by use of crossed suspension cords. A speed
of but six miles an hour was attained by the industrious work of eight
men operating an ample screw propeller. A decade later Tissandier, with
a balloon of like design, but driven by the power of an electric motor
and bichromate of potash battery, attained a speed of six to eight
miles an hour.

[Illustration: FIG. 19.—DUPUY DE LOME’S DIRIGIBLE, 1872.]

The two vessels were safe but of no practical value, for lack of
sufficient power to cope with the wind. Their motors were fundamentally
unadapted to the purpose of swift propulsion, and incapable of
development to very great lightness and strength. Furthermore, the
vessels themselves were unsuitably designed for speed; their shape
being one of too much resistance, and their dynamic balance being
that of a pendulum, or clumsy parachute, rather than that of a vessel
adapted to cleave the air with celerity, grace and steadiness. If there
had been danger of fire from placing the motor and screw near the gas
bag, that might justify or excuse the clumsiness of design in the craft
of De Lome and of Gaston Tissandier; but, having perfectly safe motors,
it is astonishing that they did not place the center of mass and the
line of thrust more nearly in the line of resistance. This obvious
requirement was duly recognized by several of their contemporaries,
notably by Hänlein in Germany, and by Captain Renard of the French War
Department, and had been observed by Jullien.

Captain Charles Renard proved to be a worthy inheritor of the dreams,
experience and inventions of the first century of aëronautical
votaries. He did not, indeed, have the picturesque madness displayed
by some of his predecessors; he did not project schemes of marvelous
originality or boldness; but he manifested uncommonly good judgment
and excellent scientific method in combining the researches and
contrivances of others with those of himself and his collaborator,
Captain Krebs. As a consequence they produced the first man-carrying
dirigible that ever returned against the wind to its starting point,
and the first aërial vessel whose shape and dynamic adjustment even
approximated the requirements of steady and swift navigation in a
surrounding medium presenting various conditions of turbulence or calm.
Captain Renard had been studying and designing dirigibles since 1878
in coöperation with Captain La Haye and Colonel Laussedat, president
of an aëronautic commission appointed by the Minister of War; and had
endeavored to secure from the latter an appropriation sufficient to
construct a dirigible; but his request was at first denied, owing
to the waste of funds on similar projects in 1870. However, with the
help of Gambetta, who promised a sum of $40,000, Renard was enabled to
proceed. In the meantime he had been made director of the laboratory at
Chalais Meudon, seconded by Captain Krebs.

[Illustration: FIG. 20.—RENARD’S DIRIGIBLE, _La France_, 1884.]

These officers first worked out the separate elements in the design of
their motor balloon before proceeding to build on a practical scale.
They chose the torpedo form for their gas bag, thereby ensuring in
the hull itself, projectile stability, and diminution of resistance.
They placed the car near the envelope, thus minimizing the disturbing
moment of the screw thrust, and the resistance of the suspension cords.
They employed an extraordinarily powerful electric motor actuating a
large screw so as to obtain a strong thrust with the least effort.
In addition they adopted the best ideas of their predecessors in
aëronautical design; the internal ballonet of Meusnier, and the
close fitting cover of De Lome, with crossed suspension cords. But
unfortunately they used an electric motor instead of some light engine.
Finally, having carefully computed its requisite dimensions, they
proceeded to construct the elegant air ship, _La France_, which was
tested in 1884 and aroused anew the hope of ultimately conquering the
air.

Further details of this successful ship are of interest. Its hull
was 165 feet long, 27.5 feet in greatest diameter, at one fourth the
distance from its front end, and cubed 66,000 feet, thus having a
buoyancy of two long tons. It was kept rigid under varying conditions,
by means of a ballonet filled with air driven in by a common fan blower
coupled to the motor. Beneath the envelope, a long narrow rectangular
car made of bamboo, covered with silk, was suspended from the cords
of the balloon cover which embraced the hull throughout nearly its
entire length. The car was 108 feet long and 6 to 7 feet across,
carried at its forward end the propeller, at its rear a rectangular
rudder, and between them the aëronauts and the batteries and electric
motor. A sliding weight was used to alter the poise of the ship, and a
guide-rope to soften its descent.

The electric motor and battery which furnished the propulsive power
were designed expressly for such use, and were considered at the time
to be remarkably light and effective. The motor, which was designed
with the assistance of M. Gramme, weighed 220.5 pounds, and developed
nine horse power. The battery, composed of chlorochromic cells, was the
result of the researches of Renard himself. Having made a careful study
of the best geometrical arrangement of the parts of the cell, Renard
found that this battery would deliver to the shaft one horse power for
each eighty-eight pounds of its weight. Thus the power plant rivaled
in lightness the steam engine of Giffard, and at the same time was free
from danger; but apparently it could not be much reduced in weight,
whereas Giffard’s steam-power plant could be reduced tenfold, as shown
by Renard’s contemporaries.

The trials of _La France_ in 1884-85 were most successful and
encouraging; not that they represented or pointed to the complete
mastery of aërial navigation, but because they so far surpassed all
previous achievements. The vessel moved through the air as steadily as
a boat on the water, and obeyed her rudder perfectly, heading against
the wind, or at any angle to it, or turning entirely about, at the will
of the aëronauts. On her first voyage from Chalais, August 9, 1884, she
traversed a distance of four and one half miles in twenty minutes, made
various evolutions in the air with the greatest ease, and returned to
her point of departure. The following account of this voyage is given
by Renard:

  “As soon as we had reached the top of the wooded plateaus which
  surround the valley of Chalais, we started the screw, and had
  the satisfaction of seeing the balloon immediately obey it and
  readily follow every turn of the rudder. We felt that we were
  absolutely masters of our own movements, and that we could
  traverse the atmosphere in any direction as easily as a steam
  launch could make its evolutions on a calm lake. After having
  accomplished our purpose, we turned our head toward the point
  of departure and we soon saw it approaching it. The walls of
  the park of Chalais were passed anew, and our landing appeared
  at our feet, about 1,000 feet below the car. The screw was
  then slowed down, and a pull at the safety-valve started the
  descent, during which, by means of the propeller and rudder,
  the balloon was maintained directly over the point where our
  assistants awaited us. Everything occurred according to our
  plan, and the car was soon resting quietly on the lawn.”

Six other similar voyages were made within the two years following,
and we have as a result, that in five out of the seven trials, the
balloon returned to its point of departure. Its failure to return in
the other two trials was due, in the one case, to the breaking down of
the motor; in the other, to the resistance of a strong wind which made
it necessary to land at a distance from the starting point. The last of
these remarkable voyages was performed in presence of the Minister of
War, on September 23, 1885. The balloon started from Calais and sailed
against the wind directly to Paris, passed over the fortifications,
described a graceful curve and returned to its place of departure,
recording an average speed of 14.5 miles an hour.

The torpedo form of hull, chosen by Renard and Krebs, has two important
advantages; one is projectile stability, the other is economy of
propulsive power. Owing to the blunt bow and long tapering stern, the
center of mass is well forward, while the center of side wind pressure
is more to the rear. As a consequence, if the vessel should encounter a
quartering wind-gust, or have her nose slightly turned from the course,
she would promptly right herself like a dart or an arrow. If on the
contrary, the hull were a symmetrical spindle, the vessel would move
forward in unstable equilibrium, and, once slightly diverted from her
course, would tend to deviate further, like an arrow with unloaded head.

The second advantage mentioned is also worth attention, viz.: that at
ordinary transportation speeds a longish spindle has less resistance
with a blunt bow than with a very sharp one. Renard and Krebs did
not account for this fact; but the present writer, by determining
separately the skin friction and the impactual resistance of the air,
proved that in sharpening the bow beyond a certain best form, its
friction increases faster than its head resistance diminishes, the
most suitable shape being that of a torpedo whose nose has a radius
of curvature of about two diameters, and its stern a radius of about
twelve diameters.

While the successors of Giffard in France were thus engaged in
developing dirigibles driven by muscular or electric power, a few
German experimenters were applying gas and benzine engines to such
vessels, with better promise of ultimate practical success and
usefulness. The first of these was Hänlein, who in 1872 advanced the
meritorious project of driving a well shaped balloon by means of a gas
engine taking its fuel from inside the balloon, and making good the
loss by pumping air into the ballonet. This balloon was of far better
design for swiftness and kinetic stability than the contemporary one of
Dupuy de Lome. Its hull was a well pointed cylinder 164 feet long, 30
feet in diameter and of 85,000 cubic feet capacity, made air-tight by
a thick coating of rubber inside, and a thin one outside. The car was
rigidly suspended near the envelope and carried a 6 horse-power Lenoir
gas engine actuating a large screw. Notwithstanding that the buoyancy
was small, owing to the use of coal gas, this air ship attained a speed
of 15 feet per second. By employing hydrogen, a much larger engine
could have been carried, entailing a much swifter speed. During its
trial the balloon was kept near the earth’s surface, held loosely by
ropes in the hands of soldiers. The air ship was remarkably successful
for that early date, and had the potency of greater achievement
than its contemporaries in France; but owing to lack of funds its
capabilities were not fully developed. If it had been inflated with
hydrogen, and propelled by use of gas and petrol, so that the loss
of weight would compensate for the loss of buoyancy, it might have
anticipated the speed and endurance of the best air ships built toward
the close of the nineteenth century, or later.

PLATE II.

[Illustration: HAENLEIN’S GAS-DRIVEN DIRIGIBLE.]

[Illustration: WÖLFERT’S BENZINE-DRIVEN DIRIGIBLE.]

[Illustration: SANTOS-DUMONT’S DIRIGIBLE, _NO. 16_.

_Photo E. Levick, N. Y._ ]

In 1879, Baumgarten and Wölfert in Germany built a dirigible equipped
with a Daimler benzine motor, but otherwise not possessing any special
merit. An ascension was made at Leipsic in 1880, but owing to improper
load distribution the vessel reared on end and crashed to earth. After
further experiments, an ascension was made on the Templehofer field,
near Berlin, in 1897, but this ended disastrously; for the benzine
vapor ignited; the fire spread to the balloon, and the vessel fell
flaming to the earth, killing Wölfert and his assistant. Baumgarten had
died some years before.

In 1897, an aluminum air ship invented by an Austrian engineer, named
Schwartz, was launched on the Templehofer field. Its hull was of
cylindrical form with conical ends, made of sheets 0.008 thick, and
stiffened with an internal frame of aluminum tubes. Being leaky and
inadequately driven, it voyaged but four miles, drifting with the wind,
then fell to earth with considerable shock. The pilot, a soldier of the
Balloon Corps, escaped by jumping, before the vessel struck ground, but
the frail unbending hull was soon demolished by the buffeting of the
winds as it lay stranded on the unyielding earth. This was the second
air ship built after the plans of poor Schwartz, the first having
collapsed on inflation. He had, however, the credit of being the first
to drive a rigid air ship with a petrol motor, and thus to inaugurate
a system of aërial navigation capable of immense development, in
the hands of sufficient capital and constructive skill. Thus the
rigid type, conceived and crudely tried by Marey Monge and Dupuis
Delcourt in the early part of the century, began to approach practical
realization toward the end of the century.

The process of inflating with hydrogen such a rigid hull is
interesting. Schwartz’s plan, carried out by Captain Von Sigsfeld,
was to place the hydrogen in one or more sacs inside the hull, thus
expelling the air and filling the space, then withdrawing the sacs and
leaving the hydrogen within. A better plan is to have a single sac
inflated with air just filling the hull like the lining of an egg, then
to force the gas between the lining and metal wall of the hull, thus
expelling the air from the sac, which when completely collapsed can be
removed. Practically the same result can be obtained by use of a thin
fabric covering one half the inner wall, like the lining of an egg.
Further provision can easily be made for manipulating the ballonet in
such a case.




                              CHAPTER IV

              INTRODUCTION OF GASOLINE-DRIVEN DIRIGIBLES


We have now traced the art of balloon guidance and propulsion from its
earliest inception to the close of the nineteenth century. It was a
period of extravagant hope and chimerical scheming, but withal a period
fruitful in devices of fundamental value. The best experiments paid no
dividends, but they prepared the way for really useful vessels. The
methods of manipulation and control had been sufficiently developed
to answer immediate needs. The air ship was at least dirigible, if
not practical. It kept its shape, obeyed its rudder, rose and fell
according to the operator’s will. It was, however, a fair-weather
machine, beautiful in appearance, but helpless in any considerable
wind. Speed was now the desideratum, and the attainment of this
involved new difficulties. The storm-proof balloon was still a dream.

Naturally one inquires what velocity makes a dirigible air ship really
practical, assuming all other requirements satisfied. The minimum
allowable speed depends largely upon the locality and season. On Long
Island an assured velocity of forty to fifty miles an hour would
seem desirable; for there the winds are swift and the water near. In
Washington, or Berlin, thirty miles an hour is enough, though each
additional mile per hour must be regarded as a considerable gain on
a small margin of progress in facing a stiff breeze. Colonel Renard
has estimated, from a study of the wind records near Paris, that a
dirigible is practically useful in that locality if it can maintain a
speed of twenty-eight miles an hour for ten or twelve hours; since in
that case it can maneuver 81 days in 100.

Renard’s own graceful ship attained a speed of but half that much. In
order, therefore, to give his vessel the desired usefulness its speed
must be doubled. This would require an eightfold[11] increase of motive
power without increase of weight. Evidently then the cardinal requisite
was a light durable motor of extraordinary output. Such motors
fortunately were now coming into the market, owing to the development
of gasoline engines for automobile racing.

The year 1898 witnessed the commencement of two famous systems of
navigation by the lighter than air, one in France, the other in
Germany, destined quickly to revolutionize the art, and to establish
it on a practical basis. The leading exponents of these two systems
were Señor Don Alberto Santos-Dumont, a rich young Brazilian living in
Paris, and Count Ferdinand von Zeppelin, Germany’s stanch old admiral
of the air. Both achieved success by applying the gasoline engine to
the propulsion of elongated balloons, but by very different methods.
Santos-Dumont, apparently ignoring, or fearing to adopt, the excellent
hull and car designed and used by Renard, began where Tissandier left
off, with a symmetrical hull and low-hung car, thus producing a safe
aërial pendulum, if not a racing machine; then by degrees he gradually
felt his way to something more efficient. Zeppelin began with a long
cylindrical hull pointed at the ends, rigidly framed like that of
Schwartz, and supporting its car and propellers well aloft near the
line of resistance. His was a bold and effective design but difficult
to execute. Santos-Dumont scored the first success, and startled the
world by his spectacular flights; but ere long he was surpassed by
other builders of non-rigid balloons. Zeppelin won his success slowly
and by heroic perseverance in the face of enormous obstacles, finally
emerging as the most successful and illustrious figure in the history
of aëronautics. The achievements of these two pioneers and colleagues
make the first decade of the twentieth century memorable in the annals
of aërial navigation.

Santos-Dumont, who spent his early years on his father’s large coffee
plantation in Brazil, had, during boyhood, dreamed of navigating the
air, and in 1897, at the age of twenty-four, made in France his first
ascension in a spherical balloon. While living at Paris during that
year he gave much time to motorcycling, automobiling and operating
spherical balloons, of which he possessed two constructed after his own
ideas; one, the smallest in the world, designed for solitary voyages,
the other large enough for more than one person, intended for social
excursions. Thus by way of amusement, and probably by impulse rather
than deliberate purpose, he was equipping himself to become both the
designer and the pilot of his future dirigibles.

Having acquired experience and skill in operating both balloons and
engines, the young enthusiast set about realizing his boyhood dream
of navigating the air independently of the course of the wind. His
first dirigible was designed to carry his weight of 110 pounds and a
3½ horse-power petroleum engine taken from his tricycle, and reduced
in weight to 66 pounds. The hull was a cylinder of varnished Japanese
silk, 82½ feet long including its pointed ends, 11½ feet in diameter
and 6,354 cubic feet in gas capacity. A ballonet, or air pocket,
occupied the lower middle of the envelope. The basket for the little
pilot, engine, and two-blade propeller was suspended far below the
hull, to which its cords were attached by means of small wooden rods
inserted into hems along each side of the envelope, for a great part of
its length. The poise of the vessel was controlled by shifting weights
fore and aft, while the turning right and left was effected by means
of a silk rudder stretched over a steel frame. On the whole it was a
crude and primitive affair, but of considerable interest as the first
dirigible of a young man destined to give a strong impulse to the
development of motor balloons of the non-rigid type.

After some preliminary tests, the little air ship and pilot soared away
from the Zoölogical Garden in Paris, on September 20, 1898, rising in
the face of a gentle wind, to the wonder and delight of a large crowd
of witnesses, some of them professional aëronauts and very skeptical
as to the outcome of this venturesome experiment. The ship maneuvered
round and round overhead of the applauding throng, steering readily in
all directions. Then the green navigator ascended a quarter of a mile
and merrily continued his evolutions in the direction of the Longchamps
race course. But when he wished to descend he observed the envelope
contracting in volume, and was appalled to find that he could not
pump air into the ballonet fast enough to keep the hull distended. It
became swaybacked, and “all at once began to fold in the middle like a
pocket-knife; the tension cords became unequal and the balloon envelope
was on the point of being torn by them.” As he was falling swiftly
toward the grassy turf at Bagatelle, he called to some boys who were
flying kites, to grasp his guide-rope and run against the wind. They
understood and ran so swiftly with the canted balloon that it played
kite, and descended with a moderated fall, landing the frightened
aëronaut safely on the turf.

Except for the doubling of his long balloon, Santos-Dumont’s first
voyage was satisfactory, and he returned to Paris elated. He had found
it easy to steer in all directions. He could change his level hundreds
of feet without discharge of gas or ballast, by merely canting his
balloon, and allowing it to run obliquely up or down grade. He had
stemmed the wind and gone whither he pleased, at such speed as to make
his clothes flutter. And best of all he had found no danger in using a
gasoline motor near an inflammable gas bag. The mere buckling of the
long bag was a trifle, to be remedied by using an air pump adequate to
maintain the flabby thing well inflated. He felt, therefore, that he
had the conquest of the air well in hand, and that he was drifting into
air ship construction as a life work. Small wonder that he continued
his conquests till he had built, in less than one decade, fourteen
motor balloons.

_Santos-Dumont No. 2_ was closely patterned after its predecessor,
but was a little larger and carried a rotary fan worked by the motor,
to keep the balloon plump by filling the air pocket, or ballonet. On
May 11, 1899, an ascension was made from the old starting place, but
in rainy weather. As the vessel rose its hull contracted faster than
air could be pumped into the ballonet, the long bag doubled worse than
before, and dropped into the trees with its chagrined but fearless
rider.

The _No. 3_, which followed, was a short, thick vessel, 66 feet long
by 25 feet in diameter, having in outward appearance the features of
Dupuy de Lome’s very stable and very slow dirigible. It was apparently
a safety ship for a scared young man who had not yet learned fully to
appreciate Renard’s elegant design. It served for a few pleasant trips,
while the inventor was screwing up courage to build another cylindrical
vessel, and gradually realizing the advantage of an elongated car such
as Renard had employed in _La France_. Not only was the hull short
and thick, but it was further secured from buckling by a horizontal
stiffening pole placed between it and the basket, and from which the
latter was hung. After some voyages in _No. 3_, which the captain found
very tractable, and probably capable of fifteen miles per hour, he was
ready to begin a new vessel.

The _No. 4_ was a compromise between the better features of _No. 3_
and its predecessors. The elongated hull and ballonet were resumed,
and the stiffening pole was elaborated into a longish car resembling
Renard’s, but of triangular cross section. On this long trussed frame
were placed the motor, propeller, rudder and the rider in his basket.
A seven horse-power engine turning, at one hundred revolutions per
minute, a screw propeller having two blades, each 13 feet across, gave
a thrust of 66 pounds. Frequent trials of the ship during the summer
of 1900, in presence of the Exposition crowds, brought the inventor
into extraordinary prominence, and secured for him the “Encouragement
Prize” of the Paris Aëro Club, consisting of the yearly interest on
one hundred thousand francs, this being one of M. Deutsch’s numerous
foundations for the promotion of aëronautics.

In the spring of 1900, M. Deutsch de la Meurthe had established another
prize which Santos-Dumont now greatly coveted, and hoped ere long to
win. This was a cash sum of one hundred thousand francs to be awarded
by the Scientific Commission of the Aëro Club of France to the first
dirigible that, between May 1 and October 1, 1900, 1901, 1902, 1903,
1904, should voyage from Saint Cloud to and around the Eiffel tower,
and return within half an hour. The distance to the tower and back,
not counting the turn, was nearly seven miles, and the estimated speed
required to fulfill the conditions for winning the prize, even in calm
weather, was 15½ miles per hour.

As Santos-Dumont thought his _No. 4_ scarcely swift enough to win
the Deutsch prize, he enlarged it by inserting an additional length
of sixteen feet at its middle, supplied it with a stronger car, and
applied a larger engine, naming the new vessel so formed, his _No.
5_. Its hull was 109 feet long, 17 feet in largest diameter and cubed
nearly 20,000 feet. A four cylinder air-cooled petroleum motor driving
a screw propeller having two blades, each 13 feet across, gave a thrust
of 120 pounds, at 140 revolutions per minute, and produced such draft
as to give the inventor pneumonia. Among other novelties water ballast
was used, and piano wires replaced the old-time suspension cords.

The _No. 5_ proved so powerful and swift that on July 13, 1901,
Santos-Dumont attempted to win the Deutsch prize. Starting from the
Aëro Club grounds at Saint-Cloud in presence of official witnesses,
at half past six in the morning, when the air is usually stillest,
he turned the Eiffel Tower in the tenth minute, thus gaining twenty
minutes for the home stretch. But on his return he encountered an
unexpected head wind, and after a terrific struggle reached the
timekeepers at Saint-Cloud in the fortieth minute.

To add to the romance of this voyage, the genii of the upper elements
stopped his motor, shortly after his return, and the bold sailor in his
shining ship landed in a stately chestnut tree very near the house
of the Princess Isabel, daughter of Dom Pedro. She very thoughtfully
arranged a breakfast for him and sent it up in a basket, where he was
at work disengaging the balloon, at the same time inviting him to call
and relate to her the story of his voyage. A few days later she sent
him a medal of St. Benedict “that protects against accidents.” He wore
the medal, and on his very next trial escaped without a scratch from an
appalling accident which might have terminated fatally. He continued to
wear the gift of that gracious princess, on a thin gold chain circling
his wrist, and many a time thereafter endured unscathed the most
dreadful accidents, as if he possessed a charmed life.

On August 8, 1901, the dauntless aëronaut again sailed for the coveted
prize, at the same still morning hour, sacred to duels and aërial
contests. In nine minutes he turned the tower and headed bravely for
home. But soon a leaky valve let the balloon shrink and the wires
sag into the whirring propeller, which therefore had to be stopped.
Santos-Dumont now had the choice of drifting back against the tower
and destroying his vessel high in air, or of descending at once, by
allowing the balloon to sink without discharge of ballast. He chose
the latter course, hoping to land on the Seine embankment; but instead
his balloon struck the top of the Trocadero hotel, exploded and fell
in fluttering shreds into the courtyard. Some firemen who had been
watching the flight from a distance, came with a rope and found
the long car leaning like a ladder against the wall of the court,
the balloon shreds hanging from it in graceful folds, and Captain
Santos-Dumont perched aloft in his wicker basket wearily waiting for
St. Benedict’s further aid. As usual, he was rescued intact.

On the evening of his fall on the roof of the hotel Santos-Dumont
issued specifications for his famous _No. 6_, which surpassed
all its predecessors in safety and speed. It had the shape of an
elongated ellipsoid with pointed ends, measured 110 feet in length,
20 feet in major diameter, 22,239 cubic feet in volume, and had an
absolute ascensional force of 1,518 pounds. It was driven by a twelve
horse-power four-cylinder water-cooled engine which gave the propeller
a thrust of 145 pounds. To insure against buckling of the gas bag, an
air pump connected with the motor, kept the ballonet under constant
pressure, regulated by an escape valve through which the excess of
air passed outward. To secure the envelope against rupture, due to
the expansion of the hydrogen at unusual elevations, a stronger valve
was used to let the gas escape from the envelope into the atmosphere.
Thus the air escape valve kept the pressure constant in the partially
distended ballonet, and consequently also in the surrounding gas
envelope itself; while the stronger gas valve in the envelope opened
only in an emergency, when the gas pressure had fully collapsed the
internal air pocket and was threatening to explode the envelope. With
all its improvements this new vessel was finished and inflated by
August 4, being a work of twenty-two days, and after some preliminary
trials was ready to try for the Deutsch prize.

The day of triumph followed quickly. On October 19, 1901, at 2.45
P.M., Santos-Dumont again headed for the Eiffel Tower in presence of
the official witnesses. In spite of a wind of six meters per second
striking him sidewise, he held his course straight for the goal, and
turned it in the ninth minute, as in his preceding attempt. On the
return he had to struggle against a quartering wind and the caprice
of his motor, which sometimes threatened to stop, and again spurted
so actively as to turn the ship upward at a steep angle. The mighty
throng below, in the Auteuil race track and the Bois de Boulogne, sent
up immense applause, then suddenly held its breath in alarm, as the
vessel pitched violently. But the hardy little rider was self-possessed
and at home on his vaulting Pegasus. Alert to every prank he held his
course straight for the timekeepers and passed over their heads at
exactly twenty-nine and one-half minutes after starting.

His unmercenary disposal of the two rich awards which he had won seemed
no less commendable than the dauntless industry which achieved such
rapid success. The Deutsch prize amounting in all to one hundred and
twenty-five thousand francs he divided into two unequal parts. The
greater sum of seventy-five thousand francs he gave to the prefect
of police of Paris, to be used for the deserving poor; the remainder
he distributed among his employés. The Encouragement Prize of four
thousand francs a year, mentioned before, he also declined to retain,
but instead he founded with the money a new prize at the disposal of
the Aëro Club. As a second reward for his triumphal voyage around the
Eiffel Tower, he received from the Brazilian government one hundred
and twenty-five thousand francs and a beautiful gold medal bearing
appropriate and very complimentary inscriptions.

Now that the stimulus and excitement of striving for the Deutsch prize
was over, the ardent inventor was free to develop and test his air
ships in a deliberate and scientific manner. He therefore set about
building specialized types of motor balloons, and practicing with them
over all kinds of territory, smooth and rough. Within the next six
years he constructed eight more air ships making altogether fourteen,
besides his various free balloons, to say nothing of the aëroplanes and
hydroplanes which he found time to develop. But before indulging in
these new luxuries he would have more experience with his _No. 6_.

When the cold weather set in, following his victorious flight about
the Eiffel Tower, Santos-Dumont went with his _No. 6_ to Monaco, to
practice air cruising over the Mediterranean. The Prince of Monaco
had erected for him an “aërodrome,” or balloon shed, facing the sea
and very near shore. On pleasant days the daring pilot would cruise
up and down the bay, not far from shore, trailing his guide-rope over
the waves with the greatest ease, and to the applause of thousands of
spectators. But on February 14, 1902, he set forth on a pleasure cruise
over the bay with insufficient gas pressure, and thus came to grief.
The bag grew flabby; the hydrogen poured to its higher end; the vessel
reared up so steeply that the propeller had to be stopped to avoid
its cutting the envelope. Rather than drift at the mercy of the wind,
the pilot opened the valve and sank slowly to the water where he was
rescued by a boat. On the following day the parts of his _No. 6_ were
fished out of the sea and sent back to Paris. His few days’ practice
had taught him the delights of guide-roping over the waters, and his
accident induced him in future to sew unvarnished silk partitions
across his balloons, to prevent the hydrogen passing too suddenly from
one end to the other.

Returning to Paris he built for himself an “aërodrome,” provided
with great sliding doors like the one at Monaco, and equipped with a
hydrogen plant, constructive appliances, and everything needed for
the rapid rebuilding or repair of air ships. It stood in a vacant lot
surrounded by a high stone wall and was made of posts covered with red
and white canvas, so that it looked like a great striped tent. Inside,
the central stalls were 31 feet wide, 165 feet long, and 44½ feet
high,[12] the whole enclosure having accommodation for seven dirigibles
all inflated and ready for instant service. When completed, in the
spring of 1903, it was at once used to harbor three new air ships.
These were the _No. 7_, designed for racing contests; the _No. 9_,
called the Runabout, a minim air ship used for calls and short pleasure
trips; and the _No. 10_, called the Omnibus, intended for several
persons, with ample supplies for a considerable journey.

The _No. 7_, which excelled its predecessors in length and bulk, was
intended greatly to outstrip the best of them in velocity. The first
air ship had attained fourteen miles per hour, the _No. 6_, nearly
twenty miles an hour in winning the Deutsch prize, and over twenty
miles per hour on subsequent occasions, though provided with a motor
rated at only 12 horse power. The new vessel which had little greater
resistance than _No. 6_, was to carry four times the internal pressure,
or about 12 centimeters of water, and to be propelled by an engine of
60 horse power. The inventor expected therefore to attain a speed of
between forty and fifty miles per hour. A very lofty expectation for
that day, and one still unrealized for many years.

The racing air ship, or _No. 7_, was of cigar form, supporting a long
car beneath, and generally resembling the _No. 6_, but slightly more
tapering. Her length was six times her major diameter, and her volume
45,000 cubic feet. The envelope was made of two layers of the strongest
French silk, four times varnished, and was built exceptionally thick
at the stern, where the differential outward pressure is greatest in
flight. The propulsion was effected by a 60 horse-power water-cooled
four-cylinder Clément engine actuating two screw propellers 16½ feet
in diameter, one in front the other at the rear of the car. The poise
and maneuvering were to be controlled in the usual way, by means of the
rudder and shifting weight. The inventor seemed not to realize that
the bow of his vessel was too sharp to cleave the air with minimum
resistance, though his predecessor, Jullien, in 1850, had discovered
experimentally that a torpedo form is better for speed than the
symmetrical spindle form used by Santos-Dumont in his racing vessel. He
did, however, in time, learn that the torpedo form of hull is better
for stability of forward motion, and hence adopted that form in his
little _Runabout_.

The _No. 9_ was a thick torpedo-shaped air ship originally cubing only
7,770 feet, though later enlarged to 9,218 feet. It was so thick as
to appear nearly egg-shaped. In order to make it respond promptly to
the rudder Santos-Dumont drove it through the air blunt end foremost,
but with apparent regrets, thinking that it would cleave the air
more easily than sharp end foremost. In this he was mistaken; for
the writer has shown that a body of such shape encounters much more
resistance—roughly one hundred per cent more—when driven sharp end
foremost than when driven blunt end forward. This fact furnishes one
reason why most whales and swift fishes have blunt bows and long
tapering sterns. However this be, the practical man felt his way to
success, whether right or wrong in his theory of resistance. When
actuated by a three horse-power Clément motor, weighing 26½ pounds, the
little air ship carried its jaunty pilot twelve to fifteen miles an
hour on many a merry trip about Paris and its environs.

The _No. 10_, or _Omnibus_, was a well shaped vessel of nearly eighty
thousand cubic feet capacity, and amply provided with steering
devices. Its hull tapered slightly from front to rear, terminating
in projectile-shaped ends, and had a length of nearly six times its
major diameter. Underneath was suspended a long car provided with
aëroplane surfaces, in addition to the usual rudder, for controlling
its movements.

Its arrow-like appearance was suggestive of some of the greatest German
balloons of the decade. Indeed, the _Omnibus_, if well powered, might
have proved a very swift vessel, in addition to a powerful carrier.
But she was designed merely for easy going passenger service, for the
purpose of popularizing aëronautics and stimulating its growth.

Santos-Dumont now had three typical air ships, a spacious and well
equipped “aërodrome,” and ample facilities for advancing the science
of motor balloons on a moderate scale. He could not, however, maintain
the ascendency in this branch of science in France; for he encountered
the rivalry of great wealth employing highly trained engineering and
constructive talent. He could, however, still promote the art as a
pioneer and a popularizer. This he continued to do. With his little
_Runabout_ he would one day guide-rope along the boulevard, another
day take up a little boy, another day send up a beautiful young lady
to navigate the air alone for a short distance, another day voyage
over the military parade grounds and with his revolver fire a salute
of twenty-one shots to the President of France, and give exhibitions
to arouse the interest of the War Department. But he could not keep
pace with the new giants in aëronautics, and he did not attempt
it. Nor did he ever build a vessel of sufficient power, speed and
durability to be purchased by the French nation. That honor went to his
opulent contemporaries who had not failed to take cognizance of his
contributions to the aërial art.




                               CHAPTER V

             PRACTICAL DEVELOPMENT OF NON-RIGID DIRIGIBLES


In 1899 the Lebaudy brothers, wealthy sugar refiners in Paris,
commissioned their able engineer, Julliot, to make investigations
and develop plans for a large and swift air ship. This he did with
the assistance of Surcouf, a well-known manufacturer of balloons at
Billancourt, Paris. Emulating the example of Santos-Dumont and certain
German aëronauts in making their plan, they adopted the light petroleum
engine for motive power, but experimented on a larger scale, thus
creating a new era in military aëronautics in France. Their first
vessel was the _Jaune_ whose bag was built at Surcouf’s place, and
its mechanical part at the Lebaudy Sugar Refinery. When launched,
in 1902, it so pleased the owners that they determined to continue
the experiments on a larger scale. Their second air ship, called the
_Lebaudy_, after fulfilling various tests, was accepted by the French
government and formed the beginning of its modern aërial fleet.

Moisson, near Paris, where the balloons were kept, now became quite an
aëronautical center. Here, under military supervision and the skillful
management of the aëronaut Juchmes, other dirigibles were built in
rapid succession. Of these the _Patrie_ was launched in 1906, and the
_République_ in 1908, both fine swift vessels capable of voyaging many
hours and carrying many passengers. The Lebaudy vessels were the first
air ships of the “semi-rigid type,” in which the long and flexible
envelope, or hull, is provided with a rigid keel or floor, from which
the car is suspended with its machinery and passengers. They are,
therefore, of unusual interest both for their scientific design and for
the stimulus they imparted to the growth of aërial fleets. For this
reason they may well be studied in some detail.

The first Lebaudy air ship, called the _Yellow_, because of its color,
had an envelope constructed of a rubber-treated cotton fabric, made in
Hanover and covered with a yellow coating of lead chromate, to ward off
the sun’s actinic rays from the rubber, and thus prevent deterioration.
Her hull, which was cigar shaped and inflated with hydrogen, measured
183 feet in length, 32 feet in diameter, and 80,000 cubic feet in
volume. She was propelled by a 40-horse-power Daimler motor actuating
twin screws, and attained a maximum speed of twenty-six miles an hour.
During her first year’s service she made many ascensions, returning to
her starting point twenty-eight times out of twenty-nine. Her longest
voyage, made at Moisson, June 24, 1904, was sixty-two miles in two
hours and three quarters, with an average speed of twenty-two miles
an hours. But in November, 1902, while landing in a high wind at the
end of her voyage from Paris to Chalais-Meudon, she was wrecked by
colliding with a tree. Her motor, however, was uninjured, and a new
envelope was at once prepared.

The second vessel, called the _Lebaudy_, and brought out in 1904,
though resembling her predecessor, had a number of improvements in
detail. Her hull was somewhat larger than the _Jaune_, and no longer
pointed at the stern, but rounded off to an ellipsoidal shape, and
provided, like the rear of an arrow, with guiding, or steadying planes.
It measured 190 feet in length and 94,000 cubic feet in volume. It
was provided with two windows for internal inspection, and had an air
bag of 17,650 cubic feet, divided into three parts. This air bag was
inflated by a rotary fan near the main body, driven by the motor during
flight, and by a storage battery when at rest. Suitable horizontal
and vertical sails were used to steady and guide the vessel; also a
guide-rope and anchor were carried. The car, suspended by steel ropes,
ten feet below the hull, carried the passengers and supplies; also
the motor actuating twin propellers, one on either side. At night an
abundance of light was available, each passenger carrying a small lamp
fastened to his clothes, the car itself bearing a powerful acetylene
projector in its front, and two other lamps of 100 candle power each,
to illumine the vessel. It was an elaborate affair, costing fifty to
sixty thousand dollars, and was the outcome of experiments costing ten
times that sum.

PLATE III.

[Illustration: THE _LEBAUDY_.

_Photo E. Levick, N. Y._]

[Illustration: _LA PATRIE._

(Courtesy E. L. Jones.)]

[Illustration: LEBAUDY’S _MORNING POST_.]

The _Lebaudy_, with these various improvements, gave much satisfaction
to her owners, and received favorable recognition from the French War
Department. During the thirty ascensions and voyages of her first
year’s service, she proved herself a swift vessel, easy to control,
very stable, and safe to land on solid ground. The Minister of War,
who had followed her developments with much interest, appointed a
commission to test her value for military service, with a view to her
adoption by the government. The test required that the balloon remain
in active service three months, always being anchored in the open, and
that it perform certain prescribed maneuvers and voyages. In one of
these it sailed with three persons on July 3, 1905, from Moisson to
Meaux, an air-line distance of 57 miles in two hours and thirty-five
minutes, at an average speed of 22 miles an hour, thence to Chalons,
61 miles in three hours and twenty minutes. Here it was anchored to
some trees, but presently was caught in a strong wind, lifted high in
the air, then dashed violently against other trees, with the complete
destruction of its envelope. Within eleven weeks it was repaired
in the military riding school at Toul, nearby; then, after some
evolutions, returned to its harbor at Moisson. Other maneuvers were
made subsequently, in which five officers were carried at one time,
and interesting experiments were tried, such as dropping a sand bag
upon a given spot, photographing fortifications, etc. The Minister of
War, accompanied by two officers and other passengers, made a trip on
October 24th, which was the seventy-sixth voyage of this stanch vessel.
On November 10th, the hard-worked and successful air ship went into
winter quarters, being now the property of the French government, and
the first of her modern aërial cruisers.

The _Patrie_ and the _République_, planned on the general lines
of the _Lebaudy_, but in ascending scale of magnitude, were built
expressly for the French government, and experienced brilliant if
ill-fated careers. Both vessels had whale-shaped hulls, with rather
sharp-pointed noses and rounding sterns. The original volume of the
_Patrie_ was 111,250 cubic feet, which was later increased to 128,910,
by the insertion of a cylindrical section at the major diameter of the
hull. The _République_ had a volume of 2,000 cubic feet more than the
_Patrie_, and a length of 200 feet, or a little less than the enlarged
_Patrie_. She also had a diameter of 35½ feet as against 33¾ in the
sister vessel. As the technical reader may like more complete details
of these two noted air ships, a fuller account is given in Appendix III.

The _Patrie_ was a swift and graceful ship which, during its brief
activities in 1906-7, made many remarkable trips at an altitude of
about half a mile, and frequently maneuvered with the troops. She
sailed with excellent stability, had a speed of about 28 miles an hour,
and, with four men, had a radius of action of 280 miles. In November,
1907, carrying four passengers, she voyaged from Paris to Verdun,
on the German frontier, where she was to be stationed. In spite of
a quartering wind, the total distance of 175 miles was traversed in
seven hours and three quarters, or at an average overground speed of
25 miles an hour. But while at Verdun, after some maneuvers, she was
too insecurely anchored to the ground by means of iron stakes. A strong
wind came, tore out the pickets, and overpowered the soldiers, some
two hundred in number, who were trying to hold the vessel. As she was
pulling them along the ground, they were ordered to let go. The huge
ship bounded high into the air, soared across France, England, Wales,
and part of Ireland, then far out over the Atlantic where she vanished,
leaving no trace behind.

The _République_ also had a brilliant but ephemeral career, from July,
1908, to September, 1909. She surpassed the _Patrie_ not only in bulk
and buoyancy, but also in power and speed. She had an 80-horse-power
motor as against the _Patrie’s_ motor of 60 to 70 horse power. She
could carry eight to nine men, had a speed of about thirty miles an
hour, and a radius of action of 500 miles. She made a number of long
flights and manifested satisfactory steadiness and stability. But on
September 25, 1909, while maneuvering near Paris, one of her propellers
broke and tore a great gash in her envelope. At once, with outrushing
gas and collapsing hull, the great ship fell 500 feet crashing to the
earth, a total wreck, and killing her crew of four officers. This
disaster illustrated forcibly the advantage of the cellular system of
balloon construction, and drew more favorable attention to the rigid
type of air ship cultivated in Germany.

The famous firm that produced the _République_ brought forth, in
1909, two other fine vessels patterned after it, the _Russie_ and _La
Liberté_, built respectively for Russia and France. The _Russie_ made
her first voyage on May 29th, ascending 600 feet with eight passengers,
and maneuvering under perfect control. After her official trial,
in June, she was sent to St. Petersburg, being the first dirigible
furnished to a foreign government by a private concern. The _Liberté_
was launched the last week in August and, after various practice and
official tests, was accepted by the French government two months later.
On a notable voyage, made on September 20th, she sailed ten hours with
her Panhard motor constantly working.

The escape of the _Patrie_ was a loss keenly felt by the French people,
but soon compensated by the generosity of M. Deutsch de la Meurthe.
This liberal patron of aëronautics had a dirigible of excellent design,
whose hull, based on the plans of Colonel Renard, was contrived and
built by E. Surcouf, director of the Astra aëronautic establishment,
along with H. Kapferer, while its other parts were built by Voisin,
both of Billancourt. In September preceding the accident to the
_Patrie_, he had offered the use of his air ship, the _Ville de Paris_,
to his government, which accepted the gift with the understanding that
it was not to be delivered except in case of war or emergency. When,
therefore, in November, 1907, the disaster occurred to the _Patrie_,
M. Deutsch at once placed his dirigible in the hands of the military
authorities.

[Illustration: FIG. 21.—_La Ville de Paris._]

The _Ville de Paris_ showed considerable resemblance to her prototype,
the _France_ of 1884, but differed from that elegant vessel in various
important features. Her hull was shaped like a wine bottle with its
thickest end, or bow, brought to a sharp projectile point, and its
other end furnished, like an arrow, with four fixed guiding surfaces
to steady its flight. These guiding surfaces were elongated, finlike,
cylindrical sacs, inflated as shown in the illustration. The hull
measured 200 feet long, 34½ feet in major diameter, 112,847 cubic feet
in volume. Heavy bands of canvas with their edges sewed along the
sides of the balloon served as flaps for the attachment of the cords
suspending the long car beneath. With this long suspension the weight
of the car was more evenly distributed over the envelope than in the
Lebaudy balloons. An interesting improvement in this air ship was the
stabilizing planes, placed above the car, fore and aft, to lift or
depress aëroplanelike, thus enabling the pilot to raise or lower the
vessel, also to alter her trim, or to check her pitching. As might be
expected, her flight was very steady, but as the motor developed only
70 to 75 horse power, her velocity did not exceed twenty-five miles per
hour. In January, 1908, she made a run of 147 miles in seven hours, six
minutes, with an average speed of 21 miles an hour. Further details of
construction are given in Appendix III.

We now have had examples of the three leading types of motor balloons;
the rigid, the semirigid, the flexible. The rigid type, as exemplified
in the Schwartz and Zeppelin air ships, is characterized by its
solidly trussed hull of invariable size and form to which all other
parts are directly attached. The semirigid type, exemplified in the
Lebaudy vessels, has a flexible hull, generally of woven fabric, with
a trussed floor or platform for its ventral part, from which the car
is suspended. The flexible type, as seen in the _Ville de Paris_, the
_France_, and its predecessors, consists of a flexible hull entirely
devoid of stiffening framework, together with a car, usually quite
long, suspended from the bag directly. These are all of the important
kinds in use at present. A combination of balloon and aëroplane has
been tried by Santos-Dumont, Malecot, and others, but thus far has
not resulted in a very successful and distinct type. Of the many
powerful, swift, and elegant balloons which sprang into being after
the success of the Lebaudy vessels, all could be classified under the
above three types. Neither kind proved preëminently the fittest for
all service, but the semi-rigid and flexible balloons multiplied most
rapidly; partly, no doubt, because of their cheapness and convenience
of management. We may review briefly this new crop of air ships, before
turning to the novel and huge rigid vessels of Count von Zeppelin.

The _Ville de Paris_ was followed, in 1909, by the _Clément-Bayard_,
a slightly larger vessel of very similar pattern, constructed for the
Russian government for $40,000. It also, like the _Ville de Paris_,
was built by the Astra Society. The most striking feature of this new
balloon was its curious stern with its bulblike steadying surfaces.
These fin surfaces were not flat, as in the _Patrie_, nor cylindrical,
as in the _Ville de Paris_, but of pear form, with the blunt ends
pointing rearward and inflated like the rest of the hull. Apparently
these tail bags were not economical of power, since, as is well
known, a pear shape encounters greater resistance when moving sharp
end forward than when moving blunt end forward. However this be, the
stabilizing force proved very effective. The vessel was driven by a
Clément-Bayard motor of 100 horse power actuating a wooden screw placed
in front of the long car, as in the _France_. A speed of 30 miles an
hour was attainable, and the ship could accommodate eight passengers.
On one occasion it made a round trip from Sartrouville, traversing 125
miles at an average speed of 27 miles an hour. It was acquired by the
Russian government on August 23, 1909, having on that day completed
its third official test, and satisfied the requirement of rising 1,550
meters and voyaging two hours at a height of 1,200 meters. Two notable
incidents of that voyage were that the air ship made a new record for
altitude, and on landing was caught by a squall which tore it from the
hands of thirty men, after which, owing to motor failure, it drifted
freely across country, tripped on a willow, and fell into the Seine,
whence it was rescued after considerable pains and labor.

Other vessels presently built by the Astra Society may be listed,
together with their size in cubic meters, as follows: _Ville de
Bordeaux_, 3,300 m^3;[13] _Ville de Nancy_, 3,300 m^3; _Colonel
Renard_, 4,000 m^3; _España_, 4,000 m^3; _Clément-Bayard II_, 6,500
m^3; _Transaerienne I_, 6,500 m^3; _Flandre_, 6,500 m^3 (228,579
cubic feet). These were among the most noted air ships produced in
France toward the close of the first decade of the twentieth century.
On the whole they proved to be swift and stable ships adapted either
for military use, or for exhibitions and sport, and even for regular
transportation of passengers.

The _Ville de Nancy_ was one of the conspicuous dirigibles of the
summer of 1909. It was constructed primarily for use at the Exposition
at Nancy, and was owned by the Compagnie Générale Transaerienne, an
aërial passenger transportation society organized at Paris, in
March, 1909, with a capital of one million francs. This society planned
to inaugurate an aërial line from Paris to Bordeaux, in 1910, equipped
with other vessels of the Astra construction, more powerful than the
_Ville de Nancy_, and capable of transporting a dozen passengers.

PLATE IV.

[Illustration: _LA VILLE DE PARIS._

_Photo E. Levick, N. Y._]

[Illustration: _COLONEL RENARD._

_Photo E. Levick, N. Y._]

The _Ville de Nancy_ was slightly smaller and slightly more powerful
than the _Clément-Bayard I_, besides differing in minor details. It
measured 55 meters in length, 10 meters in greatest diameter, and
cubed 33,000 meters, as against the 35,000 meters of its predecessor.
It was driven by a 100-horse-power Bayard-Clément motor actuating a
Chauvière screw propeller at the front of the car. The car itself was
made of steel tubes covered with fabric, and near the engine with
sheet aluminum. The tail bags were an evident improvement on those of
the previous air ships, being less blunt at the rear, and therefore
less adapted to generate a retarding suction. They were still rather
bulbous, however.

This splendid vessel made various interesting voyages during the
summer of 1909, the first on June 27th, piloted by Surcouf and
Kapferer, directors of the Astra Society. On July 14th, she maneuvered
at Longchamps, side by side with the _République_, thus contrasting
nicely with the ship designed by Julliot. It was the first time two
dirigibles navigated together in regular maneuver. The _Ville de Nancy_
was naturally the swifter, having greater power and less bulk than
the other. About the middle of July she sailed from Sartrouville to
Nancy, where she was to sail about the Exposition grounds and make
daily excursions, carrying passengers for 100 francs per trip. These
voyages proved very popular, being the first of their kind, and in
themselves quite attractive. As the vessel was endowed with excellent
stability and had manifested high speed, she was well suited to be the
first regular passenger air ship, and the herald of the aërial liners
projected to cruise between Paris and Bordeaux.

The _Colonel Renard_ was closely patterned after the _Ville de Nancy_,
but was larger and more powerful. She measured 212 feet in length,
140,000 cubic feet in volume and carried an engine of 120 horse power,
driving a Chauvière propeller. On July 13th she made her first trip,
cruising one hour with notable facility, then reëntered the hangar[14]
of the Astra Society, at Beauval near Meaux. Thence, on August 23d, she
sailed for Rheims to compete in the aëronautical races, arriving after
a very successful cruise. On August 29th, she circled the ten kilometer
rectangular course at Betheny, near Rheims, five times in 1 hour, 19
minutes, 40 seconds, thus winning the Prix des Aëronats,[15] of 10,000
francs offered for the vessel that should accomplish, in the least
time, those five rounds, aggregating 50 kilometers. The showing was not
remarkable, but the vessel could sail much faster in a straightaway
voyage.

The prize-winning _Renard_ was quickly followed by the _España_, a
vessel of the same size and pattern, built for the Spanish government
by the same capable firm. During October this fine air ship made
several trial trips, carrying seven men. On November 2d she made
a splendid official test voyage of five hours, sailing from the
Astra aërodrome, at Beauval, to Paris and return, a distance of 250
kilometers in 5 hours and 10 minutes, or at the average rate of 31
miles an hour for the entire course. On November 5th, she started on a
ten-hour voyage, with five men and fuel for fifteen hours; but after
five hours, stopped her engine, and came to earth, owing to the bending
of the main shaft of the motor.

Besides the great auto balloons designed by Julliot and Surcouf, of
which the _République_ and _Colonel Renard_ are examples, a number of
convenient cruisers were brought forth in 1909 by the Zodiac Company.
One of the leading spirits in this enterprise was the famous Count de
la Vaulx, well known for his auto balloon designs and his long voyages
in sphericles. The chief merit of these modest air ships, which ranged
in volume from 25,000 cubic feet upwards, was cheapness and facility of
demounting and shipment. They were intended to popularize the art among
the masses, by giving everyone a chance to make a voyage at no great
expense. Besides their applicability to sport, touring, and public
uses, some were designed for considerable speed and endurance; which
qualities, together with their demountability and partial independence
of hangars, were expected to give them military value. They were of
the flexible type, so arranged that the various parts were easily
detachable, so as to be packed for transportation, by wagon or car.
The smaller ones might be called semi-navigables, since they had the
organs of a swift motor balloon, but, like the common sphericles,
could easily be demounted and hauled home—a likely issue on a day of
any considerable wind. The first one cost $5,000, cubed 25,000 feet
and, with its 16-horse-power engine, traveled 13 miles per hour. Its
hull had the form of a whale with docked and rounded tail. From this
body hung an elongated car with a screw at the rear and elevating
planes in front. Others of similar make, but larger, followed in rapid
order, their common mission being that advocated by Santos-Dumont, in
the early part of the decade, when he produced his _Runabout_ and
_Omnibus_—to give everybody a ride.

[Illustration: FIG. 22.—_Le Petit Journal_, ZODIAC TYPE.]

PLATE V.

[Illustration: _ZODIAC III._]

[Illustration: _ZODIAC IV._]

The _Zodiac I_ was quickly followed by vessels _II_ and _III_, cubing
respectively 1,200 and 1,400 meters. The _No. II_ had a speed of
twenty, or more, miles per hour, and carried two passengers when
inflated with coal gas, three with hydrogen. The _No. III_, of torpedo
form, measured 133 feet long, 28 feet in major diameter, carried four
persons, and sailed 25 miles an hour with her 40-horse-power Ballot
engine. On August 29th, piloted by Count de la Vaulx, she competed with
the _Colonel Renard_, at Rheims, for the _Prix des Aëronats_, making
five rounds of the ten kilometer course in one hour and twenty-five
minutes, this being at the average speed of 22 miles an hour. On
October 30th, again piloted by the same renowned aëronaut, she sailed
from Brussels to Anvers, rounded the lofty Cathedral spire, and
returned to her aërodrome, traversing a distance of sixty kilometers in
one hour and twelve minutes, or with an average speed of 31 miles an
hour, a good showing for so small an air ship.

A very handsome dirigible, named the _Belgique_, was constructed early
in 1909, by the skillful aëronautical engineer, Louis Godard, of Paris,
in collaboration with the prominent Belgian engineer and sportsman,
Robert Goldschmidt. It was a flexible balloon of elegant torpedo form,
measuring 175 feet long, 30 feet in major diameter, and 106,000 cubic
feet in volume. It was propelled by two 60-horse-power Vivinus engines
actuating two screws, made of fabric stretched over radial sticks,
and placed at either end of the spindle-shaped car. The control was
provided for by ample keel surface, an elevating plane in front,
and ingeniously designed fins on the rear of the hull to steady the
motion. The entire structure showed much originality and skill. When
the dirigible was tested near Brussels, on June 28th, it was piloted
by Louis Godard, the famous expert in sphericals, accompanied by
Goldschmidt. Godard’s début in this capacity was reported as excellent.

The Italian government brought forth, in the summer of 1909, a swift
and elegant auto balloon showing considerable originality of design.
It has a porpoise-shaped hull of 2,500 cubic meters capacity, divided
into seven compartments, so as to obviate the accident which wrecked
the _République_. An ample keel along the rear bottom, and large
aëroplane surfaces at the stern, serve to guide and steady the vessel.
Propelled by twin screws well above a short car, she readily attained
thirty miles an hour, carrying four persons. On October 31st, starting
on her seventeenth voyage, she cruised from the aëronautic park, Vigna
de Vale, near Rome, to Naples and back to Rome by ten o’clock at
night, having sailed over the edge of the Mediterranean Sea and over
the French squadron in the bay, remaining fourteen hours in the air
and traversing 520 kilometers, or 323 miles. It was one of the finest
voyages of the year. Further details of this Italian military dirigible
_No. I bis_, together with illustrations, are given in _Aërophile_ for
January 15, 1910, together with its prototype the dirigible _No. I_,
which maneuvered so successfully in 1908.

England and America all along had pursued an oriental, or
semicivilized, policy toward the auto balloon, languidly watching
the progress elsewhere, and hoping some time to enjoy the fruition,
if not the glory, of the costly and successful experiments made in
other countries. In 1909, however, the British government appropriated
nearly $400,000 for aëronautics, and the United States House of
Representatives voted $500,000, but promptly reversed its action,
and gave nothing, though it may be said that even then there was a
growing sentiment in favor of a more liberal policy. The movement to
secure the beginning of an aërial fleet in England is summarized in the
following paragraph.[16]

PLATE VI.

[Illustration: _LA BELGIQUE._]

[Illustration: ITALIAN MILITARY DIRIGIBLE _NO. I BIS_.]

  “The naval authorities were entrusted with the building of a
  rigid ship, whilst to the military department was delegated the
  work of building non-rigid and semi-rigid ships. A national
  air-ship fund was organized by the _Morning Post_ with the
  object of purchasing a French Lebaudy semi-rigid dirigible
  which would be presented to the War Office; whilst Mr. Arthur
  du Cros and other members of the Parliamentary Aërial Committee
  arranged for a _Clément_ non-rigid air ship of new design, to
  sail from Paris to London, and also to qualify for purchase as
  a unit of the British aërial fleet.”

The non-rigid auto balloon ordered from Clément, and afterwards known
as the _Clément-Bayard II_, was the masterpiece of that skilful
designer, and occupied his best thought and energy for eighteen
months, aided by his devoted and capable engineer, Sabathier. She
was completed in the Clément-Bayard factory at Lamotte-Breuil in
April, 1910, and during the next five months made thirty-two test
ascensions and practice voyages. In particular she took a conspicuous
part in the military maneuvers at Picardie during the early half of
September, where with wonderful precision and airworthiness she made
forced voyages in fair weather and foul, remaining, when so desired,
in continuous communication with the land office by means of wireless
telegraphy. Finally, on a fair day, September 16th, the tried and
perfected vessel was brought forth from her hangar for the long
contemplated voyage to London, her machinery and rigging in trimmest
order, and her car furnished with supplies for twenty hours, or thrice
the anticipated time of transit.

The voyage was a glorious achievement for aëronautics, and for the
enthusiastic constructor and his devoted aids. Starting at seven
o’clock in the morning, with seven men aboard, including happy Clément,
Sabathier, and an English delegate, the whalelike cruiser sailed
directly to London with admirable regularity, covering the entire
distance of 242 miles in six hours, or at the rate of forty miles
an hour, which is better time than could be made by land and water.
Enthusiastic cheers from the English spectators greeted the arrival of
this French dirigible, built for the English government. Then quietly
the English soldiers took the vessel in hand, as if performing a
familiar duty, and housed her in the _Daily Mail_ hangar, at Wormwood
Scrubs. Thus simply and without unusual incident terminated the first
motor-balloon cruise between the two countries, and one of the finest
voyages in the history of aëronautics.

In outward appearance the _Clément-Bayard II_ closely resembled her
predecessor, except for the absence of empennage on her envelope. In
the whalelike elegance of her hull she was, in fact, a reversion to the
trim and efficient model of Renard’s dirigible of 1884, which in turn
was a fair copy of Jullien’s model of 1850, all having excellent forms
for speed and stability. But the new vessel was of greater size and
power than her predecessor. Her net buoyancy was sufficient to carry
twenty passengers. Her average speed tested in a round-trip voyage was
about 50 kilometers or 31 miles per hour when her two motors developed
200 horse power, and 55 kilometers or 34 miles per hour when the
engines developed their maximum effort of 260 horse power. The details
of construction were so elaborate and important, and so representative
of the best aëronautical workmanship of the time that a full account of
their chief features is presented in Appendix III. In passing it may be
added that some time before sailing to England the _Clément-Bayard II_,
because of her excellent workmanship and maneuvers, received the first
prize at the review of dirigibles by the French Minister of War.

PLATE VII.

[Illustration: _CLÉMENT-BAYARD I._

(Courtesy E. L. Jones.)]

[Illustration: _CLÉMENT-BAYARD II._

_Photo E. Levick, N. Y._]

[Illustration: FIG. 23.—_Clément-Bayard II_, 1910.]

The dirigible to be purchased with the money secured by the popular
subscription organized by the _Morning Post_ was ordered from the
Lebaudy factory at Moisson in July, 1909, to be delivered directly
through the air to Farnborough before November 6, 1910. This
stipulation was severe enough, but furthermore the vessel was to
be a considerable departure from any thus far built at that famous
factory, and was to be the largest air ship yet constructed in France.
As usual the general design of the huge balloon was entrusted to the
distinguished aëronautical engineer, Henri Julliot, and this was a
certain guarantee of its successful operation.

The general features of this great military dirigible resemble those
of her prototype, the _Patrie_, differing chiefly in the shape of her
hull and the method of stiffening. The hull itself was more longish
than the _Patrie’s_, but had the same sharp prow and blunt stern; for
a blunt stern offers better support to the empennage planes, though
it increases the resistance more than a tapering stern. The trussed
framing to stiffen the ship was no longer a platform inserted in the
base of the hull, but a long trussed beam of cruciform cross section,
made of steel tubing and suspended intermediately between the hull and
car.

The hull was of excellent workmanship and bold design. The envelope
was of rubberized tissue, measured 338 feet in length, 39.4 feet in
diameter and cubed 353,000 feet. Its length was, therefore, 8.5 times
its diameter, an extraordinary proportion for a balloon of the flexible
type. The hull was provided with three ballonets, two ripping panels,
and various valves, as shown in the scale drawing.

[Illustration: FIG. 24.—MORNING POST DIRIGIBLE, 1910.]

The car, made of steel tubing and large enough for twenty persons,
carried two Panhard-Levassor motors of 135 horse power each, actuating
two Chauvière wooden screws, sixteen feet in diameter, placed on either
side, well outward and upward, the transmission gear permitting either
engine, or both, to drive the screws at one time. Below the car and
well forward was a ground keel, or post, on which the whole vessel
could pivot with the wind, when riding at anchor, while a shorter
ground post was placed at the rear of the car.

The controlling surfaces were adequate and skillfully arranged. To
maintain steadiness and directness of flight, fixed empennage planes,
both horizontal and vertical, were provided, some attached to the stern
of the hull, others at the rear of the trussed suspension beam. To
direct the up and down movement, ailerons placed well to the front and
rear of the long framing, were turned about conjunctively in opposite
directions, thus causing the vessel to raise or lower her bow. Needless
to say, all these navigation appliances worked with ample force and
effectiveness from the beginning of the earliest tests.

After four preliminary ascensions the great air ship started from
Moisson to her destination at Farnborough, having on board Henri
Julliot, Louis Capazza, the pilot, Alexander Bannerman, director of
the aëronautic military school at Aldershot, and five other men. It
was a triumphant and glorious voyage, one of the most splendid in
the history of aërostation. Piloted by aid of chart and compass, and
by signal fires and captive balloons arranged along her route, the
vessel followed a direct course, without check or hindrance, crossing
a wide part of the English Channel and arriving before the hangar at
Aldershot, where the British soldiers awaited her, and where she was
safely landed, having made the whole voyage of 230 miles in 5.5 hours,
at a level varying between five hundred and two thousand feet. As
shown by the accompanying map, about one third of the route lay over
the Channel, or, more accurately, 78 miles, which was traversed in two
hours. Thus the whole journey was accomplished at an average speed
of nearly forty-two miles an hour, or in less time than it could be
effected in any other way than through the air.

[Illustration: 15 Novembre 1910

FIG. 25.—ROUTE OF BRITISH MILITARY DIRIGIBLES FROM FRANCE TO ENGLAND,
1910.]

The United States War Department, in 1908, started an aërial squadron
by purchasing from Thomas S. Baldwin, for $10,000, a tiny air ship of
the flexible type, a trifle larger than Santos-Dumont’s _Runabout_, but
in fact the smallest military dirigible then in existence. It had a
rubberized gray silk cylindrical hull slightly tapering toward the rear
and terminating in ogival ends, its length being 96 feet, its major
diameter 19½ feet. From this was suspended, by means of netting and
steel cables, a longish car having at the rear a double rudder working
about a vertical hinge, at the front an elevating plane and an 11-foot
wooden screw driven by a Curtiss 20-horse-power water-cooled engine.
With two men aboard, this vessel readily attained over twenty miles an
hour in a straightaway course, and at times more nearly thirty miles an
hour. Its total ascensional force was 1,350 pounds, of which 500 were
available for men, ballast and supplies.

Santos-Dumont’s most strenuous disciples outside of France were found
among the German military officers. These advocated and promoted both
the semirigid and the flexible types of auto balloon, with such ability
as to match the best productions of the foremost French designers.
The most successful pioneers of these two types in Germany were
respectively, Major von Gross, commander of the balloon battalion at
Tegel, near Berlin, and Major Von Parseval of the Bavarian army, and
director of the Society for the Study of Motor Air Ships.

Beginning in 1907, a number of Gross auto balloons were built in
succession, for the German Aëronautical Battalion, by Master Engineer
Basenach, under the supervision of its commander, Major Gross. The
first was intended only as a model, though it was large enough for
two passengers. It cubed 63,000 feet, but having an engine of hardly
more than 20 horse power, was necessarily slow. It was succeeded by
the _Gross I_, and others, all having rigid ventral parts, like the
_Patrie_, but with hulls of rather better form for speed and bulk
combined, having blunter bow and longer stern.

PLATE VIII.

[Illustration: _U. S. SIGNAL CORPS DIRIGIBLE I._

(Courtesy U. S. Signal Corps.)]

[Illustration: _GROSS II._

(Courtesy E. L. Jones.)]

The second Gross air ship, built in 1908, cubed 176,000 feet, and
attained a speed of 27 miles per hour, driven by two 75-horse-power
Daimler motors. On September 11th of that year, with four persons
aboard, she made a round trip from Berlin lasting 13 hours, covering
176 miles, and attaining altitudes up to 4,000 feet. This was one of
the finest voyages known at the time. This air ship was purchased by
the German government, named _Gross I_, and sent to Metz. A detailed
description is given in Appendix III.

The _Gross II_, brought forth in April, 1909, resembled her predecessor
in build, but had greater power and speed. Her hull cubed 176,000
cubic feet, had a blunt bow, full body and sharp stern, was provided
with horizontal and vertical keels, a sliding weight, and a ballonet
at either end. She was propelled by two Körting engines of 75 horse
power each, actuating two three-blade propellers. Under the action of
her keels and stabilizing planes and rudder, her motion was steady and
precise. A special feature of this air ship was the wireless telegraph
equipment by which she could send messages in all directions over a
range of 300 miles or more. She made many practice voyages during the
season of 1909, sometimes alone, again in concert with other auto
balloons and with troops. In August she made a fine voyage of sixteen
hours, from Tegel to Apolda and return, traversing 470 kilometers.

The above described vessel was followed by others, large and small.
The _Gross III_ measured 70 meters long, cubed 7,500 meters, and was
propelled by four Körting motors aggregating 300 horse power. This was
a splendid vessel, and one of extraordinary speed.

Various auto balloons of the Parseval type were designed by Major Von
Parseval of the Bavarian army, who also was one of the inventors of the
kite balloon. Satisfactory experiments with his air ship were made as
early as 1906. These formed the basis of larger vessels, subsequently
constructed in the same factory of August Riedinger of Augsburg,
for the Motor Air Ship Study Society, of which Parseval was general
manager. This society, organized practically at the command of the
Emperor, purchased the Parseval patents and began the development of
auto balloons as a business enterprise, soon furnishing a series of its
flexible air ships to the German army.

After the experiments of 1906, the Parseval air ship was enlarged from
2,500 to 2,800 cubic meters, its length becoming 52 meters and its
major diameter 8.7 meters. Its hull was of cylindric form, with rounded
bow and egg-shaped stern; had two air bags—one fore, the other aft—and
at the stern carried two fixed horizontal planes and a vertical rudder.
From this envelope the car, made largely of aluminum, was hung by steel
cables, and on its bottom had trolley wheels resting on suspension
cables joining the front and rear parts of the hull. The vessel was
propelled by a 50-horse-power Mercedes motor actuating a four-blade
screw propeller 13 feet in diameter, mounted between the car and hull.
This screw was made of thin steel tubes covered with shirting. Among
the merits of Parseval’s air ship may be mentioned its lightness and
demountability, and its kite-like effect on the air, got by canting
the hull while the car, rolling on the suspension cables, allowed
the screw mounted above it to thrust horizontally. The canting was
effected by giving one ballonet more air than the other, thus causing
its end of the hull to sink. The speed was about twenty-five miles per
hour.

PLATE IX.

[Illustration: _PARSEVAL I._

(Courtesy W. J. Hammer.)]

[Illustration: _PARSEVAL II._

(Courtesy E. L. Jones.)]

The second _Parseval_ was of greater bulk and power than her
predecessor. Her hull which was of cylindric form, with round prow
and pointed stern, measured 190 feet long, 30.5 feet in diameter, and
113,000 cubic feet in volume. She resembled her predecessor in the
arrangement of the two ballonets, and in the “loose,” or trolley,
system of suspension of the car. The propeller was a unique patented
device of Von Parseval’s. It had four cloth blades so weighted with
lead as to stand out firmly under centrifugal force, assuming an
effective shape for propulsion, though limp and deformed when at rest.
Various interesting evolutions were performed by this vessel in the
autumn of 1908, including tests imposed by the military authorities,
as a condition of purchase by the government, one requirement being a
voyage of one hour at an altitude of 1,500 meters; another requirement
being a continuous cruise of twelve hours. These tests completed,
the Motor-Luftschiff-Studien-Gesellschaft sold its proud ship to the
Vaterland for 210,000 marks.

About the same time the War Department purchased the _Gross I_, already
described, and Zeppelin’s third great ship, naming it _Zeppelin I_.
Germany thus began her program of developing a great aërial fleet,
by acquiring three powerful and well tried ships, each capable of
remaining all day in the air, and having a radius of action of several
hundred miles. They were frequently called upon to make test voyages in
all kinds of weather, to maneuver with the troops, to pass in review
before the Emperor, at times conveying prominent officers and members
of the noblest families, including Prince Henry and the Crown Prince,
who manifested a fondness for navigating about their newly opened
empire of the sky. But sometimes the tests were crucial. On September
11, 1908, both the _Gross_ and _Parseval_ were summoned to Potsdam by
His Majesty. They set forth from their sheds, at Tegel, in face of a
strong wind. After journeying some distance they each had to abandon
the voyage, the _Gross_ returning home, and the _Parseval_ falling to
the ground owing to an accident.

The third Parseval air ship was brought forth on February 18, 1909, by
the Luftfahrzeug-Gesellschaft, an aëronautical firm founded by merging
the Motor-Luftschiff-Studien-Gesellschaft with the A. E. G. This vessel
closely resembled her predecessor, but possessed greater size, power,
and perfection of detail. Her hull at first measured 224 feet long,
47 feet in diameter, and 198,000 cubic feet in volume, but later was
enlarged to 235,000 cubic feet by increasing its diameter.

Her car, which could accommodate twelve passengers, was framed of steel
tubing covered with canvas, and was divided into two parts, separated
by the big gasoline cylinder running athwart ship, the passenger cabin
being to the fore, the engine room aft. Here were stationed the two
engines, of 120 horse power each, actuating reversible right and left
_Parseval_ screws 13 feet in diameter, located to the rear, well aloft
and outward on either side. In the forepart of the passenger cabin was
space for the pilot and his navigating appliances; his chart desk, his
valve controls, his statoscope, manometers, etc.

The great ship with her nine tons burden was to have sailed from
Bitterfeld to Frankfort, for the Aëronautical Exposition, but owing
to excessive gales, she was sent by rail. Once there, she made many
excursions, at times carrying passengers at a schedule rate, reported
to be 200 marks for a voyage of one to two hours. In October she made
an inter-city excursion covering a distance of nearly 500 miles, during
which she passed four nights in the open air, finally returning in
good form to Frankfort. On October 27th she made a farewell tour about
Frankfort, then voyaged along the Main and down the Rhine valley to
Cologne, there to participate in the aëronautic military maneuvers,
together with the _Parseval I_, the _Gross II_ and the _Zeppelin
II_. Having passed creditably through these and other operations in
the autumn, she was eventually stationed at Tegel, as a part of the
national fleet.

The fourth _Parseval_, a smaller vessel, was built for the Deutscher
Aëro Club early in 1909. Her hull cubed 113,000 feet, and her framing
was made of the strongest materials, carefully hollowed, to eliminate
undue weight. At the rear of the car, on either side, were two
100-horse engines, driving two _Parseval_ propellers at a common speed,
whether both engines were in operation, or only one. In many respects
she resembled her immediate predecessors, and her little successor
_Parseval V_ of 1,200 cubic meters capacity and 30 meters length, built
for the Imperial Automobile Club.

The maneuvers at Cologne constituted the first grand demonstration of
the new fleet of military dirigibles, and proved a severe test of the
powers of the air ships, even when manned by experienced crews and
commanded by regular military officers. Two companies of the balloon
corps battalion were in attendance. Large provisions of hydrogen loaded
on wagons, each carrying 100,000 cubic feet, were kept in readiness to
be attached to an express train and rushed at the first alarm to any
balloon in need of replenishing. On Sunday, October 31, three of the
dirigibles representing each type, _Zeppelin IV_, _Parseval I_, _Gross
II_, left Cologne together, by official order, and returned after
flights of 7, 10 and 11 hours respectively, covering in the aggregate
930 miles. Again, leaving Cologne shortly before noon on November 3d,
they went down the Rhine, simulated a concerted attack on the great
fortress of Eherenbreitstein, and returned in the evening, each having
covered 155 miles. And so on for many days they continued to execute
maneuvers under military orders and in severe forced marches.




                              CHAPTER VI

                    DEVELOPMENT OF RIGID DIRIGIBLES


Count Ferdinand von Zeppelin, the famous cavalry general of Würtemburg,
and hero of the Franco-Prussian war, after retiring from the army,
organized, in 1898, a limited liability company for the purpose of
developing a new type of dirigible which he had long contemplated.
It was to be a vessel far larger and swifter than any the world had
yet seen. In the summer of 1900, after two years of industrious
experimental research and active construction, he brought forth from
his floating laboratory on Lake Constance, near Manzell, the first
of those wonderful air ships which have aroused such expectation and
enthusiasm in Germany. In outward appearance and in its chief features
of design it typified the whole series of motor balloons thus far
developed and navigated by that illustrious inventor. Many valuable
improvements were added, as a result of trial and the advance of the
collateral sciences; but the fundamental plans seem to have proved as
practical as they were bold and original. One by one were surmounted
the greatest obstacles, physical, financial and finally political; for
the Prussian Ministry did not favor his project at first, and many
aëronautical adepts were adverse to it. Those huge ships faced the fury
of many a tempest; their dauntless builder endured the storm of hostile
criticism; but in the end, builder and ships alike won the plaudits of
a proud empire and of an astonished world.

Outwardly a Zeppelin balloon may be described as a long cylinder with
ogival ends and a V-shaped keel running the length of its bottom. From
afar the cylinder and pointed ends appear circular in cross section,
but they are sixteen-sided. About one-third the distance from either
end of the great ship a small boat is suspended from the hull so
closely that at those places the keel is omitted to make room. These
two boats are rigidly connected with the hull and support it when the
vessel rests on, or is towed along the water. Within them are the crew
and petroleum engines, while above them and outward on each side of
the hull, and fastened to it by outriggers, are two pairs of screw
propellers, so placed as to exert their united thrust along the line
of resistance. In some cases the crew can walk through the V-shaped
keel from one boat to another, the passageway being illuminated here
and there, by transparent covering, or windows of celluloid, along the
sides and floor. Again an observer may climb up through the hull and
take observations of the sky from above. Telephones, electric bells,
and speaking tubes serve to transmit intelligence from one part of the
vessel to another.

The frame of the hull is formed of sixteen longitudinal beams, or
girders, of trellised metal work running from prow to stern and
riveted at regular intervals to cross bridges of similar trellised
metal work, each cross bridge being a sixteen-sided wheel with
trellised rims strengthened by radial rods running inward to a
central flange of sheet aluminum. Thus the body of the vessel is
divided into many compartments, each bounded by two wheels, and the
surrounding longitudinal beams. Each compartment contains a hydrogen
balloon, or sac, which fairly fills it and exerts a lift against
the longitudinal beams and against a netting formed of ramie cords
stretched from wheel to wheel, diagonally between beams at their
inner corners. Similarly the outward corners of the beams are joined
by strong diagonal wires for the purpose of rigidity, and the whole
external frame is covered with a heavy fabric which forms the outer
skin, or wall of the hull. Between this skin and the hydrogen bags
are air spaces, as also between bag and bag. Thus the whole vessel is
buoyed up by numerous thin hydrogen sacs, protected by the frame and
outer skin from the direct sun, from foul weather, and from external
shocks. The gas bags are also separated from each other by the bridge
work and flanges of aluminum.

PLATE X.

[Illustration: _GROSS III._]

[Illustration: ZEPPELIN AIRSHIP STRUCTURE.]

Obviously there is a material advantage in having many gas cells and
two propelling plants; for if one fails it may not prevent navigation.
The tandem arrangement of bags separated by the wheel-like cross
bridges also allows the balloon to rear any amount without material
displacement of the gas, or dangerous increase of pressure; for it must
be remembered that a single hydrogen sac extending the full length of
an up-ended balloon of such length, would have an outward pressure of
about thirty pounds per square foot greater at the top than at the
bottom. The poise of the vessel is maintained by shifting weights, and
also by use of fins, or rudders, when driving through the air; but
those arrangements vary in the different machines. So much for the
general features of these wonderful ships, of which four were built
during the decade from 1898 to 1908, and several more since that period.

The construction and trial of Count Zeppelin’s first air ship proved a
formidable task, requiring all his resources of money and mechanical
skill. As it rivaled in size and fluid displacement a large ocean
liner, it could not well be launched and landed, except on the water.
It was therefore housed in a wooden shed 472 feet long, floating on 95
pontoons, and so anchored as to swing freely with the wind and assume
its direction. This shed, as well as the ship, was very costly, and
in an unfortunate hour was torn from its moorings by a tempest, which
did other damage entailing great expense and time for repairs. The
inventor’s resources were becoming strained; for, as reported, the shed
cost $50,000, while the first balloon cost more than twice that sum.

Finally, the first launching was officially set for June 30, 1900. The
lake was thronged with people massed along the shores, and dotting
its surface with every kind of craft, from the fisherman’s primitive
boat to the handsomest private yacht, or launch. All day the expectant
multitude waited, only to learn at dusk, that the inflation was not
completed. Next day they tarried again till evening, and merely saw
the raft on which the balloon rested, towed out of the floating house.
On the third day, July 2d, those who waited were rewarded with an
interesting spectacle. The long stiff air ship was drawn forth from
its shed, like a ram rod from a gun. Count Zeppelin, with two men,
occupied the front boat, while two others took the rear one. After
careful adjustment the vessel was liberated, at eight o’clock, rose
slowly and advanced over the water, accompanied by the droning of its
propellers and the shouts of the delighted spectators, who realized
that they might be witnessing the commencement of a new epoch in
aërial navigation. But the voyage was not an unqualified success.
The controlling mechanism became deranged, the framework was bent,
and the propellers could not be worked properly. A gentle wind was
blowing and the vessel drifted with it, having an independent speed
of only thirteen feet per second, at best. At eight-twenty she reached
Immenstadt and landed on the water, having voyaged three and one half
miles, and having attained a height of thirteen hundred feet on a part
of the journey.

At that date the _Zeppelin I_ was by far the largest and most
elaborate air ship ever constructed. Her hull measured 416 feet long,
38 feet across, cubed nearly 400,000 feet, weighed 9 tons, and had a
displacement of 10 tons. The trellised frame was made of aluminum, and
its body comprised seventeen compartments, of which fifteen were 26
feet long, and the other two 13 feet long. The outer cover was of linen
treated with pegamoid and tightly stretched. The hydrogen sacs were of
thin fabric. The propulsion was effected by two benzine motors, one in
either boat, which together developed 32 horse power, each driving,
by means of bevel gears and shafting, a pair of four-blade propellers
3.77 feet in diameter, at 1,100 revolutions per minute. Steering
sidewise was effected by means of vertical rudders, while the trim was
controlled by horizontal rudders at either side of the vessel, as also
by means of a sliding weight which could be drawn fore and aft by means
of a winch. Naturally some of these details were superseded ere long by
better devices suggested by subsequent experience.

On October 17, 1900, _Zeppelin I_ made her second voyage, and with much
better result. Starting from the same balloon house at Manzell, at
four-forty-five, she promptly rose a thousand feet, and maneuvered in
a seven-mile wind, steering in great curves at the will of the pilot.
At times the speed was nearly twenty miles an hour, as determined by
continuous observations of the balloon’s position, taken from three
points of a triangle, together with the velocity of the wind on its
course, duly recorded by an anemometer. Finally a landing on the water
was made at six o’clock, without mishap.

This last demonstration left the Count triumphant in other respects,
but without sufficient funds to bring his invention into practical
use. He must, therefore, look for additional money for the proper
continuation of his great work. The financial task thus ensuing
occupied much of his time during the next five years, but he finally
secured capital enough to continue his experiments and to build a
second airship. This was completed and ready for trial in the latter
part of 1905.

_Zeppelin II_ resembled its predecessor in appearance, but embodied
many improvements suggested by the former trials. Its hull was 414
feet long, 38 feet in diameter, held 367,000 cubic feet of hydrogen
in its sixteen gas bags, and weighed with all appliances and cargo,
about nine tons. It was, therefore, about ten per cent smaller than
its predecessor; but at the same time it was far better powered than
the earlier one, and more effectively controlled. Each boat carried
an 85-horse-power Daimler benzine motor, actuating two enlarged
propellers. Ample steering surfaces, operated by the helmsman in the
front boat, served to turn the great ship about either of three axes
and, at the same time, to displace her bodily up and down in the air,
either by direct lift or by canting her hull so that her screw thrust
and the pressure on her sides would produce the desired translation.

Two trials of Zeppelin’s second air ship were made on the Borden-See,
one on November 30, 1906, the other on January 17, 1907; but both
met with serious accident. In the first trial the balloon was towed
by a motor boat some distance, then cut loose in the wind, which
was carrying it forward faster than the boat. But it soon became
unmanageable and plunged into the water, suffering considerable damage.
In the second trial it flew for a short time at a speed of thirty
feet per second, when the engines were developing 36 horse power.
Some maneuvering was effected in a strong wind, but presently the
propellers stopped, the vessel dropped to the shore and was anchored on
the ground. During the night it was so badly damaged by the wind that
Count Zeppelin ordered it to be taken to pieces to furnish material for
further construction.

The loss of two mammoth air ships after such brief trial seemed
enough to appall even a sturdy general of the Prussian army; but
Count Zeppelin was too resolute to waste time in futile tears and
hopeless dejection. Strong natures are usually stimulated by disaster,
and aroused to fuller energy, to grimmer determination, if not to
desperate hazard. However, not desperation, but buoyant hope and high
expectation, based on ample experience, were now his ruling motive. Had
not his ship attained thirty feet per second with less than one fourth
her motive power? The year began with disaster indeed, but he intended
it to terminate in glorious victory. And such, indeed, was the happy
issue.

October, 1907, witnessed the launching of _Zeppelin III_. She had the
same length as her immediate predecessor, but she was a luckier vessel
and better powered. On her official trial she voyaged at the height of
half a mile, carrying eleven persons sixty-seven miles in two hours
and seventeen minutes, or at more than twenty-nine miles per hour.
This was a record velocity exceeding that of the best military balloon
in France. At times she attained a velocity of fifty feet per second,
thus considerably outspeeding the swiftest ocean liner. Moreover, her
stability and steering qualities were excellent. With pardonable
elation, therefore, the illustrious inventor could report to the
Minister of War the complete success of his experiments. And with good
reason the German government now granted financial aid to test more
fully the merits of the rigid system of construction.

With this assistance the industrious aëronaut erected a new floating
house on the Borden-See at Friedrichshafen, and began the construction
of a still larger air ship embodying further improvements in various
details. _Zeppelin IV_ was 446 feet long, 42.5 in diameter, held
460,000 cubic feet of hydrogen in her sixteen compartments, and had a
total buoyancy of sixteen tons. She had a surplus buoyancy of over two
tons, carried a crew of 18 men, and had an estimated range of action
of eighteen hundred miles. When drawn from her shed in the autumn of
1907, her great buoyant hull resting lightly on the water supported by
her two floating cars, she had all the appearance of a royal passenger
express ready for important service. In general features the vessel
was like her three predecessors, but in the center of the keel, with
transparent floors and windowed sides, was a special stateroom designed
for passengers only. This seemed very suggestive, if not prophetic,
of the future trend of aërial navigation. Moreover, the mechanism of
propulsion and control were increased in power and effectiveness.
In each boat-like car was a 110-horse-power Daimler benzine engine,
actuating a pair of three-blade propellers about 15 feet in diameter.
A large vertical rudder, mounted on the extreme end of the stern, and
supplemented by a pair of smaller vertical rudders at either side of
the stern, served to steer the vessel right and left. For steering
up and down, as also for exerting a direct lift up or down, four
superposed planes like a Venetian blind were placed at either side of
the hull fore and aft, at about the same level as the propellers. In
addition the hull was provided, like a feathered arrow, with fixed
fin-like planes at the stern, both vertical and horizontal, for
securing steadiness of flight.

Several trials of this leviathan were made preliminary to her official
government test which, if satisfactory, assured her purchase by the
German government for $500,000. At the builder’s suggestion this test
should include a voyage of 24 hours duration, a safe descent on land or
water, an ascent to 4,000 feet, and the fulfillment of various secret
requirements. In the autumn of 1907 a successful voyage of eight hours
was easily accomplished. In the early part of the next summer, 1908, a
series of voyages were made which aroused intense interest throughout
the civilized world. On June 13th the great ship, starting from her
harbor at Friedrichshafen, sailed over the Alps to Lucerne, steering
in among the mountains; here buffeted by eddies, and cross currents,
there stemming such stiff head winds that her shadow could hardly
creep forward over the ground, again driving through a dark lowering
hailstorm which pelted with ominous thunder on her resounding hull; but
at length reaching Lucerne safely, then returning in triumph to her
harbor at Friedrichshafen. For twelve hours the stanch vessel endured
the elements, by no means hospitable, and in that period voyaged 270
miles at an average speed of 22 miles an hour. It was a record journey
and a triumph in the art.

The following picturesque account of a flight in Count von Zeppelin’s
gigantic air ship, written by Emil Sandt, appeared in the _Scientific
American Supplement_ of August 15, 1908:

  “Early in the morning Professor Hergesell, Freiherr von
  Bassus, Dr. Stalberg, Herr Uhland, and myself set out in
  Count Zeppelin’s launch for the shed in which the great air
  ship is housed. When we arrived everything was in readiness
  for us. Count Zeppelin is proud of the fact that his colossal
  craft can be drawn in and out of the shed with very little
  help. In seven minutes the huge gas bag had emerged, and a
  few minutes later we were floating up to the sky. I took my
  station in the central car or cabin, a comfortable room flooded
  with the yellow light that filters through the translucent
  balloon fabric of which the walls, the floor and the ceiling
  are constituted. Comfortable seats suspended from fine chains
  provide a seating capacity for a dozen passengers.

  “For a great portion of their length the walls are provided
  with celluloid panes. The floor is also transparent wherever
  it is not used as a footway. Seated comfortably in the central
  car, I could look down through my knees and see the green
  earth, water, people, cities and castles far below. I could
  also see birds circling around and fluttering anxiously,
  evidently frightened by the strange giant of the air.

  “We crossed over to the Ueberlinger See, traversed the
  intermediate neck of land, and turned into the valley of the
  Rhine at Konstanz. Here I left the central car and walked
  toward the rear car along the keelway, which is flanked with
  balloon cloth, and which is closed at the end of the keelway
  by a celluloid door. I opened the door and stepped out on the
  narrow aluminum gangway, which runs down sharply to the rear
  car. The gangway has no protecting handrail. It is merely
  ribbed to give a better foothold. That apparently flimsy
  structure bridges a chasm of twenty feet between the end of the
  keelway and the car. From below, the passage from the keelway
  and the car must seem perilous indeed, but up in the air ship
  itself no fear is felt. I stood on this narrow bridge and gazed
  on the landscape. To the north I could see the Hohendtwiel.
  Behind us lay the Swabian See glistening in the morning’s sun.
  In the southeast I saw Thurgau wrapped in violet light. On the
  horizon the lofty peak of the Saentis rose broad and jagged,
  capped with ice and snow. Below us writhed the Rhine. I looked
  across at the propellers. Count von Zeppelin had signaled full
  speed ahead. The giant air ship trembled. The propellers seemed
  like disks, revolving with furious speed and yet as transparent
  as a locust’s wings. They gave out a note like that of a deep
  organ, so loud that the human voice, even when lifted to a
  shriek, could hardly be heard.

  “I walked down to the rear car to obtain a better view. Here
  the gigantic craft could be seen in a wonderful perspective.
  The sensation was strange. The giant ship obediently sank and
  rose. Obediently moved to the right or to the left, slavishly
  following the slightest pressure of the human hand. Sometimes
  its angle was such that the entire fabric seemed inclined like
  a kite. At times the forward car lay below us; at times we had
  to look up at it.

  “As we neared the splendid falls of the Rhine at Schaffhausen,
  the Count brought the air ship down, in order to ascertain
  whether the eddies occasioned by the waterfall would have any
  effect.

  “We turned into the Reusstal, but were buffeted by the wind
  all the way up the valley. To the south the sharp jutting
  peak of Mount Pilatus hove in sight. Soon Lucerne appeared, a
  jewel among cities. The lake itself shimmered brightly where
  it was struck by the sun; its darker portions lay like an
  emerald, held in a setting of heliotrope. It was like a melody
  in colors. Below us in Lucerne itself there was a hubbub and
  a great jubilation. The streets were crowded with gayly clad
  people. The roads were a-swarm. Zeppelin guided his air ship
  down, and allowed it to glide full speed over the city at the
  height of a church steeple.

  “We traveled over the Vierwaldstaetter See, and crossed to
  Knessnacht, to Zug Lake, and up northward to Zug itself. Then
  came the most difficult task which Professor Hergesell had
  assigned to the air ship. The craft was to carry us straight
  across to Lake Zurich, through a narrow pass where it would be
  caught in a veritable cyclone. The motors groaned and rattled.
  The propellers howled a deep groaning song. The air ship did
  all that it could. The wind was dead against us, traveling
  with a velocity of nearly thirty-one miles an hour. The Count
  could easily have arisen and escaped the fury of the blast,
  but it was his purpose not to avoid obstacles, but to court
  them. Whenever the great air ship showed signs of swerving, it
  was brought back to its course. Far below us in the valley the
  sharply marked shadow of the air ship, crawling slowly from
  tree to tree, showed us how hard it was struggling. There were
  minutes when it seemed as if we stood stock still, despite the
  infernal music of the propellers. Gradually the nose of the
  craft was thrust forward; once more the air ship mastered the
  winds. We had forced our way through the pass, and were dashing
  on at full speed. The vast shadow below us traveled with the
  velocity of a bird over the mountain, valleys, cliffs and rocky
  points, over railway embankments and road, over water and land.”

Two attempts were made in July, 1908, to complete the government test;
but they proved abortive, and in the second one the hull was damaged by
the wind pushing it sidewise against the shed, as it was being towed
out by motor boat. This accident caused a delay of two weeks, much
to the disappointment of the expectant populace. As a consequence
Zeppelin resolved to begin the next attempt unheralded. He had the
repairs made quickly and all was ready early in August.

On Tuesday, August 4th, at six forty-five in the morning, the great
twenty-four hour test for the government began, without previous
announcement, but with fairest prospect of success. Sailing from
Friedrichshafen, Zeppelin purposed to follow the Rhine as far down
as Mayence, then return in a direct line to his starting point. All
went splendidly at first. He passed Constance at seven o’clock in
the morning, Basle at nine-thirty, Strassburg about noon, then with
slower speed passed Mannheim at two-fifty and Darmstadt at four-thirty.
At about six o’clock a descent was made at Oppenheim, eleven and a
quarter hours after starting. The air ship had voyaged 270 miles at the
average speed of 22 miles an hour. A wonderful demonstration it was
for the inhabitants of that historic valley, and a glorious tour for
the brave old sailor and his crew. Resuming the voyage, Mayence, the
turning point, was reached at eleven o’clock at night, and the vessel
was headed for home. But now the engines, being overworked, could
not maintain the usual speed, which therefore was lowered to twelve
miles an hour. Next morning at eight o’clock, after Stuttgart had been
passed, a descent had to be made at the village of Echterdingen, to
adjust and overhaul the machinery. Ninety-five miles of the return had
been made in nine hours.

It was most unfortunate that a landing had to be made without a harbor,
particularly as a gale was in pursuit of the vessel. Ere long she was
torn from her moorings by a squall, carried into the air, and set on
fire, probably by an electric discharge. Immediately the great hull was
enveloped in flame and completely destroyed, leaving a tangled network
of distorted framing. It was a dismal termination to the greatest motor
balloon voyage in the world’s history up to that date; for the vessel
had been in the air continuously for twenty and three-fourths hours and
had traveled 378 miles.

The hardy and venerable hero of so many voyages and long continued
experiments quite broke down at the sight of his grandest vessel in
ruin. But an unlooked for and a sudden turn of events brought him the
greatest triumph in his darkest hour. While the world expressed its
grief and sympathy his loyal countrymen hastened to his relief in an
admirable burst of enthusiasm. Within twenty-four hours the government
had made him a grant of $125,000, and subscriptions offered in all
parts of Germany brought the sum to over $500,000. By October, 1908,
the total gift amounted to $1,500,000, which was paid to the Zeppelin
Air Ship Company, formed for developing and building air ships on a
large scale. A tract of 300 acres was secured at Friedrichshafen for
an air ship factory. Here was erected the necessary shops, hydrogen
plant, balloon harbor, and everything necessary to enable the company
to construct several mammoth air ships each year. To these new grounds
the Count’s former interests were gradually conveyed, while his old
station, with its air ship dock on Lake Constance, was converted into a
military post by the German government.

After the destruction of _Zeppelin IV_, its predecessor, the Count’s
third air ship, was again prepared for service and for new triumphs.
Her hull was lengthened by the addition of a cylindrical section having
the length of one compartment, or about 26 feet. This alteration gave
a considerable increase of net buoyancy with but slight increase of
resistance. The dimensions now were: length 446 feet, diameter 38
feet, volume 423,768 cubic feet. The gas was contained in sixteen
sacs, twelve in the cylindrical part and two at each end. The ship
was propelled by two 85-horse-power engines, supplied with sufficient
gasoline for a forty-one hour voyage at 25 miles per hour. The loss of
gas by leakage was less by weight than the loss of fuel. The famous old
cruiser, thus remodeled, was operated in the autumn of 1908 with her
usual precision and grace; thus winning new distinction and renown. On
one occasion she had as passengers the Crown Prince and the Kaiser’s
brother, Prince Henry. The Emperor himself witnessed the demonstration,
and decorated the Count, referring to him as “the greatest German of
the century.” Soon afterward the ship was taken over by the government
and assigned to the Prussian Battalion of Aëronauts, being christened
_Zeppelin I_, since it was the first vessel of the kind taken into the
military service.

Beginning with March 9, 1909, the military _Zeppelin I_ was kept in
active operation by the officers, and subjected to a wide variety of
tests day by day. She was driven through rain and snowstorms, at all
elevations up to a mile; she was anchored over land and over water,
sometimes exposed for hours to a gale; she was steered in and out of
her shed without the aid of her floating raft; she was sent on long
trips, landed in the open country, by day and by night, and returned to
harbor in safety. On one occasion she carried twenty-six passengers for
over an hour and a half; again she made an endurance flight of thirteen
hours. These maneuvers exhibited for the first time many capabilities
of the ship, which all along had been stoutly affirmed by the inventor,
but questioned by his critics.

On April 1, 1909, at four o’clock in the morning, the renowned
_Zeppelin I_, with the Count as helmsman, started through the rain
and wind on a voyage from Friedrichshafen to Munich, a hundred miles
distant. The ship followed the railway as far as Ulm, guided by the
station lights, which were kept burning all night to mark the route. As
she approached Munich, at the appointed hour of nine next morning, her
approach was announced from afar by the droning of her machinery and
propellers, whereupon she was welcomed by loud music from many bands
and the joyous ringing of all the bells in the city. The Prince Regent
of Bavaria and a great throng of applauding citizens awaited her at the
Teresenhohe park. Presently the swift cruiser approached, sailing over
the steeple tops like a monstrous arrow. She halted before the Regent
and dipped her bow three times, in graceful salute. Then she circled
widely over the city, intending to land at the Oberwiesenfeld Parade
Grounds, where part of the garrison troops were drawn up to receive
her. But now, while so near the goal, she found it difficult to stem
the increasing gale, and unsafe to land; so, with her bow pointed to
the city, and propellers humming furiously, she gradually yielded to
the storm, and drifted slowly backward toward the northeast.

The crucial hour had come for this stanch vessel and her audacious
captain. They wrestled with the storm bravely and obstinately, but
were beaten back steadily, with no port in view. The Count determined
to weather the gale till it should spend its fury. He coolly sent an
aërogram to Munich, saying that all was well and that he might reach
the city late in the day. Observing a suitable place to land, near
the village of Loiching, he pointed the prow of his ship downward,
approached the earth and cast anchor. As the front car touched the
ground it was grasped by the willing hands of thronging peasants and
villagers. Presently the ship was taken in charge by a military
relief party which the Count had hailed on the way, at Guendelkoven,
and which had hastened to his aid in automobiles. Fifty soldiers, in
regular shifts, that night held the bow of the vessel by a short leash.
The anchor was firmly fastened, and additional ropes secured the bow
to an unwheeled wagon loaded with stones. Thus all night long that
mighty hull swayed to and fro in the passing storm, securely as a ship
anchored at sea.

PLATE XI.

[Illustration: ZEPPELIN DIRIGIBLE RESTING ON THE WATER.

_Photo E. Levick, N. Y._]

[Illustration: ZEPPELIN DIRIGIBLE OVER ZÜRICH.

_Photo E. Levick, N. Y._]

Next morning the vessel was well replenished and headed for home, by
way of Munich. The return was easy, for the wind had nearly reversed
its course. Sailing at 32 miles an hour, with a quartering current,
the stormbeaten ship soon reached Munich, where she was hailed with
boundless enthusiasm. The Prince Regent entertained the Count during
his sojourn of three hours, and decorated him with a gold medal. The
ship then sailed for Friedrichshafen, with the full speed of the wind
and of her propellers, at one time attaining 68 miles an hour. At
nightfall she landed gently on the lake near Manzell, having weathered
that tempestuous voyage without serious mishap.

This was a splendid proof of her stanchness; but a few days later
she was put through other tests quite as severe, one being a night
voyage of thirteen and a third hours, after a day of busy maneuvering.
Following this came her still longer voyage, to Metz, where she was
stationed as a frontier war vessel, and one of a considerable fleet
contemplated by the German government.

In the meantime the energetic Count had started his fifth vessel, or
military _Zeppelin II_, which now was nearing completion at the works
of the Zeppelin Air Ship Construction Company. Her hull measured 446
feet in length, had a diameter of 42½ feet, and a volume of over
half a million cubic feet. It also had a ladder running through one
of the compartments to a platform on its top. Her motors of 220 horse
power were taken uninjured from the wreck of the old _Zeppelin IV_ at
Echterdingen.

Without previous notice this new air ship set forth in a rain on the
evening of May 29, 1909, headed toward Berlin, having on board the
Count and seven other men. The purpose of the voyage was merely to
exercise the ship; not to reach any definite goal; but by mistake she
was reported on her way to Berlin, so that the Kaiser and his retinue
waited some hours in vain to receive her. She voyaged bravely past
Nuremberg and Leipsic to Bitterfeld, within 85 miles of the capital;
then turned for home, the Count being unaware of the hopes he was
disappointing. She returned successfully past Weimar and Stuttgart,
then, near Goeppingen, descended on an open plain to take on gasoline
from a neighboring petroleum refinery. As they were nearing the ground
in a heavy rain, Count Zeppelin, who was acting as pilot, suddenly
beheld, just before them, a half dead pear tree, with gaunt bare limbs.
He gave a sharp order to starboard the helm; but his aëronaut, worn by
too long service, thrust the helm to port, and the ship, impelled by a
sudden gust, plunged head on against the tree. Her prow was wrecked,
the frame and envelope being wrenched and torn for a distance of 100
feet.

The disaster seemed complete, but the dauntless Count was equal to the
emergency. Twenty workmen were summoned from Friedrichshafen, sixty
miles away, and sped to the rescue in automobiles. Electric wires from
a nearby plant were stretched to furnish light for night repairs. The
grounds were guarded by police and troops. The hull was detached from
the tree; furnished with a temporary prow of young firs covered with
balloon cloth; relieved of the forward motors and other impedimenta;
furnished with fresh supplies; and, in exactly 28 hours from the
mishap, was ready for the homeward voyage.

Slowly the crippled air ship sailed for Friedrichshafen, followed by
the white-haired inventor in an automobile, unmoved and triumphant.
A mighty shout ascended from the immense crowd of witnesses who had
assembled from many quarters. All Germany was elated and jubilant. The
great voyage and the prompt recovery from apparent disaster were a
triumph of the whole people, for they had helped their hero to build
this ship, and now participated in his victory over the spite of
fortune and the elements. The Emperor telegraphed his congratulations,
affirming his renewed confidence in the rigid system. Without further
difficulty the vessel reached her port at an easy gait of ten miles an
hour, thus completing a memorable voyage of seven hundred miles—one of
the most glorious in the history of aëronautics.

If the citizens of Berlin were disappointed on this occasion,
they had not long to wait for an aërial visit from the wizard of
Friedrichshafen. On August 27th, at 4.45 A.M., his crew of five men
sailed for Berlin via Nuremberg and Leipsic in his sixth air ship,
his latest and largest, hurriedly finished for the Berlin voyage.
It cubed 533,000 feet, and was driven by two Daimler engines of 150
nominal horse power each. In the afternoon they reached Nuremberg,
circled over the city and landed for the night. Starting at 2.15 next
morning they battled their way toward Leipsic against a strong wind,
and at 6.45 P.M. landed for the night at Bitterfeld, where they arrived
with a broken propeller. Here Count Zeppelin joined them. The next
morning, after a good night’s rest and some repairs, they started at
half past seven, in a dense fog, which, however, soon cleared. Finally
they arrived at Berlin at half past twelve o’clock, as the people were
returning from church. They circled over the city, to the delight of
the multitude of spectators who thronged the house tops, parks, and
thoroughfares, finally reaching the parade ground at Tegel. Here,
after saluting the Emperor, the happy navigator maneuvered before the
imperial tribune, greeted by the thunderous Hoch! Hoch! of a hundred
thousand throats, and the ringing of all the church bells of the
nation’s capital. The venerable Count was graciously received by the
Emperor and members of the royal family. After spending the day at
Berlin, the crew sailed for Friedrichshafen, about midnight, where,
after various accidents and delays, they arrived in safety on September
6th.

In some respects this was Von Zeppelin’s crowning voyage of the year,
though effected with a hurriedly finished vessel, not yet thoroughly
adjusted. In mechanical execution this journey was equaled on many
other occasions; for those great air ships were kept in active service
and were everywhere hailed with enthusiasm. Both the Emperor and his
people were proud to number those grand cruisers among the nation’s
aërial warships. With general commendation, therefore, was received
the announcement that four large _Zeppelins_ were ordered for the use
of the German navy. And not surprising was the announcement that other
inventors were at work on designs for dirigibles of the rigid type.
The projects of these new rivals, who began to appear in 1909, are set
forth in the following account:[17]

  “Count Zeppelin, who proved that air ships have a practical
  future, is no longer undisputed ‘king of the air.’ His rivals
  have taken his pattern, and improved it until soon air ships
  will be able to keep afloat for many days and in that case to
  cross oceans. A type of this modern ship is the first Schütte
  leviathan of wood and steel bracing, now nearly finished at
  Mannheim. It is expected to lift its twenty-four and one-fifth
  tons one and a quarter miles, because its beam is sixty feet
  as compared with the forty-four feet of the _Zeppelin II_.
  The car is one hundred and thirty feet long, with a cabin to
  accommodate thirty passengers. The new ship displaces nineteen
  thousand cubic meters, as against fifteen thousand in the
  _Zeppelin III_. It is expected to carry a cargo of five to six
  tons supported by ten spherical sustaining chambers, and eight
  ring-shape reservoir chambers connected by a secret apparatus.
  These eight reservoirs automatically receive all expanding gas
  that escapes from the sustaining chambers, thus conserving the
  entire supporting power. Four motors of combined five hundred
  and forty horse power will drive the propellers. Expert opinion
  predicts a speed of thirty-seven to forty-three miles an hour,
  three miles faster than the _Gross III_, at this writing the
  fastest air ship in the world. The whole enterprise is backed
  by Mr. Lanz, a rich manufacturer, who is president of the
  German Air-Navy League. A wooden-braced ship of equal equipment
  and size, designed by the Engineer Rettich, is well under way.

  “Another rival of the _Zeppelin_, so far only projected, has
  been designed by the Engineers Radinger and Wagner, and is
  intended to be an advance in endurance. It should float for
  fifty days without replenishing gas. It is planned to have a
  rigid hull of hollow paper tubes and steel bracing and to be
  thirty per cent lighter than a _Zeppelin_ built of aluminum,
  in any equal size. Drum-shape compartments are to hold the
  sustaining hydrogen, none of which is to be lost through
  expansion by the sun, as any surplus will be compressed by
  automatic pumps into the hollow tubes.[18] Having six thousand
  meters less displacement than the _Zeppelin III_, it will carry
  a reserve of seven hundred cubic meters of gas. Thirty-two
  per cent of its weight-carrying capacity will be given up to
  passengers, fuel, and baggage. Engines of two hundred and
  forty-two combined horse power are expected to develop a speed
  of forty to fifty miles an hour. Larger craft of the same type
  would, of course, carry much heavier cargoes and have higher
  speed. This type of ship, soon to be placed in the construction
  cradle, is expected to cross the ocean easily with fifteen
  passengers.”

In keeping with the lively growth of these great ships was the
formation of the German aërial transportation company, with a capital
stock of $750,000, reported in _l’Aérophile_ for December, 1909. A line
of large _Zeppelins_ was to connect Baden-Baden, Mannheim, Munich,
Leipsic, Cologne, Düsseldorf, Berlin, Dresden, Essen and Frankfort.
The first two auto balloons of this line were to be the _Zeppelin
IV_ and _Zeppelin V_, to be put in commission in the spring of 1910.
The _Zeppelin IV_ was to cube 706,000 cubic feet, and carry twenty
passengers in three cars, each containing a motor. The _Zeppelin V_ was
to be constructed of a remarkably light rigid alloy “electrometal,”
and was to carry at least thirty passengers. This enterprise certainly
formed an appropriate termination to the first decade of practical auto
ballooning.

The projected passenger line of the German Air Ship Society was
inaugurated the following summer with serene audacity and fairy-like
magnificence. The first ship employed, _Zeppelin VII_, was a huge
vessel of unusual power, speed and elegance of appointment. She was
485 feet long by 46 in diameter, cubed 690,000 feet, and carried three
engines totaling 420 horse power and competent to drive her 35 miles
per hour. Midway beneath her hull and rigidly joined to it, was a
passenger car thirty-five feet long, having a vestibule at one end, a
lavatory at the other, and five compartments between them, with seats
for twenty persons. Beyond the ends of the car were open decks leading
to the boats fore and aft containing the machinery.

At three o’clock on the morning of June 22, 1910, with Count Zeppelin
in charge, and a dozen passengers aboard, this majestic auto balloon
sailed from Friedrichshafen up the Rhine Valley for Düsseldorf, three
hundred miles, and after a prosperous voyage of nine hours, made an
easy landing. Next morning at eight thirty she voyaged from Düsseldorf
to Dortmund, thirty-seven miles north, sailing at a general height of
one thousand feet, over some of the finest industrial parts of Germany.
Then she returned to Düsseldorf with her delighted passengers who were
all enthusiasm for the new mode of travel so auspiciously begun. Of the
thirty-two persons aboard, the majority were regular public passengers
who had paid fifty dollars each for the trip, several of them tourists
from various countries, and ten of them women.

The maiden voyage of this first air liner was a marvel and dream
of delight to the fortunate few traveling in such celestial style.
The comforts and splendors of the service quite surpassed their
expectations. Seated in that fairy car of aluminum framing lined with
mahogany and rosewood inlaid with pearl, they looked from spacious
windows over the beautiful German landscape gliding beneath them, and
enjoyed visions fit for itinerating gods. Along the shining waters of
the Rhine, and over its castellated crags, and among its rolling hills
terraced with luxuriant vineyards, now lapped in the glory of summer,
and above stately cities murmuring with multitudinous life, they sailed
in serenest comfort and security, marveling at their own strange
career through the sky, and equally regarded with wonder by all the
inhabitants below, not to say written and read about by millions in all
parts of the civilized world. The delights of land and sea travel were
happily mingled, without their inconvenience. Neither dust nor smoke
was here, nor rattle of iron rails, nor lurching and rolling from heavy
seas. Quite otherwise. The senses were charmed with the fanning of
fragrant winds forever and uniformly blowing, with the melodious drone
of the swift propeller wheels, with the green glories of the earth and
purple splendors of the sky. When the tourist was sated with these he
could turn to his book; when tired of his chair he could stroll to and
fro in the car on a soft carpet, or along the trellised deck beyond;
when his appetite called, he could answer with the choicest food and
wine; for every convenience of an ample buffet was available. It was
all so enchanting if only practical.

Encouraged by these trials the company announced, and hoped to make,
voyages at frequent intervals. But in this they promptly encountered
difficulties. On June 28th the _Deutschland_ started from Düsseldorf on
a four-hour cruise, with nearly a score of passengers, mostly newspaper
representatives. But she remained in the air longer than intended.
Passing Solingen she tried to reach Eberfeld, but ineffectually; nor
could she find a landing place. Toward five o’clock she was caught in
a great rising wind and carried one mile aloft like a passive balloon
in a vortex or thunderhead. Here much gas was lost by expansion, and
presently, as the ship emerged from a snow cloud in the upper vortex,
with cooled gas and hull laden with precipitation, she descended at a
terrible velocity. With crippled motive power, the vessel could not be
supported dynamically by the impact of the air against her sustaining
planes and against her canted hull, for lack of forward speed. At
length with a terrific crash she struck upon the forest of Teutoberg,
80 miles from Dusseldorf, a great tree trunk piercing the rear boat and
projecting among the terrified crew. Here the vessel lodged with her
stern and controlling gear badly wrecked, and here she was abandoned
by the passengers, with her huge hull resting on the branches forty
feet from earth. Ere long she was retrieved by a company of infantry
who sawed down the trees, dismantled the ship, and returned the parts
on railway trucks to Friedrichshafen, to be used in building another
vessel.

Thus in both civil and military aëronautics the pioneers had to endure
many losses and grievous hardships; but the direst disasters often mark
the way to the greatest victories.




                                PART II

                          GROWTH OF AVIATION




                              CHAPTER VII

                         MODEL FLYING MACHINES


From time immemorial man has admired the aërial evolutions of
wing-gifted creatures, and aspired to imitate them. But which
evolutions should he attempt first? Which if any are practicable for
the ponderous lord of creation? The question is still pertinent.

Nature in her bounty bewilders us with wondrous models. All about
and overhead, with exquisite art, they challenge us to float or fly.
Before the flower-bell drifts the ruby-throat, his long bill in the
honey-hearted bloom; now bulletlike he leaps through boundless space.
Why not adopt that style of locomotion? Call your rainbow equipage to
the door, and take the family forth in purple state, to the music of
melodious wheels.

If the humming bird will not serve, look above you. There rides
the dark-winged master of aërial motion, throned like a god on the
impetuous wind. Mark his majestic sweep as all day long, with unbeating
pinion, he scours the wide plain and rugged regions of the hills,
unwearied, reposeful, deliberate; now skimming the fragrant forest, or
meadow; now scaling the precipice, or swinging above the abyss; now
soaring cloudward beyond the range of human vision. There is a model
for the ambitious and the brave!

Or turn to mid ocean when the hurricane, shearing the tops of the
arched billows, scatters them in foam and spray over the watery chaos,
and the big ship strains in the storm. See the long-winged albatross,
white vision of joy in the darkness, careering all playfully round
the imperiled vessel, and above the monstrous waves; wheeling in glad
curves, frolicking in the face of the tempest, riding, without toil or
trepidation, the rudest[19] winds a thousand miles over the sea. What a
jocund pace for man!

Of all the charming modes of flight now possible to us it is certain
that our ancestors could copy but one with any hope of success. Minus
motive power they could not imitate the direct flight of the homing
pigeon, much less the mid-air pause of the bumblebee floating round a
daisy. Hence there remained to them only passive flight on nonvibrant
wings. The gliding of vultures, of gulls, and of certain quadrupeds and
fishes, they could imitate with profit; but when they essayed power
flight they invariably and egregiously failed.

The art of aviation presents two main groups of fliers. The first
comprises the various man kites, parachutes, gliding machines, soaring
machines. These may be called passive flyers, because they carry no
motive power, but ride passively on the air by the force of gravity or
a towline.

The second group comprises the bird-like flap-wing machines, called
orthopters by technical people; the screw-lift flyers, called
helicopters; the aëroplanes, also called monoplanes, biplanes,
triplanes, according to the number of superposed main lifting surfaces;
and lastly the gyroplanes, whose sustaining surfaces may turn over and
over, like a falling lath, or whirl round and round, like a boomerang.
These all may be called dynamic, or power, flyers. The technical
names, however, are not so important, as they are numerous; for the
whole aëronautic nomenclature is in a formative, not to say chaotic,
state. We may, therefore, like Adam, name the creatures as they pass
before us for review or discussion.

Disregarding the crude essays at human flight, recorded in the early
literature and history of many peoples, we may notice first the well
authenticated sketches of Leonardo da Vinci. His fertile mind conceived
three distinct devices for carrying a man in the air. But he and his
successors for nearly four centuries could do little more than invent.
For lack of motive power they could not navigate dynamic flyers,
however ingeniously contrived.

[Illustration: FIG. 26.—DA VINCI’S HELICOPTER.]

Da Vinci’s first design, as shown in Fig. 26, provides the operator
with two wings to be actuated by the power of both arms and legs,
through the agency of very ingenious harness. With this device
an acrobat could fly forward and downward, to the delectation of
a multitude; but he would have to be caught on something soft to
escape injury. Since Leonardo’s day the experiment has been tried
occasionally, with varied results, sometimes grotesque, sometimes
tragic. He doubtless realized the impracticability of an orthopter
actuated by human muscle, and yet he has had many followers. The
orthopter is still a favorite device cultivated by a few persons who
propose to work its wings by means of a gasoline motor. Doubtless the
feat is physically possible, and may be accomplished in time.

[Illustration: FIG. 27.—DA VINCI’S PARACHUTE.]

Da Vinci’s second flyer was a helicopter, as shown in Fig. 26. An
aërial screw 96 feet in diameter was to be turned by a strong and
nimble artist who might, by prodigious effort, lift himself for a short
time. Though various small paper screws were made to ascend in the air,
the larger enterprise was never seriously undertaken. Many subsequent
inventors developed the same project; but the fellow turning the screw
always found it dreadful toil and a hopelessly futile task. Of late
the man-driven helicopter has been abandoned, but the motor-driven one
is very much cultivated. Scores of inventors in recent years, aided by
light motors, have been trying to screw boldly skyward, and some have
succeeded in rising on a helicopter carrying one man.

Da Vinci’s third scheme for human flight, as shown in Fig. 27, was a
framed sail on which a man could ride downward, if not upward. This
device never fails to navigate with its confiding sailor. Sometimes
he lands in one posture, again in another; but voyage he must, with
the certainty of gravitation. Leonardo is, therefore, the father
of the parachute. This, in turn, has had a varied offspring. The
common parachute, the aërial glider, the soaring machine, or passive
aëroplane, that rides the wind without motive power and without loss of
energy.

The foregoing sketches by the great artist were made toward the year
1500, and there the science stood for nearly three centuries. Much
speculation followed, but no substantial progress. Mathematicians
proved by figures the inadequacy of the human muscle to achieve human
flight. Dreamers demonstrated the same by launching themselves from
high places, and breaking their bones on the unfeeling earth, before
unpitying crowds. Finally came the balloon, giving a new impetus to an
embryo art.

The earliest of Da Vinci’s aëronautic ideas to be practically realized
was the parachute. The exact date of its first employment is not
exactly known. In the year 1617 Fauste Veranzio published in Venice
a good technical description of the construction and operation of
the parachute, accompanied by a clear illustration, as shown in
Fig. 28. But the first authentic account of a parachute descent of
a human being is that given by Sebastien Lenormand. This dauntless
inventor, on December 26, 1783, descended from the tower of the
Montpelier Observatory, holding in either hand an umbrella sixty inches
in diameter. A few days later he sent to the Academy of Lyons the
following description of his improved parachute, illustrated in Fig. 29:

  “I make a circle 14 feet in diameter with a heavy cord; I
  attach firmly all around, a cone of linen whose height is 6
  feet; I double this cone with paper laid on the linen to render
  it impermeable to air; or better, instead of linen, taffeta
  covered with gum elastic. I place all about the cone small
  cords, which are attached below to a wicker frame, and forming
  with this frame an inverse truncated cone. Upon this frame I
  place myself. By this means I avoid the ribs and handle of
  the umbrella, which would add considerable weight. I am sure
  to risk so little that I offer to make the experiment myself,
  after once having tried the parachute with different weights to
  make sure of its solidity.”

[Illustration: FIG. 28.—VERANZIO’S PARACHUTE.]

Previous to Lenormand’s experiments, Blanchard, the aëronaut, had
dropped small parachutes from his balloon, sometimes carrying animals,
but never a human being. For unaccountable reasons the world had to
wait fourteen years longer to see a man make the new familiar parachute
descent from a balloon. On October 22, 1797, in presence of a large
crowd Jacques Garnerin ascended in a closed parachute to a height of
3,000 feet, then cut loose. The people were astonished and appalled;
but they soon saw the umbrella-shaped canvas spread open and oscillate
in the sky with its human freight. As it was but eight yards in
diameter, it descended rapidly and struck the ground with violence,
throwing Garnerin from his seat. He escaped with a bruised foot,
mounted a horse, and returned to the starting point, where he received
a lively ovation.

[Illustration: FIG. 29.—LENORMAND’S PARACHUTE, 1784.]

After this experiment, parachute descents became popular the world
over, and have been repeated up to the present time substantially
without change. A slight improvement in the construction was made by
cutting away the top of the canvas, thus allowing the air to escape
sufficiently to check the oscillations; but no radical change in
the design has come into general use. It would seem easy to have
transformed the craft into a traveling parachute gliding down the sky
like a great bird on out-stretched wings. Such a device would enable
the aëronaut to sail some miles and direct his course in the air. If
fair skill had been acquired it might have hastened the advent of human
flight twenty years, so far as it is practicable without the aid of
the internal combustion motor. For two decades ago Maxim produced an
abundantly powerful steam engine; but could find no one to furnish him
a manageable glider on which to mount it. Now, indeed, such gliders are
available; but they were developed by aviators, not by balloonists, or
parachutists, who should have effected that advance many years ago.

Curiously enough, Nature has furnished a traveling parachute which
seems never to have been imitated by man, though not difficult to
copy. It is a large two-winged seed, which when dropped in any poise,
immediately rights itself, and glides gracefully through the air. The
seeds grow on a tree in India, bearing the name _Zanonia Macrocarpa_,
and when shaken from its branches look like so many sparrows sailing
earthward in wide curves. Artificial gliders of this type are easy to
construct, and would make interesting toys. However, if man has not
copied such natural models, he has done much better, by making his
gliders concave below instead of concave upward, as are the beautiful
Indian seeds.

An interesting model of a traveling parachute, quite as efficient as
the gauzy-winged seed, is shown in the accompanying figure. It is a
sheet of paper twenty inches long by four inches wide, having a quarter
inch strip of tin folded in its forward margin, and having its rear
margin turned upward slightly, to steer the little craft from a too
steep descent. In order to improve the stability of the paper plane,
its sides may be bent upward. The model when dropped in any attitude
quickly rights itself, and sails down a gently sloping course, the rear
margin functioning as a rudder or tail.

[Illustration: FIG. 30.—PAPER TRAVELING PARACHUTE.]

One of the earliest trustworthy and scientific accounts of
experimentation with an aërial glider was given by Sir George Cayley in
_Nicholson’s Journal_, in 1809 and 1810. After a careful study of the
principles of stability, he, in 1808, constructed a glider spreading
300 square feet of surface and weighing with its load 140 pounds. It
had wing surfaces slightly inclined to each other, and a tail inclined
enough to determine a gentle downward course. “When any persons,” says
Cayley, “ran forward in it with his full speed, taking advantage of a
gentle breeze in front, it would bear him up so strongly as scarcely
to allow him to touch the ground, and would frequently lift him up and
carry him several yards together. It was beautiful to see this noble
white bird sail majestically from a hill to any given point of the
plain below it, with perfect steadiness and safety, according to the
set of the rudder, merely by its own weight, descending in an angle of
about 18° with the horizon.”

Sir George Cayley made a brave start in the science of dynamic
flight, marshaling to it all the mechanical resources of his day. He
applied the most reliable data of fluid resistance then available. He
formulated the laws of equilibrium and control of a flying machine
quite as well as any of his successors for two generations. He
estimated the propulsive power required to carry a man, and computed
the weight of the newly invented Bolton and Watt steam engine capable
of supplying that power. He even conceived the idea of burning a gas
or inflammable vapor behind a piston, thus anticipating the modern
aëronautical motor. But the project as a whole was too formidable at
that time for the genius of this one man, or of his generation of
colleagues. Sailing flight they could have practiced with profit to the
advancement of aviation, but power flight on a practicable scale had to
await the long evolution of the internal combustion engine.

The next great advancement in the devices and principles of aviation
was made by another Englishman, and a worthy successor to Sir George
Cayley. In 1842 Mr. Henson patented the aërial equipage shown in
the accompanying illustration. It was what in present-day parlance
is called a monoplane, being in fact the first commercially planned
aëroplane known to history. As seen at a glance it consisted of a large
sustaining surface rigidly trussed and driven through the air by two
propellers actuated by a steam engine. It was to be guided up and down
by means of a horizontal rudder, and guided to the right and left by
means of a vertical rudder, seconded by a keel cloth; both rudders
being at the rear of the large plane. The machine was designed to be
launched by running down an inclined plane or track. Fuller details
of this first patent aëroplane are given in the following official
description in the South Kensington Museum of a model aëroplane
constructed by Henson and Stringfellow:

  “The model consists of an extended surface, or aëroplane,
  of oiled silk or canvas, stretched upon a bamboo frame made
  rigid by trussing both above and below. A car is attached to
  the underside of the aëroplane to contain the steam engine,
  passengers, etc. It has three wheels to run freely upon when
  it reaches earth. Two propellers, three feet in diameter,
  are shown with their blades set at 45°. They are operated by
  endless cords from the engine. Behind these is a fan-shaped
  tail stretched upon a triangular frame capable of being opened
  out, closed, or moved up and down by means of cords and
  pulleys. By this latter arrangement ascent or descent was to be
  accomplished. A rudder for steering sideways is placed under
  the tail, and above the main aëroplane a sail was to be
  stretched between two masts rising from the car, to assist in
  maintaining the course. When in motion the front edge of the
  machine was to be raised in order to obtain the required air
  support. To start the model it was proposed to allow it to
  run down an incline—e.g., the side of a hill, the propellers
  being first set in motion. The velocity gained in the descent
  was expected to sustain it in its further progress, the engine
  overcoming the head resistance when in full flight. Experiments
  were eventually made on the Downs near Chard, in Somerset, and
  the night trials were abandoned, as the silk became saturated
  from a deposit of dew. After many day trials, down wide
  inclined rails, the model was found to be deficient in stable
  equilibrium for open-air experiments, little puffs of wind
  or ground currents being sufficient to destroy the balance.
  The actual machine was never constructed, but in 1847-48 F.
  Stringfellow built a model which is supposed to be the first
  flying machine to perform a successful flight.”

PLATE XII.

[Illustration: HENSON’S AËROPLANE.]

[Illustration: ADER’S AËROPLANE.

_Photo E. Levick, N. Y._]

The creation of Henson’s flying machine at that early period is one
of the most original and fruitful achievements in the century-long
development of the modern aëroplane. Barring the torsional wing-tips
invented more recently, it hardly differs in principle from the
successful monoplane of to-day. The same mode of propulsion, the same
mode of sustention, the same mode of launching and lighting, the same
mode of steering and control. What has been added since is not so much
original invention as perfection of detail through the combined efforts
of many designers. After Cayley, Henson, as nearly as any one person
was the inventor of the flying machine. He did not bring his conception
to practical maturity, nor was that to be expected; but he did lay
down the broad lines which have led others to success. His ideas still
feature every practical aëroplane, and particularly every successful
monoplane. Indeed, it is now possible to construct an aëroplane from
Henson’s description that will fly, even in breezy weather, with
a stability practically as good as that of the early Voisin and
Antoinette machines before the use of the aileron or torsional wing was
practiced. It is all a question of wise proportioning and sufficient
motive power.

So much for Henson’s contrivance as an abstract invention. The
concrete, full scale machine was to spread 6,000 square feet of
surface, weigh 3,000 pounds, and be propelled by a high pressure steam
engine of 25 or 30 horse power. The machine was not completed on a
large scale, and wisely so; for it was inadequately powered, and,
moreover, required many refinements of detail to make it entirely
practical. These improvements had to be left to succeeding inventors
with accumulated experience and resources.

In 1844 Mr. Henson began the construction of a steam-driven model,
in partnership with his friend, Mr. Stringfellow, who designed the
motor for it. They experimented together for some weeks with only
meager success, but gaining valuable experience. A model of the
Henson-Stringfellow machine is on exhibition at the South Kensington
Museum.

In 1846 Stringfellow built a steam model aëroplane about the size of a
large soaring bird, and weighing all together, with fuel and water, 6½
pounds. A special feature of this model was that its main surfaces were
sloped like the wings of a bird, _slightly concave below and feathered
toward the back_; thus making it more efficient and stable in flight.
With a good head of steam, and propellers whirling, the model ran down
a stretched wire, leaped into the air “and darted off in as fair a
flight as it was possible to make, to a distance of about 40 yards.”
Thus the first power-driven aëroplane to fly successfully was the
little steam model constructed by Stringfellow in 1846.

[Illustration: FIG. 31.—WENHAM’S AËROPLANE, 1866.]

In 1866, two decades after the flight of Stringfellow’s monoplane,
Mr. F. H. Wenham, another Englishman illustrious in the annals of
aëronautics, patented the multiplane; that is, an aëroplane comprising
two or more superposed surfaces. This proved to be a valuable
contribution to the art of aviation, and continues in use at the
present time. The device furnished an increase of sustaining surface
without enlargement of the ground plan. It moreover lends itself
conveniently to a strong and simple trussing of the surfaces. Some
designers protest that superposed surfaces blanket one another; but the
advantages just named seem amply to compensate for this objectionable
feature. If the surfaces be properly spaced, very little interference
is found; moreover, any blanketing that may occur diminishes the drift
as well as the lift,[20] though not necessarily in the same proportion.

Wenham’s aëroplane is illustrated in Fig. 31. The rider lies underneath
the multiple wings, so as to diminish the resistance to progression
through the air. The apparatus could thus be used as an aërial toboggan
for coasting down the atmosphere. To prolong the flights two flappers
actuated by a treadle were to be employed, their ends being hinged at
a point above the operator’s back. Though the device was patented, no
very serious efforts were made to operate it practically. Once, indeed,
the inventor took his glider to a meadow and mounted it, during a lull
in the evening wind, but soon a gust caught him up, carried him some
distance from the ground and toppled him over sidewise, breaking some
of the surfaces. The machine disclosed some good working principles;
but it was inadequately ruddered, and too feebly constructed, to
weather the buffets of the prevailing ground currents.

PLATE XIII.

[Illustration: STRINGFELLOW’S AËROPLANE (FRONT).

(Courtesy Smithsonian Institution.)]

[Illustration: STRINGFELLOW’S AËROPLANE (SIDE).

(Courtesy Smithsonian Institution.)]

Adopting the scheme of superposed surfaces then recently devised
by Wenham, Mr. Stringfellow in 1868 constructed the interesting
steam-driven model shown in Plate XIII. This consists essentially of
three superposed planes, rigidly connected by rods and diagonal wires,
propelled by a pair of screws actuated by a high pressure steam engine,
and guided by a tail. The three planes aggregated 21 feet in length and
28 square feet in surface; totaling, with the tail, 36 square feet.
The engine was rated at one third of one horse power. Its weight is
not known, but may be roughly surmised from the fact that a separate
engine exhibited simultaneously by Stringfellow weighed thirteen pounds
per horse power. The model was entered for competition in the London
Aëronautical Exhibition of 1868. In actual operation, however, it seems
not to have excelled the monoplane of 1846; but still it is of much
interest as being the prototype of the multiple-wing aëroplane now in
common use. It seems to have been the first aëroplane having two or
more sustaining surfaces joined by rods and stayed by diagonal cords
after the manner of a Pratt truss. This historic little model was
purchased by Professor Langley for the Smithsonian Institution, and
is now to be seen suspended from the ceiling of the National Museum,
beside Langley’s own models and Lilienthal’s epoch-making glider.

[Illustration: FIG. 32.—PENAUD’S AËROPLANE TOY, 1871.]

In 1871 M. A. Penaud produced the interesting toy aëroplane shown in
Fig. 32. The model is propelled horizontally forward by a single screw,
actuated by twisted rubber, and is fastened, as shown, to the middle of
a long stick or backbone. The center of mass of the machine is well to
the front, tending to plunge the model earthward like a heavy-headed
arrow; but this down-diving is promptly checked by the tiny rudder
which is so inclined as to counteract the diving proclivity. That is
to say the rudder dips so as to receive the aërial impact on its upper
surface; which impact increases with the speed of flight and causes
the bow to rise, until the weight before the wings just balances the
impact on the rudder at the rear. The equilibrium is thus automatic, on
the principle expounded by Sir George Cayley sixty years earlier. This
quaint little bird when liberated in the Garden of the Tuileries flew
a distance of 131 feet in eleven seconds, much to the delight of some
members of the French Society for Aërial Navigation. It may be added
that Penaud, who was a most promising and clever aëronautical inventor,
contemplated a twin-screw monoplane large enough to carry two men, but
died in his early manhood, before the project could be realized.

[Illustration: FIG. 33.—TATIN’S AËROPLANE MODEL, 1879.]

In 1879 M. Victor Tatin made some very promising tests with the model
shown in Fig. 33, so promising, in fact, as to convince many that human
flight was even then practicable. This little flyer was a twin-screw
monoplane mounted on wheels, and actuated by an oscillating compressed
air engine, the whole machine weighing 3.85 pounds, and supported by a
silk plane measuring 16 by 75 inches. The central body of the aëroplane
was a thin steel tube three feet long by four inches in diameter
containing the compressed air, and weighing only one pound and a half,
though strong enough to endure a pressure of twenty atmospheres. When
the model was allowed to run round a board walk 46 feet in diameter,
tethered to a stake at the center, it quickly acquired a speed of 18
miles an hour, rose in the air, and flew a distance of fifty feet.

A remarkable deduction from the very careful measurements made with
this machine was that it carried at the rate of 110 pounds per tow line
horse power, when flying at an angle of 8 to 10 degrees. Mr. Tatin
concluded: “These experiments seem to demonstrate that there is no
impracticability in the construction of a large apparatus for aviation,
and that perhaps even now such machines could be practically used in
aërial navigation. Such practical experiments being necessarily very
costly, I must to my great regret, forego their undertaking, and I
shall be satisfied if my own labors shall induce others to take up such
an enterprise.”

Tatin’s faith in the practicability of a large aëroplane was later
voiced by Mr. Chanute in his valuable book, _Progress in Flying
Machines_, published in 1894, but now unfortunately out of print.
Recalling that Maxim had recently produced a large motor weighing
complete only ten pounds per horse power, he says: “Aviation seems to
be practicably possible, if only the stability can be secured, and an
adequate method of alighting be devised.” Since the above quoted facts
and opinions were published, no competent man well informed in the
science of aviation has for one moment doubted the feasibility of human
flight.

[Illustration: FIG. 34.—HARGRAVE’S MODEL SCREW MONOPLANE, 1891.]

In 1891, twelve years after Tatin’s experiment, Lawrence Hargrave, of
Sydney, Australia, made a similar compressed air monoplane, with a
single-screw propeller, but without wheels for launching and lighting.
The model, which is shown in Fig. 34, had a wing-spread of 20 square
feet, weighed about three pounds, and flew 128 feet in eight seconds.
The weight carried was at the rate of 90 pounds per horse power, a very
encouraging result. Two years later he described a small steam engine
which he had developed, weighing 10.7 pounds per horse power, and
capable of driving the model about two miles, though he did not use it
for that purpose, being engrossed with other researches.

One interesting outcome of his numerous experiments was the Hargrave
Kite, now more familiarly known as the box kite. A good example of
his kites is the type shown in Fig. 35. This consists of two arched
biplanes mounted tandem on a backbone, or connecting framework. The
kite floats steadily, and was thought suitable for the body of a flying
machine to be driven by an engine and propeller. Thus meteorology is
indebted to aëronautics for its most useful kite.

[Illustration: FIG. 35.—HARGRAVE’S KITE.]

A very novel and interesting type of aëroplane model was tested by
Mr. Horatio Phillips in 1893. After careful preliminary experiments
with various forms of curved “sustainers,” or lifting surfaces, tested
in a wind tunnel, to determine which were most suitable wing forms,
he finally constructed the flying apparatus shown in Plate XIV. This
consisted of a compound aëroplane composed of many superposed narrow
curved slats, the whole resembling an open Venetian blind. These
curved blades, or sustainers, measured 12 feet long, 1.5 inches wide,
2 inches apart, and were held in a frame sharpened to cleave the air
with slight resistance. The entire aëroplane spread 136 square feet
of lifting surface, and was mounted on a truck as shown, carrying a
steam engine and boiler, to actuate a two blade propeller 6 feet in
diameter. The whole apparatus weighed 330 pounds, to which a dead load
was usually added, and ran around a circular wooden track 628 feet in
circumference, being tethered at the center, as in Tatin’s experiment.
The apparatus readily lifted itself, when running at a speed of 28
miles an hour, and carried at the rate of 72 pounds per horse power,
the added load weighing at times nearly one fourth that of the machine
itself. The ultimate purpose of the experiment was to prepare the
way for a one-man aëroplane like that shown in the lower part of the
figure. This latter model actually carried a man across a field in
1904, but was found defective in longitudinal balance, because perhaps
of its inadequate horizontal rudder. Apparently Mr. Phillips had in
1904 a machine capable of well-balanced flight, if he had made the
rudders large enough, and provided a mechanism for rotating the slats
at either wing end, so as to control the lateral poise, as proposed by
the present writer in 1893, for practically that same flier (see page
229).

Phillips’s aëroplane shows a distinct advance over its predecessors,
even Wenham’s multiplane, because of the careful curving of the
sustainers. Tatin’s flat wing machine had, indeed, shown a greater
efficiency as a whole, but that was likely due to less proportionate
body resistance. To Phillips we owe the introduction of superposed
arched surfaces, now so commonly used in mechanical flight. Whether he
was wise in using so many narrow wings, instead of a few broad ones,
was a question to be answered by precise measurement.

Prof. S. P. Langley, like Mr. Hargrave, made numerous flying models,
trying, in turn, the power of twisted rubber, compressed air and
steam. He constructed scores of gauzy winged contrivances which
flitted about like huge butterflies or birds, till their mission
was accomplished—that of illustrating a scientific principle to his
inquiring mind. One by one they came into existence, enjoyed an
ephemeral life, and then were consigned to the aëronautical attic of
the Smithsonian Institution, a storehouse of quaint flying creatures.
It was a most interesting collection which well merited preservation
as the “juvenile” creations of an illustrious man. But the first
experiments of Langley, like the similar ones of Hargrave, were of
value chiefly as training to the inventor himself; they were not
important advances in the art of aviation. Such advances were to follow
the long preliminary training.

PLATE XIV.

[Illustration: PHILLIPS’ TETHERED AËROPLANE.]

[Illustration: PHILLIPS’ AËROPLANE.]

On May 6, 1896, Dr. Langley launched the picturesque steam model,
which, to his mind, first proved conclusively the practicability of
mechanical flight. It was the crowning success, and, as he thought
then, probably the termination of his aëronautic labors. “I have
brought to a close,” says he, “the portion of the work which seemed
to be peculiarly mine—the demonstration of the practicability of
mechanical flight—and for the next stage, which is the commercial
and practical development of the idea, it is probable that the world
may look to others. The world, indeed, will be supine if it does not
realize that a new possibility has come to it, and that the great
universal highway overhead is now soon to be opened.”

As shown in Plate XV, Langley’s first successful steam flying machine
is a tandem monoplane[21] with twin screws amidships. It measures
nearly 13 feet from tip to tip of its wings, about 16 feet along its
entire length, and weighs with motor and propellers 30 pounds. The
boiler weighs 5 pounds, the engine 26 ounces, and the power developed
was between 1 and 1.5 horse power. The model is therefore somewhat
larger than a large condor, and very much more powerful.

Being too small to carry a pilot, it was launched over water, to
obviate wreckage on landing. The machine was capable of flying several
miles continuously, but in the actual test on the Potomac River the
flight was limited, in order to prevent the model passing beyond
the shore. The flyer was placed on launching ways on the top of a
houseboat, hurled rapidly forward by force of a spring, and liberated
in space, with engine and propellers running at full speed. Its
subsequent behavior has been graphically described by an eyewitness,
Dr. Alexander Graham Bell, in the following passage, published in
_Nature_, May 28, 1896:

  “On the occasion referred to, the aërodrome, at a given signal,
  started from a platform about 20 feet above the water, and
  rose at first directly in the face of the wind, moving at all
  times with remarkable steadiness, and subsequently swung around
  in large curves of perhaps a hundred yards in diameter, and
  continuously ascending till its steam was exhausted, when at
  a lapse of about a minute and a half, and at a height which
  I judged to be between 80 and 100 feet in the air, the whole
  ceased turning, and the machine, deprived of the aid of its
  propellers, to my surprise did not fall, but settled down so
  softly and gently that it touched the water without the least
  shock, and was in fact immediately ready for another trial.

  “In the second trial, which followed directly, it repeated in
  nearly every respect the actions of the first, except that the
  direction of its course was different. It ascended again in the
  face of the wind, afterward moving steadily and continually in
  large curves, accompanied with a rising motion and a lateral
  advance. Its motion was, in fact, so steady that I think a
  glass of water on its surface would have remained unspilled.
  When the steam gave out again it repeated for a second time
  the experience of the first trial when the steam had ceased,
  and settled gently and easily down. What height it reached at
  this trial I can not say, as I was not so favorably placed as
  in the first, but I had occasion to notice that this time its
  course took it over a wooded promontory, and I was relieved of
  some apprehension in seeing that it was already so high as to
  pass the tree tops by 20 or 30 feet. It reached the water in
  one minute and thirty-one seconds from the time it started, at
  a measured distance of over 900 feet from the point at which it
  rose.

PLATE XV.

[Illustration: LANGLEY’S STEAM MODEL.

(Courtesy Smithsonian Institution.)]

[Illustration: LANGLEY’S GASOLENE MODEL.

(Courtesy Smithsonian Institution.)]

[Illustration: LANGLEY’S TWO SURFACE GASOLENE MODEL.

(Courtesy Smithsonian Institution.)]

  “This, however, was by no means the length of its flight. I
  estimated from the diameter of the curve described, from the
  number of turns of the propellers, as given by the automatic
  counter, after due allowance for slip, and from other measures,
  that the actual length of flight on each occasion was slightly
  over 3,000 feet. It is at least safe to say that each exceeded
  half an English mile.

  “From the time and distance, it will be noticed that the
  velocity was between 20 and 25 miles an hour, in a course
  which was constantly taking it ‘up hill.’ I may add that on a
  previous occasion, I have seen a far higher velocity attained
  by the same aërodrome when its course was horizontal.

  “I have no desire to enter into detail further than I have
  done, but I can not but add that it seems to me that no one who
  was present on this interesting occasion, could have failed to
  recognize that the practicability of mechanical flight had been
  demonstrated.”

In passing it may be added that in 1899 this model was again flown
successfully, having superposed surfaces; for its inventor all along
recognized the structural advantage of the bridge trussing in biplanes.
If he preferred the monoplane, or single-tier arrangement, it was
because the best flights were obtained with such models.

Many persons now thought that Langley would do well to rest on his
laurels, leaving to others the “commercial and practical development”
of his ideas. But he had caught the aëronautic fever. Like many another
poor son of fancy, he was haunted by magnificent dreams. Now, perhaps,
was stirring in his mind that vision of his childhood when he lay on
his back in the New England pasture and “watched a hawk soaring far
up in the blue, and sailing for a long time without any motion of its
wings, as though it needed no work to sustain it, but was kept up there
by some miracle.” Mr. Andrew D. White declares that Professor Langley
was a poet by nature. Whatever the dominant impulse, he followed his
“aërodrome” like one possessed. It was the all engrossing pursuit of
the latter years of his life, entailing how much vexation, toil and
unjust censure!

In 1898 the Board of Ordinance and Fortification, after carefully
studying the flights of 1896, appropriated $50,000 to enable Professor
Langley to build a one-man flyer. He first tested a gasoline driven
aëroplane having one fourth the linear dimensions of the man-carrying
one. In external appearance this model resembled the steam “aërodrome,”
described above, but was considerably larger. It spread 66 square feet
of surface, weighed 58 pounds, and developed 2½ to 3 horse power.
When ready for the test, August 8, 1903, this beautiful white-winged
creature was taken to the middle of the Potomac, 40 miles below
Washington, mounted on the launching ways, swiveled into the eye of
the wind and shot forth like a stone from a catapult, her engine and
propellers humming merrily.

The flight must have been very graceful and dignified, for it
elicited commendation even from the squad of reporters present, men
who customarily recorded such events with uncontrollable mirth and
ridicule. Dr. Langley merely remarks: “This was the first time in
history, so far as I know, that a successful flight of a mechanically
sustained flying machine was seen in public.” It was also the first
successful gasoline[22] aëroplane, and the forerunner of the host
of flyers presently to spring up in all parts of the world. Its
flight though very brief, owing to a surcharge of gasoline, was so
satisfactory in all its dynamic features, that it seemed to justify an
immediate launching of the one-man machine, with which like maneuvers
were anticipated. As will appear in the sequel this prospect of fair
sailing was beset with unsuspected shoals.

We have now traced the growth of the aëroplane from its earliest
conception to the present time, as exemplified by working models. First
came the parachute of Da Vinci and others, whose sole function was
to carry a weight softly to earth, with no provision for steadiness
of motion, or control of direction. Then, in the beginning of the
nineteenth century, arrived the gliders adjusted for steadiness,
equilibrium and a predetermined slanting course in the air; beautiful
passive birds, actuated by gravity, but riderless and awaiting the
advent of artificial motive power. Then suddenly appeared Mr. Henson’s
wonderful _project_; a large man-carrying aëroplane, provided with
a motor, propellers, rudders, wheels for launching and landing—an
impossible scheme for that day, but destined to be realized in
the course of two generations. Henson’s idea was doubtless the
most prolific in the history of aviation. After this followed the
numerous instructive models, actuated by twisted rubber, steam,
gasoline, compressed air—economic contrivances for ascertaining the
secrets of propulsion, equilibrium and control, of the prospective
man-flyer. These may be said to have demonstrated the practicability
of man-flight, though many contemporaneous and allied experiments, to
be noticed presently, all contributed to the triumphs subsequently
achieved by the race of sanguine, daring and tireless inventors.

[Illustration: FIG. 36.—LAUNOY AND BIENVENU’S HELICOPTER, 1784.]

In this brief outline, the two other main types of flyers, the
orthopters and helicopters, have been omitted. The orthopters, or wing
flapping machines, have been very numerous, but have not yet approached
practical success in use. Though a man-carrying orthopter has not yet
been produced, an elegant pigeon-like model operated by rubber has been
made by Pichancourt, which flies and balances nicely. The helicopters,
or direct-lifting screws, have more than once raised their weight and
that of the helicoptrist, or navigator. These latter, therefore, seem
to be of sufficient interest to merit a short historical review.

Leonardo da Vinci, the fertile pioneer in aviation, missed one novel
device worthy even of his genius. He constructed aërial screws of
paper, but he did not endow them with motive force. Such an achievement
was in his power, and would have ranked him with Archytas of Tarentum,
who 400 B. C. invented the kite, and an artificial dove said to have
flown, no one knows how. Having escaped Da Vinci’s ingenuity, the power
helicopter failed to materialize for three centuries, but finally
appeared in France.

In 1784 Launoy and Bienvenu, the first a naturalist, the second a
mechanician, exhibited before the French Academy the interesting toy
shown in Fig. 36. This was the first power-driven helicopter, and is
said to have lifted itself in the air quite readily. As may be observed
it consists of two coaxial screws rotating in opposite directions
actuated by the power of an elastic stick, like a bow. The screws were
each about one foot in diameter and made of four feathers; one screw
being fastened to the top of the rotating shaft, the other fastened
to the bow, which rotated in the contrary direction. The little model
excited much interest, particularly as its inventors expected to build
a man-carrying helicopter on the same plan. The larger project was
obviously without merit; for no combination of springs can maintain
flight for more than a few seconds even on the most favorable scale.

A more powerful toy helicopter was produced by Mr. Horatio Phillips in
England in 1842. This was a single aërial screw emitting jets of steam
which compelled it to spin, on the principle of a lawn sprinkler, or
a Hero engine. The whole apparatus weighed two pounds, and had screw
blades inclined 20° to the horizon. The steam was generated by the
combustion of charcoal, niter and gypsum, as in the fire extinguisher
previously invented by the same ingenious man. The performance of this
curious helicopter, is thus described by Mr. Phillips: “All being
arranged, the steam was up in a few seconds, then the whole apparatus
spun around like a top, and mounted into the air faster than any
bird; to what height it ascended I have no means of ascertaining. The
distance traveled was across two fields, where, after a long search, I
found the machine minus the wings, which had been torn off from contact
with the ground.”

“The distance traveled was across two fields.” For vagueness this
surpasses the poet’s measure—“as far as oxen draw the plow in a day.”
It would be most interesting to have an exact description of this
classical experiment, when for the first time a flying machine rose
in the air propelled by a heat motor. It would be desirable also
to know the possibilities of such a helicopter, particularly since
Prof. Cleveland Abbe has proposed to employ a like agent to carry
meteorological instruments into the higher atmosphere.[23]

[Illustration: FIG. 37.—FORLANINI’S HELICOPTER, 1878.]

A still more ambitious helicopter was that shown in Fig. 37 invented by
Professor Forlanini, an Italian Civil Engineer, and launched in 1878.
The lower screw was fastened to the frame of a steam engine, the upper
screw was attached to the crank shaft. Steam was supplied from the
globe shown beneath, which was two thirds filled with water, and well
heated over a separate fire just before an ascension. As the globe was
merely a reservoir of hot water and steam, carrying neither fuel nor
furnace, its power waned rapidly. The best flight lasted about twenty
seconds, attaining a height of 42 feet. The apparatus weighed 77
pounds, spread 21.5 square feet of screw surface, and lifted about 26.4
pounds per horse power.

Many other helicopter models have been tried from time to time, with
various sources of power, without, however, yielding any important
results beyond those already given. But these were sufficiently
encouraging. If a large machine could be made to lift as many pounds
per horse power, it would be easy to build one competent to carry
a man. That, indeed, has been done on several occasions. Of the
various inventors who have built man-lifting helicopters M. Cornu and
M. Bréguet, in France, seem to have been first to attain a measure
of success. While their machines have raised a passenger directly
from the ground, they have not yet maneuvered in horizontal flight
with sufficient speed to be of practical service. However, a few
helicoptrists in various countries are still industriously at work, and
hope eventually to rival the aëroplanists in the mastery of flight.
There will doubtless be room in the sky for both. Perhaps also there
will be occupation and a mission for both.




                             CHAPTER VIII

                     NINETEENTH CENTURY MAN-FLYERS


Having traced the growth of winged models from their earliest beginning
to the time when they proved the possibility of mechanical flight, we
may now study the evolution of larger machines, designed to carry human
beings. Considering first the aëroplane, we may follow the two general
methods advocated by various inventors for launching a man safely in
the air, both of which led to success. The first of these may be called
Henson’s method, the second Lilienthal’s, coupling them with the names
of their distinguished pioneer exponents. Henson in 1842 proposed
that the pilot should mount a full-power machine, run along a smooth
course, and glide into the air without previous experience in the art
of navigating. Lilienthal recommended careful preliminary training on a
glider, by which the novice should acquire sufficient skill in parrying
the wind to qualify him to manage a dynamic machine, under its more
complex conditions of control. Others, more cautious still, contended
that automatic equilibrium should be secured before a rider risked his
bones on the aërial bronco; while still others thought the uncertain
beast should be tethered to some point in the sky, say a balloon or
taut wire, or the end of a pole; so that however he bucked, or reared,
he should not fall over on his rider.

We have noticed in the first chapter some picturesque man-flights,
usually deplorable or tragic; and always fruitless for lack of
scientific method in experimentation and report to the world. There can
be no doubt that such flights were accomplished, mainly, of course,
by the aid of gravity; but the difficulty is to ascertain the exact
nature of any given performance, the specifications of the apparatus,
and the principles of equilibrium and control. Gradually, however, the
experimenters improved both in the construction of man-carrying devices
and in the manner of imparting their results to their colleagues, or
successors; and so the flying enterprise began to assume a progressive
aspect, attended with that scientific dignity which invests secure
and continuous advance in any branch of knowledge. Little of value,
however, can be gleaned from any such flights made prior to the middle
of the nineteenth century. From that time forward observers and
inventors made definite and fairly methodical efforts to develop the
art of gliding and soaring in the air, the first fruit of which was to
hasten the advent of the modern aëroplane.

A French novelist and aëronautic writer, G. de la Landelle, relates
an amazing adventure in the art of soaring, which may have some
foundation in fact, though savoring strongly of fiction. An experienced
sailor, Captain Le Bris, having observed the albatross soaring without
wing-beat, determined to imitate the fascinating flight of that
limber-winged spirit of the sea. To such end he built the bird shown in
Fig. 38, a ninety-pound albatross, with arched wings fifty feet across
and articulated to the boat-like body. In this the brave aviator would
stand upright, turn the wings and tail to maintain his balance, and
steer grandly through the sky. Placing this long-winged creature across
a cart driven by a peasant, he stood erect and headed against a breeze;
the wings set low to prevent lifting till an opportune moment, and the
bird held down to the car by a rope which the captain could quickly
release. When the horse was a-trot, and the wind blowing freshly, Le
Bris raised the front edges of the wings. Thereupon the albatross
tugged upward, and the mooring rope was slipped, but accidentally
whipped around the driver’s waist. The horse galloped away with the
cart; the bird, with the exultant sailor on its back, soared 300 feet
into the air, and incidentally carried up the peasant, dangling at
the end of the rope and howling with fright. Noting the distress of
his passenger, the kindly captain sailed close to earth, so that the
peasant might disembark and run to his horse, meaning then to hie away
for a long cruise in the clouds. But with this change of weight the
vessel seemed not to navigate well; so she was brought skimming to
land, with no mishap save a slight damage to the advancing wing, which
broke as it touched the ground.

[Illustration: FIG. 38.—LE BRIS’ AËROPLANE, 1855.]

Having repaired the great bird’s wing, Captain Le Bris next made
a launching from the arm of a derrick, 30 feet above the ground,
overlooking a quarry 70 feet deep. The attendant swains stood
open-mouthed, wondering whether this madman would overleap the clouds,
or promptly butt out his brains on a jagged rock. When the wind blowing
from the quarry seemed to float him in perfect poise, he tripped the
suspension hook, and headed for the precipice on even keel. He was now
happily launched, and keen for an aërial journey; but after passing
the brink, he seemed to encounter an eddy which tilted his craft
forward. The vessel dipped and rose; the captain plied his levers,
turning now the tail, now the pinions. He crossed safely over the
invisible breakers, and reached the quiet air of the quarry on level
wing. But now his forward speed was lost, the great bird sank rapidly
and crashed upon the rocky bed below. The wary seaman anticipating a
bump, sprang upward to soften his fall; but a lever rebounding from the
shock, hit one of his legs and broke it.

Some twelve or thirteen years later, in 1867, Le Bris, aided by a
public subscription at Brest, built a second albatross, with which
he made a number of small flights, sometimes riding it himself, and
sometimes replacing his weight by ballast. On one occasion the loaded
bird, held by a light line, rose 150 feet and advanced against the
wind. Suddenly the sailors holding the line observed it slacken, and
saw with amazement the long-winged creature soar forward 600 feet, as
stately and serene as its living prototype. Presently encountering a
sheltered and quiet region of air before some rising ground, it settled
softly to earth in perfect equipoise. But on a subsequent launching
from the same favorable ground, the dumb creature pitched forward and
plunged to the earth where it lay shattered and torn in a hopeless
tangle. Le Bris looked on the wreck in despair, surveying sadly the
remains of his once cherished bird; then sat upon the débris a long
time, his head between his hands, his heart broken, his mind tortured
with anguish. Impoverished, chagrined, derided, he now must abandon
the albatross business. Five years later this intrepid sailor of sea
and air was killed by some ruffians, in 1872, while a constable in his
native place, and after a period of honorable service to the state in
the Franco-Prussian War.

The story is more romantic than instructive, for want of exact data.
To give the experiments their proper value to others, fuller details
of the mechanism should be furnished, and adequate measurements of the
speed and direction of the aërial currents. At one time the sailing
was even, at another, rough, though outwardly the conditions appeared
the same. Apparently the successful flights occurred when the bird was
launched to windward from rising ground, that is, when the current had
an upward slant, to exert a propulsive effort. This species of soaring
has been observed frequently in nature, and has been imitated both with
models and with man-carrying gliders. Nevertheless Le Bris’ experiments
were very remarkable for the time, and, if adequately reported, might
have proved to be of much interest and value to aëronautical science.

Another Frenchman alert to the glory of aërial motion was L. P.
Mouillard, the poet-farmer of Algeria. From boyhood he studied the
birds with unabated interest and pleasure. He would journey miles to
attend the “morning prayer” of the starlings in the forest of Baba-Ali;
noting, just before sunrise, how their melodies suddenly hushed, and
the forest seemed to bound upward, and heaven filled with the music of
innumerable wings. He would time the shadow of the high bird of passage
riding the hurricane from continent to continent. He saw the tyrant
eagle fold his wings in mid air and plunge a thousand feet in ferocious
swoop after the swift-fleeing duck or rabbit. He loved to watch the
great tawny vulture on the mountain top shake the dew from his vast
plumes, straddle the morning wind, and all day long, with never a beat
of those grand pinions, soar godlike through immensity, the marvel
and delight of the nether world. When the electric wind of the desert,
blowing from Central Africa, brought the big scavengers and noble birds
of prey, he sat on the ground scrutinizing their majestic flight and
planning to imitate it. He would lie in ambush where the silent-rowing
owl darted at dusk through the timber, fierce and swift as the eagle;
a dreadful thing, with its night piercing eyes, its big ears and beak,
its horrid talons, its sudden shriek startling the forest with ominous
echoes. No feature escaped him, and least of all an aërodynamic one.

For thirty years he continued these studies. He would bring home
the birds, lay them on their backs and mark their contour on paper,
measure their projected area, weigh and compare them. He formulated
curious conclusions about sailors and rowers, the functions of tail and
quill feathers, weight and wing-spread, bulk, agglomeration of mass,
resistance and velocity. He notes that only massive birds soar well,
the broad-winged ones requiring a moderate wind, the narrow-winged ones
requiring a gale, and sailing with perfect ease in a tempest; and he
concludes that man may imitate both types. His book[24] is replete with
charming anecdotes, observations and quaint theories, interesting alike
to ornithology and aviation.

But Mouillard did more than theorize; he built soaring machines and
soared a little. His third and best glider, illustrated in Fig. 39, was
a tailless monoplane made of curved agave sticks screwed to boards,
and covered with muslin. The aviator, standing in the open space C,
harnessed the plane on with straps looped round his legs and shoulders,
and fastened to the points D D. His forearms, passing under straps,
rested on the board, enabling him to tilt the whole by shifting his
weight. In order to vary the dihedral angle between the wings, they
were hinged together and actuated by rods running from the man’s feet
to the ends of the boards, hardly as far out as the center of wind
pressure, thus apparently stressing his legs like a wishbone.

[Illustration: FIG. 39.—MOUILLARD’S AËROPLANE.]

He now sent the home folks away from the farm, buckled on his wings and
walked along the prairie road waiting for a breeze. The road was raised
five feet above the plain and bordered by ditches ten feet wide. His
wings felt light; he ran forward to test their lift, and he thought to
amuse himself by jumping the ditch. The result is thus expressed in his
own words:[25]

  “So I took a good run across the road and jumped at the ditch.
  But, oh, horrors; once across the ditch my feet did not come
  down to earth; I was gliding on the air, and making vain
  efforts to land; for my aëroplane had set out on a cruise. I
  dangled only one foot from the soil, but, do what I would, I
  could not reach it, and I was skimming along without the power
  to stop. At last my feet touched the earth; I fell forward
  on my hands; broke one of my wings, and all was over; but
  goodness, how frightened I had been! I was saying to myself
  that if even a light wind-gust occurred, it would toss me up
  30 to 40 feet into the air, and then surely upset me backward,
  so that I would fall on my back. This I knew perfectly, for I
  understood the defects of my machine. I was poor, and I had not
  been able to provide myself with a more complete aëroplane.
  All’s well that ends well. I then measured the distance between
  my toe marks, and found it to be 138 feet.

  “Here is the rationale of the thing. In making my jump I
  acquired a speed of 11 to 14 miles per hour, and just as I
  crossed the ditch I must have met a puff of rising wind. It
  probably was traveling some 8 to 11 miles per hour, and the
  two speeds added together produced enough pressure to carry my
  weight.”

He repaired his wing and repeated the test a few days later. A violent
wind gust came; picked him up from the earth, and whelmed him over. In
his alarm he allowed his “wish-bone” to spread, and the wings to fold
up like those of a butterfly at rest, pinching him between them like
a nut in a nutcracker. One wonders whether the overwheeling vultures
witnessed this gentleman’s flight with any sense of humor.

After mature reflection, Mouillard concluded that he should give his
aëroplane a rudder, and flex the wings, in order to insure adequate
control. But here he halted, being a poor man unskilled in the art
of construction. He had reached the limit of his endowments. He had
observed faithfully and described charmingly the wonderful flights
of various birds; but he must leave to his technical successors the
pleasure of imitating or excelling those extraordinary maneuvers—leave
them the pleasure, the sacrifice, the long years of toil and danger,
accompanied perhaps by indiscriminate applause or derision.

In the meantime another distinguished disciple of the birds was
energetically at work in Germany. No less ardent than Le Bris, or
Mouillard, Otto Lilienthal was far better equipped and circumstanced.
He was a graduate of the Potsdam Technical School, and a student
for three years in the Berlin Technical Academy. He was engaged in
practical construction ten years in various machine shops at Berlin.
After 1880 he operated a flourishing machine factory of his own. From
boyhood he with his brother Gustavus had carefully studied the flight
of birds, and had made numerous experiments in aviation. On moonlight
nights in their little home place of Anclam, in Pomerania, the boys
would run downhill, flapping their home-made wings, like Dædalus and
Icarus, but with no other danger than discovery and teasing by their
neighbors. At Potsdam and Berlin they continued to experiment and to
construct wings of increasing size and power. Thus Otto Lilienthal
reached early manhood thoroughly trained by his long courses in the
technical schools and shops, brimming with well pondered ideas,
strengthened by continuous observation and experiment, and in financial
circumstances which permitted him to devote time and money to the
unremunerative pursuit of aviation. To this may be added that his
mature years were cast in a time when the allied sciences could aid
him far more than they had aided his predecessors of the preceding
generation.

After careful research for the most efficient form of alar surface,
Lilienthal resolved to imitate the birds. First he would build a pair
of arched wings, and learn to coast down the atmosphere, balancing
and steering like a stork in the gusty and treacherous current. He
would thus acquire the pilot’s skill, and ascertain the towline power
required to sustain a given weight. Then he would add a suitable
propelling mechanism, test it cautiously, and acquire the mastery of
dynamic flight. Incidentally, perhaps, he would learn to ride all over
creation without motive power; for he was convinced that certain great
birds soar without muscular effort, and that man could acquire this
delightful art in favorable weather. To strengthen the plausibility
of that doctrine, he announced his discovery that the general trend
of the wind is three and a half degrees upward, a fact inexplicable
and almost incredible to his illustrious confrère of the Smithsonian
Institution.[26] Such was Lilienthal’s ample program; more, indeed,
than he would live to accomplish, though possibly not beyond his power
of achievement, if he could have lived to enjoy the hale long years of
his illustrious countryman aëronaut, Count Von Zeppelin.

In the year 1891 Lilienthal made his first series of trials in sailing
flight. His glider was the bird-shaped apparatus shown in Plate XVI,
made of willow wood covered with waxed sheeting. It weighed about 40
pounds, and spread 107 square feet of surface. Taking this in his arms
he first ran 24 feet along a raised board and jumped off, gliding
through still air. Then, elevating the board to a height of six feet,
he repeated the run, jump and glide, always landing very softly. Thus
he became “king of the air in calm weather,” a title still creditably
sustained by his numerous successors of the present day; for as yet no
one “mounts the whirlwind and directs the storm.”

Next he went to some little mounds in a field beyond Werder, and jumped
from these, gradually lengthening his flights till he attained a range
of nearly 80 feet. As he was now gliding in light winds, he found it
necessary to add a vertical rudder, in order to preserve his balance
easily, and keep his bow toward the direction of the wind. His complete
apparatus was, therefore, a birdlike affair, with two rigid wings and
a double tail for steering vertically and horizontally. He found also
that he could fly longer and alight more softly when the wind was
blowing—an obvious possibility.

Encouraged by this experience Lilienthal explored the country about
Berlin for sailing ground where he could make long glides, whatever
the direction of the wind. Such a region he found near Rathenow, where
the Rhinow hills, covered with grass and heather, slope gently upward
from the flat plowland to a height of over 200 feet. This he thought
an ideal coasting ground; for he felt the aërial currents very smooth,
and he could always select clear land sloping ten to twenty degrees
toward the wind. Here in the summer of 1893, with a new and improved
glider, he made many flights, finally ranging from 200 to 300 yards,
steering up and down, or to right and left at will; sometimes pausing
in mid air, and several times returning to the starting point. This was
more than coasting; for a mere coaster never maintains, nor returns
to, his original level. It was a fair start at true soaring, the ideal
locomotion. A glorious sport it was, sailing like an eagle high over
the landscape and over the heads of the astonished spectators.

The new machine resembled its predecessors in form and maneuver; but
differed in dimensions. It was a birdlike craft with parabolically
arched wings and a double tail. It measured 7 meters across, spread
14 square meters of surface, weighed with the rider 200 pounds, and
in calm air could sail down a slope of 9°, at a speed of 9 meters
per second. This was very efficient sailing, the work of gravity
being hardly two horse power. With the man lying prone, as eventually
planned, the economy would be still greater.

PLATE XVI.

[Illustration: LILIENTHAL’S MONOPLANE GLIDER.

(Courtesy W. J. Hammer.)]

[Illustration: LILIENTHAL’S BIPLANE GLIDER.

(Courtesy W. J. Hammer.)]

[Illustration: PILCHER’S MONOPLANE GLIDER.]

The craft was thought also to possess stability; and this it had, in a
measure, about those two axes corresponding to the two rudders; but the
control about the third axis, effected by dangling the legs to right
or left, was extremely crude and primitive. It was in keeping with his
adage: “to contrive is nothing; to construct is something; to operate
is everything.” If he had contrived more intelligently, he would have
operated more easily, and avoided those wild and dangerous dancings in
space. A more scientific adage would read: “To design effectually is
everything, to construct is routine, to operate is play.”

The marvel is that Lilienthal, the observant, the technically trained,
the practically skilled, should operate for three years, then patent,
an aërial glider having two rudders, but lacking the third rudder,
or torsional wing, now so commonly used throughout the world. But
doubtless he contemplated a device for preserving the lateral balance
without shifting his weight; for he acknowledged the economic advantage
of lying prone on the machine, and stated that this might be done after
some important improvements in the apparatus had been made.

Having executed nearly two thousand flights with his monoplane,
Lilienthal in 1895 built a two-surface glider. He found this still
easier to control, and now thought he had sufficiently acquired the
art of sailing to justify his undertaking the next and more difficult
art of imitating the rowing flight of birds. He had constructed a
ninety-pound engine, of two and a half horse power, to actuate the
wings of his glider; but, before applying this motor, he went to the
Rhinow Hills for a little further experience in sailing. Previously
he had remained in the air twelve to fifteen seconds; but he wished to
exceed this record.

On the 9th of August, 1896, he made a long glide to prove the
effectiveness of the horizontal rudder, and then wished to undertake
a second flight of the greatest duration feasible. No intimation had
he that this sail would prove disastrous. Giving the timepiece to his
assistant, he set forth on a level course, but suddenly dipped forward
and plunged headlong to earth through a height of fifty feet. He was
dragged out from the débris with a broken spine, from which he died the
following day.

The machine on which the father of aërial gliding made his last flight
is shown in Plate XVI. Of the hazardous nature of its construction Mr.
Chanute thus writes: “The two surfaces were kept apart by two struts,
or vertical posts, with a few guy wires, but the connecting joints were
weak, and there was nothing like trussing. This eventually cost his
most useful life. Two weeks before that distressing loss to science,
Herr Wilhelm Kress, the distinguished and veteran aviator of Vienna,
witnessed a number of glides by Lilienthal with his double-decked
apparatus. He noticed that it was much wracked and wabbly, and wrote to
me after the accident: ‘The connection of the wings and the steering
arrangement were very bad and unreliable. I warned Herr Lilienthal very
seriously. He promised me that he would soon put it in order, but I
fear that he did not attend to it immediately.’”

It will be observed that Lilienthal gave fair attention to the merits
of both the monoplane and the biplane, the two familiar types in
lively competition at the present hour. The first he found in Nature;
the second he could have found in England, as the developments
principally of Wenham and of Phillips. His example and prestige did
much to promote the biplane; but he seems to have had no very decided
preference for either. Though he found his biplane very satisfactory,
he thought of returning to the monoplane.

In April, 1896, he wrote:[27] “I am now engaged in constructing an
apparatus in which the position of the wings can be changed during
flight in such a way that the balancing is not effected by changing
the position of the center of gravity of the body. In my opinion this
means considerable progress, as it will increase the safety. This will
probably cause me to give up again the double sailing surfaces, as it
will do away with the necessity which led me to adopt them.” He thus
seems to have studied the two types impartially, and to have invented a
means for balancing the machine without shifting the center of mass.

Lilienthal had given a powerful and permanent impulse to aviation,
both by his writings and by his practical experience in the air. He
first showed quantitatively the advantage of arched wings, by carefully
derived tables of wind pressure; then he mounted the wings himself
and taught the world, by bold and frequent flight, the art of aërial
gravity sailing. The two remaining achievements, dynamic and soaring
flight, he was to undertake as promptly as possible. If his life had
been spared, no doubt he would have contributed much to the advancement
of these arts, both by example and by direct effort; for he was in the
prime of life, full of energy and daring, highly equipped, and ardently
devoted to his favorite science. He began his studies in aviation at
the age of thirteen and died at the age of forty-eight years.

Among the admirable traits of the father of sailing flight must be
mentioned his scientific liberality and _esprit de corps_. Though he
patented his invention he did not conceal, or withhold, his discoveries
when he could publish them properly. These discoveries were made at
a great sacrifice of time and means, and must have appeared to him
valuable trade secrets; yet he published all his scientific data, his
theories, and observations; he encouraged his confrères in various
countries to witness and emulate his experiments, to share intimately
his laboriously developed knowledge of aviation, to join hands with
him in hastening the advent of practical flight. Such is the _esprit
de corps_ which has ever prevailed among truly scientific men, as
distinguished from the mercenary and commercial; such are the unselfish
investigators whom the world delights to honor, both for their genius
and for their liberal contributions to the common and permanent
possessions of humanity.

Before his death Lilienthal had the pleasure of knowing that competent
disciples were emulating him in doctrine and practice. One of the
earliest and cleverest of these was Percy S. Pilcher, Assistant
Lecturer in Naval Architecture and Marine Engineering at the University
of Glasgow. In the summer of 1895 he built the glider shown in Plate
XVI. This, like Lilienthal’s, was a double-tailed monoplane arched fore
and aft; but, better than his for manual control, it was straight from
tip to tip, like the designs of Henson, Penaud, and other predecessors.
This improvement was introduced to prevent side gusts from rocking the
craft so readily as they do the V-shaped gliders. His best sailer, the
_Hawk_, shown in the figure, had wings curved one in twenty, about one
third from their front edge.[28] Sometimes he sailed downhill; again
he was towed or launched, like a kite, by means of a cord, running
through five-fold multiplying gear, and drawn by running boys, or a
horse. In both cases he controlled the machine to his own satisfaction,
making in 1897 smooth downhill glides of 700 feet length, from an
elevation of 70 feet.[29] He had also visited Lilienthal, but only
after achieving success at home.

Having acquired some skill in sailing, Mr. Pilcher began work on a
power machine. This was to be propelled by a screw actuated by an
oil engine, and was to be mounted on wheels backed by stiff springs.
Having observed his speed of descent in gliding, he computed that
two tow-line horse power would float him and his machine, weighing
together 220 pounds. A like result was obtained when he was flown as
a kite. He was, therefore, on the straight road to achieving human
flight on a screw-propelled, wheel-mounted monoplane. If he had been
more cautious he might have been the first person to achieve human
flight in a practicable type of dynamic machine; for he seems to have
equaled, if not excelled, his German master in aëroplane design. But
like the master he provided inadequately for the structural strength
of his glider, and braved too far the dangers of gusty weather. One
stormy day, September 30, 1899, wishing to please several persons who
had come a long distance to see him, he made two trial flights in a
gentleman’s park near Rugby. The second of these proved fatal. The
spectators heard a cracking noise, saw the tail break, and the whole
craft plunge headlong to the ground. Poor Pilcher was mortally hurt and
died thirty-four hours later, without ever regaining consciousness. He
was then in his thirty-third year.

Had this talented young Briton and his German tutor both lived, there
would doubtless have been a pleasant race and rivalry between them;
for the pupil was forming opinions and plans sufficiently divergent
from those of his master and friend. He did not approve Lilienthal’s
high wings and low center of gravity, nor his V-shape for lateral
equilibrium, nor his flapping wing tips for propulsion, nor his method
of launching the dynamic machine. Fortunately both published their
ideas and experiments, leaving to their successors the task of judging
the merits of their designs, and of adding any improvements that might
still be required in order to achieve final success.

Contemporary with Pilcher, Mr. Octave Chanute and Mr. A. M. Herring,
in America, were emulating the work of Lilienthal. Mr. Chanute was an
experienced civil engineer, who had previously written a history of
aviation, and experimented with numerous flying models; Mr. Herring,
his employee for the time, was a mechanical engineer who had assisted
in Langley’s experiments, and previously had flown a Lilienthal glider,
and had made researches in the science of mechanical flight. On June
22, 1896, accompanied by two assistants, they went into camp among the
sand dunes, on the southern shore of Lake Michigan, to study the art of
navigating an aëroplane without artificial motive power. Mr. Chanute
thought that the maintenance of equilibrium under all circumstances
was at that time the most important problem of aviation; and that
until automatic stability was secured, it would be premature and
dangerous to apply a motor. He wished to evade, for he did not relish,
Lilienthal’s way of balancing by shifting the body and kicking wildly
at the stars. His main purpose, therefore, was to acquire the pilot’s
science; but secondarily he would learn much about the architecture
of gliders, the behavior of air currents, the elements of propulsion
and sustentation.

PLATE XVII.

[Illustration: CHANUTE’S FIVE DECK GLIDER.]

[Illustration: HERRING IN CHANUTE BIPLANE.]

[Illustration: HERRING’S COMPRESSED-AIR BIPLANE.

(Courtesy Carl Dientsbach.)]

They made some flights with a Lilienthal monoplane; but, finding this
unsafe and treacherous, they discarded it in favor of a multiple-wing
glider designed by Chanute, which after many empirical modifications
in the placement of the sustaining surfaces, assumed the form shown in
Plate XVII. This glider resembled the Lilienthal biplane in having the
surfaces vertically superposed, the rider below them, and the rudder in
the rear; but it was a five-decker whose wings, on either side, could
swerve fore and aft, so as to bring the center of lift always over the
center of gravity, in order to prevent excessive rearing or plunging.
This glider was found very tractable in a twenty-mile wind, and in a
thirteen-mile breeze would sail down a slope of one in four.

After further study, the five-decker was replaced by a three-decker;
which presently was deprived of its obtrusive and unessential lower
surface, thus assuming the familiar form shown in Plate XVII. As will
be observed, this was a radically new and elegant design, consisting
of two superposed arched surfaces held together by vertical posts and
diagonal wires, like a Pratt truss. It was, in fact, the renowned
“Chanute glider” which has been copied by so many succeeding designers
of biplanes.

The Chanute glider weighed 23 pounds, spread 135 square feet, and
readily carried a total weight of 178 pounds at 23 miles an hour. It
was provided, as shown, with side planes and a double rudder, and
this latter was elastically connected to the main body to insure
steadiness of flight, on the principle of the elastic wing margins used
by D. S. Brown in 1874. This craft was found easy to manipulate in
launching, sailing and landing, a two-inch shift of the pilot’s weight
equivalencing a five-inch shift on the Lilienthal monoplane. It was
steady at a speed of twenty to forty miles an hour through the air,
even when the wind was blowing seventeen miles an hour overground. The
angle of descent was 7.5° to 11°, depending on the speed and trend of
the wind. The work of gravity expended in maintaining steady flight was
at the rate of two horse power for the 178 pounds, a good showing with
the rider vertical.

Summer passed before Mr. Chanute could perfect the invention for
automatic stability by means of swerving wings; but otherwise the
gliding experiments were very satisfactory. The strong and simple
biplane evolved during those few weeks of fruitful study, though not
an original creation, having been foreshadowed theoretically and
experimentally, in the work of Wenham,[30] Stringfellow, Lilienthal,
Phillips, and Hargrave, was nevertheless an important contribution to
the science of aviation, by reason of its strength and simplicity of
design, its efficiency, its stability, and, best of all for that day,
its record for good flights and safety. All who could appreciate it
understood that the addition of a light motor would transform it to
a dynamic flyer, navigable at least in mild weather. The most eager,
perhaps, was Mr. Herring; for he had not only mastered this glider,
but some years previously had flown successfully rubber-driven models
very much resembling it in design. These two aviators, therefore, came
to a parting of the ways, Chanute still pursuing automatic stability,
Herring impatiently heading for dynamic flight by the shortest route
available. Had they continued together on a practical course, they
might, ere the close of the century, have anticipated at least the
early flights of the French aviators, if they could have constructed or
purchased an adequate motor.

After some further development of the aërial glider to adapt it
to power flight, Mr. Herring began the construction of a dynamic
aëroplane. He had previously built very light steam and gasoline
engines,[31] and deemed the latter best for a perfected flyer, though
preferring steam or compressed air in a first experimental test.

When seen by the present writer in October, 1898, at St. Joseph,
Mich., Mr. Herring was about to launch himself in the compressed-air
driven biplane shown in Plate XVII. It was essentially a powered
Chanute-Herring glider, steadied by a double tail, and controlled by
shift of the pilot’s weight, the tail being elastically attached.
The writer then suggested that both a glider and a dynamic aëroplane
should be controlled entirely by steering and balancing surfaces, on
the principle set forth in his paper of 1893; and, in particular,
indicated that the lateral balance should be controlled by changing the
inclination of the wings on either side, while the double tail should
be used to steer and steady the aëroplane sidewise and vertically; in
other words, that a torque about each of the three rectangular axes of
the machine should be secured from impactual pressure, thus obviating
the need for shifting the pilot’s weight. Mr. Herring, while making no
objection to this proposal, intimated that he had a device for insuring
control without shifting the pilot’s weight, but believed the most
important effort for the moment should be to make a short flight with
the machine as it stood, for the purpose of enlisting capital, then
to add the controlling devices at leisure. He expected to remove the
wheels shown in the figure, hold the aëroplane against a stiff breeze
from Lake Michigan, start the propellers, strike a soaring attitude,
and fly forward for a few seconds against the wind.

The successful accomplishment of such a flight covering an overland
distance of seventy-three feet in eight or ten seconds, against a wind
of thirty miles an hour, was reported in the Chicago _Evening News_,
of November 17th of that year; but the present writer has not been
able to ascertain the reporter’s name, or that of any other witness to
the event, which, if true, is well worthy of verification and detailed
record.

In following the votaries of passive flight, as represented by
Lilienthal and his school, we have overlooked the great man-carrying
bird of Clément Ader, one of the most prominent and successful aviators
of that active period. If the reports be true, Ader may justly claim to
be the first person to navigate the air in a dynamic flying machine.
However, it must be observed that his achievements did not at first
arouse in France a great pitch of exultation and enthusiasm. There
seemed at the time to be some skepticism as to the practicability of
his device. But later cordial reparation was made by placing it on the
Stand of Honor at the Aëronautical Salon, held in the Grand Palais, at
Paris, in December, 1908.

Clément Ader set out in life with the fixed determination to make
a fortune, then to build a practical flying machine. Adopting the
profession of electrical engineer, he quickly accumulated enough
capital, as he thought, to realize his early ambition. He next visited
Africa to study at close range the great soaring birds that Mouillard
had described with so much admiration and vivacity. Going to Algeria
he disguised himself as an Arab, and, with two Arab guides, journeyed
to the interior where he watched the great soaring vultures, which
he enticed with bits of meat to perform before him their marvelous
maneuvers, wheeling in wide circles, and without wing beat, from earth
to sky.

After several years of study of the anatomy and flight of birds, Ader
began, at the age of forty-two years, to construct an aëroplane. His
first machine was a birdlike monoplane mounted on skids, or wheels,
and driven by a 40-horse-power steam engine actuating a screw, placed
forward. The total weight was 1,100 pounds, the spread 46 feet, the
length 21 feet. The _Eole_, as he called it, received its first
open-air test on the morning of October 9, 1890, in the grounds
surrounding the Chateau d’Armainvilliers, near Gretz, a portion of the
course being so prepared that the trace of the wheels would be visible.
When everything was ready for the trial, Ader mounted the machine, in
presence of a few friends, ran quickly over the ground, urged by the
propeller thrust, then rose into the air and sailed 150 feet. Such is
the report of the witnesses to what is claimed as the first flight of a
human being in a power-driven flying machine.

Subsequently this bold inventor built _Eole No. 2_, which, by special
permission of the War Department, he tested on a prepared track, 2,400
feet long, on the Satory Camp. Over this course he ran his machine
several times, and on one occasion flew 300 feet; but on alighting
broke one of the wings.

Ader, now having spent one and a half million francs on his
experiments, placed the _Eole_ on exhibition in order to raise money
for their continuation. In this venture also he was successful,
being presently subventioned by the French War Department to build an
aëroplane for its use. His subsequent labors are concisely set forth in
_Automobilia and Flight_ for February, 1909, as follows:

  “Under these new conditions the workshop in the Rue Pajou was
  abandoned for larger premises in the Rue Jasmin, where the
  construction of the _Avion_ was commenced in May, 1892, all
  persons engaged with the construction being under a military
  vow of secrecy. The motor was built first, and tested before a
  commission composed of army officers and some of the leading
  technicians of France. It was found to develop 30 horse power
  for a total weight of 32 kilogrammes; and even now, though
  seventeen years old, is regarded as a _chef d’œuvre_. In the
  spring of 1897 the _Avion_ was ready to make flights. Like its
  predecessors it was modeled on the form of a bat; but, although
  the wings could not be flapped, they could be folded, and
  could be advanced or retarded horizontally.

  “Everything appearing satisfactory, Ader informed the military
  commission that he was ready to undergo tests; the committee
  met at the workshops in the Rue Jasmin on August 18, 1897;
  were pleased with the machine, and ordered flights to be made
  immediately at Satory. It was not, however, until October 12th
  that a flight was attempted on the carefully guarded military
  ground, and in the presence of General Mesnier. The apparatus
  covered a distance of 1,600 yards, and although it did not fly,
  for this distance it is certain that on several occasions it
  completely left the ground. Ader declared that according to
  whether the wings were carried forward or to the rear, it was
  the front or the rear wheels only which left the ground. The
  pressure in the generator at this moment varied between 3 and 4
  atmospheres. On increasing it to 6 or 7 atmospheres none of the
  wheels touched.

  “Satisfied with the results of the test, General Mesnier called
  the commission together for further trials on the following
  day, October 14, 1897. Unfortunately it was a rough, squally
  morning, that would have prevented many a modern aviator from
  bringing a machine into the open. But as the officers had been
  brought together specially for this purpose, a flight was
  attempted.

  “‘After several revolutions of the propellers, and a few yards
  covered at a moderate speed, we were off at a high rate of
  travel,’ wrote Ader, who was at the wheel on this memorable
  occasion. ‘The pressure was about 7 atmospheres. Almost
  immediately the vibrations of the rear wheel ceased, and,
  directly after, those of the front wheels were no longer felt,
  showing that we had entirely left the ground. Unfortunately
  the wind had increased in strength, and I had some difficulty
  in keeping to the line that had been marked out. I increased
  the pressure to 9 atmospheres, and immediately the speed
  increased considerably, the vibrations ceased again, showing
  that we had once more left the ground. Under the influence of
  the wind the aëroplane had a constant tendency to drift to
  the right, away from the circular track that had been marked
  for it. Finally, with the wind broadside on, the machine was
  in a rather dangerous position, for it was being still more
  rapidly driven out of its course. I increased the pressure
  still more and put the rudder hard over to the left, with the
  result that for a few seconds the machine worked back towards
  the track and still maintained itself in the air. But it was
  impossible to struggle against the wind, and finding that the
  machine was being carried towards some artillery sheds, and
  somewhat unnerved by the speed at which the ground appeared to
  be rushing past, I stopped the engine; there was a shock, and I
  was on the ground.’

  “Ader was uninjured, but his machine was rather badly smashed.
  It had certainly flown, but with such difficulty in the face of
  the wind that the army commission was evidently little inclined
  to report favorably upon it. Several weeks passed without any
  communication being received from the War Department; then it
  became apparent to Ader that the Government had no longer faith
  in his invention. This was proved early in the following year
  by an official communication to the effect that no further
  funds could be allotted to this work. Discouraged at the
  abandonment after forty years’ labor and the expenditure of
  about two million francs, Ader commenced the destruction of his
  machines. The earlier ones were destroyed, but the _Avion_, the
  one which had appeared before the army commission, was saved
  and sent to the Museum of the Arts et Métiers in Paris.”

The last aëroplane, or _Avion_, weighed 1,100 pounds, spread 270 square
feet, and was driven by a 40-horse-power steam engine actuating twin
screws projecting before the bird-shaped flyer. The engine weighed but
7 pounds per horse power—quite a remarkable achievement for that day.

In following the votaries of passive flight, as represented by
Lilienthal and his school, we have overlooked the great dynamic
aëroplane of Mr. Maxim, one of the most prominent aëroplane builders of
that active period. Having in 1889 made elaborate experiments on the
atmospheric resistance of sustaining surfaces, and on the thrust of
screw propellers, he proceeded to build the gigantic aëroplane shown
in Plate XVIII, the greatest flyer thus far known to history. It was a
twin-screw multiplane mounted on a platform forty feet long by eight
feet wide, and having four wheels running along a track eight feet
wide and half a mile long. Above the rails of this track were guard
rails to prevent the flyer from rising more than three inches during
the tests. The whole machine weighed 3.5 tons, spread 5,500 square
feet of surface, and, at a speed of 40 miles an hour, lifted more than
a ton, in addition to the weight of the three men and 600 pounds of
water. Its propelling plant comprised a naphtha tubular boiler, and a
compound steam engine of 350 horse power actuating twin screws 17 feet
10 inches in diameter which gave a thrust approximating 2,000 pounds.
These screws were made of American yellow pine, covered with canvas and
painted, then smoothly sandpapered to reduce the friction; for Maxim,
like certain French aviators, erroneously imagined that a polished
surface has less air friction than a dead even surface. The framework
was composed of seamless steel tubing stayed with steel wire. The
aëroplane was to be steered right and left by a rudder, and up and down
by horizontal planes, one fore, another aft, and its lateral stability
was to be secured by side planes set at a dihedral angle. A meritorious
feature for that day were the superposed arched surfaces whose framing
was smoothly covered below and above by skillfully stretched fabric,
causing the air to flow evenly without wasteful eddies.

PLATE XVIII.

[Illustration: MAXIM’S AËROPLANE.

(Courtesy W. J. Hammer.)]

[Illustration: LANGLEY’S LARGE AËROPLANE.

(Courtesy Smithsonian Institution.)]

Many runs along the track were made to test the working of this
great apparatus before trusting it to launch forth in free flight.
Dynamometers gave independently the thrust of the screws, and the lift
of the wings on the front and rear axles. The ascensional planes for
controlling the fore and aft equilibrium were tested during the run,
as also the practical operation of the propelling plant. During the
trials of 1893 the machine frequently lifted clear of the lower track,
and flew forward resting against the guard rails above the wheels.
Finally, on a gusty day, the lift against the upper track caused this
to give way, whereupon the machine rose into the air with Mr. Maxim
and his assistant, then toppled over on the soft earth, suffering
some damage to its framework. Here the experiments were discontinued
for lack of funds, having indeed demonstrated that a large weight
can be carried in dynamic flight, but having proved little as to the
feasibility of controlling an aëroplane in launching, in free flight,
and in landing.

Compared with the work of his contemporaries this achievement of Mr.
Maxim was herculean, both in construction and expenditure, the cost
being reported as nearly one hundred thousand dollars. It raised high
hopes for aviation. It proved conclusively not only that a flying
machine could be made to lift a pilot, but that it could carry hundreds
of pounds additional weight. It still holds the world’s record for
magnitude of machine and cargo. But it had two great defects; it was
improperly balanced and it was inadequately powered; for, as Mr. Maxim
says, “the quantity of water consumed was so large that the machine
could not have remained in the air but a few minutes, even if I had had
room to maneuver and learned the knack of balancing in the air.”[32]
These defects, however, would soon be remedied by the work of others,
and particularly by the costly experiments of the automobilists, who
were rapidly developing a light gasoline motor suitable for aviation.

The inventors thus far noticed had developed most of the important
features of the present-day flying machines, but had not provided
adequate mechanism for preserving a steady lateral balance. The present
writer had proposed the combination of a double rudder and torsional
wings to steer and control a flyer, and had published a paper setting
forth its general principle and describing a specific device; but
inventors had little need for a third rudder till they encountered
the dangers of dynamic flight in gusty weather. The paper referred
to was presented to the Third International Conference on Aërial
Navigation, in August, 1893, under the title, _Stability of Aëroplanes
and Flying Machines_, and was published with the proceedings of the
conference.[33] It discusses mainly the question of automatic stability
and steadiness; but recommends personal control during the experimental
period. It concludes as follows:

  “We have been considering the question of automatic stability,
  in so far as it may be secured in the construction of the
  craft itself,[34] apart from a pilot, or special equilibrating
  devices. The application of the latter would give exercise
  to an infinite amount of ingenuity, and would, perhaps, best
  be left to the fancy of the individual inventor. One curious
  design, however, occurs to me, which, since I have not seen it
  described elsewhere, may be worth a moment’s notice.

  “Suppose a Phillips’s machine (see Plate XIV) to be provided
  with a double tail, and to have a vertical fin extending
  longitudinally along its entire length, well above the
  center of gravity. These would steady its flight and promote
  stability. _Suppose also that its sustaining slats were
  pivoted, so that a pilot could at pleasure change their
  inclination on the right and left side independently. He could
  then set the engine for a desired speed, sweep forward along
  the earth with the sustainer slats horizontal, and at will
  mount into the air, by giving the slats an upward inclination.
  Once in the air he could raise or lower the machine by slightly
  changing the angle of the slats; he could wheel to right or
  left by giving one set of slats a little different slope from
  the other; he could arrest all pitching, rocking and wheeling
  by a slight counter movement of the sustainers._ It would be
  necessary, of course, to preserve a rapid forward motion, for
  it is a peculiarity of the compound aëroplane that, if it comes
  to a standstill in the air, it will drop plumb down with a
  frightful plunge until it acquires headway.”

The succeeding paragraph disclosed a specific contrivance embodying
the principle just given. This showed two levers rotating drum shafts
for actuating wires adapted to change the impact angles of the wing
surfaces. Accordingly this much of the mechanism of control, together
with the broad device of the torsion wings, has been the common
property of inventors since the publication of that paper. Furthermore,
the combination of torsional wings and a double rudder, either fixed or
movable, has been public property since that date.[35]

Little was said about the manner of manipulating the double rudder and
torsional wings; for the rules of manipulation would vary in different
machines, depending upon structural design and external conditions.
For example, if the proposed fin and vertical rudder were ample and
suitably placed, the lateral balance could be controlled by merely
twisting the wings, without touching the vertical rudder; but if the
fin and rudder were not adequate, the lateral poise would be controlled
by twisting the wings and working the vertical rudder conjunctively.
A novice might prefer leaving the rudders fixed and controlling the
poise in short flights by twisting the wings by means of a single lever
having two independent movements, one to rotate the wings oppositely,
the other to rotate them identically.

The principle of control expressed in italics had been set forth also
in a preceding paragraph. Having proposed means for securing both
stability and steadiness about each of the three axes of an aëroplane,
the text continued:

  “These ends could probably be attained very well by mounting
  two compound aëroplanes on a long backbone,[36] somewhat after
  the manner of the Hargrave cellular kites, and adding a
  compound rudder to the whole.” ... “_If the inclination of the
  sustainers, front and back, could be altered independently,
  it might be feasible for a pilot to preserve the equilibrium
  of the machine even when its center of gravity was frequently
  shifted, as by the moving of passengers to and fro._”[37]

At that date, 1893, an inventor doubtless could have secured a broad
claim on a mechanism embodying the torsion-wing-and-double-rudder
mechanism of control. But in those days aviation was pursued largely
as a liberal study by scientific men who wished to hasten the advent
of practical flight, by presenting important physical measurements
and principles which could be freely employed by all. Accordingly the
three-rudder system of control seems not to have been claimed by an
inventor much before the close of the nineteenth century. Since then it
has been patented in one form or other by many practical aviators, some
endeavoring to claim the whole broad contrivance, others claiming more
restricted devices.

The static principle of the torsion wing is a familiar one in
elementary mechanics. It is this: a torque of given magnitude and
direction has the same effect on a rigid body whatever its point of
application. The longitudinal torque, or moment, may therefore be
exerted by the wings, by suitable rudders, by forward planes, by any
auxiliary planes, or fins, however placed or moved for the purpose.
Accordingly there seems to be an unlimited variety of concrete
patentable devices available to the inventor for securing impactual
torque about the longitudinal axis, or either of the other two axes.
But in planning such devices it is well to remember that the moment of
a couple increases with its arm, so that in a wide aëroplane the wing
tips may best furnish the torque; while in a high short-winged machine,
vertical planes, fins, or rudders may give the desired longitudinal
moment. Obviously such vertical guiding or controlling surfaces may be
so placed as to tilt the machine toward the center of curvature of its
path, at the same time opposing the centrifugal force, and exerting a
torque about the vertical axis tending to steer the flyer along its
path.[38]

The principle of projectile stability is another consideration of
some importance in aviation, or more generally in all submerged
navigation, whether of air or water. A submerged body has projectile
stability if its nose tends always to forerun its centroid, and follow
a steady course. A dart is a good example; a fish, a torpedo. Thus if
a torpedo-shaped homogeneous solid be hurled in any manner through a
fluid, obliquely or even tail foremost, it promptly turns its nose to
the front and proceeds steadily along an even course; but if the body
has not true dynamical balance, it may oscillate or gyrate, or flit
about in the most erratic manner.

Projectile stability in a flyer, as in an arrow, may be attained by
playing the centroid in or near the line of forward resistance, and
well ahead of the side resistance. The reasons for this are manifest.
If, however, this arrangement be neglected, a special damping, or
controlling, device is required to preserve headlong and steady motion.
In particular, the objections to placing the centroid too low were
emphasized in the above quoted paper as follows:

  “I have mentioned the advantage of placing the center of mass
  below the center of surface; this has also its objections.
  While the stability against inversion is increased, the
  stability against rocking is sacrificed. The aëroplane so
  constructed may not easily overturn; but it will sway to
  and fro with a pendular motion. This, when lateral, is very
  objectionable, when fore and aft it is fatal to uniform
  progress, as we shall see in studying the longitudinal
  stability of flying machines. We shall then see that the center
  of mass cannot be lowered with impunity.”

Of the various flyers and models thus far studied, some manifest fairly
good, others very imperfect projectile stability. Many inventors have
been more alert to the gravitational stability and safety of the
parachute than to the kinetic stability and keen, direct flight of the
arrow. Some of the most pretentious machines imitated the thistle down
more nearly than the dart or swallow. But the exigencies of actual
flight would easily rectify such imperfections of design.

Tractional balance also is a property of some importance in fluid
navigation. This requires that the line of propulsive thrust coincide
with the line of fluid resistance. It is a property, however, that
inventors readily apprehend, and usually provide for.

In general a flyer is subject to four forces: weight, thrust, air
pressure and inertia. When these balance about any axis the craft has
equilibrium about that axis; when they balance about the three axes
the craft is completely balanced, and preserves its orientation in
flight. Devices for preserving this complete balance have already been
described; as also provision for propulsion and sustentation, launching
and landing safely.

Thus at the close of the nineteenth century all the essential
principles and contrivances of pioneer flight were worked out, except
one—a suitable motor. This was the real problem of the ages. The rest
was easy by comparison. A light enduring motor, if available to the
old time inventors, would have brought dynamic flight centuries ago.
That only could have baffled Da Vinci, Cayley, Henson, Wenham and the
long line of pioneer aviators. Eventually, of course, steam engines had
come, endowed with ample power; but costly to build and wasteful to
operate. The light automobile engine appeared in the latter nineties;
promptly thereafter followed the dynamic flyer, the snow-winged herald
of the twentieth century.




                              CHAPTER IX

              AËROPLANES OF ADEQUATE STABILITY AND POWER


The dawn of the twentieth century found several votaries contriving
aëroplanes for one or more passengers. The epoch of models had
virtually closed, bequeathing a rich heritage. The essential elements
of aviation, barring the motor, had been clearly worked out. The age
of practical flight was at hand. No further need to prove feasible
the heavier than air; for that had been done repeatedly. Scientific
design and patient trial, not invention and physical research, were now
the chief demand. Further research would improve the aëroplane, but
not bring it into practical operation. Capital, constructive skill,
judgment in adapting principles and devices already known, energy,
persistence, caution, imperturbability in danger and derision; these
were requisites. Science had led the way, with uplifted torch; let the
craftsmen follow her with kit and apron. The aëroplane was sufficiently
invented; it now wanted, not fastidious novelty, but concrete and
skillful design, careful construction, exercise in the open field.

Of the group of aëroplanists in the beginning of the nineteenth century
Mr. Hugo Mattullath, of New York, was one of the most original, daring
and resourceful. He had been a successful inventor, manufacturer and
business man, accustomed to large enterprises. In the latter nineties,
deeming the time opportune for practical aviation, he determined to
build a commercial flying machine. He would begin where Maxim had
stopped. A larger and swifter craft appeared to him most desirable.
In his judgment any clever mechanic could make a one-man flyer. “Take
that for granted and waste no time on toys!” Professor Langley’s
“aërodrome,” with every spare ounce filed away, should lift itself,
of course. It might navigate a calm; possibly even a zephyr, if no
one sneezed; but never could it carry passengers on schedule time. He
therefore would jump the little flyers, and build at once a commercial
aëroplane strong enough to defy the storm, powerful enough for regular
traffic on a business scale. That meant a ship for numerous passengers,
equipped to fly fifty miles an hour against the prevailing wind. A
glorious project indeed; an enterprise suited to a gentleman of first
rate ability.

Mattullath’s aim was aërial transportation, not exhibition at county
fairs and crowded carnivals. Regular interurban routes were projected,
terminating in ample landing floors. Broad-winged aëroplanes, huge
catamarans with shining hulls, sumptuously furnished in gold and
crimson, should convey happy crews, in all seasons, from metropolis to
metropolis. Six great engines and propellers to drive the ship, with
abundant reserve power. Melodious strains of music rising incessantly,
to soften the thunder of motors and the demoniacal howl of the wind.
Then transcontinental voyages, outsailing the nimbus, how lovely to
the anointed of fortune! Jocund savannas nestling by the sea, or in
the bosom of orchid-crested hills, should welcome to earth the silken
sojourners of the north migrating, gay-plumed and potent, to their
winter homes in tropic paradise. All the isles of ocean, all the merry
mountains, earth, sea and air, one shining empire, blissful and secure
as Olympus. Chimborazo, girt with every clime, from torrid base to
snowy peak should glow

    With alabaster domes and silver spires,
    And blazing terrace upon terrace high
    Uplifted; here serene pavilions bright,
    In avenues disposed; their towers begirt
    With battlements that on their restless fronts
    Bore stars—illumination of all gems!

Such were his holiday fancies, seldom revealed, even to his associates.
The public had no intimate part in his project. A few trusted
engineers, eminent in their profession, and a few financiers, formed
his advisory board. For two years he worked on the structural elements
of the great sails, propellers, and framing of his ship. But unhappily
when he was preparing to present his final plans to his council of
engineers, before building the large vessel, he was brought suddenly to
the close of his career.[39]

Mattullath’s proposed air ship consisted of two parallel torpedo-shaped
hulls sustained by superposed plane or slightly arched surfaces, and
propelled by feathering-paddle disk wheels embedded in the planes;
the engines, cargo and passengers to be placed within the hulls.[40]
This arrangement would enhance the comfort of the passengers at high
speeds, eliminate resistance, distribute the load on the framing,
and increase the moment of inertia of the vessel, thereby rendering
it less sensitive to side gusts. To improve the projectile stability
and steadiness, the centroid was placed as high as practicable. Large
steering planes were used fore and aft on both sides of the vessel,
whose inclination could be changed independently, to turn the ship
about its longitudinal or transverse axis. A vertical rear rudder
steered to right or left, in conjunction with the side planes. All the
posts were of double wedge shape; all the planes were canvassed above
and below to shield the framing, after the style of Maxim. The hulls,
the posts, the planes, all parts, were keenly sharpened to economize
power. The ship was to run over its smooth launching field till it
acquired a rising speed of forty to fifty miles an hour, then continue
accelerating up to velocities sufficient for competition with passenger
trains in all weather.

While one may easily point out certain questionable features in
Mattullath’s project, as for example, its odd propellers, one can not
so easily estimate its true merits. The torsion wing device for lateral
control and steering, which he claimed in his patent application,
abandoned after his death, now constitutes a very important feature of
every flying machine. His planes for fore and aft control, introduced
by Maxim, are also in general use to-day. The principle of load
distribution, which he greatly prized for diminishing stress and adding
stability, has still to be evaluated by practical test in larger craft
than any now in operation. The closed hull, for comfort and economy at
high speed, is at present popular with many designers.

One tentative assumption of Mattullath’s, made on the authority of
Maxim and Langley, was that the friction of the air is a negligible
part of the entire resistance encountered by the hull, framing and sail
surfaces. Accepting their experimental conclusion, he designed a flyer
so sharp and smooth in all its parts as practically to eliminate the
pressural, or head resistance. With no skin friction, with scant hull
and frame resistance, he could afford[41] to fly at a very slight
angle, thus minimizing the drift, or wing resistance, while at the same
time securing abundant lift by rapidity of flight. He thus arrived,
by cold deduction from the data of those prominent experimentalists,
at an aëroplane swift as the albatross, and wondrously economical of
power. But his financiers were loath to gamble on that assumption. He
therefore, at their suggestion, instigated systematic measurements
of air friction on smooth surfaces, which demonstrated that in a
sharp aëroplane flying at a very slight angle, the skin friction is
nearly equal to all the other resistances combined. These results were
obtained and published[42] some months after his death. They were
unfavorable to his project, and to all projects for attaining high
speed through the air by excessive sharpening of the vehicle.

The first dynamic aëroplane of adequate stability and power to carry a
man in prolonged flight, was that of Professor Langley. This machine
was nearly a duplicate, on a four-fold scale, of the gasoline model
previously described, which had flown many times with good inherent
equilibrium. There was accordingly every reason to expect that,
weighted and launched like the model, it would fly with the same poise
and swiftness, even if left to govern itself. Having in addition
a living pilot, provided with rudders for steering and balancing,
together with adequate fuel for a long journey, it seemed to promise
still better results than the model. But an unfortunate accident in the
launching so crippled this carefully designed craft that it fell down
helpless, without a chance to exhibit its powers of sustentation and
balance, even for a moment, in normal flight.

The first trial occurred on September 7, 1903, in the middle of the
Potomac River at Widewater, Va. The aëroplane was placed on the same
catapult, above the boat, that had previously started the models on
their smooth and rapid maneuvers. The pilot took his seat, and started
the 50-horse-power engine which ran the propellers without appreciable
vibration. Tugs and launches were placed along the course where they
might be of service. Photographers, on the water and along shore, were
ready to furnish important pictorial records of the experiment. The
aëroplane was released and sped along the track attaining sufficient
headway for normal flight; but at the end of the rails it was jerked
violently down at the front, and plunged headlong into the river,
sinking beneath the waves. Buoyed up by its floats, it quickly rose to
the surface, with its intrepid pilot uninjured, and with little damage
to the structure.

As revealed by an examination of the catapult and photographs, the
guy post that strengthened the front pair of wings had caught in the
launching ways, and bent so much that those wings lost all support. The
aëroplane, therefore, had not been set free in the air, but had been
wrenched and jerked downward. Thus the launching proved nothing of the
propulsive or sailing powers of the machine.

Those who understand the principles of aviation can judge the merit of
Langley’s “aërodrome”[43] from its mechanical description. As shown in
Plate XVIII, it was a tandem monoplane driven by twin screws amidships.
The pilot seated in the little boat could control the poise and course
by several devices; he could shift his weight longitudinally 4.5 feet,
laterally 2.5 feet; he could elevate and depress the rear double
rudder, which when untouched ensured steady longitudinal poise, on the
principle introduced by Penaud; he could steer to right and left by
turning about its vertical axis, the wind-vane rudder shown below and
rearward of the boat. The lines of lift, propeller thrust and forward
resistance passed through the centroid, or near it, thus providing
for projectile and gravitational stability. In this feature Langley’s
“aërodrome” far surpassed those of his immediate predecessors, whose
machines, by reason of their low centroid, possessed the stability of a
pendulum, rather than that of a dart, or swallow. These various devices
combined should give the craft better control in free flight than that
possessed by any of the models, which had flown successfully many times
in moderate weather.

If the projectile and steering qualities of Langley’s machine surpassed
those of its predecessors, the propelling mechanism was a still
greater advance in the art of aviation. The gasoline engine was a
marvel of lightness, power, endurance and smoothness of running. It
weighed, without accessories, 125 pounds, and developed 52.4 horse
power in actual test at a speed of 930 revolutions a minute. With
all accessories, including radiator, cooling water, pump, tanks,
carburetor, spark coil and batteries, it weighed 200 pounds, or
scarcely five pounds per horse power—a great achievement for that time.
It could run many hours continuously under full load, consuming about
one pound of gasoline per horse power per hour. Its five cylinders,
arranged radially round a single crank shaft, were made of steel lined
with cast iron, and measured 5 inches in diameter by 5.5 inches in
stroke. Its running balance was excellent. By means of bevel gears it
drove the twin screws at 700 revolutions per minute, giving a thrust
of 480 pounds, the screws being very nearly true helices of unit pitch
ratio and 30° width of blade, carefully formed of three radial arms
covered with canvas.

The whole machine weighed 830 pounds, including the pilot; spread 1,040
square feet of wing surface; measured 48 feet from tip to tip, and 52
feet from the point of its bowsprit to the end of its tail; soared at a
speed of about 33 feet a second and a ten-degree angle of flight, the
wings arching one in eighteen at one fourth the distance from their
front edge. The double rudder, at the extreme rear, measured 95 square
feet in each of its component surfaces.

It is evident from these figures, very kindly furnished by Mr. Manly,
the mechanical engineer in charge of the experiments, that such an
aëroplane had every equipment needed for a steady flight of many hours
in fair weather. A thrust of 490 pounds on well-designed surfaces
should easily carry 500 pounds of gasoline in addition to the 830
pounds regular weight of ship and pilot. This would enable the machine
to fly practically all day without renewal of supplies. It appears,
therefore, that Professor Langley had, in 1903, a dynamic aëroplane
quite the peer, in many respects, of the best that were developed
during the first decade of aviation, and that a mere accident, which
should be expected in such complex experimentation, deprived him of
the credit of the first man-flight on an adequately controlled and
powered machine. Quite true, he lacked launching wheels; but how easy
to add these, since they were proposed many times. He omitted the
front steering plane, but had a rear one serving the same purpose. The
worst that can be said is that he needed the equivalent of torsion
wings for lateral control; but in moderate weather he could have flown
successfully without them, as Farman, Delagrange, Paulhan[44] have so
fully demonstrated. Besides, Langley had already tested the torsion
wing device, and contemplated using it on his large machine.

A second launching was attempted on the Potomac River near Washington,
on December 8, 1903. This time the rear guy post was injured, crippling
the rear wings, so that the aëroplane pitched up in front and plunged
over backward into the water. After some repairs it was stowed away
in the Smithsonian Institution, where its frame and engine are still
intact, its wings having been injured in the wreck and discarded. The
experiments were now abandoned for want of funds to continue them.

Notwithstanding that Professor Langley had contributed much to the
science of aërodynamics, by his elaborate researches, and had really
developed a machine capable of sustained flight, if properly launched,
he was subjected to unmitigated censure and ridicule; for he had
incurred the enmity of various journalists and wiseacres, partly by
his official secrecy, and partly by that natural reticence which
avoids premature publicity in important scientific enterprises. This
irresponsible criticism, combined with the cessation of work which
should have brought success, profoundly grieved him, and doubtless
hastened his death. He had, however, the satisfaction of knowing that
a few competent specialists appreciated his labors, and would continue
them to abundant fruition. A few days before his death he had the
gratification of receiving, from the newly formed Aëro Club of America,
the following communication acknowledging the value of his efforts to
promote aërial travel.


                RESOLUTIONS OF THE AËRO CLUB OF AMERICA

                      _Adopted January 20, 1906._

“_Whereas_, our esteemed colleague, Dr. S. P. Langley, Secretary of
the Smithsonian Institution, met with an accident in launching his
aërodrome, thereby missing a decisive test of the capabilities of this
man-carrying machine, built after his models which flew successfully
many times; and whereas, in that difficult experiment, he was entitled
to fair judgment and distinguished consideration because of his
important achievements in investigating the laws of dynamic flight, and
in the construction of successful flying models; therefore be it

“_Resolved_, That the Aëro Club of America, holding in high estimation
the contributions of Dr. Langley to the science of aërial locomotion,
hereby expresses to him its sincerest appreciation of his labors as a
pioneer in this important and complex science; and

“_Be it further resolved_, That a copy of these resolutions be sent to
the Board of Regents of the Smithsonian Institution and to Dr. Langley.”

This kindly message from America’s foremost aëronautic society brought
a moment’s pleasure to the last hours of the illustrious scientist.
“Professor Langley was on his deathbed when these resolutions were
brought to his attention, and when asked what should be done with the
communication, his pathetic answer was: ‘Publish it.’ To all who know
his extreme aversion to publicity in any form, this reply indicates how
keenly he felt the misrepresentation of the press.”[45]

Professor Langley’s progress with the “aërodrome” was due largely to
the skill, energy and devotion of his designer and superintendent of
construction, Mr. Charles M. Manly. This talented young graduate in
mechanical engineering, of Cornell University, in 1898, went directly
from the class room to assume the chief burden of Langley’s researches
in aërodynamics, and his practical experiments in mechanical flight,
remaining till their termination in 1904. He was the confidential
secretary and adviser to his chief in that whole enterprise. When
in 1900 Dr. Langley stood baffled before the greatest obstacle in
aviation, unable to find any manufacturer, in America or Europe, who
could furnish a practical engine of the desired power, lightness and
durability, Manly came to his rescue with a design which guaranteed
success and which resulted in the wonderful gasoline motor built in the
Smithsonian shops. Finally when the aëroplane was ready to be launched,
it was Manly who bore the long weeks of trial in the malarial region of
Widewater, harassed by accidents and foul weather, not to mention the
merry agents of the press; and it was he who twice rode the ponderous
aërodrome, shot forth in mid air at the imminent risk of his life.

While Langley was building his great tandem monoplane, Wilbur and
Orville Wright of Dayton, Ohio, were developing a biplane which was
an improvement on the aërial glider of Chanute and Herring. This was
to be their preliminary effort toward achieving continuous flight.
Their first product, tried at Kitty Hawk, North Carolina, in the
summer of 1900, is shown in Plate XIX. The chief points of departure
from Chanute and Herring’s glider were (1) to place the rider prone
on the lower surface, as first proposed and tried by Wenham, forty
years’ previously; (2) to discard the vertical rudder; (3) to place
the horizontal rudder forward, as done by Mattullath and Maxim; (4)
to control the lateral balance by changing the impact angles of the
wings, as recommended by the present writer in 1893. Of these four
modifications the first was impractical for general use, though good
for soaring and possibly racing; the second was unsatisfactory and
later abandoned; the third was effective, and has been accepted by
some aviators as an improvement, but rejected by others who prefer the
rear[46] horizontal rudder; the fourth proved acceptable to them, as to
various other inventors before and after them.

With this glider they made a number of satisfactory flights. The front
rudder and the torsional wings proved adequate to control the craft
in sailing straight ahead down the Kill Devil sand hills, near Kitty
Hawk, N. C. In this, as in all their machines to the present date, sled
runners, fixed under the machine, as proposed by Ader and others, were
used for launching and landing. With a surface of 165 square feet, they
could glide down a slope of 9.5° at a speed of 25 to 30 miles an hour.
This showed only a moderate efficiency, but it was a beginning.

The glider used in the summer of 1901 was modeled after that of the
previous year, but larger. It was 22 feet wide, 14 feet long, 6 feet
high, spread 308 square feet, and weighed 108 pounds. With this a
number of glides were made, of various lengths up to 400 feet. At a
speed of 24 miles an hour gravity exerted on the aërial coaster 2½
tow line horse power, showing an efficiency nearly equal to that of
Pilcher’s glider of 1897.

In camp with the Wright brothers in 1901 was Mr. Chanute, the leading
aëronautic expert in America. They thus had the advantage of
his long experience, both as a student of aviation and a practical
experimenter. With them were also two other specialists, Mr. E. C.
Huffaker, an experienced aëronautical investigator, who had worked
successively with Langley and Chanute; and Dr. G. A. Spratt, who had
made some important investigations on the value of curved surfaces and
the travel of the center of pressure with the varying angles of flight.
The numerous animated conferences with these gentlemen were instructive
and profitable. When the season closed the brothers returned home and
experimented on curved surfaces to improve the efficiency of their
glider.

PLATE XIX.

[Illustration: FIRST WRIGHT GLIDER.]

[Illustration: SECOND WRIGHT GLIDER.]

The 1902 machine, shown in Plate XIX, had two main surfaces, measuring
each 32 by 15 feet, and a front rudder measuring 15 square feet. The
whole weight was 116 pounds. It will be noted that a vertical rudder
was now employed. This was a reversion to the design of Chanute and
Herring, but after some experience, the rudder was made adjustable,
as in Henson’s aëroplane of 1842. Its surface was 12 square feet,
but later reduced to six. With this machine they obtained between
700 and 1,000 glides during the season. It showed greater efficiency
than its predecessors, its normal angle of descent being estimated at
seven degrees or less. This was some improvement over the efficiency
of the Chanute-Herring glider, partly due, of course, to placing the
rider flat, instead of allowing him the more comfortable erect posture
adopted later.

Whatever improvements of efficiency and strength had been made,
these were of secondary importance compared with the provisions for
projectile stability and manual control. Here at last, after ten
years’ groping, was an actual glider with sufficiently high centroid
to minimize the pendulum effect, and with three rudders to give
impactual torque about the three axes. These simple provisions had
been previously pointed out in aëronautic writing, and, in the latter
nineties, had been embodied in Mattullath’s aëroplane, but not tested
in the large machine, owing to his death. The wonder is that, of all
the practical inventors of aëroplanes, Mr. Mattullath was the only
one of that period fully to grasp and adopt these main ideas before
starting to build a man-carrying machine. However, it must be added
that he had previously made small flying models, which may have
suggested the advantage of kinetic stability and the three-torque
system of control. If Lilienthal and his disciples, who laid so much
stress on gliding experience, had started like Mattullath with three
torque-surfaces, they would have missed indeed those acrobatic and
picturesque kickings at the sky, but they would have reached the
desired goal with less danger, time and expense. They displayed more
skill in riding a fractious glider than in designing a tractable
one, by providing for impactual torque about each of three axes. Had
they started with a good theory of dynamic control, they could have
dispensed with coasting entirely, and commenced aviating with short
runs over a smooth course followed by cautious leaps in the air, after
the style of certain ingenious French aviators. However, the knack
of balancing was finally acquired, and thus the glider was ready to
receive the propelling mechanism.

In 1903 a 16-horse-power engine and twin-screw propellers were applied
to the navigable glider at Kitty Hawk, as shown in Plate XX. The power
machine weighed 750 pounds, and was usually started by aid of a tow
line and falling weight which helped the craft to acquire headway.
After many trials and modifications, the first successful launchings,
four in number, were made on December 17th. The first flight lasted
12 seconds, the next two a little more, the fourth lasted 59 seconds,
covering a distance of 852 feet over the ground in the face of a
twenty-mile wind. To the superficial observer these performances did
not seem a very remarkable advance on the flights of Ader, but they
had in them greater promise and potency of practical flight. They were
the first flutterings of a fledgling endowed with the chief essential
organs of aërial locomotion—an awkward but healthy creature that had
been evolving steadily for several generations. It would grow rapidly,
and ere another half decade, increase the 59 seconds to so many minutes.

PLATE XX.

[Illustration: FIRST WRIGHT AËROPLANE (REAR).]

[Illustration: FIRST WRIGHT AËROPLANE (SIDE).]

The experiments were continued during the next two years with
increasing success. During the season of 1904, on a field near Dayton,
one hundred and five flights were made, some short, others covering the
entire circuit of the field no fewer than four times, the two largest
measuring each nearly three miles, each accomplished in about five
minutes. Various improvements were made in the propelling and steering
mechanism, and increased skill in maneuvering was gradually acquired.

In 1905 the flights were resumed with a new machine embodying some
changes dictated by experience, particularly in the method of control.
Forty-nine landings were made involving seven breakages, but no
personal injury. On September 26th a flight of eleven miles was
achieved. This was followed, within the next nine days, by flights of
twelve, fifteen, twenty-one and twenty-four miles, at a usual speed
of 38 miles an hour. After this the field practice ceased for more
than two years, and the machine was dismantled to preserve secret its
mode of construction till the patents could be disposed of. As these
performances and those preceding are of unusual interest, a fuller
account is given in Appendix IV.

The Wright brothers now had to assume in aviation the rôle of cautious
business men. The gliding experiments had been a scientific recreation,
and had been fairly well reported to engineers, except in those details
to be covered by patent claims; but the details of the power machine
were withheld, or sparingly disclosed. The brothers had sacrificed
time and money. They were making aviation a profession. They must,
therefore, be repaid. But if they exhibited too promptly their machine
and aërodynamic data, they might jeopardize their financial interests
by assisting or stimulating rival aviators. On the other hand, by
procrastination and concealment they might, in various ways, forfeit
priority and scientific credit. Chanute’s glider was already familiar
in Europe, and it was estimated to have ample efficiency for successful
flight with existent motors. Their own published experiments were
being studied and repeated. They might, therefore, expect that, at any
time, some rash or cunning fellow would bolt into the air and proclaim
to all the world that their unpublished devices, if they possessed
any novelty, were by no means necessary, as they fancied, to usher
in actual dynamic flight. The aëroplane would thus appear to be the
sudden outgrowth of fertile and mature conditions, rather than the
product of uncommon originality. Scores of aviators would immediately
spring into being—chauffeurs, mechanics, sporting gentlemen of every
dye. Light motors being now available, any intelligent artisan could
power a Hargrave kite, or Chanute glider, and soar aloft. Every odd
craft, not too absurdly designed, would navigate, with some showing.
Publicity and prize money would develop and perfect the various types
with feverish haste. But in 1905 the Wright brothers apprehended no
portentous or imminent invasion of the sky. The foreign bogie was five
years behind, being unfamiliar with sand hill practice and the torsion
wing. They would, therefore, chance the result of withholding their
data and concealing their machine. It was a curious situation; Langley
and Manly, who produced the first aëroplane endowed with all the
essential powers of prolonged flight, were bound to official secrecy;
the Wrights, who had a finished machine, tried and fairly ready for
public exhibition, were hampered by trade secrecy. These silent leaders
in aviation presented a gratifying contrast to the shouting fraternity
who, in the daily press, announced impending marvels which never
materialized.

The same year, 1905, which crowned with most success the private
flights of the Wright brothers, brought into unusual prominence
the quarter century long experiments of Prof. J. J. Montgomery of
Santa Clara College, Santa Clara, Cal. He had given much attention
to the science of aviation, particularly to passive flight, and had
constructed several successful gliders operated by himself or his
friends. The most remarkable of these machines was a glider resembling
in general appearance Langley’s tandem monoplane, but having means for
changing the wing curvature during flight, thus varying the lift on
such wing, and thereby enabling the operator to control the equilibrium
and direction during his glides in the air.

On April 29, 1905, a forty-five pound glider of this pattern bearing an
intrepid parachute jumper, Daniel Maloney, was lifted from the college
grounds by a hot-air balloon to an elevation of 4,000 feet, then cut
loose. “In the course of the descent,” writes one of his pupils, “the
most extraordinary and complex maneuvers were accomplished—spiral and
circling turns being executed with an ease and grace almost beyond
description, level travel accomplished with the wind and against it,
figure-eight evolutions performed without difficulty, and hair-raising
dives were terminated by abrupt checking of the movement by changing
the angles of the wing surfaces. At times the speed, as estimated by
eye-witnesses, was over sixty-eight miles an hour, and yet after a
flight of approximately eight miles in twenty minutes the machine was
brought to rest upon a previously designated spot, three-quarters of
a mile from where the balloon had been released, so lightly that the
aviator was not even jarred, despite the fact that he was compelled
to land on his feet, not on a special alighting gear.” This daring
performance amazed the world, and most of all, the specialists who all
along knew such a feat to be practicable. As a further description
of Professor Montgomery’s wonderful experiments may interest the
reader, the following account, written by himself, is inserted from
_Aëronautics_ for January, 1909:

  “When I commenced practical demonstration in my work with
  aëroplanes I had before me three points. First, equilibrium;
  second, complete control; and third, long continued or
  soaring flight. In starting I constructed and tested three
  sets of models, each in advance of the other in regard to the
  continuance of their soaring powers, but all equally perfect
  as to equilibrium and control. These models were tested by
  dropping them from a cable stretched between two mountain
  tops, with various loads, adjustments and positions. And it
  made no difference whether the models were dropped upside down
  or in any other conceivable position, they always found their
  equilibrium immediately and glided safely to earth.

  “Then I constructed a large machine patterned after the
  first model, and with the assistance of three cowboy friends
  personally made a number of flights in the steep mountains near
  San Juan (a hundred miles distant). In making these flights I
  simply took the aëroplane and made a running jump. These tests
  were discontinued after I put my foot in a squirrel hole, in
  landing, and hurt my leg.

PLATE XXI.

[Illustration: MONTGOMERY’S AËROPLANE.]

  “The following year I commenced the work on a larger scale, by
  engaging aëronauts to ride my aëroplane dropped from balloons.
  During this work I used five hot-air balloons and one gas
  balloon, five or six aëroplanes, three riders—Maloney, Wilkie
  and Defolco—and had sixteen applicants on my list and had a
  training station to prepare any when I needed them.

  “Exhibitions were given in Santa Cruz, San José, Santa Clara,
  Oakland and Sacramento. The flights that were made, instead
  of being haphazard affairs, were in the order of safety and
  development. In the first flight of an aëronaut the aëroplane
  was so arranged that the rider had little liberty of action,
  consequently he could make only a limited flight. In some of
  the first flights, the aëroplane did little more than settle in
  the air. But as the rider gained experience in each successive
  flight I changed the adjustments, giving him more liberty of
  action, so he could obtain longer flights and more varied
  movements in the flights. But in none of the flights did I
  have the adjustments so that the riders had full liberty, as
  I did not consider that they had the requisite knowledge and
  experience necessary for their safety; and hence, none of my
  aëroplanes were launched so arranged that the rider could make
  adjustments necessary for a full flight.

  “This line of action caused a good deal of trouble with
  aëronauts or riders who had unbounded confidence and wanted to
  make long flights after the first few trials, but I found it
  necessary as they seemed slow in comprehending the important
  elements and were too willing to take risks. To give them the
  full knowledge in these matters I was formulating plans for a
  large starting station on the Mount Hamilton Range from which
  I could launch an aëroplane capable of carrying two, one of my
  aëronauts and myself, so I could teach him by demonstration.
  But the disasters consequent on the great earthquake,
  completely stopped all my work on these lines. The flights that
  were given were only the first of the series with aëroplanes
  patterned after the first model. There were no aëroplanes
  constructed according to the two other models, as I had not
  given the full demonstration of the workings of the first,
  though some remarkable and startling work was done. On one
  occasion, Maloney in trying to make a very short turn during
  rapid flight pressed very hard on the stirrup which gives a
  screw shape to the wings and made a side somersault. The course
  of the machine was very much like one turn of a corkscrew.
  After this movement, the machine continued on its regular
  course. And afterwards Wilkie, not to be outdone by Maloney,
  told his friends he would do the same, and in a subsequent
  flight, made two side somersaults, one in one direction and
  the other in an opposite, then made a deep dive and a long
  glide, and when about three hundred feet in the air, brought
  the aëroplane to a sudden stop and settled to the earth. After
  these antics, I decreased the extent of the possible change in
  the form of wing surface so as to allow only straight sailing
  or only long curves in turning.

  “During my work I had a few carping critics that I silenced
  by this standing offer: If they would deposit a thousand
  dollars I would cover it on this proposition. I would fasten a
  150-pound sack of sand in the rider’s seat, make the necessary
  adjustments, and send up an aëroplane upside down with a
  balloon, the aëroplane to be liberated by a time fuse. If the
  aëroplane did not immediately right itself, make a flight, and
  come safely to the ground, the money was theirs.

  “Now a word in regard to the fatal accident.[47] The
  circumstances are these: The ascension was given to entertain a
  military company in which were many of Maloney’s friends, and
  he had told them he would give the most sensational flight they
  ever heard of. As the balloon was rising with the aëroplane,
  a guy rope dropping switched around the right wing and broke
  the tower that braced the two rear wings and which also gave
  control over the tail. We shouted Maloney that the machine was
  broken but he probably did not hear us, as he was at the same
  time saying ‘Hurrah for Montgomery’s air ship,’ and as the
  break was behind him, he may not have detected it. Now did he
  know of the breakage or not, and if he knew of it did he take a
  risk so as not to disappoint his friends? At all events, when
  the machine started on its flight the rear wings commenced to
  flap (thus indicating they were loose), the machine turned on
  its back and settled a little faster than a parachute. When
  we reached Maloney he was unconscious and lived only thirty
  minutes. The only mark of any kind on him was a scratch from a
  wire on the side of his neck. The six attending physicians were
  puzzled at the cause of his death. This is remarkable for a
  vertical descent of over 2,000 feet.”




                               CHAPTER X

                        ADVENT OF PUBLIC FLYING


In 1903, Mr. Ernest Archdeacon stimulated by a conference with Mr.
Chanute, at a meeting of the Aëro Club of France, founded a prize of
3,000 francs to be awarded to the first person who should sail or
fly 25 meters, with a maximum descent not exceeding one third of the
range. As yet no one in either hemisphere had flown in a practical
machine, but various aviators were industriously pluming their wings.
Captain Ferber had been a follower of Lilienthal since 1898, and a
pupil of Mr. Chanute since 1891. Dozens of votaries in France, not
to mention other countries, had entered, or were about to enter, the
aviation field. Archdeacon himself, Voisin, Blériot, Esnault-Pélterie,
Vuia, Delagrange, Tatin, Cornu, Bazin, Levavasseur and many others,
were stanch apostles of the heavier than air. Many of these were
disciples of Lilienthal, but they were destined all to be distanced
by an impetuous Hensonite, who could not realize the necessity for
spending months, or years, cautiously coasting downhill to acquire the
adroitness requisite to speed a flying chariot over the plain.

In 1906, while many aviators in Europe were developing flyers, and
cautiously testing them in various ways, by gliding above sand or
water, or swinging from a high wire or traveling arm, Señor Alberto
Santos-Dumont, of Brazil, brought forth in France the quaint and crude
biplane shown in Plate XXII. Aërodynamically this was not a great
improvement on the aëroplane of Sir George Cayley constructed 98 years
earlier; but it had a petrol motor whose power and lightness would
have astounded that talented pioneer in aviation. The motor was an
eight-cylinder Antoinette, weighing 170 pounds and developing 50 horse
power. The screw, formed of two aluminum blades, was of two meters
diameter, one meter pitch, mounted on the engine shaft, and, at 1,500
revolutions a minute, gave a thrust of 330 pounds. The total lifting
surface of the aëroplane was 650 square feet, and the weight, including
pilot, 645 pounds. This bird-shaped craft ran tail foremost through the
air, having the screw at the rear, and the rider in a small basket just
before the wings. By means of a pilot-wheel and lever, he could operate
the “tail,” i. e., the front rudder, sidewise and vertically, thus
steering the craft in two directions. The lateral balance was preserved
automatically by means of the dihedral inclination of the wings, aided
sometimes by the rider swaying his weight to right or left.

After some days of preliminary adjustment and trial, Santos-Dumont was
ready for a dash in his new aëromobile. On August 22d, 1906, he made
a brief tentative flight, the first witnessed in Europe since Ader’s
surreptitious experiment. On October 23d, he ran this strange machine
swiftly over the ground and glided boldly into the air, flying above
the excited spectators at a speed of 25 miles an hour, and covering
a distance of 200 feet, thus gaining the Archdeacon cup. Again on
November 12th, 1906, he made four flights, the last one covering 220
meters in twenty-one seconds, thus gaining the prize of 1,500 francs
offered by the Aëro Club of France for the first person who should fly
100 meters. The demonstration was made before the general public and
technical witnesses, including an official committee of the Aëro Club
of France, who reported that the aëroplane preserved good balance and a
true soaring speed independent of the acquired momentum.

Intrinsically the achievements of November 12th were crude and
primitive; but in moral effect they were very important. They marked
the inception of public aëroplaning before the professional and lay
world alike. There was no patent mechanism to conceal, no secret to
withhold from rivals, such as had shrouded the work of more circumspect
aviators in Europe and America. If Santos-Dumont was not the first to
fly, he was the first aëroplane inventor to give his art to the world,
and to inaugurate true public flying in presence of technical men, as
he had initiated modern motor ballooning. His liberal enthusiasm and
that of his colleagues, both aëroplanists and patrons, quickly made
France the world’s foremost theater of aviation, at least for the
moment. The contagion would of course spread swiftly, and involve the
entire civilized world.

Santos-Dumont’s unconventional dash into the air sounded the knell of
Lilienthalism. This slow method served to pass time profitably in the
nineties, while the gasoline motor was still developing. But with an
_Antoinette_ in hand, what live man, particularly what live Frenchman,
could tinker long years on the sand hills? Why not mount the craft
on little wheels and take a cautious little run; then after some
adjustment, make more runs followed by innocuous saltatory flights?
This would be so easy, so fascinating, so instructive. How much better
than to make two thousand preliminary jumps down the hill slope
with the body dangling wildly to keep the balance, then to redesign
the entire frame before an engine could be successfully applied!
An _Antoinette_ motor, placed on a competently designed Henson
aëroplane, would have obviated the whole Lilienthal school. However,
they did noble and opportune work, while awaiting the growth of the
gasoline engine. This school achieved success by a roundabout method
because Henson’s method was not available till the present century,
for want of a cheap, light motor. When that appeared Lilienthalism
quickly subsided. In other words, Lilienthal’s method was a passing
convenience, never a necessity. It could have been employed very
profitably in Cayley’s time to develop the art of gliding and soaring;
but in the time of Santos-Dumont and his colleagues, flying by Henson’s
method would have burst upon the world by reason of its superior value
and the allied progress, even if the Lilienthal school had never
existed. This is illustrated by the fact that Santos-Dumont succeeded
without aid from the sand-hill votaries.

PLATE XXII.

[Illustration: SANTOS-DUMONT’S BIPLANE.

_Photo E. Levick, N. Y._]

[Illustration: SANTOS-DUMONT’S _DEMOISELLE_.

(Courtesy A. J. Moisant.)]

The next daring aëroplanist to arouse the world of aviation was Henri
Farman, also a votary of the wheel-mounted flyer. He had been an adept
motorist, therefore accustomed to brisk driving. In the summer of
1907 he received from the Voisin brothers the aëroplane illustrated
in Plate XXIII. With this he made a number of preliminary flights
during the autumn, proving that his aëroplane had suitable stability
and motive power. On October 26th, on the government drill grounds at
Issy-les-Moulineaux he surpassed Santos-Dumont’s record, by flying
771 meters. But this was to him of minor importance; he was preparing
to win the Deutsch-Archdeacon prize of 50,000 francs offered for the
first person who should fly one kilometer over a returning course.
On January 12th, he convoked a committee of the Aëro Club of France
to witness a trial on the morrow. Next morning at ten o’clock, the
weather being calm and clear, his great machine ran a hundred yards
across the course, then rose gracefully into the air, and sailed away
for the 500-meter post. Here, making a wide curve, it rounded safely
and returned, passing the home line in elegant flight, thus winning the
grand prize.

The machine with which Farman achieved his first success, and which
broadly resembles his subsequent triumphal flyers, seems to be a cross
between a Hargrave kite and a Chanute glider, having a Maxim horizontal
steering plane in front. As shown in the figure it was mounted on
four bicycle wheels; was steered up and down by the front plane, and
sidewise by the box rudder seen in the rear. The rider seated between
the large supporting surfaces, and in front of his engine, operated
these rudders separately, by pushing or rotating a pilot wheel, and
abetted the automatic lateral balance by swaying his body. The machine
spread 559 square feet of sustaining surface, weighed 1,100 pounds
and carried a 50-horse-power _Antoinette_ motor actuating a single
two-blade aluminum propeller 6.9 feet in diameter by 3.6 feet pitch,
directly connected to the engine shaft. The stability in mild weather
was so great that Farman, during his first few weeks’ practice, made
over 200 flights, measuring in length from 100 to 500 yards, without
serious mishap. In gusty weather, however, his machine was defective
in steadiness, and unsafe near the ground. This objection was remedied
later by adding flexible wing margins for controlling the lateral
balance.

The age of prize flying was thus fairly ushered in by the feeble but
very important public demonstrations of Santos-Dumont and Henri Farman.
Other public flyers would quickly follow. Delagrange, Blériot, Curtiss
would soon become international figures, not to mention numerous more
recent aviators. They, were men of originality, skill and energy,
who would shortly be in the front line contesting for world laurels,
and winning them gloriously.

PLATE XXIII.

[Illustration: FARMAN BIPLANE, 1908.

(Courtesy W. J. Hammer.)]

[Illustration: FARMAN BIPLANE, 1909.]

[Illustration: HARMON IN FARMAN BIPLANE.]

Leon Delagrange, the sculptor-inventor, who first had demonstrated
the biplane, on March 30, 1907, aspired in 1908 to outfly Farman.
He now practiced industriously on the military drill ground at
Issy-les-Moulineaux, a large field which the Minister of War permitted
the Aëro Club of France to use for such purpose. Here he and Farman,
in friendly competition, flew day by day over gradually increasing
courses. At times they were joined by other aviators, and thus the
drill grounds at Issy became famous as an aviation school.

Farman’s new rival made startling progress during those frequent trials
of March, 1908. “Just imagine,” he says, “that within a week I was
able to complete my education as an aviator.” On March 17th he made an
official flight of 269.6 meters, thus winning a prize of 200 francs
offered by the Aëro Club of France for a beginner who should fly over
200 meters. Four days later he engaged in contest with Farman. Two
poles were erected 500 meters apart to mark the points about which the
men must race. The machines were brought forth from their sheds in
the morning, gleaming dimly through a dense fog, and were given some
preliminary trials. Then Farman made a flight of 2004.8 meters, going
twice around the course in 3 minutes, 31 seconds. He thus trebled his
grand prize flight of January. Presently Delagrange took wing and flew
1,500 meters in 2.5 minutes. Having been beaten by Farman, he invited
his successful rival to take a seat behind him, and the two sailed away
close to the ground, covering a distance of 50 meters. This was the
first trip ever made by two men in one flying machine. For the first
time also two machines had flown in competition over a considerable
course.

Delagrange continued to pursue Farman for the championship. On April
11th, he flew 2,500 meters, and would have exceeded Farman’s official
record of 2,004 meters, had he not touched the ground. The next day
he summoned the official committee of the Aëro Club of France to
witness and time his performance. Poles were erected at the corners
of a triangle 350, 200, 275 feet apart respectively. Around this
course he flew nearly five times, covering a distance of 5,575 meters
in 9¼ minutes. Of this range the last 3,925 meters were covered
without touching the ground. Thus at last he had out-flown Farman and
established a new official record, the total distance actually covered
being about ten kilometers, or approximately six miles. This ended,
at least temporarily, the friendly competition at Issy; for now the
aviators separated, Farman going to Belgium, Delagrange to Italy.

Delagrange’s fortune accompanied him abroad. On May 24th, he made some
impressive demonstrations on the Place d’Armes at Rome in presence of
the Minister of War and thirty thousand people. On May 27th, he flew
before the King and Queen of Italy and many other court personages,
remaining in the air nine and one half minutes, thus surpassing all
previous European records for endurance and distance. But this was
only preliminary. On the morning of May 30th, he came forth again on
the Place d’Armes, a light breeze blowing. His machine rolled quickly
over the ground, then circled gracefully ten times around in the air
at a height of four to seven meters, covering an official distance of
12.75 kilometers, and remaining aloft 15 minutes, 26 seconds. On June
22d, at Milan, he flew before 15,000 people in the Place d’Armes,
covering seventeen kilometers in 16 minutes, 30 seconds. Finally, on
September 6th, at Issy-les-Moulineaux, he flew 29 minutes, 54 seconds,
covering 14.8 miles, which proved his crowning effort for the year. As
the two flights just mentioned surpassed all previous official ones
in duration, it appears that Delagrange raised the world’s record
four times within five months, increasing his own time from six and a
half minutes in April to about thirty minutes in September, or nearly
fivefold.

In the meantime, Farman was making rapid progress, gathering prizes and
achieving wide renown. On May 30th, at Ghent, Belgium, taking with him
M. Archdeacon, he flew 1,241 meters at a height of seven meters. He
thus established a new record with two people, and won the 1,200 franc
wager made with Santos-Dumont and Archdeacon against M. Charron, who
contended that a flying machine would not, within the year, carry two
men weighing sixty kilograms each. On June 6th he flew 20 minutes, 20
seconds, covering 19.7 kilometers, thus again increasing the world’s
record, and winning the Armengaud prize of ten thousand francs for the
first aviator to remain aloft fifteen minutes in France. On September
29th and October 2d, at Chalons, he successively increased the world’s
record, and achieved his best results for the year. The first of these
trials lasted 42 minutes, covering 24.5 miles; the second lasted 44.5
minutes, covering 25 miles. This last flight was forty times as long as
the one of January, which gave him the grand prize of fifty thousand
francs, and is a good index of the wonderful progress in aviation
made in France during the year 1908. Between these two performances
he, on September 30th, sailed from Chalons to Rheims, a distance of
27 kilometers, in twenty minutes. This flight was made over trees
and houses, sometimes at an elevation of 200 feet, and was the first
town-to-town flight ever accomplished. The following day he won the 500
franc prize for height, passing over balloons 82 feet from the ground.
Such was the lively pace Farman set for the rest of the world.

Mr. Curtiss drifted into the business of building and operating air
ships and flying machines by frequent association with inventors, who
came to his bicycle works at Hammondsport, N. Y., for assistance in the
design and construction of aërial craft. He was particularly sought as
a constructor of propelling mechanism, for he had special skill and
experience in producing light gasoline engines. As a motor expert he
was invited to the laboratory of Dr. Alexander Graham Bell, at Beinn
Breagh, near Baddeck, Nova Scotia, in the summer of 1907. Dr. Bell had
developed his wonderfully light, strong and stable tetrahedral kites
to such an extent that he wished to convert them into “aërodromes” by
applying light propelling mechanism. He accordingly invited two young
Canadian engineers, F. W. Baldwin and J. A. D. McCurdy, to consult
with him regarding the structural details of his proposed flyer,
and contracted with Mr. Curtiss to supply the motive power. These
gentlemen with Lieutenant T. Selfridge, a guest of Dr. Bell, developed
so many independent ideas that Mrs. Bell suggested the advantage of
forming themselves into a scientific organization, at the same time
offering the capital required for experimentation. Acting on this
advice and generous offer, they formed themselves into the now famous
Aërial Experiment Association, whose object was the construction of a
practical aëroplane, driven through the air by its own motive power,
and carrying a man.

PLATE XXIV.

[Illustration: THE _RED WING_.]

[Illustration: CURTISS BIPLANE.]

[Illustration: CURTISS BIPLANE WITH PONTOONS.]

After some preliminary downhill glides[48] and studies with a motorless
aëroplane, the association, on March 12, 1908, brought forth their
first dynamic machine, the _Red Wing_, shown in Plate XXIV, in order
to speed it along the ice of Lake Keuka, near Curtiss’s factory; the
purpose being, not to fly, but to test the effect of the vertical
rudder. To the surprise of the twenty-five onlookers, the machine,
after running two hundred feet along the ice, serenely rose into the
air and flew 319 feet. “This,” says Dr. Bell, “was the first public
exhibition of the flight of a heavier-than-air machine in America.”
It is noteworthy also that this machine was completed and ready for
trial in less than seven weeks from the time of starting. Its design,
while embodying suggestions from each member of the association, was
attributed chiefly to Lieutenant Selfridge, who took the leading part
in evolving the plans, and who gave them his final approval, it being
the intention of the association to offer each man a chance to produce
a flying machine after his own notions, aided by the experience and
liberal advice of his fellows.

As the advantage of flying from the ice had been suggested some years
before the death of Lilienthal, it seems remarkable that this method
did not yield important results earlier in the development of aviation.
A smooth ice field is such an ideal place for testing a dynamic
aëroplane, that previous gliding experience would seem unnecessary,
providing the machines were designed with a fair knowledge of the
elementary principles of stability and control. Even glider practice
could be effectively conducted over a smooth ice field after momentum
had been acquired by aid of gravity, or a tow line. Having sufficient
momentum the aviator could test his rudders cautiously without rising,
then, after a little experience, make short glides in the air, and so
be prepared to install the motor. Landing or falling on smooth ice at
great horizontal speed, from a low elevation, is much less hurtful than
tumbling on the ground, as every bold skater knows from experience.

The aëroplane II, designed by Mr. Baldwin, aided by his associates
and their combined experience, resembled that of Lieutenant Selfridge
in the trussing of its body surfaces, but was mounted on wheels, and
provided with torsional wing tips for lateral control. When tested, it
was found easy to launch and land, besides responding very promptly to
the three-rudder control. In the hands of Mr. Curtiss, on May 22d, this
aëroplane, called the _White Wing_, flew 1,017 feet in 19 seconds, and
landed smoothly on a plowed field. This at the time was the longest
flight ever made by an aviator in his first trip on a heavier-than-air
machine.

It was now Mr. Curtiss’ turn to be captain of design and construction.
Under his supervision aëroplane III, called the _June Bug_, was ushered
forth, in the month of honeymoons. It differed from the two preceding
in having a box tail; also in having a nainsook cover, instead of the
red and white silk that characterized the _Red Wing_ and the _White
Wing_.

After some practice, this flyer behaved so well that it seemed
competent to win the Scientific American Cup offered for a public
flight of one kilometer straight away. Accordingly an official trial
was arranged with a committee of the Aëro Club of America, for the
fourth of July, 1908. It was the first official flight in the western
hemisphere, and proved in every way most satisfactory. The machine
flew 2,000 yards over an S-shaped course at a speed of 39 miles an
hour, displayed admirable control, and had abundant motive power. The
performance was an intimation and augury of the victorious flights to
come the following year. As the Association now repaired to Dr. Bell’s
summer home, the Hammondsport experiments terminated for the season.

The year 1908 also brought to happy fruition the long and persistent
experiments of Louis Blériot, the most illustrious pioneer and
champion of the monoplane. Beginning in 1900, he had tried one type
after another, of flying machine, till he became world renowned for
his fertility of invention, his daring, his picturesque accidents and
hairbreadth escapes. So long as he was not killed he was certain to
make progress; for he had every endowment that ensures success. He
possessed the energy of early manhood, having been born in 1872; he
had the thorough technical training of the Central School of Arts and
Manufactures, where he graduated in 1895; he possessed extraordinary
talent for invention and constructional detail; he had the prowess,
courage and coolness requisite for testing intractable and dangerous
flyers; he was in the world’s most active center of aviation; he
also had sufficient means. If he was late in achieving success, it
was because he preferred to develop original ideas, and could not be
content with merely copying his predecessors.

Like many other novices in aviation, Blériot began by trying to build
a machine with flapping wings that should fly like a bird. This was to
be actuated by a carbonic acid motor. In 1904 he abandoned his first
machine, of bird type, and turned to aëroplanes, beginning with a
biplane of the Farman, or Voisin type. His second machine was built by
Gabriel Voisin, one of the most experienced of the pioneer aëroplane
manufacturers. This biplane, unprovided with an engine, was mounted
on floats, towed along the Seine by a motor boat, and rose from the
surface carrying Voisin as pilot. _Blériot III_, composed of elliptical
cells, or sustaining surfaces, and powered with two _Antoinette_
motors of 25 horse power each, was tested without success on Lake
Enghien during the year 1905-6. _Blériot IV_ was made of quadrangular
cells, and launched at Bagatelle in 1906, carrying a soldier, Peyret;
but crashed to earth in its first trial. Finally in 1907, _Blériot
V_, mounted by the inventor himself, rose into the air and flew
successfully, but was lacking in stability. His sixth aëroplane was
of the Langley type, provided with a 24-horse-power motor, then with
a 50-horse-power _Antoinette_; but it was unstable fore and aft. One
day it traversed 184 meters, then fell from a height of 25 meters and
was shattered on the ground. His seventh was one of the swiftest yet
constructed, attaining a speed of nearly 80 kilometers an hour, and, in
two private trials, covering a distance of 500 meters. Thus seven years
had slipped away, leaving Blériot still in the tentative period of his
work. But now he was at the threshold of a career of brilliant success,
which soon brought him the highest honors at home and throughout the
world.

After various minor flights in the spring and summer of 1908, Blériot,
on October 31st of that eventful year in aviation, determined to
attempt a cross country voyage, as Farman had done the day before. As
will be remembered, Farman had flown from Chalons to Rheims, above
trees and houses, a distance of nearly 17 miles, thus achieving the
first town-to-town flight in history. Blériot would improve that record
at once, by flying in a closed circuit embracing several villages.

His renowned cross-country flight was directed from Toury to Artenay, a
village nine miles distant. Mounting his aëroplane _VIII-ter_, at mid
afternoon, in presence of a large gathering, Blériot followed the
course shown in Fig. 40. In the neighborhood of Artenay he landed for a
few minutes. After some slight repairs to his magneto, he reascended,
turned about and headed for home. Half way on his return course he
stopped again for a few minutes, at the Village of Santilly; then
readily reascended and flew to the neighborhood of his starting point.
He thus traveled about 17 miles in a closed circuit. This performance,
with that of Farman the day before, inaugurated the period of aërial
voyages in heavier-than-air machines. It appealed so powerfully to the
sentiment of the community that a monument was erected at Toury to
commemorate the glorious achievement.

PLATE XXV.

[Illustration: BLÉRIOT FLYING OVER TOURY-ARTENAY CIRCUIT.]

[Illustration: BLÉRIOT MONOPLANE _NO. VIII_.]

[Illustration: BLÉRIOT MONOPLANE _NO. IX_.]

[Illustration: FIG. 40.—BLÉRIOT’S TOURY-ARTENAY AËROPLANE CIRCUIT,
1908.]

A fair view of the famous monoplane, in its renowned cross-country
voyage, is presented in Plate XXV. It consisted of a single sustaining
surface firmly attached to a long trussed spine mounted on three
wheels, and carrying at its front end the gasoline motor and propeller,
at its rear end two of the rudders, the third, or lateral, rudder
being placed at the wing terminals. A part of the trussed frame was
covered, to minimize the atmospheric resistance against the framing,
pilot and engine. The vertical rudder at the rear turned the machine
to right or left; the horizontal rear rudder controlled the elevation
and pitching of the machine; the torsional wing tips controlled the
lateral stability, and could be used to cant the aëroplane or check its
listing, as in the Wright and Curtiss machines. The craft exhibited an
easy poise in the air, and possessed good equilibrium, owing to its
arrowlike structure and its three-rudder system of control. It was a
strong rival of the biplanes previously noticed, and a herald of better
things to come.

In the meantime the Wright brothers had resumed their field practice.
During the month of May, 1908, they tested their famous aëroplane of
1905, provided with increased engine power, and carrying two passengers
upright. A few brief flights were made at speeds of 41 to 44 miles an
hour, showing that all the mechanism was adequate and effective. But on
May 14th a false push on a lever, made by Wilbur Wright, brought the
flyer to earth, wrecking it too badly to be repaired in the few days
available for experimentation. These flights were but preliminary to
the official trials set for the approaching summer; for the brothers
had contracted to furnish one machine to the United States Signal
Corps, another to a French syndicate.

The Chief Signal Officer of the United States Army in December, 1907,
had issued specifications, and invited bids, for a flying machine
apparently far in advance of the art. The flyer was to carry two men
aggregating 350 pounds, was to remain aloft one hour continuously, and
was to maintain an average speed of 40 miles an hour in a cross-country
flight to and fro, covering a distance of ten miles. The contractor
must instruct two officers to operate the flyer. Furthermore the
machine must be capable of flying 125 miles without stopping. The
requirements seemed severe, even to those well versed in aviation.
Nevertheless two bids were received; one from the Wright brothers for a
biplane to cost $25,000, another from Mr. A. M. Herring for a biplane
costing $20,000. Both bids were accepted for the summer of 1908; but
only the Wright contract was eventually carried out.

About the same time the Dayton inventors had sold their patent rights
in France to a syndicate in that country. The contract specified
a machine for two passengers, having a speed of 50 kilometers an
hour, and a range of 125 miles. Furthermore, the inventors agreed to
instruct three pupils to manage the aëroplane. The fulfillment of
these two contracts occupied some months, but presented no formidable
difficulties. Though neither of the brothers had ever flown an hour,
and though both were comparatively unskilled as operators, they had
such faith in their invention that they undertook to launch themselves
publicly in untried machines, Wilbur Wright in France, Orville in
America, at about the same time.

Of these two tests, the one conducted by Orville Wright at Fort Myer,
near Washington, was the most successful at first. After a few brief
preliminary trips, he suddenly astonished the world by phenomenal
flying. On the morning of September 9, 1908, he made a voyage above
the drill ground lasting 57 minutes, 31 seconds, and again in the
evening another flight lasting one hour and three minutes, this time
before a throng of distinguished spectators. Immediately thereafter
he took aboard Lieut. Frank P. Lahm for a flight of six minutes’
duration. These records were improved day by day, and all things
seemed propitious for the official tests of speed and endurance.
But on September 17th, while sailing with Lieutenant Selfridge at a
height of about 75 feet, a blade of the right-hand propeller struck
and loosened a stay wire of the rear rudder. Instantly the wire coiled
about the blade, snapping it across the middle. Thereupon the machine
became difficult to manage, and plunged headlong to earth, throwing the
men with their faces on the bare ground, fatally wounding Lieutenant
Selfridge, and seriously injuring Mr. Wright. Lieutenant Selfridge did
not recover consciousness, and died within three hours, from wounds
on the forehead and concussion of the base of the brain. Mr. Wright
suffered a fracture of the left thigh and of two ribs on the right
side. The aëroplane was badly shattered in its framing, but the engine
was practically intact. This accident terminated the tests for the
season; but ere long a date was set for their resumption during the
following year.

PLATE XXVI.

[Illustration: WRIGHT BIPLANE OF 1908.]

[Illustration: STANDARD WRIGHT BIPLANE OF 1910.]

[Illustration: WRIGHT RACING BIPLANE OF 1910.]

Wilbur Wright began his demonstration for the French syndicate on the
plain of Auvours, ten miles from Le Mans, France, on August 8,
1908. For some weeks his flights were very brief, owing to the balky
condition of his engine; but this difficulty was removed by the middle
of September. After the accident to his brother he remained inactive
for a few days; then, to reassure his supporters, he raised the world’s
record by flying a distance of over 52 miles, remaining aloft 1 hour,
31 minutes, 25 seconds. After this he continued at frequent intervals
to make long flights, quite usually taking a passenger with him, and on
several occasions a lady. His endurance, his altitude, his abandon and
perfect control amazed and delighted Europe. Incidentally he won some
valuable prizes, beating the French records for duration, distance and
elevation. Once he rose to a height of 380 feet. On September 21st, he
flew 42 miles in 1 hour and 31 minutes; on October 11th, he carried a
passenger an hour and ten minutes; finally on the last day of the year
he flew 77 miles in two hours and twenty minutes, thus winning the
much coveted Michelin prize, of twenty thousand francs for the longest
distance flown during the year. It was a triumphal close to the most
progressive and eventful year in aviation—the first year of exhibition
flying, the inaugural year of a noble art.

Having completed the speed and distance tests at Le Mans by the close
of the year 1908, Wilbur Wright went to Pau, in the South of France,
for the winter practice with his three pupils, Count de Lambert, Paul
Tissandier and Alfred Leblanc. Here on the vast trial grounds at Pont
Long, six miles from Pau, he had a commodious hangar with a workshop
on one side, and on the other, apartments for the aviator and his
mechanics. He arrived with his pupils, on January 14th, and next day
was joined by his brother and sister, who had followed him from Paris,
Orville being now well recovered from his injuries received at Fort
Myer. In a short time the machine was set up, and early in February
began its regular service, having a pair of levers for the teacher and
another pair for the passenger. The pupils quickly acquired the art of
steering, being first allowed to control one lever, with Mr. Wright
holding the other; then being entrusted to manage the whole machine,
with their tutor as passenger; and finally becoming themselves teachers
of the newly acquired art. Only a few hours’ practice was needed to
attain proficiency, the whole time in the air aggregating hardly half a
day for each pupil, though the lessons extended over many days.

A pleasant feature of the sojourn at Pau and Le Mans was the number
and character of the visitors, and the boundless enthusiasm displayed
toward the new art. Tens of thousands of people from the neighboring
places, and tourists from many parts of the earth assembled to see the
flights; statesmen, military officers, scientific and parliamentary
delegations, representatives of innumerable periodicals. Queen
Margherita, having missed a flight on her first visit to Le Mans,
came a second time, and remained three hours standing on the field,
fascinated by the wonderful aërial equipage. The King of Spain, Alfonso
XIII, who visited the aërodrome at Pau, on February 20th, manifested
the keenest interest and delight in examining the aëroplane and seeing
it fly; first with the pilot alone, then with an extra passenger. He
took a seat in the machine beside Mr. Wright, discussed its working,
and expressed his deep regret that reasons of state prevented him from
making an ascension. A month later the King of England, who was at
Biarritz, adjourned to Pau, where he remained to witness two unusually
fine flights. He expressed the greatest pleasure in the performance,
questioned the brothers about the details of the machine, and
complimented them on their achievement.

From Pau, Wilbur Wright went to Italy, about the end of March, to
fulfill an engagement to give demonstrations and lessons in the use of
the biplane. He was welcomed at Rome by the King of Italy, on April 2d,
and later gave a public exhibition of flying, to aid the sufferers in
the recent earthquake at Messina. His flights were attended with great
enthusiasm, and his lessons in aviation were quickly mastered; his
pupil, Lieutenant Calderara, soon making public flights alone. A rare
sight it was, this modern winged chariot soaring above the ruins of
that ancient campagna, bearing with it a moving-picture camera.

By the end of April Mr. Wright had finished his task in Italy, and was
journeying homeward with his sister and brother by way of London, where
they enjoyed the hospitalities of the Aëronautical Society of Great
Britain; and where, on May 3d, the brothers received the beautiful gold
medal of that famous society, the oldest aëronautical organization in
the world.

The return to America was primarily for the purpose of completing
the official tests at Fort Myer; but incidentally the brothers must
find time to receive new honors and ovations. While in the shop at
Dayton, working vigorously to complete a new aëroplane for the War
Department, in the hope of finishing the demonstrations by June 28th,
the limit of their allotted month, they were showered with attentions
too numerous for their comfort. They must drop their tools in order to
go to Washington to receive the gold medal of the Aëro Club of America
from President Taft, at the White House, on June 10th. On June 17th
they must witness an elaborate demonstration in their honor at Dayton,
where they received a gold medal from the city, another from the State,
and another from the Federal Government. Finally late in June, they
arrived in Washington with the rehabilitated biplane, to make good
their contract with the Signal Corps.

The early tests of this aëroplane were not an unmixed triumph for the
Wright brothers and their well-wishers. At first the machine failed to
fly completely about the drill ground. It took the air with difficulty,
and came to the earth on the first turn. Some lack of adjustment in the
frame was suspected. The motor was accused of weakness. The launching
weights[49] were too light. The brothers explained that a new flyer
is like a new horse; the driver must learn his idiosyncrasies before
attempting to show him off to advantage. They intimated also that
they would be pleased to have the great throng of prominent people,
who flocked daily to the drill ground, kept away until their flying
instrument was properly tuned for public performances. They discouraged
superfluous attentions. The big legislators who ventured audaciously
to peep into the sacred shed containing the marvelous machine, were
hailed by the military guard, and unceremoniously marched across the
line among the plain people. It was a dreadful shock to these mighty
signors, and many a fat lawmaker cursed audibly, vowing never to vote
a cent for flying squadrons. But still they haunted the drill ground
daily, despite the long journey and the late dinner; for they were
fascinated by the untold and unconjecturable possibilities of the new
art.

June 28th came quickly, obliging the patient aviators to beg another
extension of time. They were granted thirty days longer, which seemed
to them more than necessary; but in this judgment they were mistaken.
One accident after another delayed the consummation of their official
task of flying one hour above the field, then five miles across country
and return. Finally, on July 27th, Orville Wright, who was making all
the flights, took with him Lieut. Frank P. Lahm, and sailed gloriously
for one hour, twelve minutes and forty seconds, before ten thousand
delighted spectators. It was an ideal summer evening, and all the
maneuvers were performed with excellent poise, security and grace. A
new world’s record was established. Now all the vast throng from the
President and his cabinet to the simplest laborer, appreciating the
achievement as a triumph for America and for humanity, burst forth into
prolonged acclamation and applause.

The cross-country flight was next in order. The course from Fort
Myer to Alexandria lay over scattered forests and a deep valley. The
flight seemed a difficult and hazardous enterprise; but the brothers,
confiding in their machine, seemed to have little apprehension of
failure or peril. Indeed, they seemed most concerned about the bonus
to be secured by flying at an average rate exceeding the contract
speed of 40 miles an hour; for each additional mile an hour would pay
them $2,500 above the normal price of the aëroplane. They accordingly
declined to fly in any but very calm weather, no matter how vast the
gathering of visitors, or how illustrious. They wished, of course, to
expedite the final and crucial test; but they could not always have
ideal conditions, and would not take undue chances. On the evening
after the endurance test the engine balked, owing to the clogging of a
rubber pipe from the gasoline tank. Dusk came on, and the disappointed
crowd went home to a late dinner. The Secretary of War, who was
present, very kindly granted a third extension of time, covering the
rest of the month. Next evening it was a trifle breezy. Wilbur Wright
announced that the flight could be made, but that the bonus would
be less than on a still evening; he would therefore wait for calmer
weather. Twelve thousand people were turned away disappointed. There
was muttering among the impatient and warm of blood. It was remarked
that the War Department could easily drop these procrastinated
experiments and buy a practical aëroplane in the open market for
$5,000. But the discommoded officers good-naturedly allowed the thrifty
sons of Dayton to have their way in striving for a large bonus, beyond
the normal price of $25,000.

On the following evening the weather was clear and fairly still. All
was in readiness for the flight to Alexandria and return. Orville
Wright, taking with him Lieut. B. D. Foulois, circled the drill ground
on easy wing, then sailed directly across country for the captive
balloon at Shuter’s Hill. In a few moments they vanished beyond the
forest, and for a while even the most optimistic were doubtful of their
safety. At length they reappeared sailing homeward at very great speed.
The machine proudly circled the drill ground amid thunders of applause,
and landed softly at the lower end, beyond the shed.

The multitude hastened to congratulate the aviators on their marvelous
performance. For everybody it was a scientific and national triumph;
for Wilbur Wright it was something more. With pencil and pad he quickly
computed the bonus, surrounded by a wall of reporters. “Wise old
Wilbur,” remarked one, “he knows the worth of coin in a crude republic.
While Fame blows her trumpet he counts the solid gain.” The figures
showed an average speed of 42.6 miles, making the bonus $5,000. The
voyage was one of the finest ever executed up to that date; it was
a glorious termination to a long and troublesome, but epoch-making
demonstration. Now there remained only the task of instructing two
officers to fly, and this was leisurely accomplished by Wilbur Wright
in October.

As shown in Plate XXVI the Wright aëroplane used at Fort Myer in
September, 1908, was a twin screw biplane mounted on skids and having
the three-rudder system of control. The rear rudder turned the machine
right or left, the front rudder raised or lowered it, the warping of
the wings controlled the lateral poise. The turning right or left
could be effected on level wing; but the inventors canted the machine
sidewise, to obviate skidding, or sidewise gliding of the craft, due
to centrifugal force. These three-rudder movements were performed by
three separate levers actuating suitable mechanism; but they could be
performed easily by a single lever having three separate movements, as
preferred by some designers. The aëroplane in launching ran along a
monorail, accelerated by a towrope passing over pulleys, and attached
to a falling weight comprising nearly a ton of iron. The dimensions of
the various parts are given as follows by Major George O. Squier,[50]
the officer in charge of the experiments:

  “The aëroplane has two superposed main surfaces 6 feet apart
  with a spread of 40 feet, and a distance of 6½ feet from front
  to rear. The area of this double supporting surface is about
  500 square feet. A horizontal rudder of two superposed plane
  surfaces about 15 feet long and 3 feet wide is placed in front
  of the main surfaces. Behind the main planes is a vertical
  rudder formed of two surfaces trussed together about 5½ feet
  long and one foot wide. The motor, which was designed by the
  Wright brothers, has four cylinders and is water cooled. It
  develops about 25 horse power at 1,400 r. p. m. There are two
  wooden propellers 8½ feet in diameter which are designed to run
  at about 400 r. p. m. The machine is supported on two runners
  and weighs about 800 pounds.”

On the whole the demonstrations at Fort Myer in 1909 did not greatly
enhance the prestige of aviation. They were attended by too many delays
and accidents, and too much waiting for ideal weather. As a consequence
the guardians of the national purse were not clamoring for an aërial
flotilla. Some few, no doubt, understood that the aëroplane could
brave more than a zephyr with safety; but the general public accepted
the demonstrations at their face value. The unthinking multitude did
not realize that with sufficient incentive, such as war presents,
the Wright brothers could repeat those brilliant flights, of the end
of July, under more severe weather conditions. Fortunately, events
were transpiring elsewhere which vastly increased the popular fame
and valuation of the new art. This refers more particularly to those
startling achievements in aviation abroad which were largely stimulated
by competition and prizes.

After the Fort Myer flights the Wright brothers separated, Orville
going to Germany to represent their interests and give demonstrations;
Wilbur exhibiting at the Hudson-Fulton celebration in New York, and
teaching the Signal Corps officers to manipulate the newly purchased
government aëroplane. As usual, both achieved distinction in their new
fields. At Potsdam, on October 2d, Orville Wright, after a ten-minute
flight with Crown Prince Frederic William, ascended alone, mounting
steadily in circles for fifteen minutes, and reaching an elevation
roughly estimated at 500 meters, after which he descended safely in
five minutes. On September 18th, he made a new record at Berlin by
carrying a passenger, Captain Englehardt, for 1 hour, 35 minutes and 47
seconds. Wilbur Wright, on September 9th, flew from Governor’s Island,
in New York harbor, to and around the Statue of Liberty, then returned
to the point of departure. On October 4th, starting from the same
point, he flew over the waters of New York Bay and above the Hudson
River to a point opposite Grant’s Tomb, then returned to Governor’s
Island, covering a distance of about 19½ miles in 33½ minutes. The
trip upward was made at an elevation of about 200 feet, through a
stratum disturbed by vortices rising from the steamer smokestacks, and
eddies caused by the northeast wind blowing over the tall buildings.
The return was made at a level of 50 feet on the Jersey side of the
river where the air was less turbulent. He intended later in the day
to make a long flight, but, owing to the bursting of a cylinder head,
he stopped his demonstrations and returned to Washington to finish
his instruction of the Signal Corps officers. This was easy routine,
and it afforded opportunity to try the effect of transferring one of
the forward steering planes to the rear and applying it there as a
fixed horizontal tail, as used by Voisin, Curtiss and others. The new
arrangement was reported to increase the longitudinal steadiness of the
aëroplane, and was used in subsequent Wright aëroplanes.

The brothers now ceased public flying for a while, to attend to the
business of manufacturing and selling their craft. They formed an
American company, enlarged their facilities for constructing machines,
procured grounds for training operators, and prepared generally to
fill orders both for aëroplanes and for public exhibitions. Not the
least of their labor was to defend their patent claims, which they
wished to be interpreted so broadly as practically to exclude all
flyers whose lateral poise is controlled by changing the angle of
incidence of the wings, or of lateral stabilizing planes. This was
not an easy undertaking, since the torsion wing was a well-known
device, having been described many times in public print, and having
figured in earlier patents and experiments in various countries. To
add to the difficulty, their patent claims apply specifically to the
warping of normally flat sustaining surfaces, the warping of arched
wings having been patented by Prof. J. J. Montgomery, whose invention
antedates theirs.[51] However, if they produced no novel and radical
invention in aviation, they, like Santos-Dumont in aëronautics, were
first to achieve some measure of practical success, by applying a light
automobile engine to a familiar machine in which former inventions
and ideas were skillfully employed. On this ground of practical
success they strove for an interpretation broad enough to establish
a monopoly covering even Montgomery’s rights, which apparently they
were infringing. But when to this end they applied for a preliminary
injunction restraining Curtiss from using his system of control, and
Paulhan from using Farman’s system, they were unable to convince the
court of the justice of their petition, and the injunction suit was
vacated.




                              CHAPTER XI

                     STRENUOUS COMPETITIVE FLYING


The cardinal allurements in aviation for 1909 were the prize offered
for the first flight across the English Channel, and the prizes to be
won at the world’s first aviation meet, scheduled for the last week
in August of that year, at Rheims, France. The desire to win these
honors stimulated to livelier effort the most noted designers and
operators of aëroplanes, all of whose machines were represented at the
great tournament. It also brought into sudden prominence several new
aviators. Young men, little versed in the science or literature of
flight, took to wing, and in a few days found themselves world-famous.
Aërial chauffeurs, skillful and daring, delighted vast throngs of
people, kept the cables warm with news, and incidentally filled their
purses with money. Thus the trade of aëroplane jockey was one of the
interesting products of this eventful year.

The first half of the aviation season of 1909 brought forth many
improvements which seemed to augur well for the public demonstrations
to follow. Hubert Latham, with the swallowlike _Antoinette_ monoplane,
designed by Levavasseur, the inventor of the _Antoinette_ motor, began
soaring grandly in the sky and into fame. Paul Tissandier, on May 20th
at Pau, established a new French record by flying 1 hour and 2 minutes.
The Voisin brothers were perfecting in detail their boxlike aëroplanes,
noted for inherent stability, and destined to achieve further renown
during the summer, under the dexterous hand of intrepid young Paulhan.
This new and daring young aviator, after a few practice flights, began
making world records. On July 15th, he flew 1 hour, 7 minutes and
19 seconds. On July 18th he made a new world’s record for altitude,
driving his Voisin aloft 150 meters at Douai. Impatient Roger Sommer,
rejecting his own make of biplane, purchased a machine from Farman,
and after a little practice, broke the world’s record for distance on
August 7th, by flying at Chalons, 2 hours, 27 minutes, 15 seconds. Many
others were advancing in skill, and would erelong achieve excellent
results. Most strenuous of all, perhaps, were Curtiss and Blériot, the
champions of high speed, respectively in the biplane and monoplane, and
Farman, the winner of large prizes.

In the latter part of April, Henri Farman tested a new biplane of
his own design and manufacture, which proved very satisfactory. It
resembled his former craft, but was provided with small balancing
planes hinged to the rear margins of the wings near their tips.
This machine, furthermore, was provided with both landing skids and
wheels, the latter yielding to any unusual stress by means of elastic
connections, so that the skids took up the shock. With this improved
biplane, Farman beat his former records by flying continuously 1 hour,
23 minutes, at Chalons, on July 19th. Four days later he made a new
cross-country record by flying from the Chalons parade ground to Suppe,
about forty miles, in 1 hour and 5 minutes. These flights were gently
suggestive of what might be expected at Rheims the following month.

During the opening period of the 1909 aëroplane season, Glenn H.
Curtiss brought forth a new biplane, designed for the Aëronautic
Society of New York, with the coöperation of his new partner, Mr. A.
M. Herring, and began active practice for various prizes at home and
abroad. After some brief trials at Hammondsport, N. Y., he shipped his
aëroplane to Morris Park, in order to participate in the Aëronautic
Society’s first flight exhibition of the year. On June 26th he flew,
but without official witness, far enough to win one of the $250
prizes offered to the Aëro Club of America by its president, Mr.
Cortlandt Field Bishop, for the first four persons who should fly one
kilometer. He now wished to make an official flight for this prize
and also for the Scientific American trophy, a beautiful engraved
silver cup—which he had won a year previously for the first public
flight of one kilometer, made in America, but which now should go to
the person making the longest official flight of the year 1909, not
under 25 kilometers. But the Morris Park race track proved unsuitable
for such contest, being too restricted. He therefore took his biplane
to Mineola, Long Island, where he could practice on a wide plain, and
possibly make some new records. Here a triangular course 1.3 miles long
was staked off, and some short trial flights were made. Then Mr. C. M.
Manly, who was official timekeeper for the Aëro Club of America, was
notified that a trial for the prize would be made.

The demonstrations near Mineola were most successful, and proved the
beginning of a brilliant summer for Mr. Curtiss. On July 17th he won in
quick succession both of the prizes mentioned above. The trial for the
smaller prize began at 5.15 in the morning and lasted but 2½ minutes,
followed 6 minutes later by the start for the coveted cup. In both
cases the machine took the air with ease and grace, after a 200-foot
run over the rough marsh land. In the cup trial the first twelve
turns, aggregating 25 kilometers, were accomplished in 33½ minutes,
but the machine continued for seven more rounds, and finally landed
in excellent form, just 52½ minutes after it had crossed the starting
line. The actual measured distance flown was 24.7 miles, but the true
distance traversed by the machine was probably 30 miles, making the
time speed between 30 and 40 miles per hour. This was slow, indeed, but
the control was satisfactory. Those who wished for high speed would
find it in the new aëroplane which Mr. Curtiss would presently take to
Rheims for the speed contest, in which he was to fly as sole champion
of the United States.

The type of machine used by Mr. Curtiss in 1909 was a natural outgrowth
of his previous ones, but very much perfected in power and finish. It
was a biplane mounted on a three-wheeled chassis, two wheels under the
main body and one well to the front, so as to prevent toppling forward.
It was propelled by a single screw at the rear, directly connected to
a water-cooled motor of the Curtiss make. Its flight was controlled
by three rudders exerting torque respectively about the three axes of
the aëroplane, supplemented by two fixed keels, a vertical one in the
front and a horizontal one in the rear. Of the three rudders mentioned,
one in the rear turned the craft right and left, like a boat, one in
the front raised or lowered her, while the third or lateral rudder,
consisting of small horizontally pivoted planes between the wing-ends,
and turning oppositely to each other, controlled the lateral poise.
These lateral rudders, or winglets, used by Curtiss, Farman and others,
are commonly called _ailerons_.

PLATE XXVII.

[Illustration: _BLÉRIOT XI_ WITH MOISANT AVIATOR ON MEXICAN BORDER.]

(Courtesy A. J. Moisant.)

[Illustration: _BLÉRIOT XII._

(Courtesy E. L. Jones.)]

Louis Blériot with his two new machines, his _No. XI_ at Douay and his
_No. XII_ at Issy-les-Moulineaux, practiced nearly every fine day in
June and July, making fast progress in the art, and achieving some
notable records. By warping the wings he could keep his balance better
than in former years, and dare more severe weather. On June 12th, he
made a straightaway flight of 820 feet in his _No. XII_, taking as
passengers A. Santos-Dumont and A. Fournier, the entire weight being
1,232 pounds. This was the first flight of three passengers in an
aëroplane. On June 25th, despite a strong wind, he circled in his _No.
XII_ eleven times about the parade ground at Issy-les-Moulineaux in 15½
minutes, maintaining excellent stability. Next day he made 30 circuits
in 36 minutes, 55⅗ seconds, stopping finally because of spark failure
due to excess of oil. On July 4th, at the aëronautic meet at the Juvisy
Aërodrome, for sufferers from the earthquake in the south of France,
he flew in his _No. XI_ for 50 minutes, 8 seconds, at a height of 50
to 80 feet, finally stopping because of feed trouble in his engine.
This flight was his second up to that date. On July 13th, he made a
new cross-country record by an early morning flight in his _No. XI_
from Etampes to within eight miles of Orleans, stopping some minutes
en route, to show the practicability of his monoplane. Thirty-five
minutes after landing, his machine was taken apart and shipped back to
his factory at Neuilly, near Paris. After this record he received gold
medals from the Aëro Club of Great Britain and the Aëro Club of France.
He was also awarded the _Prix de Voyage_ of 14,000 francs, of which he
himself received 5,000 as pilot, 4,000 as constructor, while 3,000 went
to the motor manufacturer and 2,000 to the propeller designer.

The monoplanes _No. XI_ and _No. XII_ represented Blériot’s most
successful types. They bore a family resemblance to his preceding
machines, but had a more vigorous lateral control due to warpage of
their main surfaces instead of the wing-tips, as of old. Both were
provided with a single-screw propeller in front, and both were mounted
on three-wheeled chassis with shock absorbers. The larger machine, or
_No. XII_, had a wing surface of 337 square feet; the smaller a surface
of 151 square feet. The latter, on its historic cross-Channel trip,
carried a three-cylinder air-cooled Anzani engine.

Hubert Latham, in his beautiful _Antoinette_ monoplane, began to
achieve distinction for himself and his admirably designed long-tailed
flyer early in the spring, and, ere midsummer, was one of the favorite
idols of the thronged aërodromes. He preferred a lofty course; he
cut through the sky with the precision and grace of a winged-spear;
he fascinated the spectators by the steadiness of his sweep. The
French reporters declare they saw him roll and light cigarettes in
full flight. Not only did he delight the artist, but he surprised the
official measurer. Toward the end of May he established a new monoplane
record by a flight lasting 37 minutes and 3 seconds. On the 5th of
June he flew continuously 1 hour, 7 minutes and 37 seconds, at a speed
of 45 miles an hour. This was done in a wind and heavy rain which
drenched and blinded him, finally inducing him to come down. On June
7th he carried a passenger, something new for a monoplane. In July he
increased the altitude record by flying 450 feet high. Next day he
flew across country from Arras to Douai, 12½ miles, in 20 minutes.
Very reasonably, therefore, he announced, his intention of sailing for
England above the waters of the turbulent strait.

The _Antoinette_ monoplane resembled, at a distance, a long-winged
fish with its head cut off and replaced by a screw-propeller. It had a
skifflike body with the screw in front, followed by the _Antoinette_
engine, then by the pilot’s seat, the tail part carrying fixed
horizontal and vertical fins and movable horizontal and vertical
rudders. These rudders together with _ailerons_, or warping wings,
controlled the poise in flight. The body was mounted on a light chassis
having cushioned wheels, and a landing skid for absorbing shocks. The
engine employed no carburetor, and was cooled by water which turned
to steam in the engine jackets, condensed in tubes on the side of the
prow, then was pumped back to the jackets.

PLATE XXVIII.

[Illustration: _ANTOINETTE_ MONOPLANE OF 1909.

(Courtesy W. J. Hammer.)]

[Illustration: _ANTOINETTE_ MONOPLANE OF 1910.]

The cross-Channel prize, above mentioned, was a cash sum of one
thousand pounds, offered by the _London Daily Mail_ for the first
successful flight from France to England. Many would fain have it,
though the voyage seemed dangerous, if not foolhardy. Of the various
aviators who coveted the prize, Latham and Blériot were the most
strenuous in competing for it. The bold boy tried first.

Housing his aëroplane on the high cliff facing the Channel near Calais,
Latham looked toward England, impatiently waiting for placid weather,
and a chance to soar. The venture was hazardous. By some it was deemed
rash, owing to the uncertainty of having to alight upon the water, if
the motor should fail. But the brave youth was less alarmed than the
old aviators, who had no intention of competing with him. So, with a
boy’s confidence, he brought forth his huge-winged _Antoinette_, on
July 19th, skimmed along the ground, soared grandly above the high
cliffs, and sped over the waters at a great elevation, as usual in his
aërial voyages.

Latham’s flight was magnificent, but brief. Owing to spark failure
and the stoppage of his motor six miles from the French shore, he
settled promptly, but skillfully, down upon the sea. When found by
the accompanying torpedo boat destroyer, detailed to follow him from
Calais, he was seated on the aëroplane, serenely smoking, buoyed up by
the great hollow wings. He was quickly brought to shore, undaunted and
eager for another trial; but in the rescue his frail flyer was roughly
handled and very much wrecked.

Louis Blériot now hurried to Calais eager to attempt the cross-Channel
flight. Placing his little monoplane, _No. XI_, in a tent on a farm
near Calais, he waited an opportune moment to sail. On Sunday, July
25th, he was routed from bed very early by his friend, Alfred LeBlanc,
and taken forth all reluctant to the field, for preliminary practice
before sunrise; for the weather was favorable and he should sail as
soon as the sun arose. Though suffering from a foot burned in a recent
accident, he discarded his crutches and mounted his winged machine with
eager courage, remarking: “If I cannot walk I will show the world that
I can fly.” For some minutes he circled about the ground where, even
at that early hour, many scores of people were assembling. All was now
in readiness; the flyer was in excellent trim, the pilot in buoyant
spirits, and the torpedo boat destroyer, _Escopette_, well out at sea
to escort her swift aërial charge as well as might be.

The moment of departure had come. Blériot, buttoned in his
close-fitting suit and hood, sat on his white-winged machine, headed
for the cliff, and surrounded by a group of well-wishers. At 4.35 the
light-wheeled craft with propeller whirring, sped along the ground,
rose gracefully in the air and shot bravely over the precipice, with
the hustling aviator on its back. The admiring spectators were wild
with excitement and joy. But there was one sad group in Calais that
morning. Latham and his watchers, who had been waiting for better
weather, rose in time to see his rival on the wing, but too late for
pursuit, as the wind had suddenly risen. The unwary boy remained
behind, weeping with disappointment.

Blériot was now soaring high over the sea, faring toward Dover without
a guide or a compass. For some time he could observe the _Escopette_
following him, her great column of smoke obscuring the new risen sun.
Presently both shores vanished, and for ten minutes he could descry
neither land nor signal of any kind. He was sailing over the sea at
forty miles an hour and drifting with the air he knew not whither; but
he allowed his fiery steed to follow its instinct, as a bewildered
horseman does sometimes. Along the horizon now appeared the white
cliffs of the English shore. He was headed not for Dover but for
Deal, carried adrift by the southwest wind. Three boats crossing his
course seemed plying for some port on his left, and hailed him with
lively greeting. He could not well inquire the way, but he followed
the general course of the vessels, soaring high aloft. At length he
saw a man on the cliff violently waving the tricolor, and strenuously
shouting: “Bravo! Bravo!” He plunged in the direction of the signaler,
whom he knew to be his friend M. Montaine. On nearing the earth he was
caught in a violent turmoil of air and whirled about. Wishing to land
at once, he stopped his power sixty feet aloft, and swooped abruptly
down with an awakening thud upon the old English soil, sleeping in the
peaceful sunlight of a Sabbath morning.[52]

Blériot’s landing was the greatest jolt to British insularity since the
birth of steam navigation. Nevertheless it was welcomed with unfeigned
delight as emphasizing the triumph of a new art which enriches all
people. Shortly afterward was erected on the spot a monument in white
granite having the plan and size of the renowned _No. XI_ monoplane.

Sportsmanlike, Latham wired his congratulations to Blériot, expressing
the hope to follow ere long. Two days later he flew across the Channel
to within one mile of the English coast, where he had to land in the
water again because of motor failure. This time he struck the sea
violently and suffered a broken nose. His goggles were shattered and
cut his face.

The big competitive flyers of the world now turned toward Betheny
Plain near Rheims, where the first International Aviation Meet was to
be held August 22-29, 1909. Here was a place to make record flights,
to win rich prizes, and to achieve great distinction. A well-designed
aërodrome had been prepared for the occasion. In the midst of a broad
plain was marked by means of high poles, or pylons, a rectangular
course, measuring roughly one by two miles, or more exactly, 1,500 by
3,500 meters. At one end was the judges stand, the grand stand, the
café and the aëroplane sheds. The numerous cash prizes offered for
speed, for distance, for endurance, for altitude, etc., totaled in
value nearly forty thousand dollars. But the most coveted prize of
all was the James Gordon Bennett Aviation Cup, together with $5,000
cash, the winner of which should have the honor of placing the next
international contest in his own country. This should be awarded to the
aviator having the best speed over a two-round, or 20-kilometer course.
The next most desired prize was a cash sum of $10,000 for the longest
flight. A special charm of the tournament was that each fortunate
entrant should meet the distinguished aviators from all localities, and
should fly in presence of a world-gathering. Aëroplanes of all the most
successful types were there, numbering together thirty-eight machines.

The first day of the great aviation week, Sunday, August 22d, was
devoted to elimination trials to determine which aviators should
represent France in the race for the Bennett trophy. Of the seventeen
entrants in these trials the three who should cover two rounds of
the course in the shortest time should be selected as champions, the
next six, in order of speed, to act as reserve pilots. But owing to
the severe weather of that day, only six of the seventeen entrants
succeeded in flying well enough to be admitted in either capacity.
Of these six the cup champions were: Blériot, Lefebvre, Lambert and
Latham; the reserve champions being in order, Tissandier, Paulhan and
Sommer. These men won their places by bold flying in rough conditions;
for rain had fallen heavily during the previous night, and the wind
was still blowing in swift and gusty current over the sodden field.
Indeed, the weather seemed anything but propitious at the opening of
that great experimental tournament, on the success of which should be
based the estimates and forecast of so many subsequent meets. Swift
clouds overhead, and black flags displayed on high masts, indicated
that flying would be impossible. A passing storm raged at five o’clock
in the afternoon. But toward evening the face of Nature brightened,
and with it the hopes of the aviationists. The weather at last became
ideal. Nearly all the aëroplanes came forth, and at six o’clock no
fewer than seven were on the wing at one time. Some of them were
doing most startling feats. Lefebvre would make a threatening swoop
at the grand stand, then circle swiftly away. Blériot, in a moment of
unsteadiness, charged a wheat stack with his swift monoplane, damaging
his sharp-bladed propeller. Count de Lambert sailed under Paul
Tissandier, heedless of the aërial wake beneath. The crowds applauded
and cheered every novel and bold maneuver. The closing hour with its
sunny calm atmosphere and its vivacious well-pleased populace, presaged
greater joys for the morrow. Sir Henry Norman, who was present,
declared that those events marked the birth of a new epoch in human
development.

Monday, the second day of the meet, dawned fair and calm, with
promise of settled weather. It was the last qualifying day for
the ten-thousand-dollar long-distance prize, the Grand Prix de la
Champagne. No one who had not flown a reasonable space on, or before
Monday, could take part in the trials for that coveted honor on
Wednesday, Thursday and Friday. The aviators were about early, and many
had qualified before evening. Several of the pilots tried for speed
records. Blériot, with an 80-horse-power monoplane, made one round of
the course in 8 minutes, 42⅖ seconds. Curtiss, in his 60-horse-power
biplane, lowered the time to 8 minutes, 35⅗ seconds. This was an
achievement of the greatest concern, since Curtiss stood alone, as
champion of America, against the more experienced flyers of Europe.
He thought of nothing, engaged in nothing, except the speed trials,
for in these he hoped to win, with his 60-horse flyer, even against
renowned Blériot, in his 80-horse machine. Other interesting events
were designed solely to entertain or amuse the people. Lefebvre again
furnished merriment by sweeping over and under, and around Paulhan, who
was flying at an elevation of 25 feet. M. Kapferer had navigated from
Meaux, in the dirigible _Colonel Renard_, and sailed about the grounds,
with fine effect.

Tuesday should have brought ideal conditions and performances; for it
was the day set for the visit of M. Falliéres, President of France.
But the morning was dark, with ominous clouds gathering over the
aërodrome, and black flags streaming in the strong wind. When the
President arrived, though the clock told four, no flying had yet begun.
He examined the machines, held an informal reception, and at five took
his box in the grand stand. Presently Bunau-Varilla in his Voisin
biplane, rocking in the fifteen-mile wind, flew past, waving his hat to
the distinguished spectators. After him came dauntless young Paulhan
who also passed the President, shortly before the latter, with his
party, returned to the railway station. He flew at an elevation of 300
to 500 feet, his Voisin heaving and lurching in the tumultuous wind,
like a boat on the breakers. He had no lateral stabilizing plane, so
he let his box kite rock. The people were appalled, but what cared he
for wind gusts, so far from earth? Let the craft roll and pitch; he
was not uneasy. On the return lap he raced and beat a railway train.
These were but inklings of what he would do with increased experience.
Latham followed presently on his long swift monoplane, to the delight
of all who love the graceful in mechanism and motion. Ere long he
was chased and overhauled by Blériot, in his cross-Channel flyer.
This was exciting, but Blériot produced still greater enthusiasm by
beating the speed record, lowering it to 8 minutes, 4⅖ seconds, for
one round of the 10-kilometer (6.21 mile) course. The day was ended,
and the spectators were charmed again by the spectacular evolutions
of Lefebvre, who cavorted in the air before the grand stand, cutting
impressive curves and figure “8’s.”

Wednesday morning, the fourth of the meet, was heavy with black clouds,
which presaged unfavorable weather. The winds were light, but still
nothing transpired till late in the afternoon to break the monotony
of waiting. During this long interval the crowd could amuse itself
with gossip, refreshments and music, and with an occasional flight of
lesser moment. About four o’clock Paulhan set forth in a six-mile wind
to try for the Grand Prix de la Champagne. His lumbering Voisin had
a speed of hardly more than thirty miles an hour, but it was driven
by a very reliable 50-horse Gnome 7-cylinder motor, whose body spins
round a fixed crank, carrying the propeller with it. No one at first
expected a very long flight. The wind rose, sometimes exceeding 20
miles an hour, tossing the young pilot terribly, and once throwing
him so far within the course that he must turn a complete circle in
order to round the corner post, or pylon. But he kept right on, so
long as there remained a drop of fuel. He first broke Wilbur Wright’s
best record, by 23 minutes, then Sommer’s recent record, by 6 minutes,
finally landing, at half past six o’clock, with a new world’s record
of 82 miles in 2 hours, 43 minutes and 24⅘ seconds. The people were
frantic with excitement; they clapped their hands and waved thousands
of handkerchiefs; they rent the air with tremendous applause as he
was borne toward the grand stand on the shoulders of his clamorous
comrades. Others at the same time had been flying with varied fortune.
During Paulhan’s long demonstration, Fournier had encountered a
miniature whirlwind, turned over in the air, at a great height, and
crashed sidewise to the ground, with some injury to his nose, and with
much damage to the wings and tail of his machine. Latham, wishing to
lower his circuit time, flew thrice around the course, but without
improvement. During his flight, a splendid rainbow appeared, which
together with the _Antoinette_ dragon fly soaring high aloft with
Latham on its back, produced an impressive spectacle.

Thursday morning brought fine weather and the promise of an eventful
day. As a consequence serious efforts were made to excel all previous
records, particularly for speed, duration and distance. In the forenoon
Latham flew 43.5 miles in the _Antoinette XIII_. In the afternoon Count
de Lambert, in his Wright biplane, flew 72 miles. Blériot entertained
the throng by carrying Delagrange as passenger; but while sailing near
the ground he encountered some dragoons, turned sidewise to avoid
striking them, and plunged into a fence, breaking his propeller. But
the great sensation of the day was Latham’s afternoon flight for the
Grand Prix, in his _Antoinette No. 29_. Starting with plenty of fuel
and favorable weather, he rose to a high level and flew till his supply
was exhausted, at times encountering rough winds and for a while
plowing through a rainstorm. It was the banner flight of the week thus
far; for it surpassed all other long ones in distance and speed, though
not equaling Paulhan’s in endurance. His total range, when compelled
to alight through exhaustion of fuel, was 95.88 miles, in 2 hours,
18 minutes, 9⅗ seconds. This showed an average speed of 41.63 miles
an hour for the whole distance, while the speed for his first round
was 44.65 miles an hour. For this great achievement he could thank
his 50-horse, 8-cylinder _Antoinette_ motor, one of the lightest in
existence, for that power.

Friday, August 27th, was the last day allotted for the distance, or
Grand Prix contest. After the wonderful new records of Paulhan and
Latham, people were marveling what might happen on the final day. Many
assumed, of course, that Latham’s record of 96 miles would remain
unsurpassed. At four-thirty, Latham started on another long flight, in
his _Antoinette_ monoplane _No. 13_, followed presently by Farman and
Sommer in Farman biplanes; these flying six to twelve feet from the
ground, with gallant Latham soaring aloft nearly three hundred feet in
his swift long-winged fish, and occasionally gaining a lap on them.
Sommer stopped after three rounds, because of motor trouble. Latham’s
fuel gave out after a voyage of 68.35 miles, and he glided to earth.
Farman continued to plod along on his slow, low-wandering craft, with
little attention. Others were in the air, with biplanes and monoplanes,
entertaining the populace—Blériot, Curtiss, Delagrange, Tissandier,
Bunau-Varilla—these had the applause. Presently the spectators
remembered that ground-skimming Farman had been a very long time on the
wing. He now became the center of rapt attention. Slowly he distanced
Paulhan’s great world’s record of Wednesday; slowly he distanced
Latham’s greater world’s record of Thursday; but still he plodded away.
The sun sank on his flight; darkness came on the field, so that he
vanished from view at the far end of the course. At the close of the
nineteenth round he landed in the dark before the grand stand, limp
and exhausted, having journeyed 3¼ hours and traversed 118.06 miles.
For the second time he had won a $10,000 prize; nineteen months ago by
flying 1 kilometer, to-day by flying 190 kilometers. A searchlight was
thrown upon him. He was pulled from his machine and carried upon the
shoulders of his friends, receiving a prolonged and tremendous ovation.

The seventh morning of the tournament, Saturday, August 28th,
came with a beaming smile, promising good flights and a pleasant
termination of the glorious cup contest for the highest speed in two
rounds of the 10-kilometer course. The air was calm, mild and hazy
above the Betheny plain. The flyers were in fine mood for great
achievements. The thronging groups of well-dressed men and women
awaited further startling events, with varied animation and constant
chatter. The day was well diversified with interesting flights; but,
of course, not with long ones. The chief interest centered in the
leading cup-champions—solitary Yankee Curtiss and great Blériot with
his 80-horse monoplane, supported, if need be, by his allies in the
contest, Lefebvre and Latham.

Curtiss, shortly after ten o’clock, made a preliminary trial, lowering
his best anterior time. With this he was so pleased that he prepared
immediately for the one official flight allowed in that contest. He
filled his small gasoline tank, replenished his radiator, signed a
legal paper certifying this to be his trial for the cup, and at once
took wing, circling before the grand stand, then crossing the line at
full speed. The biplane pitched perceptibly at its unusual gait, but
turned the corner in easy curves, completing the first round in 7.57⅖,
the second in 7.53⅕; the total time being 15 minutes, 50⅗ seconds, and
showing an average speed of 47.04 miles an hour.

About noon Blériot came forth with his 80-horse monoplane _No. 22_,
which was expected to eclipse the Curtiss biplane, but in reality
proved exasperatingly slow. At two o’clock he tried another propeller,
with little encouragement. An hour later he tried again with a
four-blade propeller, but descended before completing the round. After
tinkering for an hour, aided by several mechanics, he flew to his shed,
shortly before five o’clock. As no start was allowed after five-thirty,
he hastened zealously and started his official flight at five-ten. The
mighty monoplane cut the air at terrific speed, without pitching, or
rolling, and finished the first round in 7.47⅘, or 5⅔ seconds less
than Curtiss’ best lap. The overjoyed French throng rent the air with
frantic bravos! Curtiss and Mr. Bishop were silent, appreciating the
skill of that fiery antagonist, with his monster engine. As the steady
birdlike craft turned the last pylon, and swept homeward in magnificent
career, the timers called out the seconds. The throng listened with
abated breath and then with alarm. Blériot had lost speed in the
second round. When he crossed the line his total time was 5⅗ seconds
greater than that of his only rival. The conqueror of the Channel, the
champion of France, was defeated and the international trophy must go
to America, won by a taciturn, calculating Yankee, never before seen in
Europe, and hardly known to fame.

Other official flights for the cup during the day were made by Latham
and Lefebvre for France, and by Mr. Cockburn, champion for England,
the latter bird-man sailing into a stack of wheat in the middle of
his first round, then wheeling to earth. Incidentally Henri Farman
established a new world’s three-man duration distance and speed record
by carrying two passengers ten kilometers in 10 minutes 39 seconds.
Thus ended the chief day of the tournament, leaving the contestants in
the following order of speed: Curtiss, Blériot, Latham, Lefebvre.

Of the other leading prizes, that for the fastest single round was
taken by Blériot; that for the fastest three-round flight was won by
Curtiss on Sunday, with a record of 23 minutes, 29 seconds for the
thirty kilometers; the Altitude Prize was won by Latham, who attained
an elevation of 508.5 feet; the Prix des Mecaniciens was won by
Bunau-Varilla in a flight of 100 kilometers; the Prix des Aëronats
was won, on Sunday, by the large dirigible, the _Colonel Renard_,
in a voyage of 50 kilometers, or 31.06 miles, at an average speed of
24.9 miles an hour. Along with the chief prizes, many smaller ones of
considerable value were awarded, thus summing up the total of $37,000.

The small band of men who organized the first international aviation
meet, with the Marquis de Polignac as president, and the great wine
merchants of the Champagne district as their supporters, were now
elated and triumphant. They had undertaken a novel and costly sporting
enterprise, regarded by many as hazardous, or rash, even though
sanctioned by the Aëro Club of France. For an enormous attendance
would be required to meet the expense of preparations and prize money.
It was doubtful whether the few available aviators could draw large
crowds to Betheny for a week, even in ideal weather, and there was risk
of sending the critical populace away displeased if abundant flights
were not made. The whole event might prove a painful fiasco, if rains
and high winds should predominate; for were not aviators notoriously
reluctant to fly in rough weather? Vain apprehensions, ignoring the
reckless and intrepid daring of the Gallic sportsmen! Nothing short of
a week’s continual tempest could have kept them down.

The great tournament was a triumph, not only to the courageous
promoters, but also to the aviators, the manufacturers, the whole of
mankind. It astonished both actors and spectators. It marked a new
epoch in the art of aëroplaning. It inaugurated a magical and wholly
novel kind of recreation and public amusement that should be demanded
at once in all civilized countries. It eradicated, in a measure, the
inveterate notion that the aëroplane is essentially a fair-weather
machine. With a cheap instrument capable of flying scores of miles
in rain and wind, what applications might not come, of the greatest
import to the world?

The fashion set at Rheims was imitated in other cities. Before the
close of the year 1909, aviation meets were scheduled for Brescia in
Italy, Berlin, Juvisy, near Paris, Blackpool and Doncaster, England.
The succeeding year was to have more such events than the really
capable aviators could attend. In both hemispheres, sums in cash,
equaling or exceeding those at Rheims, would be offered by many
prominent communities, eager to witness such novel and thrilling
entertainment as only dexterous aviators could furnish. But it would be
learned also that considerable financial risk attends an aviation meet,
unless good judgment mark the choice of site, season, pilots and the
executive agencies. Several of the meets following the one at Rheims
succeeded neither in defraying expenses nor in furnishing competent
aviators to repay the trouble of holding the tournament. The meets
held in England were practically failures. A most interesting flight,
however, was performed by Latham in a wind of 25 to 35 miles an hour.
This itself was a very impressive achievement. The Brescia meeting was
remarkable for the turbulence of its aërial currents and for Rougier’s
record high flight of 645 feet.

The two most wonderful flights in the autumn of 1909 were those of
Count de Lambert and Farman. During a meet at the Juvisy aërodrome,
Lambert, on October 18th, after circling the ground a few times on a
Wright biplane, attaining a height of 450 feet, started for Paris,
steadily ascending in the direction of the Eiffel Tower. Circling this
at an altitude of about 1,300 feet, he returned to Juvisy at 5.30
P.M., having journeyed 30 miles over that dangerous route, in about
50 minutes. This indicated that lofty flying might enable one to
pass safely over a city, even with an unreliable motor, since, if the
propeller stopped, a glide of many thousands of feet could be made, to
choose a landing. Farman’s flight was less spectacular, but quite as
marvelous. On November 4th, while competing for the Michelin trophy
for the longest distance traversed in 1909, he flew continuously for
4 hours, 6 minutes, 25 seconds, voyaging in that time 144 miles, at
an average speed of 35.06 miles an hour. This proved to be the record
distance-and-endurance flight for the year. Other men spoke of sailing
all day in a machine carrying ample gasoline, but failed to make good
their words.

PLATE XXIX.

[Illustration: ESNAULT-PELTERIE MONOPLANE, EARLY PATTERN.

(Courtesy W. J. Hammer.)]

[Illustration: ESNAULT-PELTERIE MONOPLANE OF 1910.]

Unheralded, but quite astonishing, were the flights of Santos-Dumont
in September, 1909. Though conspicuous as a pioneer in aviation, he
for a while had been absorbed in other affairs, and had not kept pace
with his brother aëroplanists in France, since his bold and brief
dashes into the air in the early days of the art. During the season of
1909, however, he developed a surprisingly small and simple monoplane,
spreading 102 square feet of wing surface, and weighing in complete
running order, 259 pounds. It was driven by a Darrac motor, mounted
above the main surface, carrying the propeller directly on its shaft,
and having radiator tubes along the inner surface of the main plane.
Its triangular trussed frame was wheel-mounted, and tapered rapidly
to the rear, terminating in horizontal and vertical rudders. With
this tiniest flyer he sailed across country from St. Cyr to Buc, 4¾
miles, in five minutes, at the unprecedented speed of 55 miles an
hour, repeating the performance several times, according to report. He
also left the ground after a run of 60 feet, in an unofficial trial.
Characteristically, he presented to the public the scale drawings of
his machine, with all rights to its use.

A very original type of monoplane was developed by Robert
Esnault-Pélterie, who began experimenting in 1903. As shown in Plate
XXIX, its body frame was covered to reduce air-resistance, and was
provided with ample keel surface to promote directness and steadiness
of flight. The weight was borne on two wheels in tandem, aided by
wheels at the wing tips to preserve the lateral balance when the
machine was resting. When under way the lateral poise was controlled by
wing warping; the motion about the other two axes being controlled by a
horizontal and a vertical rudder, the latter being “compensated,” that
is, having its axis near the center of side pressure, when in action.
An air-cooled motor of 30 to 35 horse power with a direct mounted
four-blade screw formed the propulsion plant. Though the “R. E. P.”
aëroplane, as it was commonly called, did not achieve great distinction
at first, due, perhaps, to the inventor’s being over original, and
making all its parts himself, instead of buying some high-class engine
and propeller, as other successful aëroplanists had done, still his
machine was greatly admired by technicians for its excellent finish and
the fastidious, thorough and patient manner in which its young inventor
labored to make it perfect, both in design and construction. It was
regarded as a future record breaker, which, indeed, it was destined to
become on further improvement.

Although little was accomplished in building aëroplanes in other
countries than America and France, up to the beginning of 1909, that
year witnessed some good flights in homemade machines in Germany,
England and Canada. In November, 1909, Herr Grade, in Germany, made
a flight of 55 minutes in his monoplane. Mr. S. F. Cody, who
constructed a biplane for the British army, flew over forty miles
across country on September 8th, high above trees and buildings,
remaining on the wing for 63 minutes. The machine spanned 52 feet,
weighed with the pilot, nearly a ton, and was controlled by front
and rear vertical rudders and two lateral rudders, well in front, so
geared that if worked oppositely the machine listed, while if worked
identically it rose or fell. In Canada Dr. Alexander Graham Bell and
his associates continued the experiments, already described, begun
in 1908 by the Aërial Experiment Association. In 1909 their fourth
machine, the _Silver Dart_, flew many times round a course on the
frozen lake, Bras d’Or, traversing, all told, about 1,000 miles in 100
flights.

PLATE XXX.

[Illustration: GRADE MONOPLANE.

(Courtesy E. L. Jones.)]

[Illustration: CODY BIPLANE.]

The last months of this strenuous year, 1909, and of the first decade
of dynamic flight, closed without further startling developments. True,
some records were made, but they merely pleased, not perturbed the
world, now accustomed to marvels. Be it recorded, however, that, with a
Voisin biplane, Paulhan, on November 1st, flew 96 miles in 2 hours, 20
minutes, and on November 20th flew 1,960 feet high in a Farman biplane;
on December 9th, Maurice Farman, mounted on his own type of biplane,
rode through the icy atmosphere from Buc to Chartres, a distance of 40
kilometers, in 50 minutes, the longest town-to-town flight up to that
date; and on December 31st he flew from Chartres to Orleans, a distance
of 41.6 miles, in forty-six minutes. But several fine achievements
which the world anticipated for that year remained unattempted. The
great prize flight of 183 miles from London to Manchester was still
untried, though several machines and pilots seemed equal to the voyage,
and $50,000 would be awarded by Lord Northcliffe to the brave aviator
who should accomplish that journey in not more than three stages and
within a period of twenty-four hours. Neither had anyone yet flown
to an elevation of one kilometer. These tasks were left over as
allurements for the succeeding year.




                              CHAPTER XII

                            FORCING THE ART


The decade that inaugurated dynamic man-flight had closed without fully
demonstrating the capabilities of such aëroplanes as had been so far
developed. No considerable altitude record had as yet been achieved. No
very long cross-country flight had yet been attempted, though for many
months the New York _World_ had offered $10,000 for the first aërial
voyage from Albany to New York, and the London _Daily Mail_ had long
offered $50,000 for a flight from London to Manchester. The uses of the
aëroplane for scouting by land and sea had not been tested, much less
its probable value in aggressive warfare. Such experiments were for
the immediate future, as also the development of specialized types of
machines for racing, for climbing, for burden bearing, for distance,
for endurance, for landing on water, for rising from water, for
protection of passengers from severe weather. To air men and spectators
alike the future of the art promised to be quite as captivating as the
past.

The first startling achievements to usher in the new decade were the
great altitude flights. New world records followed in rapid succession
all through the year 1910, with marked persistence and wonderful
progress. Levels that had been regarded as the peculiar region of motor
balloons were passed one after another, until the aviators vanished
beyond the clouds, their limbs palsied with cold, and their aëroplane
wings whitened with frost. Though the greatest prizes were not offered
for this species of flight, and frequently none at all, it had an
abiding fascination for both the flyers and the public. At the same
time it proved to be as safe as it was theatrical and popular.

The starter in this exciting race for cloudland was Hubert Latham,
already the official holder of the world’s altitude record. At Bouy,
on January 7th, in presence of official witnesses, he rose in his
_Antoinette_ monoplane, describing a great upward spiral till his
barometer recorded 1,050 meters; then returned to earth with like ease
and precision, landing softly near his hangar, before his assistants,
transported with enthusiasm. He had touched the goal of Gallic
ambition, having driven his aëroplane to the height of one kilometer.

Latham’s tenure of the world’s altitude record quickly passed to
his doughty rival, Louis Paulhan. At Los Angeles, on the twelfth of
January, Paulhan, mounted on a Farman biplane, ascended 4,165 feet, as
against Latham’s record of 3,444 feet. This was a great step upward,
due not only to Paulhan’s prowess and dexterity, but also to the
science and constructive skill of the less spectacular gentlemen in the
designing room, workshop and laboratory.

Latham strove again for the world’s altitude record and gained it on
July 7th at the second Rheims tournament, by driving his _Antoinette_
to a height of 4,541 feet.[53] But again his victory was soon eclipsed;
for two days later, Walter Brookins at Atlantic City ascended 6,175
feet in a Wright biplane. An American was thus the first to fly above
one mile, as a Frenchman had been first to pass the 1-kilometer limit.
The 2-kilometer and 2-mile elevations were exceeded before the close of
the year, as shown by the following table, which also manifests a fair
distribution of honors among various nations and types of machines:

  --------+------------+------------+---------------+------------
    Feet  |  Aviator   |  Aëroplane |     Place     |   Date
  --------+------------+------------+---------------+------------
    3,445 | Latham     | Antoinette | Betheny Plain | January 7
    4,165 | Paulhan    | Farman     | Los Angeles   | January 12
    4,541 | Latham     | Antoinette | Rheims        | July 7
    6,175 | Brookins   | Wright     | Atlantic City | July 9
    6,604 | Drexel     | Blériot    | Lanark, Sc.   | August 11
    8,271 | Morane     | Blériot    | Havre, France | September 3
    8,406 | Chavez     | Blériot    | Issy          | September 8
    9,104 | Wijnmalen  | Farman     | Mourmelon     | October 1
    9,714 | Johnstone  | Wright     | Belmont Park  | October 31
   10,499 | Leganeaux  | Blériot    | Pau           | December 9
   11,474 | [54]Hoxsey | Wright     | Los Angeles   | December 26
  --------+------------+------------+---------------+------------

Such lofty flights have proved a severe test of both the aëroplane and
the pilot. In the lighter atmosphere the engine must turn the propeller
at higher speed to secure the same thrust, and the aëroplane must sail
faster to support the same weight as at the lower levels. Thus more
power is required on high, though the explosive medium, being less
dense, is less capable of exerting power. The driver has, therefore, to
jockey his machine with assiduous care and alertness, at a time when he
is least fitted for exertion, owing to fatigue, cold, and it may be,
physical discomfort due to the great change of atmospheric pressure.
But still, both aëroplane and pilot are capable of ascending well above
any levels thus far attained.

After the triumphant altitude flights of 1910 the aëronautical
skeptics could no longer contend that the aëroplane was useless in
transportation and warfare, because of its inability to fly above
high land or the usual range of the guns of battleships and coast
fortifications. Most of the important mountain passes lie below 10,000
feet. The safe elevation for motor balloons menaced by terrene guns is
taken to be much less than two miles, and in military practice they
usually operate below the one-mile level. The aëroplanes, therefore,
may not only cross mountain ranges, but may also scrutinize, or
grievously molest, land forces, marine squadrons and perhaps even the
great gaseous cruisers of the atmosphere, which they can far outspeed,
and may even destroy.

The increase in speed of flight during 1910 was also quite remarkable.
The official record by which Mr. Curtiss won the Bennett Aviation
Contest at Rheims, in 1909, showed a speed of 47.04 miles an hour.
Still higher velocities, ranging from 50 to 60 miles an hour, were
reported later in that season from England and France. In 1910,
however, at the Rheims aviation meet, Morane, with a Blériot monoplane,
covered the 20-kilometer course in 12 minutes 45.2 seconds, or at an
average speed of 66.2 miles an hour, showing a gain of forty per cent
on Mr. Curtiss’s speed of the preceding year. Still better was achieved
at the international tournament held at Belmont Park in 1910. Le Blanc
in a 100-horse Blériot monoplane, especially designed for speed,
covered nineteen laps of the 5-kilometer course at an average rate of
61 miles an hour, and his fastest lap at the rate of 71.68 miles an
hour, thus exceeding Curtiss’s speed of the previous year by fifty per
cent. Other spurts during the latter part of 1910 were reported to have
attained nearly 80 miles an hour over a closed circuit, though perhaps
not a level one. The best results were achieved with machines having
high power engines, small surfaces and slight forward resistance.

The advance in long-distance flying in 1910 more than kept pace with
the progress in speed. The best achievement at the close of the
preceding year had been Farman’s flight of 144 miles at an average rate
of 35.06 miles an hour in a closed circuit. At the Rheims aviation meet
in 1910, Jan Olieslaegers, in a Blériot monoplane, driven by a Gnome
engine, covered 244 miles in a rectangular course, at an average speed
of 48.31 miles an hour. At Buc, on the 28th of October, an aviator of
three months’ practice, Maurice Tabuteau, in a Maurice Farman biplane,
driven by a Rénault engine, flew over a closed circuit, covering 288.8
miles at an average speed of 47.9 miles an hour. At Pau on December
21st, M. G. Leganeaux, in a Blériot monoplane, flew for the Michelin
Cup, covering 516 kilometers or 320.6 miles in six hours and one
minute, or at an average speed of 53¼ miles an hour—a splendid showing.
Finally, at Buc, on December 30th, Tabuteau, flying for the annual
Michelin prize, covered 362.66 miles in a Maurice Farman biplane with
an 8-cylinder 60-horse Rénault motor. The average speed in this very
long flight was 47.3 miles an hour, or practically the rate by which
Curtiss won the international contest of the preceding year. Of course
a considerably better showing of both distance and velocity could have
been made on a longer course.

The world records for cross-country flying and for endurance and load
illustrate both the increasing perfection of the machine and of the
pilot’s skill and confidence. At Los Angeles, on January 19th, Mr. and
Mrs. Paulhan, in a Farman biplane, flew together 21 miles overland from
the aviation field to Redondo and Hermosa Beach and return. On January
31st Van der Born made a world’s duration record with a passenger on
a Farman biplane, flying 1 hour 48 minutes 50 seconds. On March 5th,
Henri Farman, who had previously twice broken the world’s duration
record for a pilot with two passengers, set a new and astonishing
pace at Mourmelon, by carrying Mr. Hevardson and Madame Frank in
easy flight for 62.5 minutes on his new biplane. In France, on April
3d, Emile Dubonnet on his _Tellier_ monoplane flew from Juvisy to La
Ferte-Saint Aubin, a distance of 109 kilometers or 70 miles in 1 hour
and 50 minutes, thus winning the ten-thousand-franc prize offered
by _La Nature_ for the first straightaway flight of 100 kilometers
to be effected in less than two hours, over a previously indicated
course. This fine record voyage was achieved in a machine never before
thoroughly tried. At Chalons-sur-Marne, on April 8th, Daniel Kinet,
a Belgian, mounted with a passenger on a Farman biplane driven by
a 50-horse Gnome engine, broke the world’s record for duration and
distance for two persons by flying round a closed circuit 2 hours 19¼
minutes, covering a distance of 152 kilometers, or 94 miles. On April
17th, H. Farman, with a passenger in his biplane, voyaged from Etampes
to Orleans, 28 miles. Next day, Paulhan, mounting the same machine,
flew 108 miles, and the following day 42 miles. This tour established a
new cross-country record for total distance, for single stage distance
with one passenger, and for duration and single stage distance with two
passengers. During the same month Farman made a new record for four
passengers by carrying three gentlemen for 1 hour and 4 minutes on his
new biplane, spreading 47.6 feet. On June 9th, two French officers,
Lieutenant Fequant piloting and Captain Marconnet observing, flew
on a Farman biplane from Bouy to Vincennes, 145 kilometers, in two
hours and a half, thus breaking the world’s cross-country distance and
duration record for a pilot with a passenger. On June 13th, Charles K.
Hamilton, in a Curtiss biplane, flew from New York to Philadelphia, a
distance of 86 miles in 103 minutes, and returned the same day, thus
completing 172 miles in one day. This was an exhibition flight made for
_The New York Times_ and the _Philadelphia Ledger_, for a sum reported
to be $10,000. It was a sequel to Glenn H. Curtiss’s memorable flight
on June 5th, down the Hudson River from Albany to New York, for the New
York _World’s_ $10,000 prize. Hamilton’s average speed was 50 miles
an hour going and 51 miles returning. On August 29th, at Lille, Louis
Bréguet is reported to have carried with him on a biplane of his make,
five passengers, who, together with the gasoline, weighed 921 pounds.
It may be added that the Bréguet biplane of that date was advertised
and guaranteed to carry a cargo, or extra load, of 250 kilograms. It
thus appears that by 1910 the aëroplane had grown powerful enough for
an aërial cab service, and that it could carry sufficient explosive
gelatine to derange a battleship.

The contest for cross-country records continued unabated all that
memorable year. During the first three days of September, Jean
Bielovucic, a youth of twenty-one, mounted on a new type of Voisin
biplane, with but a few days’ practice, flew from Paris to Bordeaux,
covering 540 kilometers, or 336 miles, in four stages, comprising
altogether 6¼ hours on the wing. In spite of severe weather, at times,
he beat the regular express train and established a new world’s record
for cross-country straightaway distance flying with stops. On August
17th, Alfred Le Blanc, finished a six-stage tour round a hexagonal
circuit northeast of Paris, with the finish at Issy, near Paris,
covering a total distance of 785 kilometers, or 440 miles, in 12
hours 56.4 seconds effective time. On September 7th, Weyman flew with
a passenger from Paris to Clermont near the Puy de Dome, covering
205 miles in one day, while trying for the Michelin prize of 100,000
francs, for a flight to the Puy de Dome inside of six hours. On
December 18th, Thomas Sopwith, competing for the longest flight across
the Channel and into Belgium, on a British-built aëroplane, flew from
the Isle of Sheppy across the Channel, and landed at Beaumont, Belgium,
covering a distance of 174 miles in 3.5 hours. At Buc, on November
27th, Laurens, in a 60-horse R. E. P. monoplane, flew with his wife 53
miles at an average speed of nearly 50 miles an hour. On December 22d,
Lieutenant Cammerman, a French army officer, won the L. Weiller prize
by flying across country with a passenger, 147 miles in 4 hours and 2
minutes.

These are but a few of the records which serve to illustrate the
progress in cross-country flying during that year of strenuous and
world-wide popular demonstrations. But the bare numerical statement of
facts can give no conception of the delight and exultation aroused in
millions of souls who witnessed or learned of these marvelous human
achievements. They were the advancing triumph of a proud and fortunate
generation, happy in realizing one of the fondest dreams of the ages.
Often during one of these cross-country flights the aëroplane was
accompanied by a swift railway train whose passengers were delirious
with enthusiasm. The entire route was thronged with people assembled
from afar. It was a general holiday for all the fortunate cities and
villages along the way. Mills and factories blew their whistles and
forgot the serious business of life, homes were deserted, schools
were dismissed; the whole population for the time congregated in
the open; bearded mechanics in their aprons, bare-armed housewives
holding their children aloft, girls and boys with wondering eyes, all
shouting, waving banners, throwing up hats, and hailing with tumultuous
demonstration that strange and huge-winged creature gliding from
horizon to horizon with the steadiness, precision and directness of a
mighty projectile. But beyond stating the records of this season of
aërial wonders, only a passing notice can be given to some of the more
conspicuous events.

The most famous overland voyages of the season 1910 began with the
race for the London _Daily Mail_ prize of $50,000, offered by Lord
Northcliffe for the first person who should fly from London to
Manchester, 183 miles within twenty-four hours, with not more than
two stops. An Englishman, Claude Grahame-White, comparatively new in
the pilot’s art, was first to undertake that difficult and perilous
adventure. Starting from London, without competitor, on April 24th, he
flew in his Farman biplane, from London to Rugby, thence to Hademore,
about halfway to Manchester, landing at a quarter past nine o’clock
at night, after a four-hour trip, and hoping to reach Manchester next
day. But during the night his aëroplane, which was left in the open,
was damaged by the wind, thus necessitating repairs and a new start. On
April 27th, while he was strenuously mending and adjusting his biplane
for a new start, Louis Paulhan, who the day previously had arrived from
France with a Farman biplane to enter the contest, was also vigorously
setting up and adjusting his machine.

At half past five in the afternoon, Paulhan suddenly set out for
Manchester. Mr. White, who was much fatigued and expecting to start on
the morrow at dawn, after much-needed rest, learned toward six o’clock
that his rival was on the wing, and hurriedly sailed from London,
hoping by skill and good chance to overtake the flying Frenchman.
The race was now the most exciting event in the world. The first
flyers of France and England were competing for the greatest prize
yet offered in the history of aviation, competing in a most modern
and extraordinary race, attended with abundant danger and hardship.
The contestants were evenly matched in mechanism and capability, but
the Frenchman had gotten the march on the unwary Englishman. Paulhan
followed the Northwestern Railway, at times outracing the special
pilot train carrying his mechanics and supplies. At ten minutes after
eight o’clock, he landed at Lichfield, having covered 115 miles. Mr.
White had landed five minutes before eight near Roade, after flying
fifty-nine miles.

Next morning, Paulhan sailed away at a quarter past four. Mr. White,
hoping to overtake him, had started at dead of night and covered
twenty miles before Paulhan had started. It was a heroic effort, but
unavailing. At twelve minutes after five, Mr. White landed at Hademore,
having completed two thirds of the entire journey. Twenty-five minutes
later Paulhan landed on the outskirts of Manchester, greeted by a
thousand persons. He had covered the whole distance in 4.2 hours, and
had fulfilled all the essential conditions for winning the great prize.

The next world-famous aëroplane voyage was that of Glenn H. Curtiss for
the New York _World’s_ prize of $10,000 for the first aërial journey
from Albany to New York, allowing two stops. Aviators had been yearning
for this prize since the previous year, but had been too timidly shying
at the dangers of the route. After most careful preparations for this
voyage, Curtiss, bearing a letter from the Mayor of Albany to the
Mayor of New York, sailed away at seven o’clock on Sunday morning, May
29th, accompanied by a New York Central special train, bearing his wife
and a few friends and newspaper men. He landed an hour for supplies
and adjustment at Camelot, 41 miles down the river, and thence flew to
Spuyten Duyvil, at the northern extremity of New York, having completed
the required distance, 128 miles, in 2 hours and 32 minutes, or at the
rate of 50.52 miles per hour along the course. An hour later, he flew
down the river to New York Harbor and landed on Governor’s Island,
where he received a becoming ovation.

Perhaps the most exciting incident of the voyage to Mr. Curtiss was his
transit of the Storm King Mountain. As he was flying through the narrow
gap at this place he caught the down-rolling air on one side more
than on the other, and dropped very suddenly sidewise 30 or 40 feet.
By shifting his front control, he quickly gained headway and promptly
righted his machine.

Commenting on Mr. Curtiss’s average speed of 50 miles an hour and his
rugged course, _Aëronautics_ makes comparison between his voyage and
Paulhan’s great prize flight as follows:

  “Paulhan took 4 hours 12 minutes elapsed time to cover 183
  miles when he won the _London Mail’s_ $50,000 and made it in
  two stages of 117 and 66 miles each. The 117 miles were covered
  in 2.39, a rate of nearly 44 miles per hour. A night’s sleep
  intervened and the remaining 66 miles were covered in 1.23, a
  rate of nearly 48 miles per hour. The average for the above
  was 44.37 miles per hour. Paulhan could have landed at almost
  any time and started again, whereas Curtiss could not have
  started if he had had to land in the water, and for the whole
  distance there was scarcely a suitable space for landing on the
  ground, as for nearly the entire way rocky, wooded hills with
  precipitous sides line the river.”

The most audacious and marvelous aëronautic exploit of the year was the
flight of George Chavez across the Alps from Brig to Domodossola, in
his attempt to win the prize of 70,000 francs offered by the Italian
Aviation Society for the first aëroplane flight from Brig to Milan, a
distance of 75 miles. From the nine volunteers for this contest who
presented themselves to the committee in charge, five competitors
were selected, and these for several days made tentative efforts to
scale the lofty pass, but were baffled by the wind or fog. Finally at
one-thirty, on September 23d, the conditions being favorable, Chavez
rose, from Briegen-Berg, in his white-winged Blériot, spiraled upward
1,000 meters, circling around the vast amphitheater of the mountains,
and in nineteen minutes appeared in magnificent career well above the
Simplon Pass, probably 7,000 feet above the sea, whence he glided
grandly down the Italian slope, parrying the rude cross winds and
finally reaching Domodossola, where the enthusiasm was at its climax.
Here he expected to land on a level spot to replenish his supplies,
thence proceed over the easy remaining two thirds of his journey. But
though the perilous pass had been crossed so successfully, disaster
appeared in the valley when least expected. As the aëroplane was
gliding thirty feet high over the level tract chosen for landing, it
met a sudden gust, its wings collapsed, and it fell crashing to earth,
pinioning its brave pilot under the débris.

Poor Chavez suffered severe wounds about the face and head, had both
legs broken, and for some moments lay unconscious. But he was soon
revived by his friends and taken to a hospital, where he died four
days later. Thus ended the career of a brave and most promising youth
of twenty-three. He had taken his pilot’s license only in February,
1910, yet had established a new world’s record on September 8th, by
driving his Blériot to an elevation of 8,406 feet. He was of Peruvian
parentage and born in Paris.

The exact nature of the accident was never ascertained, but it was
surmised that the sudden starting of his engine preparatory to landing
overstressed some part of the structure already fatigued from hard
usage. However this be, the committee recognized that Chavez had with
excellent skill covered all the really difficult and dangerous part
of this journey. Accordingly they very generously waived the exact
letter of the rules, and awarded him one half the prize, though he had
completed but one third of the journey.

Quite as dangerous, spectacular and brilliant as the flight across
the Alps, though less arduous, was Hubert Latham’s aërial voyage over
Baltimore. On previous occasions cross-city flights had been made,
but never one of such length or one executed under such exacting
conditions. At various times aviators had flown above Paris, Rome,
Berlin, etc. On October 14th Mr. White had flown across Washington,
landing on a narrow street between the White House and War Department;
on October 15th Leganeaux had flown above Paris with a passenger; but
these were short flights over an uncharted course. Latham’s voyage
was unique; for he had to follow a long and a prescribed course over
the business section and closely built residence portion of the city.
This great exploit was an exhibition flight made on the invitation
of the _Baltimore Sun_ for a sum of $5,000. It was to be made at the
time of the Baltimore aviation tournament at Halethorpe, Md., and was
calculated to be seen by half a million people; for the whole city was
to be notified and would cease its usual activities to witness the rare
and hazardous demonstration.

The voyage was triumphant and glorious in every feature. Starting from
the aviation ground, seven miles south of Baltimore, about noon on
November 7th, Latham drove his beautiful _Antoinette_ about the field
in an ascending spiral, like some imperial bird taking its bearings;
then, chart in hand, deliberately sailed away over his elaborately
prescribed journey. This was a figure 8 course with its bottom at the
aviation field and its center at the _Sun_ Building in the heart of
Baltimore, the whole length being 22 miles. As the long-winged bird
in majestic poise, with the intrepid rider on its back, approached
in the distance, soaring 1,000 feet above the gleaming waters of the
Chesapeake, the great bell of the City Hall sounded a mighty peal, and
the whole populace responded in tumultuous chorus; whistles, bells and
a myriad voices mingling their heartiest welcome to the bravest of
aviators. With arrowlike speed and directness he rounded the center of
the course at the _Sun_ Building, then looped the vast northern half of
the city, flying a thousand to three thousand feet high, more easily
to parry the surging eddies of the northwest wind; rounded again the
center of his course and then returned to the aviation field, where he
landed with infinite coolness before the excited throng of applauding
spectators, whose acclaim was all too feeble to express their mingled
wonder, admiration and delight. The voyage lasted forty-two minutes and
fulfilled perfectly every minute requirement, including a short circle
and salutation before the home of Mr. Ross Winans, an invalid gentleman
who had solicited this unique favor, and rewarded it with a gift of
$500. It was the climax of the aviation week at Baltimore.

Among the many brilliant flights of that memorable year of strenuous
piloting will long be remembered the voyage of the Hon. C. S. Rolls to
Calais and return without landing, and that of Mr. Sopwith, already
recounted; the splendid flight of Mr. Clifford B. Harmon in his Farman
biplane from Mineola, Long Island, to a small rounded island before
his house on the Connecticut shore, for the trophy offered by _Country
Life_ to the first person who should fly across Long Island Sound;
Henri Farman’s flight of December 18th, for the Michelin long-distance
prize, covering 288 miles, and establishing a new endurance record of
8 hours 23 minutes; Mlle. Helene Dutrieu’s flight of December 21st,
for the Coupe Femina, covering 103¾ miles in 2 hours and 35 minutes
in a Farman biplane. Interesting, too, were the first attempt to fly
from Paris to Brussels with a passenger, when Mahieu and Manihé on
starting were brought to bay by a vicious dog which violently attacked
the propeller and was cut in two; and when Loridan and Fay landed on a
tree, from which they descended by a ladder. After this followed the
glorious voyage of Henri Wijnmalen, the youthful and many-sided Dutch
sport, for the prize of 150,000 francs offered by the Automobile Club
of France for the quickest aëroplane trip not exceeding 36 hours, with
a passenger from Paris to Brussels and return. This voyage of some
320 miles was valiantly accomplished by Wijnmalen and his companion
Dufour, in a day and a half, of 13.2 effective hours, and in weather
for the most part windy or tempestuous. Finally to the foregoing list
of splendid achievements must be added the glorious voyage of John
Moisant, who in August flew with a passenger, by compass, from Paris to
London, though he had never been over the route before and had only
just learned to use an aëroplane.

The International Aviation Tournament of 1910, held at Belmont Park,
Long Island, October 22d to 31st, was the most prominent and eventful
meet of the year, and the second of its kind in history, as the
meeting of the preceding year at Rheims was the first. The present
meet was conducted by the Aëro Corporation, Limited, of New York,
under the auspices and official sanction of the Aëro Club of America,
representing the Federation Aëronautique Internationale.

This tournament was the annual aërial Olympic contest of the world, and
should have been indicative not only of the aviator’s skill, but also
of the state of national progress in the science and art of aëroplane
construction. Unfortunately, however, for the prestige of the most
deserving nations, the rules of the International Aëronautic Federation
did not confine the contestants to the use of home-built machines, to
prevent the glory of winning the international contest from passing to
the nation which merely furnished the operator, a person who might be
an illiterate jockey, and representative of a country wholly devoid of
science. As luck decided, however, the highest honor in 1910 was won by
a first-class French machine driven by a first-class English aviator.

In some respects the raw material and working elements of this meet
were most satisfactory. The site is near the wealthiest and most
populous center in America. The grounds are spacious and level,
and provided with all the equipment of a great race course; the
transportation facilities by carriage and by rail from the heart of
New York are adequate to every requirement. The personnel of the
meet comprised the most experienced and most devoted members of the
Aëro Club of America, the oldest and strongest aëronautical body in
the western world, and the only one representing the International
Aëronautic Federation. It is true the season was late and the weather
would probably be cold and tempestuous; the management was burdened by
a costly license, whether just or unjust, imposed upon it as the price
of immunity from patent litigation; the remaining time, after the final
placement of the meet, was all too short for the myriad preparations
to be made. But whatever the obstacles, physical or financial, the
personnel was paramount, and naturally made the huge tournament a
glorious triumph. It was the cardinal sporting event of the year.

The status of aviation was well represented in both pilots and
machines. Twenty-seven aviators were entered on the program, many of
them world famous. Of these Alfred Le Blanc, Hubert Latham, Emile
Aubrun were the formidable champions of France in the contest for the
James Gordon Bennett aviation trophy; Claude Grahame-White, James
Radley, A. Ogilvie represented England; while Walter Brookins, J. A.
Drexel, Charles K. Hamilton were enlisted as defenders of the coveted
cup and of American prestige. All told, the aviators brought with them
nearly two-score machines, ranging in capacity from 30 to 100 horse
power. Of these about half were monoplanes and half biplanes, for the
most part of French and American manufacture.

The prizes and remuneration awarded to the contestants were on a
scale proportionate to their skill and number. All told the winnings
aggregated more than $60,000. Further appropriations were made to
cover the expenses of the aviators, and a further sum equal to about
forty per cent of the winnings was paid for immunity from prosecution
for possible infringement of an unlitigated patent. Considering the
immense expenditures for buildings, for policing and other incidentals
of the meet, it may be readily inferred that there was an ample
deficit, and that the air men as a whole were much better rewarded
than some of the sportsmen who gave so much time and labor to the
organization of the tournament.

A conspicuous feature of the meet was the display of hardiness and
skill of several of the aviators in facing the cold and tempestuous
weather. This was particularly characteristic of Latham in his
_Antoinette_ monoplane, and of Ralph Johnstone and Arch Hoxsey in
Wright biplanes. On October 27th Latham flew round the regular course
for an hour when it was nearly impossible to turn the pylons against
the fierce wind, while Johnstone and Hoxsey performed lofty altitude
flights in a powerful gale which carried them backward, sometimes at
the rate of 40 miles an hour. As a consequence they landed in the
open country, remained overnight and returned next day. Johnstone was
carried backward to Holtsville, 55 miles east of the aviation grounds,
and Hoxsey was blown to Brentwood, 25 miles away, both landing at dusk
in open fields, and both having attained great elevations: Hoxsey,
6,903 feet; Johnstone, 8,471 feet.

An interesting novelty of the aviation week, at least to Americans,
were the erratic Demoiselle monoplanes, invented by Santos-Dumont and
piloted by Garros and Audemars. These aëroplanes were notable as having
the pilot under the sustaining plane, and the engine above with its
direct mounted propeller. The lateral stability was enhanced by a low
placement of the center of mass, and by a slight dihedral inclination
of the wings. Furthermore, as there was not much leverage or surface in
the rear double rudder, the flight was more stable than steady, like
that of a propelled parachute. In fact, the little monoplanes pitched,
rocked, and fluttered about so like huge butterflies as to provoke
constant merriment. They gave a faint suggestion of how ludicrous
aëroplane clowns could be made by one who has genius for such things.

Barring the stormy voyages above mentioned, the most memorable events
of the tournament were the Gordon Bennett speed contest, the Statue of
Liberty race and Johnstone’s great altitude flight. Of the numerous
other performances little need be said, except that they contributed
to the general success of an elaborate and most interesting program.
They served the daily need of a costly tournament; they delighted vast
throngs of spectators whose admission fees helped to promote the aërial
sport; but they did not of themselves have more than local interest, or
constitute an advance in the records of first-class achievement.

The chief race of the meet, the James Gordon Bennett speed contest,
was scheduled for Saturday, October 29th. The prize of $5,000 and the
coveted cup were to be awarded to the pilot who should make the best
average speed in 20 laps over a 5-kilometer course, aggregating 100
kilometers, or 62.14 miles. The winner should have the distinguished
honor of taking to his own country the next annual contest for the
precious speed prize.

Grahame-White, England’s foremost aviator and strongest hope in
the contest, brought forth his untried 100-horse Blériot in the
calmest part of the day, and took wing a quarter before nine. He
flew with steady poise and swift, well-sustained speed, completing
the 100-kilometer distance in 1 hour 1 minute and 4.7 seconds, at an
average speed of 61 miles an hour.

Le Blanc, the most likely winner of all, sailed at nine o’clock. He was
mounted on a 100-horse Blériot with nearly flat wings, the swiftest
monoplane of French manufacture. He was the boldest, sturdiest and
most dexterous pilot in a nation of renowned aviators, the winner of
unnumbered trophies, the “Vainquer de l’Est.” He now flew at unwonted
speed, establishing new world records at every round of the course. It
seemed evident to the timers that only an accident to this impetuous
Frenchman could retrieve the glory of England and save that of America.
Suddenly the accident came. In the last lap, when victory seemed
assured, the gasoline failed; the monoplane shot downward, knocked off
a telegraph pole, and, with broken frame and engine, fell crashing
to earth, entangling the brave aviator. Le Blanc was cut and bruised
about the forehead, and was taken to the hospital to be bandaged,
not seriously injured but in a towering rage, suspecting that some
trickery had given him a shortage of fuel. He had lost the day, though
his average speed for the whole flight was 67 miles an hour as against
Grahame-White’s speed of 61 miles.

No well-tried machine was available to defend the American prestige.
Curtiss had constructed a new monoplane designed for speed, but though
he had brought the cup to America, he was not chosen as one of its
three defenders. The little Wright biplane of 61 horse power had
flown a few minutes with great velocity, and was looked to with some
confidence. Mounted by Walter Brookins, it set out with tremendous
speed, but had only well started when the cylinders began to miss fire.
Brookins turned toward the infield to land, struck the ground with
terrific shock and tumbled violently on the field beside his broken
machine. He, too, was taken to the hospital for treatment, but was not
seriously injured.

It was now granted that Grahame-White would be the ultimate winner.
Other aviators attempted to defeat him, but lacked either the necessary
speed or endurance. The cup was accordingly taken from the nations
that had done the most to develop the practical art of aëroplaning. Of
these two nations, the one most deserving of victory, by virtue of its
more careful preparation, was defeated by an extraordinary mishap, when
victory was at hand; the other failed perhaps for want of preparation
rather than from lack of manipulative or constructive skill.

Of the various highly coveted stakes the largest in monetary value was
known as the Thomas F. Ryan Statue of Liberty Prize. This was a cash
sum of $10,000, to be awarded to the properly qualified contestant who
should fly from the aviation ground to and around the Statue of Liberty
in New York Harbor, and return in the shortest time, the airline
distance being 16 miles each way. The prize was founded by Mr. Thomas
F. Ryan, whose son, Allan A. Ryan, was Chairman of the Committee on
Arrangements of the tournament, and who though suffering with pain and
ill-health, labored so indefatigably to insure the success of the event
so germain to the aëronautical prestige of his country.

The Statue of Liberty race occurred on Sunday afternoon, October 30th,
beginning just after three o’clock. Count De Lesseps in a 50-horse
Blériot monoplane led the race, followed three minutes later by
Grahame-White. They passed toward the southwest in perfect poise and
vanished beyond the horizon unchallenged by an American contestant;
for Moisant, the American champion, had shortly before injured his
racing monoplane, and the other American racing machines had been
damaged the week before, or had not yet been fully tested. But with
admirable enterprise, Moisant telephoned Le Blanc, in New York, who
was not racing because of the accident to his 100-horse Blériot the
day previously, and offered the Frenchman $10,000 for his 50-horse
Blériot monoplane. The sale was effected in time for the race that
day. But for all that the enterprise seemed futile; for as Moisant
was preparing to start, the others were returning, Grahame-White well
in the lead, having overtaken De Lesseps. As these two aviators were
receiving the applause of innumerable spectators and the felicitations
of their friends, audacious Moisant, the impetuous soldier of fortune,
and hero of the famous flight by compass from Paris to London, started
toward the declining sun, just after four o’clock. He was determined
to win by superior skill and daring. His prudent competitors had
followed a circuitous southern route interspersed with landing places;
but he flew like a maniac straight over the church spires and crowded
buildings of Brooklyn, guided to his goal by a compass, rounded the
Statue of Liberty at a great altitude and plunged homeward with all
possible speed and directness. The megaphone announced his progress,
which indicated some hope of victory so little expected and so much
desired by the vast throng that stood gazing toward the western sun.
In headlong career the swooping monoplane shot by the judges’ stand,
circled and softly landed on the field, triumphant by 43 seconds
over the 100-horse Blériot of Grahame-White. As the intrepid aviator
approached the vast and delighted throng of spectators to acknowledge
its noisy and tumultuous ovation, he was met by the chiefs of the
tournament, draped in an American flag, and paraded before the grand
stand, “which shook in its effort to do honor to the little air
conqueror.” Ultimately, however, the prize was awarded to Count
De Lesseps, because Moisant had failed to qualify properly, and
Grahame-White had fouled the initial pylon.

The final day of the tournament was made memorable by Johnstone’s
altitude flight. The best previous record was that of Wijnmalen to an
elevation of 9,104 feet, made at Mourmelon, France. Johnstone ascended
on a small Wright machine with powerful propellers adapted to rapid
climbing, determined not only to surpass Wijnmalen but to exceed,
if possible, the ten-thousand-foot level, and win the special prize
offered for such achievement. He actually rose to the great elevation
of 9,714 feet, but could not develop power enough to continue upward.
On his descent he fully exhausted his fuel at 3,000 feet, and thence
glided to earth, landing softly, 1 hour and 43 minutes from the time of
starting.

Thus the greatest tournament of the year terminated with fine new
laurels for the science and art of aviation; for the spectacular
pilots and for the unseen men behind them—the scientific men in the
laboratories, the designing rooms and the workshops. New standards had
been established in speed, in altitude, in prowess and daring. In these
elements, the spectators could hardly ask for a better exhibition. What
is it to the onlooker to have an aëroplane go higher than the cumuli,
since at that level a thousand feet makes no perceptible difference?
What more could he wish in dexterity of manipulation and audacity in
braving the elements? One thing more, doubtless, and that is, security
and precision of flight in stormy weather. When these improvements
shall have been effected much will have been added to both the sportive
interest and practical utility of the aëroplane.

The most businesslike and crucial flying contest of the year was the
famous “Circuit de l’Est,” organized by the Paris _Matin_. It was a
competitive voyage over an irregular hexagonal course, lying generally
northeast of Paris, and having its vertices at various cities to the
east and north of the national capital. The main prize offered by
the _Matin_ was one hundred thousand francs for the first air man to
complete the entire course, doing the first side of the hexagon on
August 7th, and the succeeding sides in regular order on successive
odd days of the month, the place and hour of starting each stage
being assigned in advance. Various subsidiary prizes aggregating
nearly a hundred thousand francs more, were available for meritorious
performances at the various stages and stopping-places along the
route. But there were also penalizations for those contestants who
failed to start on schedule time and observe the rules of the course.

[Illustration: FIG. 41.—MAP OF THE “CIRCUIT DE L’EST.”]

The race began at Issy, near Paris, on August 7th, with eight aviators
on the wing—Le Blanc, Aubrun, Leganeaux, Mamet, Lindpainter, Weyman. It
terminated August 17th, headed by Alfred Le Blanc on his Blériot, and
followed by Emile Aubrun on a Blériot, then by Weyman on a Farman, all
three driven by Gnome engines actuating Chauvière propellers. Le Blanc
completed the tour of six stages, covering an air-line distance of 488
miles, in 12 hours’ effective flying, or at the average rate of 40.6
miles per hour.

This long tour on schedule time over a rough and varied country in
face of fog, wind and rain, was a most severe trial of the prowess and
endurance of the brave pilots who had the hardiness and pertinacity
to complete the voyage. Needless to add that it created unbounded
enthusiasm among millions of people who witnessed the event, or read of
it, and that the clocklike precision of the “grand raid” inspired new
confidence in the practicability of the aëroplane.

A particularly impressive feature of the event was that many of its
participants, the aviators, government officers, and members of the
controlling committee, assembled at Issy and other posts of duty,
not by rail, but by aëroplane, sailing across country from many
directions and from great distances. This matter-of-fact procedure led
many persons to believe that the period of mere demonstrations had
approached its close, and that the epoch of practical utility was at
hand; that after marveling so much at the aëroplane, with mingled faith
and skepticism, people would next calmly turn it to practical use.

Though the progress in designing and constructing aëroplanes in 1910
did not keep pace with the wonderful advance in new records, still the
inventors and manufacturers continued industriously to perfect the
details of their best standard machines, and in a few instances to
make radical innovations. The perfection in details of construction
manifested itself in the public performance of aëroplanes, particularly
in their greater reliability and their increased capabilities. The
radical innovations were mainly experimental, and not generally
exhibited, though none the less important for all that. Chief of these
perhaps were the hydro-aëroplane developments of Fabre in France, and
of Mr. Glenn H. Curtiss in America, which enabled the aviator to launch
into the air directly from the water and to alight safely on the water,
thus virtually adding a new and very important domain to the empire of
dynamic flight.

Curtiss, in 1909, succeeded in landing his aëroplane safely on the
water of Lake Keuka, first with sheet iron cylindrical floats under
each wing, and a simple float well to the front of his protruding
chassis, then with a hydroplane surface to the front as being more
effective than the float. But when he attempted to glide up from the
lake with this arrangement, he could not entirely clear the surface,
though his aëroplane under the powerful thrust of her aërial screw,
very nearly lifted from the water. Then he planned to use hydroplane
floats, of hollow wing form, and of such size that they would buoy up
the machine when at rest, and during motion would skim over the water
like a skipping stone, till the biplane should acquire sufficient speed
to rise by the dynamic reaction of the air. In the successful execution
of this plan, however, he was anticipated by Fabre, who made the first
successful flight from the water, on March 28th, 1910, at Martigues,
France. But the Frenchman was not left to bear the palm alone. Early in
the year 1911, Mr. Curtiss rose and landed successfully on the water at
San Diego Bay, Cal., by means of a single float like a flatboat placed
centrally under his biplane, seconded by small auxiliary floats at the
wing ends. A full account of these valuable contributions to aviation
is given in Appendix V.

PLATE XXXI.

[Illustration: FABRE HYDRO-AËROPLANE.

_Photo E. Levick, N. Y._]

[Illustration: PAULHAN HYDRO-AËROPLANE.

_Photo E. Levick, N. Y._]

[Illustration: MOISANT METAL MONOPLANE.

(Courtesy A. J. Moisant.)]

As shown in Plate XXXI, Fabre’s hydro-aëroplane was substantially a
monoplane mounted on three richochet floats. It was propelled by a
screw at the rear, and controlled in flight by the usual three-torque
system, in this case consisting of horizontal rudders in front,
vertical rudders front and rear, and suitable mechanism for twisting
the wings. The floats were hollow to give them static buoyancy; they
were curved fore and aft like wings, to give them dynamic lift, both in
water and in air; they were elastically constructed with thin veneer
bottoms and flexibly attached to the framing, so as to endure the
severe buffeting, at high speeds, against the uneven water surface;
they were capable of landing the machine safely on a sandy beach or
meadow, as well as on the water. Indeed, a plan was conceived for
rising and alighting on land and water indifferently.

[Illustration: FIG. 42.—DIAGRAM OF CURTISS HYDRO-AËROPLANE.
(_Scientific American._)]

The first machine weighed in flight 950 pounds and spread 280 square
feet of surface, giving a loading of 3.4 pounds per square foot. It was
driven by a 50-horse Gnome engine actuating a Chauvière propeller 7.5
feet in diameter. In the trials of March 28th, the machine cleared the
water at a speed of 34 miles per hour, and flew about one-third of a
mile, at an elevation of two to three yards; then at the will of the
operator it alighted softly on the water.

The structural design of the Fabre monoplane was novel and unique, not
to say radical. The wing framing consisted of a single Fabre trussed
beam with ribs attached like the quills of a bird, over which was
stretched the light sailcloth cover, then laced to the beam. The girder
itself was formed of two ash planks eight inches wide by one-fourth
inch thick trussed together by flat steel plates zigzagging trelliswise
between them. As all parts of the beam cut the air edgewise it offered
very little resistance, while at the same time being very strong. The
ribs being attached only at one end allowed the sailcloth to be quickly
slipped on and off for washing and proper care.

The characteristic features of Fabre’s wing construction were adopted
by Paulhan in his novel and picturesque biplane shown in Plate
XXXI. Trussed beams were used for all parts requiring considerable
stiffness, the longitudinal ones being covered with fabric to reduce
the resistance. The wings whose solid ribs were fastened only at their
front ends were quite elastic, a quality conducive to stability, as
long taught by writers[55] on aviation. In addition to the front
rudder, there was at the rear a horizontal rudder with a vertical one
just before it. To reduce the air resistance further the pilot and
passenger were to sit tandem in a torpedo-shaped car with the 50-horse
Gnome engine and fuel tank back of them. Beneath the longitudinal
girders were two Farman skids flanked with the usual wheels,
elastically connected. The machine, besides flying well, was readily
demountable. The wings could be quickly removed, thus allowing the
biplane to enter a door fifteen feet wide. The entire machine could be
packed in a case 15½ feet long by 3¼ feet square, the whole case cubing
less than six solid yards. Hundreds of them, therefore, could be stowed
away in an ocean cruiser.

The flying quality of adequately designed flexible aëroplanes is well
illustrated by the swallowlike monoplane shown in Fig. 43. This airy
creation of the distinguished Austrian engineer, Igo Etrich, came into
public prominence in the spring of 1910, though it had been developing
privately for half a decade or more. On May 14th, near Vienna, it
carried pilot Illner 84 kilometers in 80 minutes, at an elevation of
300 meters, thus surpassing all previous Austrian records for distance,
duration and altitude. Its successor, _Etrich IV_, had wing tips still
more turned up, and possessed such stability that during the meet at
Johannisthal in October, Illner circled the pylons with his hands off
the warping levers. At times he wheeled round curves of only ten meters
radius, the whole machine tilted at an alarming angle, yet maintaining
its poise with the natural ease and grace of a soaring albatross.

The prominent feature of Etrich’s monoplane was the elastic
construction of its wings and tail. Across the rigid main bars of each
wing were fastened numerous ribs with bamboo terminals, thus making
the rear margin and tip of the wing flexible. Similarly the tail, or
horizontal rudder, was framed of bamboo. Hence the pilot, by use of
control wires, could flex both the wing margins and the tail up and
down at will, to steer the machine, or he could let go the controls and
allow the distorted surfaces to spring into their normal positions,
and the machine to pursue the even tenor of its way. Moreover, the
gusts and whirls in the air, on striking the elastic rear margins of
the tail and wings, exert a propulsive effort. Thus could be utilized
the wind’s energy of turbulence, as indicated by the present writer
in 1893, in a paper on “Windgusts and Their Relation to Flight,”
published in the _Proceedings of the International Conference on Aërial
Navigation_ of that year. In passing it may be remarked that many other
aëroplane designers, notably Bréguet, have emulated Mr. Etrich, though
unconsciously perhaps, in providing elastic ribs, hinges or pivots to
permit the rear parts of the wings and tails of their machines to yield
freely to intentional or unusual impulses, and then spring back to
their normal positions.

[Illustration: FIG. 43.—THE ETRICH MONOPLANE OF 1910.]

The carefully elaborated monoplane of Robert Esnault-Pélterie, which
had been steadily improving for eight years, had now attained great
perfection of finish, and merited prominence in actual flight. As shown
in Plate XXIX, it had a general resemblance to the _Antoinette_, though
differing throughout in its manifold details. The stream-line body was
of steel tubing, braced with wire, and tightly covered with smooth
fabric to reduce resistance. A five-cylinder R. E. P. motor in front
connected directly with the two-blade propeller. The pilot sat between
the wings with the passenger before him at the center of gravity, both
having control levers when desired for instruction. The wings could be
warped and the rudders, at the end of ample empennage planes, occupied
the extreme rear as shown. An elastically cushioned skid between the
two freely turning wheels served to absorb the shock of hard landing,
though usually not touching the ground. The R. E. P. monoplane of 1910
was a very graceful, swift and strong machine, of marked efficiency.

As always happens in the many-minded development of a complex
invention, the general exhibition and use of the aëroplane led toward
uniformity of design. This became particularly noticeable during the
world-wide demonstrations of 1909 and 1910. Whatever predilection the
inventor might have for his own devices, he would rather cast them
aside than lose at the tournament and in the market. Without a monopoly
of the flying art, he could ill afford to retain too affectionately
his own second-rate device in competition with a rival having a more
effective one. Accordingly there was a judicious and general adoption
of those devices which had proved best in practice, from whatever lowly
intellect they had emanated. Thus there was a marked tendency to the
general use of starting wheels, landing skids, large warping surfaces,
and, in racing machines, to the stream line concentration of the load,
and the severe elimination of resistance.

A few examples will illustrate this tendency to choose the most
practical devices from the world’s general stock. The Wright brothers,
who, following Maxim, had been ardent votaries of the forward
horizontal rudder, discarded this in 1910 for the elastic rear
horizontal rudder introduced by Etrich. At the same time they abandoned
the antiquated catapult introduced by Langley, and adopted the
combination of wheels and skids introduced by Farman. In their racing
machine they no longer placed the aviator beside his engine, presenting
a broad front to the wind, but, like Curtiss and foreign designers,
they placed the driver and power plant in line, to diminish the
atmospheric resistance. These manifold and timely improvements indicate
clearly the advantages to mankind of an “open door” in a crescent art.

But if the Wrights adopted the most successful devices of their
neighbors, these in turn were not slow to reciprocate that policy.
There was ample recognition of the merit of the combination of warping
sustainers and double rudder proposed by scientific men before the
advent of power aëroplanes, and so admirably employed by the Wrights
and Prof. Montgomery in their early coasting flights. The warping wing
was quite generally used on monoplanes in 1910; not to mention the
_ailerons_, which frequently were an adaptation of the same principle.

As further illustrations, it may be noted that Voisin brothers adopted
the Farman _ailerons_ and abandoned the cellular type of sustaining
surface introduced by Hargrave, finding the vertical surfaces strongly
frictional and unnecessary for lateral equilibrium, in presence of
the _ailerons_. They also abandoned the forward horizontal rudder,
seeing that it could very well be omitted. On the other hand, it must
be observed that the Farmans, Sommer and Curtiss still retained the
combined fore and aft rudder. Curtiss and Farman also tried their hands
at monoplane construction, though without abandoning the biplane. The
most famous monoplanists, however, held firmly to their first love.
In this they were emulated by many new designers, Nieuport, Hanriot,
Déperdussin, etc. These show a marked tendency to employ smoothly
covered hulls shaped after the fish or torpedo.

To drive the little aëroplanes so far developed, especially the
racers, there was a general preference for a single-screw propeller
mounted directly on the engine shaft, though doubtless for machines
weighing many tons a multiplicity of such propellers would be used.
Theoretically the advantage of twin screws was conceded, but in
practice they were employed by very few constructors. The Chauvière
wooden propeller was the favorite in France, and was approved by
the constructors of propellers elsewhere, at least in its general
features. The Voisin firm, indeed, still adhered to the metal
propeller, and occasionally some experimentalist employed the more
venerable French screw consisting of radial sticks covered with fabric.
But the great records in the sporting world were achieved with solid
wooden propellers.

A special chapter would be required to describe the various motors,
even cursorily. Their relative values, however, may be summarized in
the following brief words by Réné Gasnier, in the _Aërophile_ for
November, 1910:

  “Last year we had but few light types; this year there is no
  dearth of them, and at their head stands that admirable motor
  _Gnome_, which has enabled aviators to accomplish all their
  fine performances. At first many persons had no confidence in
  the future of the rotatory motor. One must bow to the facts;
  on considering the nature of this motor it is seen to be of
  an admirable simplicity. It is evidently the typical aviation
  motor, and an approach toward the veritable rotatory motor
  which later will be the turbine. Numerous motors of four to
  eight cylinders are very well spoken of, but none attain the
  lightness of the _Gnome_. Among the air-cooled motors the
  _Esnault-Pélterie_ is remarkable for the series of trials it
  has endured, and among water-cooled motors we may cite the
  splendid performance of the _Antoinette_—2,100 kilometers in
  one week at the Bordeaux meeting. This would be quite a good
  run even in an automobile. It is noticeable that the aëroplane
  motor tends distinctly to differentiate itself from its senior,
  the automobile motor, and assume a type absolutely adapted
  to its special work. In addition to the greatest possible
  lightness, a demand now arises for a slight consumption of
  fuel, and a range of speed which is indispensable for landing.
  It is dangerous to descend rapidly with the motor at full
  speed; on the other hand, in cutting off the ignition to glide
  down, one risks not being able to restart the motor, if need
  be, while if the motor relax sufficiently the descent takes
  place in perfect security. It suffices to speed up at the right
  moment.”

The practical utility of aviation began now to be questioned. The
aëroplane had passed the primary epoch of experimental development
and was becoming a standard article of manufacture representing a
considerable industry. But what was it all worth? Aviators had flown
faster than the eagle, higher than the clouds, farther than the common
distance from metropolis to metropolis. Schools were licensing new
pilots from day to day. But what career had these before them, and what
essential function in the affairs of humanity could they perform? Some,
indeed, might fit themselves for aërial service in warfare, some for
the pleasant profession of amusing and entertaining mankind; but in the
serious business of life, what important rôle could the air men hope
to play? This was the pertinent inquiry, and it was largely a question
of the reliability and economy of the aëroplane. Improvement in these
two elements might therefore receive attentive consideration in the
immediate future.

The reliability of the aëroplane depends partly on its environment,
partly on its plan and structure, partly on the skill of its pilot.
The pilot’s skill had been admirably developed in the tournaments and
public exhibitions. The aërodynamic design conducive to stability and
steadiness, the structural design conducive to maximum strength and
resiliency, uniformly proportioned to the stress and work of each
part of the complex machine; and above all the design of the motor,
to ensure it against a thousand foibles—all these could be improved
by the patient methods of theoretical and experimental science.
The environment could, of course, be chosen. At first only the most
favorable regions need be attempted for regular transportation, regions
of level plain and farm land, or of lake and river surrounded by
country not too rough and precipitous.

The general cost of the aëroplane to mankind depends on its plan and
structure, on the methods of manufacture, on the material running
expense; but its particular cost to the passenger is determined largely
by the cupidity or business acumen of those who furnish the machine
and those who operate it. Naturally when the world first awoke in
the morning of practical sporting aviation, with a sudden and strong
relish for flying, the prices would be fabulous, not to say ridiculous.
During that hour no commercial transportation could be contemplated.
But without monopoly the prices must quickly abate; for neither the
manufacture nor manipulation of the aëroplane demand rare ability or
training. The cost of manufacture would promptly be diminished by means
of specialized tools and operatives, immediately upon the assurance
of large and continuous orders. The cost of pilotage would become
insignificant when a single chauffeur could take a dozen passengers on
one aëroplane.

So much for the human and external elements in the cost of aviation.
The inherent and material cost of the aëroplane could also be reduced,
though perhaps less readily. It was unlikely that the machine would
be built of much cheaper materials, or made much lighter per pound of
cargo. Nor were such improvements of so much importance since they
would affect only the first cost of the flyer. But an increase of
aërodynamic efficiency in the propeller and aëroplane proper, together
with increased thermodynamic efficiency in the motor, would materially
lower the current cost of transportation at any given speed. These
improvements would require careful research in the laboratory and
patient trial in the workshop and field. The refinement and perfection
of the aëroplane might therefore be looked for in those communities
where men have sufficient foresight, enterprise and liberality to endow
research, and to encourage the science and the art of aviation to
supplement each other.




                               PART III

                        AËRONAUTIC METEOROLOGY




                             CHAPTER XIII

                    GENERAL PROPERTIES OF FREE AIR


For aëronautic uses the atmosphere may be regarded as a mixture of two
substances, dry air and water. The first remains always in the gaseous
state; the second shifts erratically through all possible states. Rain
drops freeze or evaporate; sleet, snow, and hail evaporate or melt;
the aqueous vapor condenses or congeals. Thus the world is wrapped in
a dual sea, one part naturally serene, the other capricious, protean,
and turbulent. Dry air, indeed, is a composite of many gases of vast
concern in chemistry and biology; but in relation to aëronautics it
is practically a single permanent gas. This placid element and its
inconstant mate, so curiously mingled, constitute the medium whose flux
and vicissitudes the aërial sailor has duly to learn before he can
navigate with skill or safety.[56]

But these aërial oceans, the moist and dry, are of very different
depth. They commingle only in the lower levels of the atmosphere, whose
qualities vary accordingly, both physical and transportational. While
the dry air may reach up to more than a hundred miles, substantial
enough to singe a meteorite, the sea of aqueous vapor is bounded
practically by the shallow region of the visible clouds. Beyond the
feather-like cirri, which just overtop the loftiest mountain peaks,
there is scant, if any, moisture. Never rain, nor cloud is there, nor
tempest nor any great perturbation. Beyond the highest excursions of
the cirri, at an elevation of some ten miles, stretches the deep ocean
of eternal sunshine, of equable and nearly constant temperature. Into
that zone of perpetual serenity no tumult of the nether atmosphere
can penetrate; against the floor of the isothermal layer the cyclonic
currents spread and dissipate. The upper air has, of course, a
considerable drift, like a majestic river or stream of the sea, but
never turmoil or tempest disturbs its stately march.

In some respects, therefore, that lofty ocean is an ideal one for swift
transportation. But at present it is beyond the range of any navigable
craft of human invention. Occasionally, indeed, a gauzy balloon from
the hand of some inquisitive weather sage penetrates a little way into
the exalted deep next the cosmic void, bearing its delicate recorders
of heat and pressure; but it wanders alone in a silent and vast
solitude outcubing all the habitable space allotted to bird, beast
and fish; then at last sinks down to deliver the story of its strange
voyage in that lifeless outer sphere. Volcanic and celestial dust may
flourish there, tingeing the twilight with rosy flush, but no biologic
forms from the teeming underworld may find refuge or sustenance. It is
the unconquered domain of who knows what meteoric craft of the future,
sweeping the globe from continent to continent, with now unimaginable
celerity, grace and precision.

Incidentally and aside from its aëronautic interest, the composition
of the atmosphere may be presented in fuller detail, showing the
wide variations from level to level, and the manifold complexity of
the fluid we daily breathe, not to mention the myriads of motes and
germs inhabiting every inch of it. The gaseous components and their
distribution are well exhibited in the following table,[57] which
represents an average condition:

                                TABLE I

         _Percentage Distribution of Gases in the Atmosphere_

  Key:  HT = Height in Kilometers.
         A = Argon.
         N = Nitrogen.
        WV = Water Vapor.
         O = Oxygen.
        CD = Carbon Dioxide.
        HY = Hydrogen.
        HE = Helium.
        TP = Total Pressure in Millimeters.
  ----+--------------------------------------------------+--------
      |                      GASES.             |
   HT +------+-------+------+------+------+-------+------+   TP
      |   A  |   N   |  WV  |   O  |  CD  |   HY  |  HE  |
  ----+------+-------+------+------+------+-------+------+--------
  150 |      |       |      |      |      | 99.73 | 0.27 |  0.0043
  140 |      |       |      |      |      | 99.70 | 0.30 |  0.0048
  130 |      |  0.02 |      |      |      | 99.64 | 0.34 |  0.0054
  120 |      |  0.10 |      |      |      | 99.52 | 0.38 |  0.0060
  110 |      |  0.40 |      | 0.02 |      | 99.16 | 0.42 |  0.0067
  100 |      |  1.63 |      | 0.07 |      | 97.84 | 0.46 |  0.0076
   90 |      |  6.57 |      | 0.32 |      | 92.62 | 0.49 |  0.0090
   80 |      | 22.70 |      | 1.38 |      | 75.47 | 0.45 |  0.0123
   70 | 0.02 | 53.73 |      | 4.0  |      | 41.95 | 0.27 |  0.0248
   60 | 0.04 | 78.16 |      | 7.32 |      | 14.33 | 0.15 |  0.0810
   50 | 0.08 | 86.16 |      |10.01 |      |  3.72 | 0.03 |  0.466
   40 | 0.16 | 86.51 |      |12.45 |      |  0.88 |      |  1.65
   30 | 0.22 | 84.48 |      |15.10 |      |  0.20 |      |  8.04
   20 | 0.55 | 81.34 |      |18.05 | 0.01 |  0.05 |      | 39.6
   15 | 0.74 | 79.56 |      |19.66 | 0.02 |  0.02 |      | 88.2
   11 | 0.94 | 78.02 | 0.01 |20.99 | 0.03 |  0.01 |      |168
    5 | 0.94 | 77.89 | 0.18 |20.95 | 0.03 |  0.01 |      |405
    0 | 0.93 | 77.08 | 1.20 |20.75 | 0.03 |  0.01 |      |760
  ----+------+-------+------+------+------+-------+------+--------

Fixing attention first upon the gases other than water, it will be
at once observed from the table that these gases show a very uniform
mixture in the moist and turbulent region, while farther aloft the
lighter of them tend to predominate in relative proportion. This
uniformity of composition at the lower levels, which accords with
experience, is due to the constant circulation and turmoil in that
region. But for this constant agitation, the uniformity of mixture
could not last. If the atmosphere were perpetually at rest throughout,
or moving only in horizontal flow, each constituent gas would assume
the same status and distribution as if the others were absent. Each,
therefore, obeying Dalton’s law of diffusion, would form an atmosphere
of itself, independent of the others, and unaffected in density by
them. Such a condition is assumed for the higher levels. The percentage
distribution in the higher levels is calculated from the known
elasticity and density of the gases, assumed as resting in perpetual
calm at a constant temperature of .55° C. beyond eleven kilometers, or
above the highest ascent of man, and, furthermore, as having at the
earth’s surface 1.2 per cent moisture and a temperature of 11° C.

But only in the quiescent outersphere can that dynamic gradation be
established or perpetuated. Below this lofty region is the sea of
water vapor, mingled intimately with the dry air, and churned with
it, yet not sharing its uniformity of distribution. Why this rapid
diminution of moisture with elevation, as shown in the table? Because
throughout the moist region the temperature falls rapidly—about 6° C.
per kilometer ascent above the earth—thus chilling and precipitating
the vapor, whose pressural resistance to liquefaction diminishes with
waning temperature. The explanation is obvious; but why does it not
apply as well to the other elements of the atmosphere: why do not the
other gases present liquefy with falling temperature as well as the
water vapor, which is merely water in the gaseous state? The question
cannot be answered very profoundly, but an essential condition of
liquefaction of any gas can be stated in learned phraseology, after the
preliminary exposition of certain general properties of matter.

We may first set forth those general physical properties, then apply
them to answering the above question. Every known substance may exist
in either of three states, the solid, liquid or gaseous. For every
substance there is a critical temperature above which it can exist
only as a gas, and cannot be liquefied by any pressure, but below
which a suitable pressure will cause liquefaction. Below its critical
temperature a gas is called a vapor, above it a permanent gas. Now in
the free atmosphere some of the gases are never below their critical
temperatures and, therefore, cannot be liquefied by any pressure,
without special cooling; others are sometimes below their critical
temperatures and are then capable of liquefaction by sufficient
pressure, which however is not always found in free space, but can be
supplied by a compression pump; one other gas, that is water vapor,
is always below its critical temperature in the free atmosphere, and
therefore may always be turned into water by sufficient pressure at its
actual atmospheric temperature. Such sufficient pressure in the water
vapor actually occurs from time to time in all parts of the atmosphere
from the earth’s surface to the highest cirrus region, but more
frequently in the nimbus levels, a mile or two above the earth. Thus
at all parts of the lower atmosphere liquefaction of aqueous vapor is
sometimes observed, either as mist or rain, snow or ice particles, and
on the earth as dew or frost. In order to illustrate the above ideas
by numerical citation, the accompanying table is given, showing the
critical temperature and pressure of the chief gaseous constituents of
the atmosphere.

                               TABLE II

 _Critical Temperature and Corresponding Pressure of Liquefaction for
            the Chief Constituent Gases of the Atmosphere._

  --------------+-------------+-------------
                |   Critical  |   Critical
    Substance   | Temperature |   Pressure
                |      C.     | Atmospheres.
  --------------+-------------+-------------
  Dry Air       |    -140     |     39
  Nitrogen      |    -146     |     34
  Oxygen        |    -118     |     50
  Carbonic Acid |    - 31     |     75
  Argon         |    -120     |     51
  Hydrogen      |    -242     |     20
  Ammonia       |     130     |    115
  Water         |    +365     |    200
  --------------+-------------+-------------

A glance at this table shows that for the pressures and temperatures
prevailing in our atmosphere most of the constituents are permanent
gases. The conspicuous exception is water which, when in the gaseous
state, always exists as a vapor, and never as a permanent gas, since
it never even approaches the critical temperature. Fortunately for all
life on earth the aqueous vapor condenses at very ordinary temperatures
and pressures, else there would be no rainfall for irrigation and
drinking. Fortunately also the other gases do not so precipitate, else
the world might be flooded with liquid nitrogen and oxygen, entailing
who knows what disastrous consequences.

After this digression on the composition of the atmosphere, we may
henceforth regard the aërial ocean as a mixture of two substances,
dry air and water; the first, a permanent gas; the second, a
variable element, existing at times in either the solid, liquid, or
vaporous state. For the sake of convenience we may first study the
dry atmosphere, then the moist. The dynamic properties of the dry
atmosphere may in large measure be deduced by an application of two
well-established laws of physics. These will be taken in order.

By careful investigation it has been proved that throughout a
considerable range of pressure and temperature the permanent gases
very approximately obey the following law; the volume of a permanent
gas varies directly as its absolute temperature and inversely as its
pressure. In other words the product of its pressure and volume equals
the absolute temperature multiplied by a numerical constant. This may
be expressed algebraically by the following formula:

                          _PV_ = _RT_     (1)

in which _P_ is the pressure and _V_ the volume of a given portion of
gas at the absolute temperature _T_, and _R_ is a numerical constant
for the gas in question.

The value of _R_ in the foregoing equation has been determined
experimentally for the component gases of the atmosphere, and for dry
air as a whole. For dry air, which, under such conditions as surround
the aëronaut, may be treated as a single uniform gas, the equation
applied to one kilogram gives R = _PoVo/To_ = 29.27, where _Po_, _Vo_,
_To_, are respectively the pressure, volume and temperature, in the
metric system, of the one kilogram of air under standard conditions;
i. e., _Po_ = 10,330 kilograms per square meter, being the normal
atmospheric pressure; _Vo_ = 1/1.293 cubic meter, being the volume of
one kilogram of dry air at normal pressure and freezing temperature;
_To_ = 273° C., being the absolute temperature of freezing. In passing,
be it said that the absolute temperature is that measured from the
absolute zero, which on the Centigrade scale is 273° below freezing, on
the Fahrenheit, 460.6° below freezing.

The second law referred to follows directly from the principle of the
permanence of mass. It is a general observation in physics that a given
portion of matter is of constant mass, however its pressure, volume,
temperature and other conditions may vary. In particular, the mass of a
given portion of matter always equals the product of its mean density
and volume, since density is defined as the amount of mass in the unit
volume. Expressing this physical law, or relation algebraically, gives
ρ_V_ = mass = ρ_o_, _Vo_, in which ρ, _V_, are the general symbols
for the density and volume of the given portion of matter under any
condition, while ρ_o_, _Vo_, are the specific values of ρ and _V_
observed for some one state and circumstance of the substance in
question. In particular, if the mass of air be unity, we may write:

                             ρ_V_ = 1     (2)

This relation, together with that expressed in equation (1), will
enable us to deduce many of the properties of dry air and of a dry
atmosphere.

First let us observe from equation (1) the effect, in turn, of keeping
constant one of the quantities _P_, _V_, _T_, while the other two vary.
The equation shows that if the temperature of a gas is kept constant
the volume is inversely proportional to the temperature. This is called
the law of Boyle and Mariotte from its two independent discoverers,
of whom Boyle seems to have been the first. As an example of Boyle’s
law, if any empty glass, or diving bell, be inverted over water,
then submerged deeper and deeper, the air within it will shrink with
increase of pressure, its volume becoming one half when the pressure is
doubled, one third when the pressure is trebled, etc. In particular, if
the pressure changes by one unit, the corresponding change of volume
is 1/_P_ part of that volume. For example, if a captive balloon is
anchored in air at constant temperature, while the barometric pressure
changes from 30.0 inches to 30.1 inches, the volume of the balloon
will contract 1/300 part of itself.

Again equation (1) shows that if the pressure of a gas is kept
constant, the volume is proportional to the absolute temperature. This
is the law of Charles and Gay Lussac, so called from its discoverers,
of whom Charles is thought to have been the first. As an example of
this law, if a captive thin rubber balloon is heated, or cooled, its
volume will vary directly as its absolute temperature. In particular,
if the temperature is changed one degree, the volume changes 1/_T_
part of itself. For example, if the temperature of a balloon in air of
constant barometric pressure is heated from 300° C. to 301° C., its
volume will expand 1/300 part of itself. Historically, be it said, this
law of Charles and the law of Boyle were discovered separately, then
combined, giving equation (1).

Still a third, though not independent relation may be read from
equation (1), thus: when the volume of a gas is kept constant, the
pressure is proportional to the absolute temperature. In particular, if
the temperature is changed one degree, the pressure varies accordingly
by 1/_T_ part of itself. For example, if an air tank or gas tank, in a
room at 500° F., changes one degree in temperature, its pressure will
change 1/500 part.

With minute detail these three conclusions from the general equation
(1) have been set forth and illustrated, because of their practical
importance. Other valuable results may be obtained by similar
reasoning. Thus equation (2) may be read; the volume of a unit mass of
any substance is the reciprocal of its density. Hence, if in the three
foregoing conclusions, the reciprocal of the density is everywhere
written for the volume, three new relations will be obtained which
are of frequent practical use. Two of them may be expressed in the
following important law; the density of a gas varies directly as its
pressure and inversely as its temperature. Useful applications of this
law in aëronautics suggest themselves at once.

By means of the various foregoing equations, the value of either one
of the four quantities _P_, _V_, _T_, ρ, representing respectively
the pressure, volume, absolute temperature, and the density, may be
obtained in terms of any two of the others. If then any two of the
quantities is observed, the others can be at once computed. If, for
example, the pressure and temperature of dry air be observed at any
point, its density can be computed from the formulæ, also its volume
per kilogram weight, and thence its volume for any other weight. It is
important therefore to be able to measure satisfactorily at least two
of the four quantities. In usual studies of the atmosphere the pressure
and temperature are observed directly. The method and instruments
employed for that purpose are too well known to require description
here.

In some speculations the pressure and temperature of the atmosphere
are assumed, and certain interesting conclusions drawn. For instance,
if the temperature is assumed constant throughout a dry atmosphere,
the fluid will obey Boyle’s law, and it can be easily shown that the
height of such a medium is the same whether it comprise much gas or
little.[58] Again assuming the temperature and pressure constant, the
height of the normal homogeneous atmosphere can be computed by dividing
the pressure per square unit by its weight per cubic unit. In this way
the height of the normal homogeneous atmosphere has been found to be
about five miles. But these are hypothetical cases, of purely theoretic
interest. In practice the temperature may, on the average, be assumed
to decrease 6° C. for each kilometer of ascent, and the pressures may
then be computed for various elevations by use of Boyle’s law, as done
for Table I.

This leads us to a study of the gaseous properties of moist air. By
moist air is meant a mixture of dry air and aqueous vapor in the form
of an invisible elastic gas. The definition does not comprise air
containing visible steam, or mist, or cloud, but clear moist air such
as one ordinarily breathes. The study of this mixture may be preceded
by a brief account of the gaseous properties of the vapor alone.

If water in sufficiently small quantity be introduced in a vacuum
bottle at any ordinary temperature, it will promptly evaporate,
forming an invisible gas known as aqueous vapor, filling the bottle
and exerting a uniform pressure on its walls, except for the minute
difference at top and bottom due to gravity. The vapor weighs 0.622 as
much as dry air having the same volume, temperature and pressure, or
quite accurately ⅝ as much. It obeys all the laws given above for
ordinary gases and dry air. But it has one singularity; at ordinary
atmospheric temperatures, it cannot be indefinitely compressed
without condensing to a liquid. In this respect it differs from the
chief components of the atmosphere, which at ordinary temperatures
can endure indefinite pressure without liquefaction. The ammonia and
carbon dioxide in the air can, it is true, be condensed by pressure at
their usual temperatures, but not by such pressures as occur in the
free atmosphere, thus still leaving aqueous vapor the one singular
constituent.

Reverting to the behavior of the water in the assumed vacuum
bottle at fixed temperature, it may be observed that the pressure
of the invisible vapor is directly proportional to the amount of
liquid evaporated. In other words, for any fixed temperature the
vapor pressure is directly proportional to its density. When this
density reaches a certain definite amount, dependent solely upon the
temperature, no further evaporation will occur, unless some of the
vapor condenses. The pressure of saturation for that temperature has
been reached, and any attempt to increase the pressure, by diminishing
the volume of the vapor, will cause liquefaction at constant
temperature.

If, however, the space is not saturated, the mass of vapor present may
be expressed as a percentage of the amount required for saturation at
that temperature. This percentage is called the relative humidity. Thus
if the relative humidity is seventy per cent, the actual mass of water
vapor present at the observed temperature is seventy per cent of the
maximum that can exist in the given space, at the given temperature. In
other words, the relative humidity is the ratio of the actual to the
possible humidity at a given temperature.

In like manner, for any given vapor pressure there is a definite
saturation temperature, known as the dew-point. If with constant
pressure the vapor is given various temperatures higher than the
dew-point, it will remain gaseous and invisible; but if it falls in
temperature to the dew-point, liquefaction occurs, and drops of water
appear on the inner wall of the vessel. Further cooling will entail
still further liquefaction and reduction of pressure; for the lower
the temperature the less the possible mass and pressure of saturation.
But for all temperatures, down to freezing and considerably below,
some vapor exists, and obeys the same laws as at higher temperatures.
When, however, saturation occurs below freezing, the vapor may be
precipitated as snow instead of water. This is a familiar phenomenon
in the free atmosphere.

The actual mass of water vapor present in a cubic unit of space
is sometimes called the absolute humidity. A formula giving the
absolute humidity _f_, in kilograms per cubic meter, for any observed
temperature _t_, and vapor pressure _e_, may be written as follows:

                 _f_ = 0.00106 _e_ / (1 + 0.00367 _t_)

in which _e_ is the vapor pressure in millimeters of mercury, and _t_
is the common Centigrade reading. As an illustration of the actual
values of the pressure, temperature and density of saturated water
vapor, for various conditions, the following table is presented:


                               TABLE III

    _Temperature, Pressure and Density of Aqueous Vapor, in Metric
                              Measures._

  -------------+--------------+-----------------
  Temperature, | Pressure,    | Density Kilos.
  Centigrade.  | Millimeters. | per cubic meter.
  -------------+--------------+-----------------
      -25      |      0.61    |     .557
      -20      |      0.94    |     .892
      -15      |      1.44    |    1.395
      -10      |      2.15    |    2.154
      - 5      |      3.16    |    3.244
        0      |      4.57    |    4.835
      + 5      |      6.51    |    6.761
       10      |      9.14    |    9.329
       15      |     12.67    |   12.712
       20      |     17.36    |   17.117
       25      |     23.52    |   22.795
       30      |     31.51    |   30.036
       35      |     41.78    |   39.183
       40      |     54.87    |
       45      |     71.36    |
  -------------+--------------+-----------------

Now by Dalton’s law, each gas or vapor in a mixture of several behaves
as if it were alone. Thus if the foregoing experiment be conducted in
a bottle containing various gases chemically inert to water, the same
mass of water will be evaporated, and exert the same uniform pressure,
in addition to those exerted by the gases. Now the density of each
gas or vapor present, will equal its mass divided by its volume, and
the density of the mixture will equal the total mass divided by the
volume. Furthermore, it is well known that aqueous vapor is less dense
than dry air at the same temperature and pressure. From this it is at
once evident that moist air, which is merely a mixture of dry air and
aqueous vapor, must be lighter than dry air at the same temperature and
pressure. This is true whether the two fluids compared be in closed
vessels or in the free atmosphere.

Accordingly in all precise dealing with the free air, whether involving
its buoyancy, its resistance, its energy or any other mass function,
its density as affected by the humidity must be taken into account.
This can be computed from the observed pressure, temperature and
relative humidity as revealed by well known instruments, the barometer,
thermometer and hygrometer. Thus from the observed temperature and
relative humidity, the mass of vapor present per cubic meter is read
from Table III, the reader, of course, multiplying the given tabulated
mass by the observed percentage of humidity. To this aqueous mass must
be added the mass of dry air present. Then the total mass per cubic
meter is the density.

Various formulæ are available for computing the density of moist
air from the readings of the three instruments mentioned above.
Also, tables have been worked out giving the density without further
calculation. Moreover, the density of free air may be directly
measured, accurately enough for most purposes, by means of a
densimeter. A simple formula for finding the density of moist air is
as follows:

                        ρ = 0.465(_b − e_)/_T_

in which _b_, _e_, are the pressures in millimeters mercury
respectively of the moist air and its vapor, as revealed by the
barometer and hygrometer.

In practice no great error will be made in assuming the relative
humidity to be fifty per cent. For the moisture content never exceeds
five per cent of the mass of the moist air, and hence in assuming a
fifty per cent relative humidity, when there is actually a maximum
or minimum humidity, the greatest possible error in estimating the
moisture content is 2.5 per cent of the mass of moist air. Now if 2.5
per cent of a mass of air be assumed to be aqueous vapor when all is
really dry air, or conversely if 2.5 per cent of the whole mass be
assumed as dry air when it is really aqueous vapor, an error of much
less than 2.5 per cent is made in estimating the true density. No error
at all would ensue if both air and vapor were of the same density; but
since one is ⅝ as heavy as the other, the possible error is ⅜ of
2.5 per cent, or 0.6 per cent. This is a negligible quantity in all
mechanical considerations, except where great accuracy is required.

When any gas changes density or volume it also changes temperature,
unless there be transfer of heat between it and its environment. When
change of volume occurs without such transfer of heat the expansion,
or contraction, is called “adiabatic;” when it occurs at constant
temperature, the expansion is called “isothermal,” the temperature
being kept uniform by suitable transfer of heat; when it occurs at
constant pressure it is called “isopiestic.” In either case work may
be done by the enlarging gas, if it press against a moving piston,
or yielding envelope of some kind; and conversely work may be spent
on the gas in compressing it either isothermally, adiabatically or
isopiestically.

If, for example, a balloon rises rapidly its contents will expand
adiabatically, pushing the envelope out in all directions against the
static pressure of the embracing atmosphere. Thus it will do work and
rapidly cool. But if it rapidly sinks, it will contract adiabatically
and grow warm, owing to the work done by the surrounding air in
compressing it. A like thing occurs when a great volume of air rises
or sinks quickly in the free atmosphere. In this case the change of
temperature is about 6° C. for each kilometer change of level, so long
as the air remains unsaturated. A familiar example of this effect in
Nature is manifested when an uprushing column of moist air chills, and
precipitates moisture, forming a cloud toward its top. Thus a lone
thundercloud in a clear sky may mark the upper part of such a column,
or upward vortex in the air. And contrarywise, a descending column may
absorb its visible moisture, causing it to become clear aqueous vapor,
and thus vanish from view.




                              CHAPTER XIV

               GENERAL DISTRIBUTION OF HEAT AND PRESSURE


Having thus briefly examined the composition and certain gaseous
properties of free air, both dry and moist, we may now study the
atmosphere as a whole. We wish particularly to know of its distribution
of temperature and pressure; of its general and permanent circulation;
of its great periodic currents; of its vertical movements, and its
minor local winds with their pulsations of velocity and direction.
Fortunately much information is available, due both to governmental
and private research, though this was collected more for purposes of
meteorology than of aërial locomotion. Of late, however, attention has
been given to the aëronautic study of the atmosphere, which will, it is
hoped, prove valuable to the aërial navigator.

The movements of the atmosphere are due mainly to the sun’s heat and
to the rotation of the earth. The earth’s internal heat and the moon’s
attraction are other minor agencies, but these may be neglected by
comparison. The earth’s rotation also would be ineffectual in modifying
the aërial movements, except for the coöperation of the sun. Without
his influence the atmosphere, always stagnant, would simply rotate with
the globe, at constant angular velocity and uniformly graded density at
various levels. This evenness of density for any level is broken by the
solar radiation increasing the temperature and moisture, otherwise the
air would remain practically at a standstill.

Though the moisture by its lesser density causes some lightening of
the air at fixed temperature, this at most is hardly one per cent, as
already shown, and on the average is much less. Its effect, therefore,
is equivalent to less than that caused by a rise of temperature of
three degrees. But if precipitation occurs, an enormous amount of
stored sunshine, or latent heat, is liberated and applied to warming
the associated air. Thus each pound of vapor condensed may, by the
release of its thermal store, heat more than a ton of air one degree
in temperature, or more than half a ton of air two degrees, etc.
The actual number of pounds of air at constant pressure, raised one
degree Centigrade by the condensation of one pound of vapor at various
temperatures, is given in the following table:

                               TABLE IV

  --------------------------------+-------+-------+-------
  Temperature of condensation     |    0° |   25° |   50°
  Pounds of air heated one degree | 2550  | 2480  | 2407
  --------------------------------+-------+-------+-------

The sun then is father of the wind. By uneven heating of the atmosphere
it disturbs the uniform density gradation that would otherwise exist.
Thus abnormal pressures are generated which disturb the repose of the
aërial sea, causing the fluid to flow from regions of excessive to
regions of defective pressure. Hence the study of insolation[59] and
temperature distribution is fundamental to the science of the winds.

Without detailed study, we may note the aggregate insolation received
by the earth, at various latitudes, and its general effect on
terrestrial temperature. The sun emits a nearly constant stream of
radiation, from year to year, which plays continuously upon the earth
as a whole, with an intensity which varies but slightly from month to
month, due to the slightly varying distances of the earth from the
sun. Owing to the sun’s seasonal wandering across the equator, the
insolation at any latitude varies considerably month by month, and
the polar regions receive much more light than if no such wandering
occurred. The total yearly insolation for every 5° of latitude is shown
in the following table from Hann, in which the unit is the amount that
the earth would receive in one day at the time of the equinox, if the
sun were at its mean distance from the earth:

                                TABLE V

                    _Annual Amounts of Insolation_

  -----------+---------+------------
   Latitude. | Thermal | Difference.
             | Days.   |
  -----------+---------+------------
       0°    |  350.3  |
       5°    |  349.1  |    1.2
      10°    |  345.5  |    3.6
      15°    |  339.4  |    6.1
      20°    |  331.2  |    8.2
      25°    |  320.5  |   10.7
      30°    |  307.9  |   12.6
      35°    |  293.2  |   14.7
      40°    |  276.8  |   16.4
      45°    |  258.7  |   18.1
      50°    |  239.6  |   19.1
      55°    |  219.4  |   20.2
      60°    |  199.2  |   20.2
      65°    |  180.2  |   19.0
      70°    |  166.2  |   14.0
      75°    |  156.5  |    9.7
      80°    |  150.2  |    6.3
      85°    |  146.5  |    3.7
      90°    |  145.4  |    1.1
  -----------+---------+------------

From this it appears that the equator receives nearly 2.5 times as much
heat yearly as the poles. Since, moreover, the equator enjoys nearly
constant insolation, while the polar regions suffer great variations of
heat, with the varying altitude of the sun, the equatorial atmosphere
is both much hotter and more equable than the poles, and high latitudes
generally. Thus at the equator the frost level stands constantly
at 18,000 feet, while in the middle latitudes it varies greatly in
height from season to season. If, for example, a circle be drawn to
represent the earth, and above it a line to indicate the mean altitude
of the frost level in July, the frost line starting at the equator
at an elevation of 18,000 feet will decline north and south, finally
touching the earth well toward the frigid zones. The levels for other
temperatures, above and below freezing, are similarly inclined downward
from the equator to north and south. Obviously these isothermal
levels vary with the varying season, and at any fixed time differ on
different longitudes. On the plane of any given latitude the frost
line varies much less in altitude, and so for the other isothermals.
This is particularly true at the poles and equator, and everywhere at
considerable altitude. If one voyaged around the earth at the equator
at an elevation of 5,000 feet, he should find the average temperature
about 65° F. In the temperate zone, following a line of latitude
at the same height, he should have a lower temperature, but still
comparatively equable. The average annual temperature of the earth’s
entire surface is about 60° F.

In practical meteorology the temperature is observed at many points
simultaneously over a wide stretch of the earth’s surface. These
are then plotted on a weather chart, and through all points of like
temperature are drawn lines known as isothermals. These lines not only
map the earth’s surface into regions of equal temperature, but they
also show the direction of fall or rise of temperature, and its space
rate of change. This rate is called the “temperature gradient,” and
when estimated straight across from isothermal to isothermal, that is
in the direction of liveliest change of temperature, it is the maximum
gradient. Such a map is very useful in forecasting the weather. It is
but a particular instance of the more general map conceived by the
physicist, exhibiting the thermal condition of the entire atmosphere by
means of a series of equal temperature surfaces one above the other.
Here, of course, the temperature gradient at any point is the space
rate of change of temperature in any direction, being zero along the
isothermal surface and greatest normal to it.

The vertical temperature gradient is of particular interest, since
it determines the condition of fluid equilibrium at any point in the
atmosphere when the level surfaces are isothermal. If, for example, a
balanced balloon or portion of air, on starting upward from any level,
cools faster than the environing stagnant air, it will become more
dense, and cease to ascend, in which case the atmospheric equilibrium
is stable. Again, if the ascending gas or air cools more slowly than
the surrounding medium, it will become less dense, and so continue
to ascend, in which case the atmospheric equilibrium at the point
is unstable. Thirdly, if the rate of cooling be identical for the
ascending gas and its surrounding medium, the equilibrium is neutral,
and the motion will be stopped by friction but unaffected by change
of buoyancy, since no such change can occur. Of these three states of
equilibrium, the stable is dominant above the cirrus level, while below
that level each state may be found, at various times, prevailing at
random in all parts of the world, but more generally the stable and
neutral states. When the unstable condition occurs at any locality and
any level, it is usually followed ere long by a commotion or upheaval
in the atmosphere, until the temperature gradient alters to the neutral
or stable.

Many observations have been made to determine the variation of
temperature along the verticle in various places and in different
seasons. From the temperature records obtained in 722 balloon
ascensions near Paris, France, the mean fall of temperature per 1000
feet up to 20,000 feet was found to be 2°.4 in winter, 2°.8 in spring,
2°.6 in summer, 2°.5 in autumn and 2°.6 for the year. Near Berlin 3°.1
for the year was found from 75 balloon ascensions, the rate being
nearly the same for the halves of the year. Fig. 44 gives the average
of 52 winter and 65 summer temperature gradients, taken at about 8 A.M.
by means of sounding balloons sent up at Munich, Strassburg, Trappe and
Uccle. It will be noted that in both summer and winter the temperature
falls rapidly with increase of elevation, up to ten or eleven
kilometers, but above twelve remains nearly constant for all altitudes.
The difference in temperature summer and winter is interesting, also in
its gradual diminution with altitude. Another striking feature is the
inversion of gradient shown at twelve kilometers elevation, where the
temperature ceases to diminish, and may even increase with altitude.
This region is known as the upper inversion level of the atmosphere, as
distinguished from other levels at or below three kilometers height,
known as lower inversions, where the temperature gradient is sometimes
reversed, though not so illustrated in the diagram.

Thus the atmosphere divides into three marked layers. The lower
layer, three kilometers deep, is the region of turbulence and storm,
the home of heavy rain clouds, lightning, wind gusts and irregular
temperatures. The middle layer, some seven kilometers thick, bounded
top and bottom by the upper and lower inversion levels, is a clear
region of steady-falling temperature, for the most part frigid—a region
of far reaching and rapid winds, sweeping eastwardly, except near the
equator, and bearing on their backs the frosty cirrus clouds. The upper
layer reaching from the cirri to the cosmic void, is always cloudless
and very frigid, with temperature nearly constant, or maybe slightly
increasing with elevation.

[Illustration: FIG. 44.—SUMMER AND WINTER AVERAGE VERTICAL TEMPERATURE
GRADIENTS.]

A striking peculiarity of these three regions is that the lower and
middle layers may freely intermingle with each other, but never with
the upper, or isothermal layer. Owing to its constant temperature, the
upper layer floats on its neighbor like oil on water.[60] If a mass of
dry air were forced up into it from below, with the natural cooling due
to adiabatic expansion, such mass would be denser than the surrounding
medium, and hence would promptly sink back to its initial position.
Thus whatever turmoil may vex the middle or lower region, it can at
most upheave the floor of the isothermal layer, leaving inviolate the
crystal depths of the empyrean.

We may now turn to the distribution of barometric pressure in
the atmosphere and the effect of its variation. In general, the
distribution is not very uniform, but it can be graphically pictured by
drawing a series of surfaces connecting all points of equal pressure.
These are called isobaric surfaces. In a stagnant uniformly heated
atmosphere, for example, these surfaces would lie one above the other
parallel to the ocean face; but where turmoil exists, and irregular
temperature distribution, the isobaric surfaces are bent into hills
and hollows of varied form. These surfaces not only map the aërial sea
into regions of equal pressure, but they also show the direction of
fall or rise of pressure, and its space rate of change. This rate is
called the “pressure gradient.” When estimated straight across from
surface to surface, that is, in the direction of the liveliest change
of pressure, it is the maximum pressure gradient. Along this normal
direction the air tends to flow with an acceleration proportional to
the gradient. The velocity thus acquired by any portion of air in
being pushed along the line of falling pressure, combined with its
velocity due to other causes, gives its true velocity. A most important
consideration, therefore, in a scientific study of the wind is the
pressure distribution.

In practical meteorology, observations of the barometric pressure are
made simultaneously at many points on the earth’s surface, and the
readings then plotted on a map, after “reduction to sea level.” This
reduction is made by adding to each barometric reading the weight of a
column of air between the barometer level and the sea level, according
to tables prepared for this purpose. Lines called “isobars”[61] are
then drawn, at regular intervals, through all points of like sea-level
pressure, the indicated change of pressure between consecutive isobars
on the U. S. weather map being usually one-tenth of an inch of mercury.
These exhibit at once, over the entire field of observation, the
horizontal pressure gradient reduced to sea level, and commonly called
the “barometric gradient.” In meteorology, the pressure normal to the
isobar is called the gradient, and is expressed in millimeters of
mercury per degree of a great circle. On the same weather chart are
mapped the isothermal lines and wind directions for all the stations
of the weather service. From these data and the reported moisture
conditions, the meteorologist forecasts the probable weather some hours
or days in advance.

No perfectly comprehensive formula can be given for the barometric
pressure at any place and altitude, but certain general laws may be
observed. Where, for example, the speed of the air is increased along
any level of an air stream, the pressure is lessened, and conversely.
Thus, if the wind blows squarely against the front of an isolated
house, the speed will be greatly checked at the center front, and
accelerated at both sides and over the roof, thereby increasing the
apparent barometric pressure on the front, and lessening it on the
sides and over the top. A similar effect may be observed when the air
flows round the hull and framing of air craft.

Again, if the atmosphere over any locality is heated appreciably more
than its environment, the heated column tends to expand upward and
overflow aloft in all directions toward the cooler neighborhood, thus
lessening the pressure throughout the heated column, and increasing
the pressure throughout the environing atmosphere laterally. When this
effect is marked the plotted isobars often form a series of closed
curves about the heated region, manifesting a pressure gradient at the
lower levels in all directions toward the heated area. This grouping of
the isobars exhibits the familiar low pressure area of the weather map.
On the other hand, if any locality be cooled appreciably more than its
environment, the cooled column sinks, so that the surrounding warmer
air aloft flows in over it, thereby increasing the pressure over the
cooled area, and diminishing it throughout the environment. The isobars
may then form a series of closed curves about the cooled region, with a
pressure gradient along the higher levels in all directions away from
the cooled area. Of course, if heat were the only agency disturbing
the earth’s barometric pressure, there should be a parallelism between
the heat and pressure gradients; but, as already noted, the speed
or momentum of the aërial currents is also a substantial agency in
modifying the pressure lines.

It is well to remember that, while the base of a warm column of air
may, due to the overflow aloft, have less pressure than the base of
the cool environing column which receives the overflow, the high part
of the column may have greater pressure than the equally high part of
the cool. For if the columns be initially of the same temperature and
pressure, heating one of them uplifts its levels of given pressure
above those of its neighbor. When the overflow begins, a partial
equalization of pressure levels occurs, but not a complete one so long
as the flow has any head.

An interesting hygrometric feature of these highs and lows may here
be observed in passing. As already explained, when a column of air
ascends it cools by expansion, and tends to precipitate its water
content as cloud or rain; and conversely, when the air sinks it heats
by compression, thus acquiring greater moisture capacity and tending
to clarify. As a consequence, the areas of low pressure and a rising
atmosphere are usually marked by clouds and rainfall, while the areas
of high pressure and falling atmosphere are marked by clear, or
clearing weather. In the low, damp areas, then, the air feels heavy
while it is really light; in the high and dry area the air feels light,
while it is really dense, and most favorable to air men for carrying
heavy loads in their balloons or flyers. Similarly when air flows over
a mountain range the ascending stream precipitates moisture, due to
cooling by expansion, while the descending stream, on the other side,
comes down hot and dry, due to compression.

A characteristic mechanical feature of the high and low pressure areas
is the closed circulation between them, involving practically the whole
atmosphere below the isothermal layer. If we conceive the entire globe
spotted with high and low areas, we may picture the air surging upward
in the lows, flowing outward under the isothermal layer, descending in
the highs, then flowing outward along the earth’s surface toward the
lows in a continuous cycle. Thus, chiefly is maintained the vast and
multifold circulation of the atmosphere over the entire world.

In general the motion is of a vortical nature, by which is meant that
the masses of air as they flow along stream suffer more or less change
of orientation in space, the rotation at times being so slight as to
be undetectable, and again so marked as to excite wonder, as in the
whirlwind. Many of these atmospheric vortices, even though varying
in diameter from a few yards to hundreds of miles, resemble in their
behavior the gyrating column of water in a common circular basin
emptying through an orifice at its bottom. If the water is very still
when the drain opens, the column descends with imperceptible, if any,
rotation; but if the column has an initial whirl, or angular velocity,
this is magnified as the water approaches the axis of the vortex,
the tendency of the mass being to preserve its angular momentum, or
fly wheel property. A like action obtains in the great atmospheric
vortices, though here the motion far from the axis may seem like a
straight-blowing wind, rather than part of a vast whirl covering
thousands of square miles.

But even if all the air started directly for the axis of the ascending
column, like still water in a basin, it would promptly acquire vortex
motion, because it flows on the surface of a rotating sphere. The
deflection so produced is evidently greatest at the poles, and for
other places equals the polar value multiplied by the sine of the
latitude. The effect is similar to what occurs when a basin, rotating
about a vertical axis and carrying water with the same angular
velocity, is opened at the bottom. In this case the water at once
begins to gyrate within the basin, as the particles move toward its
axis.

With these preliminary generalities we may proceed to study the more
prominent movements in the atmosphere.




                              CHAPTER XV

                     PERMANENT AND PERIODIC WINDS


The winds of the world are commonly classified as the permanent, the
periodic and the nonperiodic, according to their genesis and character.
Their chief features may be briefly outlined.

The most conspicuous and important aërial current on the globe is
the permanent double vortex playing between the equator and the
poles. The heated air of the equatorial belt, uplifted by expansion,
overflows beneath the isothermal layer toward the north and south,
thereby increasing the pressure in the higher latitudes sufficiently
to generate a surface inflow along the earth, and thus maintaining a
perpetual closed circulation which is felt all over the globe. The
main features of this motion have been determined mathematically by
Ferrel,[62] and summarized as follows:

  “In the preceding part of this chapter it has been shown that,
  if all parts of the atmosphere had the same temperature, there
  would be a complete calm over all parts of the earth’s surface.
  But that, in consequence of the difference of temperature
  between the equatorial and polar regions of the globe, and
  the consequent temperature gradient, there arise pressure
  gradients and forces which give rise to and maintain a vertical
  circulation of the atmosphere, with a motion of the air of
  the upper strata of the atmosphere from the equator toward
  the poles, and a counter current in the lower part from the
  poles toward the equator, as represented by the arrows in the
  following figure, and that this of course requires a gradual
  settling down of the air from the higher to the lower strata in
  the middle and higher latitudes and the reverse in the lower
  latitudes. It has also been shown that in case the earth had
  no rotation on its axis, this would be exclusively a vertical
  circulation in the planes of the meridians without any east or
  west components of motion in any part; but that, in consequence
  of the deflecting forces arising from the earth’s rotation, the
  atmosphere at the earth’s surface has also an east component
  of motion in the middle and higher latitudes, and the reverse
  in the lower latitudes, and that the velocities of the east
  components increase with increase of elevation, so that at
  great altitudes they become very much greater than those
  at the earth’s surface; while those of the west components
  decrease with increase of altitude up to a certain altitude,
  where they vanish and change signs and become east velocities,
  now increasing with increase of altitude to the top of the
  atmosphere.

  “It has been further shown that the deflecting forces arising
  from the east components of motion of each hemisphere from the
  earth’s surface to the top of the atmosphere, in the middle
  and higher latitudes and of the upper part of the atmosphere
  in the lower latitudes, drives the atmosphere from the polar
  regions toward the equator, while those arising from the west
  components of motion in the lower part of the atmosphere in
  the lower latitudes, having a contrary effect, but small in
  comparison with the other on account of the weakness of these
  forces near the equator, tend to drive the air a little from
  the equator toward the poles. There is, therefore, a depression
  of the isobaric surfaces at all altitudes in the polar
  regions, especially in the southern hemisphere, a much smaller
  depression in the equatorial regions, and a bulging up of the
  isobaric surfaces in the vicinity of the parallel of 30° in
  the lower part of the atmosphere, the maximum being nearer the
  equator as the altitude increases, as represented in Fig. 45,
  but at high altitudes there is a minimum of barometric pressure
  at the poles and a maximum at the equator.

[Illustration: FIG. 45.—GENERAL CIRCULATION OF THE ATMOSPHERE.]

  “In the accompanying figure the solid arrows in the interior
  part represent the resultant motions of the winds (longer
  arrows indicating greater velocities), in case of an earth
  with a homogeneous surface over both hemispheres, in which
  the motions would be symmetrical in both and the same at all
  longitudes, and the equatorial and tropical calm belts would
  be situated at equal distances from each pole. The dotted
  arrows indicate the strong, almost eastern motion of the air
  at all latitudes at some high altitude, as that of the cirrus
  clouds.

  “The outline of the outer part of the figure represents an
  isobaric surface high up where the bulging up near the parallel
  of 30° disappears and the maximum pressure at the same altitude
  is transferred to the equator. For lower altitudes the isobaric
  surfaces have a bulging up at the parallel of 30°, and a slight
  depression at and near the equator. The arrows in this part
  represent the polar and equatorial components of motion, the
  former above and the latter below, except near the earth’s
  surface on the polar sides of the tropical calm-belts, where
  there is a polar component of motion arising from the air’s
  being pressed out from under the belt of high pressure. This,
  perhaps, does not extend beyond the polar circles, beyond
  which there can be little motion in any direction, except from
  abnormal disturbances.

  “For reasons given in §103, the actual mean position of the
  equatorial and tropical calm-belts are not precisely as here
  represented, but are all a little displaced toward the north
  pole, and the polar depression of the isobaric surfaces is
  greater in the southern than in the northern hemisphere.”

The conclusions from this approximate analysis are in the main
supported by observation, except as modified by the heterogeneity
of the earth’s surface. The sea-level distribution of barometric
pressure between the equator and poles, as found by Ross’ long series
of measurements, manifests a variation of about one inch of mercury,
with maxima at about 30° of latitude, north and south, as required
by Ferrel’s theory. As a further cause of the depression toward the
poles, may be mentioned the greater speed of the permanent east wind
with the consequent centrifugal lift in the atmosphere.

As to the general easterly direction of the winds at middle and
higher latitudes, that is well known from observation of the motion
of clouds and of the air near the earth. At the cirrus level the
velocity in those latitudes is almost exactly eastward. But the flow
in longitude, illustrated by the outer arrows in Fig. 45, has not
been fully determined by observation. Moreover, as Ferrel himself
showed, the unequal heating of continents and oceans sets up gradients
in longitude, especially in the northern hemisphere, thus adding
considerable disturbance to the general circulation. To this agency
must be added also the latitudinal shifting of insolation, due to the
annual march of the sun across the equator, entailing an oscillatory
seasonal shift of the hot belt, and therefore of the twin-hemispheric
cycle of the atmosphere.

Some currents of the general and permanent circulation are sufficiently
prominent to have special names, such as the _trade-winds_, the
_antitrade-winds_, the _prevailing westerlies_, and, in the lower
latitudes, the _calm belts_, where the flow is exceptionally feeble.
All these currents have been known to sailors since early times, and
have been of considerable importance in marine navigation. Eventually,
perhaps, they may be of like importance in aërial navigation.

The trade-winds are mild tropical surface currents of remarkably steady
speed and direction. Springing from the high-pressure belts in either
hemisphere, at about latitude 30°, they blow toward the equator with
increasing westerly trend. As shown in charts 46 and 47 for midwinter
and midsummer, the trade winds cover a large portion of the tropical
zones in both oceans, and shift slightly in latitude with the sun.
They are separated at the heat equator by the equatorial calm belts, or
doldrums, and are bounded north and south respectively by the calms of
Cancer and of Capricorn. Particularly interesting are the trade-winds
blowing from Spain to the West Indies, which favored Columbus on his
westward voyage, and which certain adventurous Germans have proposed
using to duplicate that memorable voyage, in air ships.

[Illustration: FIG. 46.—NORMAL WIND DIRECTION AND VELOCITY FOR JANUARY
AND FEBRUARY. (KÖPPEN.)]

The antitrade-winds, or counter trades, are lofty winds blowing over
and contrary to the trade winds. As some doubt regarding the direction
of these counter trades had existed, an expedition was sent in 1905, by
two distinguished meteorologists, Teisserenc de Bort of France, and A.
Lawrence Rotch of America, to explore the atmosphere above the tropical
Atlantic. Mr. Rotch has summarized their measurements and conclusions
as follows:[63]

  “Pilot balloons, dispatched from the island of Teneriffe and
  St. Vincent, were observed with theodolites at the ends of a
  base-line, and in this way the heights at which the balloons
  changed direction could be ascertained. Later the balloons
  were sent up from the yacht itself, which steamed after them,
  measurements being made of their angular elevation. The
  observations which are plotted in Fig. 46 prove conclusively
  the existence of the upper counter-trade. The courses of
  the balloons are represented as if projected upon the
  surface of the sea and show that the northeast trade-wind
  extended only to the height of 3,200 or 4,000 meters, and
  then gradually turned into a southerly current which, higher
  up, came from the southwest. The width of the dotted band
  represents approximately the varying velocity of the trade and
  counter-trade. Similar proofs of the northwest trade-wind,
  south of the equator were obtained by the same expedition
  during the following year, but the above suffices to show that
  it would be possible for an aëronaut in the ordinary balloon
  to start from the African coast, or from some of the islands
  in the trade-wind region, and, after drifting towards the
  southwest, to rise a few miles into the current, which would
  carry the balloon north and eventually northeast back to land.
  Nevertheless, it does happen in certain atmospheric situations
  over the tropical north Atlantic that the winds from the
  general northwesterly direction prevail up to great heights
  without any evidence of the return-trade. Near the equator the
  winds are easterly up to the greatest heights which have been
  attained.”

[Illustration: FIG. 47.—NORMAL WIND DIRECTION AND VELOCITY FOR JULY AND
AUGUST. (KÖPPEN.)]

[Illustration: FIG. 48.—TRADE AND COUNTER TRADE-WINDS.]

The prevailing westerlies are high-latitude surface winds of the
permanent circulation. In the southern hemisphere they are particularly
strong and steady owing to the comparatively unbroken stretch of
ocean. In the north also they are strong and persistent, but variable
in direction because of disturbances by local winds due to unequal
heating of tracts of land and sea. These features are well illustrated
in charts 47 and 48. Of particular interest in aëronautics is the
prevailing wind blowing from the United States to Europe, which has
been considered a suitable current for transoceanic balloon voyages.[64]

The periodic winds are those whose gradient alternates annually or
daily, due to annual or daily fluctuations of temperature on sloping
or on heterogeneous parts of the globe. The annually fluctuating winds
due to alternate heating and cooling of continents, or large land
areas, bear the general name of monsoon. Among diurnal winds the most
prominent are the land-and-sea breezes, and the mountain-and-valley
breezes. Both kinds are practically available in aëronautics; the
monsoons for long-distance travel, the diurnal winds for local use.

The general motive cause is the same for all periodic winds. When any
portion of the earth’s surface is periodically more heated above its
normal temperature, or average for the year, than the neighboring
region, the resulting abnormal temperature gradient causes a periodic
surface wind tending toward the excessively heated place, and a counter
wind above. That is, the cooler and heavier column of air sinking and
uplifting the lighter, results in a lowering of the common center of
gravity of the two columns of air, and thus furnishes the driving
power of the wind. For example, an island or a peninsula may be
considerably hotter by day and cooler by night than the surrounding
water; a continent may be much hotter in summer and much colder in
winter than the bordering ocean. Thus during the hot period a moist
wind blows landward; during the cold period a dry wind blows seaward.
If the land has vast and lofty slopes the uprush of air during the hot
period and the downrush during the cool period may be very powerful.
The currents so produced by the aggregate of local agencies, including
the deviation caused by the earth’s rotation, combine with the general
circulation of the atmosphere to form the actual wind of the place.
Thus the periodic current may conspire with the general circulation,
or oppose it; may intensify, weaken or obliterate it; may overmaster,
reverse or mask it completely.

Of the various continental monsoons of the globe the most powerful
spring from the annual flux and reflux of the atmosphere over the vast
declivities and table-lands of Asia. Here the conditions are especially
favorable. As the sun approaches Cancer, the burning deserts and high
plateaus, combining their force with the draft on the mountain sides,
generate a continental uprush that sucks in all the aërial currents of
the surrounding seas, hurling them aloft to the isothermal layer whence
they radiate as the four winds of heaven; for here at this season the
planetary circulation is disrupted, obliterated or reversed, appearing
merely as a perturbation of the monsoon at its height. In India the
force is particularly effective. Along the north the Himalayas stretch
1,300 miles in latitude, with an average height of 18,000 feet and
with sunburned areas on either side. North of this range are the lofty
plateaus of Thibet and Cashmere, south of it the desert of Gobi and
the borders of the Indian Ocean. Over this watery tract from beyond the
equatorial line, from the isles of Oceanica and from the wintry plains
of Australia, the air flows in with accumulated strength, sweeping the
Bay of Bengal and the Arabian Sea in a continuous gale bearing up the
mountain slopes incredible floods of water. Over the Arabian Sea in
summer the gale is so steady and swift that no ordinary ship can force
a passage from Bombay to the Gulf of Aden. Above the Bay of Bengal the
moist south winds, converging between the coast and headlands, pour
cloud laden up the Himalayan slopes, precipitating their whole vapor
in prodigious torrents seldom seen elsewhere. Khasia at this season
sustains a Noachian deluge, the rain at times falling nearly a yard
deep in one day and night.[65] Quite appropriately, therefore, the
summer monsoon over India, especially its component southwest wind from
the Arabian Sea, and southerly wind from the Bengal Bay and farther
east, is called the wet monsoon.

The winter monsoon of Asia, is the reverse of the summer one, both
in direction of gradient and in physical character. It is a cold
flood of air pouring from the frigid table-lands and wintry depths
of the desert, down the mountains and valleys in continual overflow
on all sides of the continent, and then far out over the sea, where
it reascends to complete its long cycle. In its descent all moisture
vanishes by heating, and no intensive temperature gradient occurs, as
in summer, to accelerate its gently modulated tide. In India the winds
from Cashmere and Thibet pour down the Himalayas toward the Arabian Sea
a clear current of air which unites with the trade-wind, increasing
its force, and forming the moderate winter monsoon of that region, or
as it is commonly called, from its lack of moisture, the dry monsoon.

The kinematic character, and the extent of both summer and winter
currents, are well portrayed in charts 47 and 48 for all the south and
southeast of Asia. Across the islands of Japan, it will be observed,
the winds blow in opposite directions summer and winter. In Siberia
the monsoon winds trend along her great rivers and valleys, generally
northward in the winter and the reverse in the summer, combining in
both seasons with the prevailing westerlies, due to the rotation of the
earth.

All the other continents have their monsoons, though less powerful
than those of Asia. In the great desert of Sahara, for example, there
is an ascending hot current in the summer, causing a strong indraught
from the Atlantic and the Mediterranean; but this is far less intense
than if its action were fortified by lofty slopes and table-lands. In
winter when the Sahara cools to nearly the oceanic temperature, little
monsoon effect is perceptible, and the general circulation continues
unperturbed. In Australia the monsoon influence is still feebler,
owing to the limited extent of the country and to the general lowness
and flatness of the land. Over parts of South America, the annual
ebb and flow of the atmosphere is considerable, particularly along
the northeastern coast, and in the whole Amazon Valley, whose aërial
currents in general conspire with the trade-winds, strengthening them
materially in the southern summer, though it is less in winter when the
continental temperature more nearly approximates that of the ocean. The
monsoons of North America have been described in some detail by Ferrel
as follows:

  “On the continent of North America we have monsoon influences
  similar to those of Asia, but not nearly so strong, because
  the extent of the continent, and consequently the annual range
  of temperature, are not so great. They are, for the most part,
  not sufficiently strong to completely overcome and reverse the
  current of the general circulation of the atmosphere, and so
  to produce a real monsoon, but they cause great differences
  between the prevailing directions of the winter and summer
  winds.

  “In the summer the whole interior of the continent becomes
  heated up to a temperature much above that of the oceans on the
  same latitudes on each side—indeed, above that of the Gulf of
  Mexico and the Pacific Ocean on its southern and southwestern
  borders. The consequence is that the air over the interior of
  the continent becomes more rare than over the oceans, rises
  up and flows out in all directions above while the barometric
  pressure is diminished, and the air from all sides, from the
  Atlantic on the east to Pacific Ocean on the west, the Gulf of
  Mexico on the south, and the polar sea on the north, flows in
  below to supply its place. On the east the tendency to flow in
  is not strong enough to counteract the general easterly motion
  of the air at the earth’s surface in the middle latitudes, and
  to cause a westerly current, but it simply retards the general
  easterly current and gives rise to a greater prevalence of
  easterly winds along the Atlantic sea-coast during the summer
  season....

  “In winter the thermal conditions over the continent are
  reversed. The interior of the continent is now the coldest
  part, and it is especially colder than the surrounding oceans
  at that season. It has also very high plateaus and mountain
  ranges. The air, therefore, of the lower strata, and especially
  those next the earth’s surface, now tends to flow out in all
  directions to the warmer oceans and the Gulf of Mexico, and
  especially to run down the long slope of plateau from the
  Rocky Mountains into the Mississippi Valley. The effect over
  the whole of the United States east of the Rocky Mountains
  is to cause the winds, which otherwise would be westerly and
  southwesterly, to become generally northwesterly winds, instead
  of southerly and southwesterly ones, as in summer. There is not
  a complete monsoon effect, but simply a great change between
  summer and winter in the prevailing directions of the winds. In
  Texas, however, and farther east along the northern border of
  the Gulf, the effect is somewhat that of a complete monsoon. In
  New England and farther south in the Eastern States the monsoon
  effect is to cause the prevailing winds to be from some point
  north of west, instead of south of west as in summer.

  “In summer, Central America and Mexico have a much higher
  temperature than that of the adjacent tropical sea on the
  southwest, and having high mountain ranges and elevated
  plateaus, there is consequently a strong tendency to draw in
  air from the southwest at this season, which not only entirely
  counteracts the regular trade-winds of these latitudes, but
  even reverses them and causes southwest winds. The effect is to
  cause in midsummer a large area here, extending far westward,
  of calms and irregular and light winds, mostly southwesterly
  ones, and an apparent widening of the equatorial calm-belt at
  this season so as to make its northern limit reach up, along
  the coast, nearly to the parallel of 20°. The effect is similar
  to that in the Atlantic west of the Gulf of Guinea and Liberia,
  except that it here appears to be some greater, and causes
  a true monsoon effect, since during the winter the regular
  northeasterly trade-winds prevail, but strengthened by the
  reverse thermal conditions of the winter season. On the eastern
  side, and over the western end of the Gulf of Mexico, there is
  a somewhat regular monsoon effect, the prevailing winds being
  easterly, or blowing toward the land, during the summer, and
  the reverse in winter.

  “Along the west coast of North America in the middle latitudes
  there is a strong monsoon influence; for the interior of the
  continent becomes heated in summer to a much higher temperature
  than that of the southwesterly ocean, and hence a strong
  current is drawn in from this direction, at right angles to
  the general trend of the coast which, combining with the
  general southwesterly winds of these latitudes in the general
  circulation of the atmosphere, causes the strong and steady
  westerly and southwesterly winds of this region during the
  summer. Farther north, up toward Alaska, the summer monsoon
  effect is combined with the current caused by the deflection
  of the continent as well as the general easterly current of
  high latitudes, so that the winds here are generally southerly,
  but still have somewhat of a monsoon character, being southerly
  and southwesterly in summer and easterly and southeasterly
  during the winter.

  “Along the northern coast of America, as along that of Siberia,
  the monsoon tendency is to draw the air from the colder land
  to the warmer ocean in winter, and the reverse in summer; and
  these effects, combined with the general easterly motion of
  the atmosphere in these latitudes, gives rise to prevailing
  southwesterly winds in winter and northwesterly ones in summer.
  The winter monsoon influence, however, is small here—much
  more so than in Siberia, for the ocean contains so many large
  islands that it has rather a continental than an oceanic winter
  temperature; and besides, it has not the influence of a warm
  current—such as the continuation of a part of the Gulf Stream
  along the northern coast of Europe and Asia.”

Similar to the monsoons in essential nature are the diurnal winds of
seacoast and mountain side. They begin with the heating of the land
in the morning, attain their maximum intensity about mid afternoon,
or during the hottest of the day, and finally are reversed at night.
Besides being so much briefer than monsoons, they are also in general
feebler and less extensive. They may be quite noticeable on calm
days, especially in clear weather and in hot climates; but usually
they are masked or entirely overwhelmed where other marked currents
occur—currents due either to the general circulation or monsoons, or
other powerful disturbing agencies.

In land-and-sea breezes, which usually extend not far inland, there is
a surface inflow of sea air during the forenoon and early afternoon,
balanced by an outflow of warm air above, rising from the heated soil.
After sundown this is reversed, the chilled air from inland pouring
out to sea, while overhead the warmer sea air is forced landward at a
higher level. These currents are strongest where the diurnal range of
temperature is greatest and where the local topography is of suitable
configuration. Particularly favorable are steeply declining shores,
narrow bays and inlets, girded by mountains or lofty hills. During
the day heated air ascends such declivities with alacrity, like smoke
through an inclined flue, while at night, when cooled by radiation
and contact with the soil, it rushes torrentlike down the valleys and
hillsides, passing out to sea, often in sudden squalls that embarrass,
or endanger, small sailing craft. Circulatory currents like the above
have sometimes been used by aëronauts to carry them out to sea and back
again to land at a different level.

In like manner the mountain-and-valley winds may be used by the
skillful aëronaut. It is well known that these flow up the courses of
rivers, cañons and land slopes generally by day, but at night reverse
their course and pour down again with considerable force. For this
reason experienced hunters place their camp fires below tent in a
sloping valley. The strength of the breeze depends, of course, upon
the daily range of temperature, and the steepness and expanse of the
slope. Such winds are deftly used by the masters of soaring flight, the
great robber and scavenger birds, and no doubt may be used by men in
motorless aëroplanes, to gain elevation, and journey great distances
without expenditure of energy.




                              CHAPTER XVI

                   CYCLONES, TORNADOES, WATERSPOUTS


Besides the periodic winds so far treated, there are prominent aërial
movements having no regular course or season. These are the nonperiodic
winds which so exercise or perplex the weather forecaster and those who
confide in him. In general such winds are of a temporary character,
arising from an unstable condition of the air in some locality, or
from unequal heating, either of which causes may generate, or briefly
sustain, an updraught, with its attendant gyration. Owing to the
whirling character of such ascending currents, they have received
various significant names, such as cyclone, tornado, whirlwind; the
three terms applying to vortices in decreasing order of magnitude. Each
in turn may be treated briefly.

The cyclone is a temporary large gyratory wind. It may last a few hours
or a few days. It may measure fifty to a hundred miles across, or it
may measure more than a thousand miles. On the weather map it is in
general marked by a group of closed isobars, showing a considerable
pressure gradient toward a small internal area where the pressure is
a minimum. To an observer looking about the earth’s surface and lower
levels of the atmosphere, the cyclone appears merely as an ordinary
wind, accompanied perhaps by rain or snow. It is not a swiftly rotating
narrow column, or cone of air, like a tornado or whirlwind, full of
gyrating dust and débris.

The motive power of a cyclone, though in general due to the buoyancy
of heated air, may spring from more than one set of conditions. Notice
has already been taken of vortices due to a hot column of air at lower
barometric pressure than its lateral environment. Take another case.
If a dry atmosphere is of uniform temperature and pressure at various
levels, but has a vertical temperature gradient a little greater than
the normal cooling of an ascending gas, a portion of air started upward
in any casual way becomes warmer than its lateral environment, and
hence continues to rise until the unstable condition due to abnormal
temperature gradient ceases. Again, while the surface stratum is in
stable equilibrium, it may happen that the second mile of air is
abnormally hot, and the third mile abnormally cold, and thus a vortex
may occur in mid air, without disturbing the face of the earth.

Whatever be the initial atmospheric condition causing the vertical
uprush, the nature of the resulting circulation is in general that of
the cyclone, illustrated, in part, by the whirling vortex of water in
a basin. As the current ascends, an indraught occurs in all the lower
regions of air, and an outflow in all directions above, sometimes
at the height of a mile or two, again in all the region next to the
isothermal layer. As the earth has at all places above the equator
a component of rotation about the vertical line, it follows that in
northern latitudes all the air flowing toward the vortex is in a whirl
opposite in motion to the hands of a watch lying face upward, and all
the outflowing air above has a like angular motion, but gradually
diminishing until it is reversed. At the lower portion of the vortex
the air whirls inward and upward with increasing velocity, while
above, it whirls outward and upward, with waning velocity, thus moving
in a double-spiral path shaped like a cord wound on an hourglass. In
the constricted part, or neutral plane of the vortex, the air moves
neither outward nor inward, but spirals straight upward. To match the
upflow, and complete the closed circulation, there must be a downflow
on the exterior of the cyclone, and since the whirl is reversed
in direction, this outer mass of downflowing reverse-whirling air
embracing the cyclone is called the anticyclone.

Between the inner and outer vortex the air is comparatively calm and
the pressure is a maximum, with steepest gradient toward the center
of the cyclone. Also the air is calm just at the axis of the vortex,
while for some distance away its speed increases as the radius of its
whirl, so that the central mass rotates practically as a solid column,
thus still further lowering the pressure near the axis. This solidly
rotating central column of air is sometimes called the core of the
vortex.

High above the center of the cyclone, where perhaps the air is sucked
downward, clarified by compression, then whirled outward, the sky is
usually clear, or thinly fogged, while without this central patch are
heavy clouds. The obscure or clear central part is called the “eye[66]
of the storm.” Through this the cirrus clouds may sometimes be seen
high above, either stationary or radiating away, if the vortex extends
so high. Sailors on the deck of a vessel passing through a cyclone have
often noticed the eye of the storm overhead, perhaps ten or twelve
degrees in diameter, and with special clearness in the tropics. To the
white, feathery cirrus clouds, scurrying away radially from the top of
the vortex, they have given the name “plumes of the storm,” or “mares’
tails.” In sailing their vessel through the center of a cyclone, they
have observed the circulatory motion of the winds and clouds, and
frequently have found the deck covered or surrounded with cyclone
sweepings, such as land and water birds, insects, butterflies, etc.,
brought into the quiet core of the vortex from the incurving winds
beyond. Further details of the motion in a cyclone vortex are given as
follows by Ferrel, §178:

  “In Fig. 49 is given a graphic representation of the resultant
  motions and of the barometric pressures for both the surface
  of the earth and for some level high up in the atmosphere and
  above the neutral plane, where the motions in the vertical
  circulation are outward from the center. The solid circles
  represent isobars at the earth’s surface and the solid arrows
  the directions, and in some measure, by their different
  lengths, the relative velocities of the wind. The heavy circle
  represents the circle of greatest barometric pressure at the
  earth’s surface, say 765 mm., while the pressure of the outer
  border is 760 mm., and the dividing line between the cyclone
  and the anticyclonic gyrations. Within this limit the pressure
  diminishes to the center, and the gyrations are cyclonic, and
  the direction of the resultant of motion inclines in toward the
  center, but beyond that limit the gyrations are anticyclonic,
  and the direction of resultant motion inclines toward the outer
  border of these gyrations. The heavy dotted circle represents
  the circle of maximum pressure at some high level, and is much
  nearer the center than that at the earth’s surface. It is
  also the dividing line between the cyclonic and anticyclonic
  gyrations at that level. The dotted arrows indicate the
  directions and in some measure the relative velocities, of the
  wind at this level. The arrows in the cyclonic part represent
  the direction of the wind as declining outward, because the
  plane here considered is supposed to be above the neutral
  plane, where the radial component of motion is outward, but
  for any level below the neutral plane the inclination is still
  inward. The arrows are shorter above in the cyclonic part and
  longer in the anticyclonic part than they are at the earth’s
  surface, since the cyclonic gyratory velocities decrease and
  the anticyclonic increase with increase of altitude.

[Illustration: FIG. 49.—VELOCITY DIAGRAM IN HORIZONTAL SECTION OF A
CYCLONE.]

  “The upper part of the figure is a representation of a vertical
  section of the air, very much exaggerated in altitude, in
  which the solid curved line represents a section of an isobaric
  surface near the earth’s surface, say of 740 mm. barometric
  pressure. The lowest part corresponds with the center of the
  cyclone and the highest part with the heavy circle in the
  lower part of the figure, and the steepest gradients with the
  longest solid arrows, since the greater the gyratory velocities
  at the earth’s surface the greater the gradients, though they
  are not strictly proportional. The second dotted curved line
  from the top represents a section of the isobaric surface of
  high altitudes, in which the highest parts correspond with
  the heavy dotted circle below, since the highest pressure at
  all altitudes is very nearly where the cyclonic gyrations
  vanish and change to the anti-cyclonic. The depression here
  is smaller because the cyclonic area is smaller, and the
  gyratory velocities less, than at the earth’s surface. The
  upper dotted line belongs to an isobaric surface still higher,
  where the gyrations are supposed to be all anti-cyclonic, and
  here, consequently, the greatest pressure is in the center, as
  indicated by the curved line.

  “As the interior of the whole cyclonic system is warmer
  than the exterior, and consequently the air less dense, the
  distances between the isobaric surfaces are necessarily greater
  in the interior than the exterior part, and so, however much
  the isobaric surface at or near the earth’s surface may be
  depressed by the cyclone gyration there, at a considerable
  altitude, if the temperature difference is great enough, it
  must become convex instead of concave.

  “The track of any given particle of air in a cyclone, resulting
  from the vertical and gyratory circulation, is that of a
  large converging and ascending spiral in the lower part, but
  of a diverging and ascending spiral in the upper strata of
  the atmosphere, and the nearer the earth’s surface the more
  nearly horizontal is the motion, since the vertical component
  gradually decreases and vanishes at the surface.

  “The whole energy of the system by which the inertia of the
  air and the frictional resistance are overcome and the motions
  maintained, is in the greater interior temperature and the
  temperature gradients, by which the circulation is maintained.
  This being kept up, the deflections and gyrations are merely
  the result of the modifying influence of the earth’s rotation,
  which is not a real force, since it does not give rise to
  kinetic energy, but merely to changes of direction.

  “It must be borne in mind that the preceding is a
  representation of the motions and pressures of a cyclone
  resulting from perfectly regular conditions, in an atmosphere
  otherwise undisturbed, and having a uniform temperature,
  except so far as it is affected by the temperature disturbance
  arising from the cyclonic conditions. Accordingly results so
  regular are not to be found in Nature, but generally only rough
  approximations to them.

  “Since the wind inclines less and less toward the center of the
  cyclone below the neutral plane and declines from the center
  above it, the upper currents above this plane in a cyclone are
  always from a direction, in the northern hemisphere, a little
  to the right of that of the lower currents, when not affected
  by abnormal circumstances.”

Observation of cyclones in Nature very well confirms the leading
features set forth on theoretical grounds. If the vortex pass centrally
over an observatory there is noted first a high barometer and calm air,
attended perhaps by scurrying cirrus clouds; next a rapidly falling
pressure and increasing wind, with dark clouds and precipitation,
commonly accompanied by thunder and lightning; then the hushing of
the storm to a dead calm, and low barometer and thinning or clearing
of the clouds overhead; then a rising barometer with renewed winds in
the reverse direction, and finally subsiding winds, rising barometer
and clearing weather. These phenomena are the more definitely presented
if the whirl is strong while its travel along the earth is slow. But
owing to their progressive easterly motions, cyclones in the north have
their moist hot southern masses elevated, chilled and precipitated
on their eastern fronts and beyond, while their rear experiences the
opposite action and is called the clearing side. Conversely in the
tropics the westerly moving cyclones have cloudy and wet rears, because
the easterly drift on high carries the precipitating masses toward the
rear. The general hygrometric appearance of a centrally passing cyclone
in middle latitude is thus described by Ferrel, §207:

  “In the regular progression of a cyclone in the middle
  latitudes somewhat centrally over a place, the cloud and rain
  area of the front part, extending far toward the east, first
  passes over, occupying a half-day, or a day and more, and
  then the front part of the ring of dense cloud with a heavy
  shower of rainfall. After this there are indications of a
  clearing up, and even the sun may break through the cloud for
  an hour or two; but presently there is an apparent gathering
  and thickening of the cloud and a second shower. This is at
  the time of the passage of the rear side of the ring of denser
  cloud. After this there is the final clearing up.”

Except for special conditions, cyclones are never stationary, but drift
along with the general march of the atmosphere, like dimpling eddies in
a stately flowing river. In general, therefore, their trend is westward
in lower latitudes, eastward in middle and higher latitudes, with a
pace slow or swift according to the prevailing current. Notably also
they have a poleward trend. Thus, if the path extends from tropic to
temperate clime, it is frequently concave toward the east and sensibly
parabolic in form. This is markedly true of those swift-whirling, small
cyclones called hurricanes,[67] and particularly those vigorous ones
blowing past the West Indies and the Philippines, and those that vex
the Indian Ocean.

As to the speed of travel of cyclones, that may be judged, at least for
northern latitudes, from the accompanying table, taken from Loomis,[68]
and showing the average monthly rate of progression in miles per hour,
of cyclone centers over the United States, the Atlantic Ocean and
Europe. In general, beyond the tropics tall cyclones travel faster than
short ones, owing to the faster drift of the higher strata.

  ----------+----------+--------------+---------
            |          |   Atlantic   |
            |  United  | Ocean Middle | Europe.
    Month.  |  States. |  Latitudes.  |
  ----------+----------+--------------+---------
  January   |   33.8   |    17.4      |  17.4
  February  |   34.2   |    19.5      |  18.0
  March     |   31.5   |    19.7      |  17.5
  April     |   27.5   |    19.4      |  16.2
  May       |   25.5   |    16.6      |  14.7
  June      |   24.4   |    17.5      |  15.8
  July      |   24.6   |    15.8      |  14.2
  August    |   22.6   |    16.3      |  14.0
  September |   24.7   |    17.2      |  17.3
  October   |   27.6   |    18.7      |  19.0
  November  |   29.9   |    20.0      |  18.6
  December  |   33.4   |    18.3      |  17.9
  ----------+----------+--------------+---------
    Year    |   28.4   |    18.0      |  16.7
  ----------+----------+--------------+---------

To find the actual speed of the wind at a place, of course, the linear
velocities of whirl and of translation must be combined; or, vice
versa, if one of these be known it can be graphically subtracted from
the observed wind velocity to find the other. This combination of two
wind components to find their resultant, or, vice versa, can easily be
done by laying off on paper, arrows of suitable length and direction
to represent the two known velocities, placing the head of one arrow
to the tail of the other, then completing the triangle, and taking its
third side to represent the required wind velocity, in magnitude and
direction. Obviously if the cyclone moves eastward, whirling oppositely
to the hands of a watch, the swiftest wind is on its right side,
which consequently is known as the dangerous side. In the northern
hemisphere, therefore, the rule for dodging a great whirlwind is to run
north, if that be practicable.

Stationary cyclones occur under favorable conditions. At least that
name has been applied to columns of hot air streaming up from a fixed
base, more or less circular. Every island in the ocean generates such
a vortex on a clear, hot summer day, since its temperature far exceeds
that of the surrounding water. All day long this uprush continues
whatever be the humidity. And if the soil slopes upward steeply, the
vortex is so much the stronger, particularly if the island be in a calm
region. Above such a tract the gulls and vultures, and possibly even
man, might soar all day without motive power. This condition and its
interesting possibility deserve investigation.

Cyclones may occur at any season, but in general they are most abundant
when the greatest temperature disturbances occur. The relative
frequency of tropical cyclones for various localities and for the
twelve months of the year is seen in the following table[69]:

       _The Yearly Periods of Cyclone Frequency in Several Seas_

  ------------+---------+---------+----------+----------+-------+-------
              | Arabian | Bay of  | S. Indian|   Java   | China |
              |   Sea.  | Bengal. |  Ocean.  |   Sea.   |  Sea. |Havana.
  ------------+---------+---------+----------+----------+-------+-------
  No. of years|   234   |   139   |     40   |    --    |   85  |   363
  No. of      |         |         |          |          |       |
    cyclones  |    70   |   115   |     53   |    12    |  214  |   355
              |         |         |Piddington|Piddington|
   Authority. |Chambers.|Blanford.|Thom and  |and       |Schuck.| Poey.
              |         |         |Reid.     |Thom.     |       |
  ------------+---------+---------+----------+----------+-------+-------
  Jan         |    6    |   2     |    17    |    25    |    2  |    1
  Feb         |    4    |   0     |    25    |    42    |    0  |    2
  Mar         |    3    |   2     |    19    |     8    |    2  |    3
  April       |   13    |   8     |    15    |     8    |    2  |    3
  May         |   18    |  16     |     7    |     0    |    5  |    1
  June        |   29    |   9     |     0    |     0    |    5  |    3
  July        |    3    |   3     |     0    |     0    |   10  |   12
  Aug         |    3    |   4     |     0    |     0    |   19  |   27
  Sept        |    4    |   5     |     2    |     0    |   27  |   23
  Oct         |    6    |  27     |     2    |     0    |   16  |   17
  Nov         |   14    |  16     |     7    |     0    |    8  |    5
  Dec         |    3    |   8     |     6    |    17    |    3  |    2
  ------------+---------+---------+----------+----------+-------+-------

The tornado is a slender cyclone or hurricane. It is usually but a
few yards or rods in diameter, and seldom exceeds one mile across its
active column, whereas a cyclone may cover an area of any size from
fifty to one or two thousand miles in diameter. Moreover, the cyclone
requires for its inception an extensive pressure gradient marked by
closed isobars, and once generated may last several days. A tornado per
contra may spring into action where the lateral pressure is uniform,
spend its force in a few moments, and leave a uniform barometric field
in its wake. In shape the tornado is usually of greater height than
width. The cyclone is far-flung laterally, but in height may not exceed
the narrow tornado, since both must terminate beneath the isothermal
layer, and commonly do not extend so high. Both vortices are caused
by the ascensional force of hot air. In both the air spirals in and
upward at the bottom, out and upward at the top, constantly cooling
by expansion, and finally descends on the outside to complete the
closed circulation. In general the tornado is the more violent and
destructive, though limited to a brief and narrow path. More aptly,
perhaps, the tornado may be called a slender hurricane of brief
duration; both of them being small cyclones, or aërial vortices, of
minor size and concentrated intensity. The relation of the tornado and
cyclone has been defined as follows, by Professor Moore:

  “The cyclone is a horizontally revolving disk of air of
  probably 1,000 miles in diameter, while the tornado is a
  revolving mass of air of only about 1,000 yards in diameter,
  and is simply an incident of the cyclone, nearly always
  occurring in its southeast quadrant. The cyclone may cause
  moderate or high winds through a vast expanse of territory,
  while the tornado, with a vortical motion almost unmeasurable,
  always leaves a trail of destruction in an area infinitesimal
  in comparison with the area covered by the cyclone.”

Two initial conditions seem essential to the genesis of a substantial
tornado. In the first place, the atmosphere of its immediate locality
must have appreciable gyration. Of course, in all extra equatorial
regions the air has some incipient whirl due to the earth’s rotation,
and this whirl is magnified as the fluid is sucked into the vortex. But
the magnification may be slight owing to the brief lateral displacement
of the air feeding the tornado. If, however, the fluid be drawn from a
considerable distance, and have from local conditions some additional
whirl superadded to that due to the earth’s rotation, the gyratory
flow in the medium near the vortical axis may be very swift. On the
other hand, the additional whirl, due to local conditions, may tend
to neutralize that due to the earth’s component, thereby leaving a
very feeble gyration, if any. But in general the rotation of tornadoes
is observed to be in the direction of the earth’s component; to the
left north of the equator, to the right south of it. This observation
is doubtless the more striking because when the accidental local spin
conspires with the permanent terrestrial one, the resultant whirl
is intensified, while in the opposite case it is so enfeebled as to
attract scant, if any attention.

In the second place, the genesis of a tornado requires unstable
equilibrium in the local atmosphere. This instability, as in cyclones,
may arise from abnormal temperature gradation. Thus, if along any
vertical the temperature falls more than six degrees Centigrade for one
thousand meters ascent, a mass of air started upward will continue to
rise, since it cools less rapidly than the environing medium. In this
way there will ensue a continuous uprush of air so long as the unstable
state endures; and the action may be very vigorous if a large stratum
of air is greatly heated before it disrupts into the cold upper layers.
In general, the loftier the tornado the more violent it is, just as
the taller flue generates the stronger draft with the same temperature
gradient.

Dynamically, the tornado may be treated as a rotating pillar of air
in which each mass of fluid fairly retains its angular momentum. This
means that for any mass of the whirling air the radius of its path,
multiplied by its circular speed, remains a constant product; in
other words, the velocity of whirl varies inversely as the radius.
Accordingly, the circular velocity is exceedingly rapid where the
radius is very small. Now, when any mass runs round a circle its
centrifugal force is known to be directly as the square of the speed of
its centroid and inversely as the radius. But by the above assumption
the speed itself is inversely as the radius. Hence, the centrifugal
force varies inversely as the cube of the radius of the inflowing
mass of air. This centrifugal force, acting on the inner layers of
air of the rotating column, must be supported by the pressure against
them exerted by the outer layers as they pass inward. Thus there is a
strong barometric gradient from the remote still air toward the swiftly
whirling parts of the vortex.

It follows from the above argument that inside a tornado the barometric
pressure may be much below the normal; and it is easy to see that if
a barometer, starting from some point on the tornado base, be moved
vertically upward it must show a declining pressure, but if moved
upward and outward it may be made to show a constant pressure all the
way to the upper portion of the vortex. The instrument would thus
travel along an isobaric, bell-shaped surface opening upward. On a
series, therefore, of concentric circles on the base of a tornado,
we may erect a family of coaxial bell-shaped surfaces to mark the
points of equal pressure, and thus map out the isobars of the vortex.
Inside these coaxial surfaces reaching to earth, others of still
lower pressure may be drawn tapering downward to a rounded point and
terminating at various places on the axis. In an actual tornado one of
these infinitely numerous funnel-shaped isobaric surfaces may become
distinctly outlined and visible, if the air has sufficient moisture to
start precipitation when it reaches a surface of suitably low pressure.
This quite usually occurs in Nature, the funnel sometimes reaching to
earth, sometimes only part way, according to the pressure at which
precipitation begins, this pressure depending, of course, on the
percentage of humidity of the uprushing air.

The form of the funnel-like cloud ere it reaches the earth is
interesting. Being an isobaric surface, it would support in static
equilibrium a free particle resting on it and sharing its rotatory
motion. The lower rounded part of the funnel is parabolic, the upper
outer part hyperbolic; the two together delineating the well-known
Rankine double vortex of hydrodynamics. Students of hydrostatics know
that when a glass of water is spun round its axis at a fixed velocity,
the dimple observed is of parabolic form, and if frozen will sustain
in repose a small shot resting on its surface and whirling with it.
Similarly the lower part of the funnel is parabolic because in it the
air rotates, as one solid body, while the broader part of the funnel is
hyperbolic because in it the air has a speed inversely proportional to
its radius of motion.

If everywhere in a tornado the circular velocity of the inflowing air
were inversely proportional to the radius, as above assumed, the speed
near the axis would be indefinitely great. This cannot be admitted.
Practically, the inflow ceases when the centrifugal force of the
gyrating stratum equals the pressure urging it toward the axis. Within
this stratum is a column of air rotating everywhere with constant
angular velocity about the vortical axis, and thus having quite calm
air at its center. Outside this solidly rotating core the air spirals
radially inward and upward. Some idea of the stream lines in such
spiral flow may be obtained from Fig. 50 if a rapid circular motion be
added to the inward and upward velocity represented by the arrows.

In the foregoing discussion no account of friction was taken. Near the
earth’s surface this dampens the whirl and centrifugal force, so that
the air flows more directly into the vortex, while farther aloft the
centrifugal force near the axis so effectually checks the inflow as
to allow the central core of air to rush up nearly unimpeded, as in
a walled flue, taking its draught mostly from the lower part. As a
consequence, the upward speed of the heated air in the tornado tube may
be enormous, supporting in its stream objects of considerable mass.

[Illustration: FIG. 50.—FUNNEL-LIKE CLOUD SOMETIMES OBSERVED IN A
TORNADO.]

The true horizontal speed anywhere in a tornado is compounded of the
velocities of gyration and of translation, as in the cyclone. Hence the
advancing side may be considerably the swifter and more destructive,
particularly more destructive since the impact of air increases as
the square of the velocity. If the vortex were stationary it would
be equally dangerous on all sides, standing erect and symmetrical;
but it drifts with the whole mass of air, sometimes quite swiftly and
often with varying speed of travel at different levels; thus, in its
slenderest forms, appearing bent and not infrequently twisted, as
it advances writhing serpentlike through the sky. Furthermore, the
intensity of whirl may fluctuate momentarily, with consequent shifting
of the isobaric surface, including that one whose form is visible
by reason of incipient condensation; and thus the funnel-like misty
tongue appears to dart earthward as a foggy downshoot from the cloud
above, whereas its parts are really rushing upward at all times very
swiftly, whether visible or not. This agile protrusion of the nimbus,
now a tongue, now a dark and mighty tower, is the strenuous part of
the storm, the abominated “twister” which the Kansan farmer sedulously
shuns, or peeps at from a hole in the ground. Unwelcome, indeed, are
its visitations, when, with mickle and multitudinous roar, it claps
his house in sudden darkness, hurls it aloft and sows its sacred relics
over all the adjoining township, “that with the hurly-burly hell itself
awakes.”

Theory, as well as experience, accredits the tornado with vast energy
and power. For, suppose a surface stratum of air one mile in area
and one thousand feet thick to increase in absolute temperature one
per cent, thus uplifting the superincumbent atmosphere ten feet. The
total energy stored in this way equals the weight lifted multiplied by
its upward displacement. The weight is a ton per square foot and the
displacement is ten feet; hence the stored energy is ten-foot tons per
square foot of the heated tract, or about 280,000,000 foot tons for
the square mile of heated air. This is equivalent to the work of one
million horses for over a quarter of an hour. A goodly percentage of
this stored work may be converted into kinetic energy in the active
part of the dry tornado. It is the energy of a vast reservoir suddenly
gushing through a tall penstock. It is a colossal upward cataract, an
aërial Niagara, a Johnstown flood suddenly liberated and quickly spent.

A vortex of that description possesses enormous devastating power, for
it is endowed with four destructive elements: rapid onset for razing,
violent spin for distorting, swift uprush for lifting, low pressure for
disrupting. These four grim powers may operate at once and in accord.
When, for example, they assault a house, the horizontal blasts push and
wrench it on the foundation, the cellar air suddenly expanding puffs it
aloft, the internal air bursts its walls or windows, the uprush carries
its members on high and scatters them wantonly to the four winds.
These powers are abundantly attested by authentic reports from many
localities.

When the tornado appears as a misty column it is familiarly called
a “waterspout,” particularly if it appears over a sea or lake. As
already explained, the visible and cloudy portion of the column is
due to condensation of the aqueous vapor in the air, as it rushes
expanding and cooling into the low pressure part of the vortex. From
the lashed and rippling sea surface, where it upcones into the base of
the spout, some water is carried aloft as spray mingling with the mist
of the chilled vapor, but not necessarily in very large proportion,
and never rising in solid body to the cloud, as popularly supposed. On
the contrary, waterspouts, however massive and formidable looking, are
very tenuous, and may occur on land or water indifferently. Doubtless
they are better defined, more regular and more familiar over water,
and hence their name; but essentially they are vapor spouts, though
mingled at times with dust or spray. Owing to rapid precipitation of
the uprushing aqueous vapor, there may be heavy rainfall on all sides
of the waterspout, so that at sea it may be difficult for the observer
to ascertain how much of the downpour is salt water and how much is
fresh. On land the downpour is sometimes mingled with débris, and even
with live fish and frogs caught up from neighboring bodies Of water.
Copious hail also may fall with the rain, if the vortex be a lofty one.

[Illustration: FIG. 51.—VERTICAL SECTION OF THE ST. LOUIS, MO., TORNADO
OF MAY 27, 1896, SHOWING THE VORTEX TUBES IN A THEORETICAL, TRUNCATED,
DUMBBELL-SHAPED VORTEX.]

[Illustration: FIG. 52.—HORIZONTAL SECTION OF ST. LOUIS TORNADO OF MAY
27, 1896.]

The following description and analysis of a representative spout is due
to Professor Bigelow of the U. S. Weather Bureau:[70]

  “The tornado may be illustrated by the St. Louis storm of May
  27, 1896. It is a truncated dumbbell vortex out off at the
  ground on the plane where the inflowing angle is about 30°.
  This vortex is much smaller than the hurricane, although of
  the same type. It is about 1,200 meters high and about 2,000
  meters in diameter on the surface. The vortex tubes are shown
  in Figs. 51 and 52. In these figures can be seen the vortex
  tubes, geometrically spaced, through each of which the same
  amount of air rises. The rotating velocity is greatest about
  300 meters above the ground, but the dimensions are such as to
  produce enormous velocities in the lower levels. The radius in
  the outer tube is taken to be 960 meters, and the inner tube
  55 meters. The radial inward velocity on the outer tube is—8
  meters per second; on the outer tube the tangential velocity
  is 13 meters per second, and on the inner 224 meters per
  second; on the outer tube the vertical velocity is 0.27, and
  on the inner tube it is 80 meters per second. On the outer
  tube the total velocity is 15 meters per second, and on the
  inner tube 270 meters per second. The volume of air ascending
  in each tube is 774,500 cubic meters per second. On account
  of the distortion of the theoretical vortex, due to the
  cutting of the lower portion by the truncated plane, and to the
  progressive motion of the whole system that constitutes the
  tornado, there is difficulty in computing the pressure to fit
  these observed velocities and radii.

  “Tornadoes occur in the southern and southeastern quadrants of
  areas of low pressure, along the borders of the cold and the
  warm masses which entered into the structure of the cyclone.
  When a cold mass is superposed upon a warm mass, as was the
  case at St. Louis, a tornado will occur if the difference in
  specific gravity be sufficient to inaugurate a violent mixing,
  and the rotation be about a vertical axis, instead of about a
  horizontal axis, as in the case of thunderstorms.”

[Illustration: FIG. 53.—VERTICAL SECTION OF SHORT TORNADO.]

The size and form of waterspouts alter greatly with the state of the
atmosphere. As Ferrel observes, they may vary “from that of a cloud
brought down over a large area of the earth’s surface in a tornado
where the air is nearly saturated with vapor and the general base of
the clouds very low, somewhat as represented in Fig. 53, to that which
occurs when the air is very dry, and when the tornadic action is barely
able to bring the cloud down from a great height into a slender spout
of small diameter, somewhat as represented in Fig. 54. Horner says that
their diameters range from 2 to 200 feet, and their heights from 30
to 1,500 feet. Dr. Reye states that their diameters on land, at base,
are sometimes more than 1,000 feet. Oersted puts the usual height of
waterspouts from 1,500 feet to 2,000 feet, but states that in some rare
cases they cannot be much less than 5,000 or 6,000 feet. On the 14th of
August, 1847, Professor Loomis observed a waterspout on Lake Erie, the
height of which, by a rough estimate, was a half mile, and the diameter
about 10 rods at the base and 20 rods above.

“Judge Williams, in speaking of the tornado of Lee’s Summit, where he
saw it, says: ‘It seemed to be about the size of a man’s body where it
touched the clouds above, and then tapered down to the size of a mere
rod.’”

[Illustration: FIG. 54.—VERTICAL SECTION OF A TALL TORNADO.]

When the tornado vortex is so tall and strong as to carry raindrops up
to freezing strata it is commonly known as a hailstorm. The congealing
occurs usually in those isobaric surfaces which dip down in the center
of the vortex, but reach only part way to the earth. As indicated
in Fig. 55, the clear aqueous vapor near the earth is condensed to
cloud on crossing an isobaric surface of sufficiently low pressure
and temperature; then it proceeds as mingled cloud and rain till it
crosses the freezing isobar into the region of snow and hail formation;
thence finally curves outwardly to stiller air and descends as a cloud
of mingled vapor, rain and frozen parts. Of this frozen shower one
part may come to earth as hail or rain, the snow and sleet melting on
the way; while another part may be redrawn into the swift uprush, and
carried aloft till its frozen drops, or pellets, have grown so large by
accretion as to plunge to earth by sheer bulk, even though they must
traverse a furious ascending wind. A good illustration from Nature of
this cycle in the center of a hailstorm is presented in the following
by Mr. John Wise, America’s adventurous pioneer balloonist:

  “This storm originated over the town of Carlisle, Pa., on
  the 17th of June, 1843. I entered it just as it was forming.
  The nucleus cloud was just spreading out as I entered the
  vortex unsuspectingly. I was hurled into it so quickly that I
  had no opportunity of viewing the surroundings outside, and
  must therefore confine this relation to its internal action.
  On entering it the motions of the air swung the balloon to
  and fro and around in a circle, and a dismal, howling noise
  accompanied the unpleasant and sickening motion, and in a
  few minutes thereafter was heard the falling of heavy rain
  below, resembling in sound a cataract. The color of the cloud
  internally was of a milky hue, somewhat like a dense body
  of steam in the open air, and the cold was so sharp that my
  beard became bushy with hoar frost. As there were no electric
  explosions in this storm during my incarceration, it might
  have been borne comfortably enough but for the seasickness
  occasioned by the agitated air-storm. Still, I could hear
  and see, and even smell, everything close by and around.
  Little pellets of snow (with an icy nucleus when broken) were
  pattering profusely around me in promiscuous and confused
  disorder, and slight blasts of wind seemed occasionally to
  penetrate this cloud laterally, notwithstanding there was an
  upmoving column of wind all the while. This upmoving stream
  would carry the balloon up to a point in the upper clouds,
  where its force was expended by the outspreading of its
  vapor, whence the balloon would be thrown outward, fall down
  some distance, then be drawn into the vortex, again be carried
  upward to perform the same revolution, until I had gone through
  the cold furnace seven or eight times; and all this time the
  smell of sulphur, or what is now termed ozone, was perceptible,
  and I was sweating profusely from some cause unknown to me,
  unless it was from undue excitement. The last time of descent
  in this cloud brought the balloon through its base, where,
  instead of pellets of snow, there was encountered a drenching
  rain, with which I came into a clear field, and the storm
  passed on.”

As might be expected the hailstones vary much in form, size and
quantity. If by chance any stones become slightly flattened they ride
level in the ascending current, and hence by aggelation grow most
rapidly on the periphery which is a line of diminished pressure. At
times they are more or less oval, and again they appear as fragments of
considerable masses of ice, broken perhaps by collision in the violent
parts of the tornado tube. Their great variety in shape and bulk may be
appreciated from the following extracts taken from the records of the
Signal Service:

[Illustration: FIG. 55.—VERTICAL SECTION OF A HAIL TORNADO.]

In _Professional Paper of the Signal Service No. 4_, describing the
tornadoes of May 29th and 30th, 1879, in Kansas, Nebraska, Missouri,
and Iowa, this passage occurs relative to a tornado at Delphos, Mo.:

  “On the farm of Mr. Peter Bock, in the adjoining township of
  Fountain, about 4 miles W. of the storm’s centre, and during
  the hailstorm that preceded the tornado, masses of ice fell as
  large as a man’s head, breaking in pieces as they struck the
  earth. One measured 13 inches in circumference, another 15, and
  a hole made by one that fell near the place of Mr. J. H. Kams
  measured 7 inches across one way and 8 the other. This immense
  fragment of aërial ice broke into small pieces, so that its
  exact size could not be determined.”

The following description is given of the tornado that visited Lincoln
County, Neb., at that time:

“At first the hailstones were about the size of marbles, but they
rapidly increased in diameter until they were as large as hens’ eggs
and very uniform in shape. After the precipitation had continued about
fifteen minutes, the wind ceased and the small hail nearly stopped,
when there commenced to fall perpendicularly large bodies of frozen
snow and ice, some round and smooth and as large as a pint bowl, others
inclined to be flat, with scalloped edges, and others resembled rough
sea-shells. One of the latter, after being exposed an hour to the sun,
measured fourteen inches in circumference.”

The following was reported by the Signal Service observer at Fort
Elliott, Tex., 1888:

  “A thunder-storm began at 4.10 P.M. and ended at 7.40 P.M.,
  moving from southwest to northwest. Hail began at 5.18 P.M.
  and ended at 5.26 P.M., the hailstones being spheroidal in
  shape and about two inches in diameter; formation, solid snow.
  The ‘break’ (hills) at the foot of the plains several miles
  northwest of station were absolutely white with hailstones for
  three hours after the storm. This was observed by everybody
  at the station; on the morning of the 26th I walked down to
  the Sweetwater Creek, three fourths of a mile distant, and saw
  great banks of hailstones which had been washed down during the
  night. The bottoms along the Sweetwater were literally covered
  with banks of hailstones from six to eight feet in depth. It
  was estimated that there was enough hail to cover ten acres to
  a depth of six feet. The hailstones killed five horses which
  were out on the prairie on a ranch six miles north of station.
  The Sweetwater Creek was higher than ever known before, the
  freshet destroying nearly the entire post garden. The high
  water is supposed to have been caused by a ‘cloud-burst’ at
  or near the foot of the plains, where the Sweetwater has its
  source; there was only 0.36 inch of rainfall at the station. On
  Sunday, May 27th, hailstones were collected on the banks of the
  Sweetwater, which had been washed down and lay in drifts 6 feet
  deep, actual measurement by the observer.”

When, after imprisonment and long sustention in a powerful tornadic
vortex, the accumulated rain or hail finally breaks through and pours
down to earth, in solid cataract, the phenomenon is commonly called
a cloud-burst. The foregoing example is a partial illustration.
The following is quoted from Espy, describing a cloud-burst near
Hollidaysburg, Penn., in which the water seems to have poured down
nearly in a solid stream:

  “On examining the northern side of this ridge, large masses
  of gravel and rocks and trees and earth, to the number of 22,
  were found lying at the base on the plain below, having been
  washed down from the side of the ridge by running water. The
  places from which these masses started could easily be seen
  from the base, being only about 30 yards up the side. On going
  to the head of these washes they were found to be nearly round
  basins from 1 to 6 feet deep, without any drains leading into
  them from above. The old leaves of last year’s growth, and
  other light materials, were lying undisturbed above, within an
  inch of the rim of these basins, which were generally cut down
  nearly perpendicularly on the upper side, and washed out clean
  on the lower. The greater part of these basins were nearly of
  the same diameter, about 20 feet, and the trees that stood in
  their places were all washed out. Those below the basin were
  generally standing, and showed by the leaves and grass drifted
  on their upper side how high the water was in running down the
  side of the ridge; on some it was as high as three feet. It
  probably, however, dashed up on the trees above its general
  level.”

Dry whirlwinds of moderate size, but sometimes of considerable
violence, frequently occur in clear weather when the percentage of
humidity is small and when the vertical temperature gradient is
unusually pronounced. In this case there may be strong agitation of
the air, rendered visible at the earth’s surface by light débris on
land, or boiling of the water at sea; but the main body of the tube is
invisible and free from mist except high up where precipitation begins,
capped by a growing patch of white cloud in a clear sky, and which
may gradually broaden and condense sufficiently to cause a shower of
rain. On land the dry whirlwind may be delineated as a tall column, by
whirling dust or sand. In this case, if the gyration is violent, the
central core may appear clean and clear owing to the centrifugal force
which keeps the grains out where they are balanced by the pressure of
the inrushing air. In such vortices the sand spout may appear to be
hollow as in the case of waterspouts whose interior cores are free
from cloud or condensed vapor. On the other hand, myriads of mild
transparent whirlwinds unmarked, except by down or humanly invisible
dust, or dim aërial refractions, may frisk and play in the boundless
sky unnoticed by the blunt eyes of men, yet constantly engaged in
generating or marshaling the clouds and in buoying upward the ponderous
eagles, the vultures and the whole brood of passive flyers whom we
have not yet learned to emulate. Thus when we remember that an upward
trend of air of scarcely one yard per second, and too feeble to support
a falling hair, is yet sufficient to carry the condor and albatross
without wing beat, it seems important to explore these minor vortices
and to ascertain their availability and practical usefulness for human
soaring.




                             CHAPTER XVII

                       THUNDERSTORMS, WIND GUSTS


Still another interesting kind of aërial disturbance is the familiar
heat thunderstorm. This is not synonymous with those electrified
tornadoes and cyclones which are accompanied by thunder and lightning,
sometimes of great violence. Most tornadoes are thunderstorms, but
not vice versa. The thunderstorm is not essentially a vortex, but
rather a wind squall marked by sudden changes of temperature and
pressure, bearing with it massive clouds fraught with rain, or hail,
and disruptive electric charges flashing frequently to earth, or
from point to point in the sky. Its approach is usually announced by
rumbling thunder and heavy black clouds along the horizon. Its duration
is brief, varying from a few minutes to an hour or two. Further
characteristics are thus expressed by Moore:

  “On land, thunderstorms occur most frequently at specific hours
  of the day or night, such as 3 to 5 in the afternoon or 9 to 10
  in the evening and sometimes even at 2 or 3 A.M., but no such
  diurnal period is observed in midocean. The phenomena usually
  occur in a pretty regular order of succession. After several
  hours of fair weather, with gentle winds, there comes a calm;
  the cumulus clouds grow larger, the lower stratum of clouds is
  seen to be moving rapidly; gusts of wind start up with clouds
  of dust, rain is seen to be falling at a distance; the movement
  of rain and dust shows that the wind is blowing out from this
  rain cloud near the ground no matter which way the rainy region
  is advancing; a few large drops fall from slight clouds and
  then suddenly the heavy rain begins. Lightning that may have
  occurred during the preceding few minutes becomes more frequent
  and more severe as the rain increases. After the maximum
  severity of rain and wind, the lightning also diminishes or
  entirely ceases, and we are soon able to say that the storm has
  passed by. If we watch its retreat from us in the afternoon
  we shall see the rear of a great cumulus on which the sun is
  shining, but through whose dark-blue curtain of cloud and rain
  nothing save occasional lightning is visible. After the storm
  has passed, the lower atmosphere soon becomes appreciably
  cooler and drier, the sky is nearly clear of clouds, and the
  wind has shifted to some other point of the compass than that
  which prevailed before the storm.”

The genesis of thunderstorms is varied and manifold. In one simple
type, a large tract of heated air in the unstable state and with a high
percentage of humidity swells upward at the center, the ascending moist
air forming, at the precipitation altitude, a growing cloud which may
become very broad, dark and bulky, drifting along over the earth with
the prevailing current. Eventually rain begins to form, or may be hail
or snow, if the heated column reaches to a great height. The falling
shower cools the air from the cloud down to the earth, increasing its
density and materially weighting it with the descending liquid or
solid particles. The showery column then sinks, especially along its
inner part where it is maturest, thus causing an outrush of cool air
along the earth, the immediate forerunner and herald of the rain. This
outrushing current pushes upward the environing clear moist air, thus
forming new margins of massive cumuli around the older nimbus widening
within, showering, cooling and sinking. Thus the rain area is broadened
and propagated, sometimes with nearly equal speed in all directions,
but generally fastest in the direction of the most unstable condition,
or of the then prevailing drift of the atmosphere. Indeed, the forward
cloud ranks may far outspeed the wind, seeming by their imperious
bluster and gigantic gloom to commandeer new recruits, as if by magic,
out of the clear sky. Before this solemn mustering and turbulent front
of the storm the black vapors suddenly startled into visible shape,
rush buoyantly upward in ragged shreds, like smoke from unseen fires,
and quickly blend with the general array of compact cloud expanding
across the sky. Again, several thunderstorms, merged like a mountain
range in solid phalanx, may sweep abreast over a continent, with long
horizontal[71] roll, ever rising in front and upheaving the sultry
air, thus replenishing perpetually the ponderous cumuli which form
the vanguard of this far-flung and titanic march of the clouds. Such
a storm is usually powerful and persistent, commonly enduring until
the sun’s decline and the shades of night have cooled the lower air,
and thus allayed the commotion by enfeebling the forces that favor its
progress.

The speed of rise of the air beneath the base of the thunderhead is
a question of some interest in aëronautics. If the ascent be so much
as a foot or two per second, one may expect the vultures to prefer
soaring beneath the thundercloud during its formative period. Here
also the aëroplanist might attempt a record flight, if the cloud were
high enough to be out of his way. But if he ventured to penetrate the
base of the thunderhead, he might find the turmoil too irregular and
strenuous for his comfort.

Of like interest is the long aërial swell that leads the advancing
storm. When will aviators make this the theater of their adventurous
frolic, careering playfully before the brow of the tempest and the
harmless rage of the lightning, gay-winged heralds of the coming
tumult, sailing perhaps with slackened motive power, yet swift and
secure as the storm-riding petrels at sea?

Besides the winds and aërial currents commonly studied by
meteorologists, are the minor disturbances which affect more
particularly the wayfarers of the sky, whether birds or men. The
atmosphere quite usually is vexed with invisible turmoils; most
sensible, indeed, over rough territory, but conspicuous also above
the smooth terrene, and at all elevations from earth to the highest
cloudland. Before sunrise, and generally in weather uniformly overcast,
these miscellaneous and nondescript movements of the air are least
active, for any given speed of the general drift of the atmosphere;
but when the sun shines and the soil is nonuniformly heated, the
disturbances become most pronounced. A whole troop of playful zephyrs
rise and set with the sun, in addition to the diurnal winds already
studied. Over the dusty plain they reveal their presence and shape
in those coiling columns that constitute the safety vents of the
atmosphere, and obviate the disruptive violence of the uprush that
would occur should a considerable region of surface air become
excessively heated. Over the city, particularly in winter, the local
turmoils of the atmospheric surf are revealed in the play of a thousand
smoky columns, and better still, when it snows, by the incessant
swell and veering of the flaky flood whose surges and eddies bewilder
the vision by their complexity. Over the water the clouds of fog
and steaming vapor are the best index of the local zephyrs, where,
it must be remembered, the rising and veering of the vapor wreaths
accompany like motions in the atmosphere. Over the forest, field and
meadow the interminable wandering of thistle down and gauzy shreds of
vegetation, now fast, now slow, now high aloft, then sheer earthward,
indicate what erratic and perpetual motions prevail throughout the open
country even on the stillest days. In the deep bosom of the atmosphere,
the parallel ranks of the cirri all across the sky mark the crests
of undulations quite as regular and tumultuous as the billows of a
wind-swept sea; while the fierce seething and upsurging of the separate
cumuli manifest the operation of vortices of prodigious energy. These
visible billows and whirlwinds suggest an infinitude of transparent
ones hardly less powerful, at the various levels unmarked by clouds.
For wherever two streams of abnormally graded densities neighbor each
other, a readjustment may occur agitating the entire region with a host
of pulsations, squalls, cataracts and fountains which the bird and
navigator must parry with proportionate care and skill.

And it is because of the amazing resistance of these wandering zephyrs,
waves and eddies that they demand the attention of aëronauts; nay,
more, it is because of the substantial labor they can perform when
adroitly encountered and duly employed. For the simplest elements of
aërodynamic science make clear that a rising zephyr hardly strong
enough to support a falling leaf is adequate to sustain the heaviest
soaring birds and aëroplanes gliding swiftly through it. In fact, the
sailors of fast air ships feel a heavy impulse and distinct shock in
plowing those mild cross winds which, to the fixed observer, seem not
like blasts, but rather as gentle swells or harmless currents. These,
therefore, have been made the subject of investigation by various
students of aëronautics.

The first incentive to the instrumental study of the fluctuations
of the wind in speed and direction seems to have been the hope to
furnish a quantitative basis for various theories of soaring flight.
Pénaud,[72] in 1875, had explained this phenomenon by postulating
an upward current. Lord Rayleigh,[73] in 1883, had made the more
general assumption of a wind having either a variable speed or a
variable direction as a necessary and sufficient condition for such
flight. Marey,[74] in 1889, and Langley,[75] in 1893, gave elementary
qualitative explanations of soaring in a horizontal wind of variable
velocity, though neither adduced concrete data to prove that the feat
could be performed in an actual wind. Each and all of those theories
may be sound enough in the abstract, but to show that they represent
realities of art or Nature they should be applied to a concrete
instance of soaring of a machine or a bird of known resistance, in a
wind of known variability.

To such end the writer in 1892 devised an anemograph for recording
simultaneously the speed of the wind and its horizontal and vertical
components of direction, while Dr. Langley devised a very light and
delicate cup anemometer for recording the variations of wind speed in
a horizontal plane, but not the changes of direction. Both instruments
were set up in January, 1893, and both investigations were published
with the _Proceedings of the International Conference on Aërial
Navigation_ of that year; but neither investigation was pushed far
enough to prove conclusively the possibility of a particular bird
or model soaring in the particular wind recorded. The two together
did, however, reveal quite astonishing fluctuations of the wind in
both speed and direction, results that have since received ample
exemplification in the more extended records of other observers.

[Illustration: FIG. 56.—UNIVERSAL ANEMOGRAPH. (The vanes are high above
the point indicated by the break in the vertical pipe.)]

Fig. 56 shows the recording anemometer for speed and double direction
constructed by the writer in 1892. A large weather vane was firmly
strapped to a vertical pipe which turned freely on ball bearings and,
by means of a small crank actuating a chronograph pencil, recorded its
fluctuations on a long sheet of paper winding on the drum from a roll
behind. On top of the pipe and about fifteen feet from the ground,
was mounted a carefully balanced horizontal vane, from which a fine
steel wire ran down the axis of the pipe to a fixed pulley, thence
to a second recording pencil. A third pencil recorded the beats of a
pendulum, thus standardizing the speed of the paper. A fourth pencil,
not shown, was designed to record the turns of an anemometer mounted
near the top of the pipe. The records of the wind speed thus secured
are omitted for lack of standardization, as the experiments were
prematurely terminated.

[Illustration: FIG. 57.—RECORDS OF WIND VARIATION IN HORIZONTAL AND
VERTICAL DIRECTION.]

Typical records of the wind direction are shown in Fig. 57 in which
the circles represent the paths swept by the wind-vane cranks that
operated the corresponding pencils. Both vanes, as shown by their
diagrams, veered quite frequently ten degrees in a short interval of
time, and not seldom twenty to thirty degrees. Frequently, also, it was
observed, in scanning the various records, that a rise or lull in the
wind speed was accompanied by a corresponding variation in direction;
but the observations were not sufficiently numerous and extended to
establish this phenomenon as a general occurrence. But as it can be
shown theoretically that a horizontal stream of air of constant cross
section and uniform velocity at each section, can not greatly fluctuate
in velocity from point to point, without more pronounced changes of
density than the barometer records, it naturally follows that the
stream must broaden where the air speed lags, and narrow where it
accelerates; in other words, it follows that there must be some change
in direction. The records were taken in the middle of a clear open
space of two hundred acres at Notre Dame University on a sunless day in
January, 1893, when the temperature was 24° F., and the wind eight to
twelve miles per hour. Their application to the theory of soaring need
not be considered here.

Further studies of the wind pulsations were made by use of a toy
balloon attached to a long thread. The first trials are thus recounted
in the paper above cited:

  “After some preliminary tests from the top of the Physical
  Laboratory of the Johns Hopkins University, during the Easter
  vacation of 1893, I ascended the Washington Monument at
  Baltimore, where I paid out the exploring line at a height
  of 200 feet. The wind was blowing toward the southeast at
  the speed of 25 to 35 miles per hour, and the sky, which had
  remained clear till 3 o’clock, was rapidly darkening, with
  indications of approaching rain. The balloon, when let forth,
  immediately fell to a depth of 30 or 40 feet, being caught
  in the eddy of the monument, then presently encountering
  the unbiased current, sailed in it toward the southeast,
  approximately level with the spool end of the thread. After
  the balloon had drawn out 100 feet of thread I checked it to
  observe the behavior of this much of the exploring line. The
  balloon rose and fell with the tossing of the wind, but did
  not flutter like a flag, as it would do if formed of irregular
  outline. Neither did the thread flutter, nor do I believe there
  is ever a tendency in a line greatly to flutter in a current
  as does a flag or sail. Presently I paid out 300 feet of the
  exploring line, whereupon the waves in the thread became quite
  remarkable. The thread then, as a rule, was never approximately
  straight. Sometimes it was blown into the form of a helix of
  enormous pitch; at other times into the form of a wavy figure
  lying nearly in a single vertical plane; and again, the entire
  exploring line should veer through an angle of 40° to 60°,
  either vertically or horizontally. The balloon, of course,
  seldom remained quiet for more than a few seconds at a time,
  but tossed about on the great billows like a ship in a storm.
  Quite usually the billows could be seen running along the
  line from the spool to the balloon, and, as a rule, several
  different billows occupied the string at one time.

  “The observations just delineated, however curious they may
  be, afford no adequate conception of the behavior of the air
  currents over an open plane, nor at a great height above the
  earth, because the Washington Monument at Baltimore stands but
  100 feet above the surrounding buildings, which undoubtedly
  send disturbances to a greater height than 200 feet. To
  supplement these explorations, therefore, I determined to
  have them repeated from the top of the Washington Monument at
  Washington and the Eiffel Tower at Paris.”

Some months later in the year, the experiment was repeated at the top
of the Washington Monument in Washington, at a height of five hundred
feet. The balloon, with a stone attached, was paid out from the north
window of the monument till it reached the ground. Then the stone was
removed by an assistant who drew the balloon well away from the huge
eddy of the great shaft, and let it fly toward the east, drawing the
thread after it like a mariner’s log in the wake of a ship. When six
hundred feet of the thread had been let out, it was observed to veer in
all directions under the varying surges of the wind. These variations
seemed larger than could be expected from the wake of the shaft alone
near its summit, where it measures about thirty feet in thickness.

Such qualitative observations, though interesting and suggestive,
are not wholly satisfactory. The same may be said of the study of
air currents by aid of smoke from tall chimneys. The eddy about such
columns may extend to a considerable height above them, and the wake
is farreaching. The experiments would therefore best be made from high
open-work towers above plane country or a broad sheet of water.

A better method perhaps would be to liberate a pilot balloon, or
discharge a bomb giving a bright compact cloud, and to trace its path
by means of two cameras, as it floats from point to point in the
aërial current. The instruments, if suitably stationed, would give the
continuous space history of the floating object; that is, its actual
path and the speed at each part thereof, or, in other words, the
magnitude and direction of the velocity at each point. But, of course,
this method would not reveal the wind’s history at any given fixed
point, as recorded by the anemograph above described.

[Illustration: FIG. 58.—RECORDS OF WIND SPEED OBTAINED BY LANGLEY.]

Fig. 58 is a typical wind-speed record obtained by Langley in January,
1893, by means of a very light cup anemometer mounted eleven feet
above the north tower of the Smithsonian Institution, and 153 feet
from the ground. The abscissæ represent time in minutes, the ordinates
wind speed in miles per hour. The records were taken in cloudy weather
and in a south-southeast wind. Other records were taken during the
month of February, showing like deviations from the mean, though at
times more pronounced; for Dr. Langley noted that “the higher the
absolute velocity of the wind, the greater the relative fluctuations
which occur in it.”

It will be observed from this record that, when the average speed was
about twelve miles an hour, the extreme fluctuation was rarely one
third greater or less than that, and on the average varied hardly
one sixth. It must be further added that the air on approaching the
anemometer had traversed a mile of the lower residential section of
the city, then crossed the body of the Smithsonian building, which
itself is half as high as the tower. It should be expected, therefore,
that this wind was, other things equal, naturally more turbulent than
if flowing in from a level plain. This surmise is justified by the
more extensive records of wind speeds shown in meteorological records
taken respectively in clear and in obstructed places. On the other
hand, even in level places where no obstruction is visible for several
miles, the wind, though it may be steady at one time, can at another
time be gustier than that shown in Langley’s record, according to the
state of the weather; for the gusts are not all due to neighboring
obstacles, but may be transmitted from afar, even from the depths of
the atmosphere.

Assuming the wind speed at any instant to vary by one sixth of the
mean, its impactual pressure will then vary by thirty-six per cent of
the pressure of the mean wind, remembering that the pressure varies as
the square of the speed. This fluctuation of the impactual pressure
tallies fairly well with that found by Professor Marvin at the top of
Mount Washington, in 1890, by means of a pressure plate.[76] He found
the variation to be approximately thirty-five per cent of the mean
pressure. Professor Hazen, however, reports but little variation in
the wind speed in the free atmosphere well above the earth. In several
balloon ascensions he suspended from the basket a lead weight by means
of a cord to which was looped the thread of a toy balloon. He found
that the little balloon sometimes moved ahead if the weight sometimes
followed it, but that in general the relative motion was very feeble,
thus indicating that the fluctuations of the velocity in the depth of
the atmosphere at those times were very slight.[77] However this be for
such distances from the earth and its protuberances, the fluctuations
of wind speed found at meteorological stations sufficiently resemble
those reported by Dr. Langley. As corroborative evidence, the reader
may be referred to the wind records published in the _Interim Report_
for 1909, of the British Advisory Committee for Aëronautics.

Without the material evidence of commotion in the atmosphere, a
moment’s reflection will make clear that such turmoil must exist, even
over a vast, smooth plain, especially in bright weather, and more
particularly over bare ground in dry weather. For it is well known
that clear, dry air transmits radiation with very slight absorption,
when the sun is well toward the zenith, and hence that the temperature
in the depth of the atmosphere is but little changed from moment
to moment, due to the passage of sunlight. At the earth’s surface,
however, the air by contact with heating or cooling soil may change
temperature rapidly. The direct sunlight falling perpendicularly upon
a perfectly absorbent material transmits nearly two calories of heat
per minute to each square centimeter of the receiving surface. It
would, therefore, under favorable circumstances, elevate by nearly
two degrees C. per minute a layer of water one centimeter deep, or
a layer of air something over a hundred feet thick, if all the heat
falling on the assumed surface were communicated to the neighboring air
stratum. In practice, a large percentage of the incident sunlight is
reflected and radiated by the soil, into sidereal space without heating
the air. But every one per cent of it caught up by the air in contact
with the earth is sufficient to heat a layer roughly one foot thick
one degree per minute. Hence, unless the heated air streamed upward
continually, the layer next the earth would quickly be raised to a
very abnormal temperature, which would result in a violent uprush. The
gradual ascension of the surface air may take place in large or small
columns, or in both kinds at once. In either case, the composition of
the ascensional motion with the general movement of the wind due to
barometric gradient must cause gustiness and marked irregularity of
speed and direction.

Various causes have been assigned for the gustiness of the winds.
Ferrel and many other writers assume that the air, especially near
the earth, is full of small vortices rotating about axes of various
inclination. These whirls, on passing squarely across a weather vane,
cause it to point one way for a moment, then presently the opposite
way, while if they cross obliquely they cause a like sudden veering of
the vane, but less extensive.

Helmholtz has proved that in the atmosphere strata of different
densities come at regular intervals to be contiguous one above
the other, and thus to beget conditions favorable to the formation
of aërial waves, sometimes so large as to set the lower regions of
air into violent commotion and thereby generate the so-called gusty
weather. He has summarized as follows some of the important conclusions
of his dynamic analysis.[78]

“As soon as a lighter fluid lies above a denser one with well-defined
boundary, then evidently the conditions exist at this boundary for
the origin and regular propagation of waves, such as we are familiar
with on the surface of water. This case of waves, as ordinarily
observed on the boundary surfaces between water and air, is only to be
distinguished from the system of waves that may exist between different
strata of air, in that in the former the difference of density of the
two fluids is much greater than in the latter case. It appeared to me
of interest to investigate what other differences result from this in
the phenomena of air waves and water waves.

“It appears to me not doubtful that such systems of waves occur with
remarkable frequency at the bounding surfaces of strata of air of
different densities, even although in most cases they remain invisible
to us. Evidently we see them only when the lower stratum is so nearly
saturated with aqueous vapor that the summit of the wave, within which
the pressure is less, begins to form a haze. Then there appear streaky,
parallel trains of clouds of very different breadths, occasionally
stretching over the broad surface of the sky in regular patterns.
Moreover, it seems to me probable that this, which we thus observe
under special conditions that have rather the character of exceptional
cases, is present in innumerable other cases when we do not see it.

“The calculations performed by me show, further, that for the observed
velocities of the wind there may be formed in the atmosphere not only
small waves, but also those whose wave lengths are many kilometers
which, when they approach the earth’s surface to within an altitude
of one or several kilometers, set the lower strata of air into
violent motion and must bring about the so-called gusty weather. The
peculiarity of such weather (as I look at it) consists in this, that
gusts of wind often accompanied by rain are repeated at the same place,
many times a day, at nearly equal intervals and nearly uniform order of
succession.”

Commandant Le Clement de Saint-Marcq has drawn some interesting
conclusions from the hypothesis that an ordinary wind consists of a
uniform current on which is superposed periodic motions in the wind’s
main direction and also at right angles thereto. But he has not
established his hypothesis by adequate observations. He assumes the
pulsations to be simple harmonic motions, which of course they would be
if they were plane compressional waves; but at the same time he shows
that the fluctuations are too large to be compressional waves, with the
concurrent slight variations of the barometric pressure.

It is still a question whether the pulsations of the natural wind be
harmonic. If so, the speed records should be sine curves, and the to
and fro acceleration of any mass of moving air should be variable for
any given pulsation. But the few records available show in many parts a
constant acceleration of the wind speed throughout a particular swell
or lull of velocity, indicating that the pulsations are not generally
simple harmonic ones.

In scanning the wind-speed records published by Langley, so many
instances of uniform wind acceleration are noticed that one naturally
inquires whether the rate of gain of velocity be sufficient to sustain
in soaring flight an aëroplane or bird held to the wind solely by
its inertia, as Langley believed to be possible. The total forward
resistance of a well-formed aërial glider, or bird, may be taken as
one eighth of its weight; hence, if poised stationary in its normal
attitude of flight, it will just be sustained by a direct head wind
having a horizontal acceleration of one eighth that of gravity, or
four feet per second. Now, the most favorable parts of the record here
shown (Fig. 58) exhibit nowhere an acceleration so great as four feet
per second, and on the average far less than that, as may be proved
by sealing the diagram. Hence, the wind here recorded was wholly
inadequate to support by its pulsative force either bird or man. But
as this record is a fair representative of all those published by Dr.
Langley, it follows that such pulsations can at best merely aid in
soaring when happily and adroitly encountered; but that they cannot
fully sustain soaring at any level, much less during ascensional flight
to great altitudes, or migrational flight to vast distances. It still
remains, therefore, to ascertain what kind of aërial currents are
adequate to sustain those marvelous feats of soaring on passive pinions
which for ages have been the delight and wonder of all keen observers,
and which are of such enduring interest to mankind. This investigation,
however, appertains more particularly to the science of applied
aërodynamics.




                              APPENDICES




                              APPENDIX I

                    STRESS IN A VACUUM BALLOON[79]

                            _By A. F. Zahm_


As inventors frequently propose the construction of a vacuum balloon,
to secure buoyancy without the use of gas, it may be desirable to
estimate the strength of material required to resist crushing, say in a
spherical balloon.

The unit stress in the wall of a thin, hollow, spherical balloon
subject to uniform hydrostatic pressure, which is prevented from
buckling, is given by equating the total stress on a diametral section
of the shell to the total hydrostatic pressure across a diametral
section of the sphere, thus:

                           2π_rtS_ = π_pr^2_

in which _S_ may be the stress in pounds per square inch, _p_ the
resultant hydrostatic pressure in pounds per square inch, _r_ the
radius of the sphere, _t_ the wall thickness.

The greatest allowable mass of the shell is found by equating it to the
mass of the displaced air, thus:

                   4π_r_^2_t_ς_{1} = 4π_r_^3ς_{2}/3

in which ς_{1} is the density of the wall material, ς_{2} the density
of the atmosphere outside.

Now, assuming _p_ = 15, ς_{1}/ς_{2} = 6,000, for steel and air, the
equations give:

        _S_ = 3_p_ς_{1}/2ς_{2} = 45 × 6,000/2 = 135,000 pounds

per square inch as the stress in a steel vacuum balloon.

For aluminum ς_{1} is less, but the permissible value of _S_ is also
less in about the same proportion.

The last equation shows that for a given material and atmospheric
environment, the stress in the shell or wall of the spherical balloon
is independent of the radius of the surface. It is also well known
that the stress is less for the sphere than for any other surface.
Hence, no surface can be constructed in which _S_ will be less than
3_p_ς_{1}/2ς_{2}. The argument is easily seen to apply to a partial
vacuum balloon, since a balloon of one nth vacuum will float a cover of
but one nth the mass and strength.

The above result was obtained on the assumption that the shell was
prevented from buckling. As a matter of fact, it would buckle long
before the crushing stress could be attained. We must conclude,
therefore, that while a vacuum balloon has alluring features, the
materials of engineering are not strong enough to favor such a
structure. Perhaps it is nearer the truth to say that such a project is
visionary, with the materials now available.

                   •       •       •       •       •

A like argument applies to the balloon reservoir in which it has
been proposed to compress the surplus gas taken from a balloon hull
on expansion of its contents by change of level or temperature. If a
given mass of gas obeying Boyle’s law be pumped into a receiver of
given shape and mass, the resultant stress in the receiver wall will be
independent of the size. Hence the material of the proposed reservoir,
if expanded to the size of the hull itself, will weigh the same, and
suffer the same increment of unit stress, for a given mass increment of
gas. Hence, instead of pumping the above-mentioned gas surplus from the
hull into the reservoir, this latter may be discarded and its mass of
material spread over the hull itself. This argument applies only if the
shapes of hull and reservoir be equally effective, as, for example, if
both be cylindrical.




                              APPENDIX II

                AËRONAUTIC LETTERS OF BENJAMIN FRANKLIN


                                                PASSY, Aug. 30, 1783.

On Wednesday, the 27th instant, the new aërostatic Experiment, invented
by Messrs. Montgolfier of Annonay, was repeated by M. Charles,
Professor of experimental Philosophy at Paris.

A hollow Globe 12 feet Diameter was formed of what is called in England
Oiled Silk, here Taffetas gommé, the Silk being impregnated with a
Solution of Gum elastic in Linseed Oil, as he said. The Parts were
sewed together while wet with the Gum, and some of it was afterwards
passed over the Seam, to render it as tight as possible.

It was afterwards filled with inflammable Air that is produced by
pouring Oil of Vitriol upon Filings of Iron, when it was found to have
a tendency upwards so strong as to be capable of lifting a Weight of 39
Pounds, exclusive of its own Weight which was 25 lbs and the Weight of
the Air contain’d.

It was brought early in the morning to the Champ de Mars, a Field in
which Reviews are sometimes made, lying between the military School and
the River. There it was held down by a Cord till 5 in the afternoon,
when it was to let loose. Care was taken before the Hour to replace
what Portion had been lost, of the inflammable Air, or of its Force, by
injecting more.

It is supposed that not less than 50,000 People were assembled to see
the Experiment, The Champ de Mars being surrounded by multitudes, and
vast Numbers on the opposite Side of the River.

At 5 O’clock Notice was given to the Spectators by the Firing of two
Cannon, that the Cord was about to be cut. And presently the Globe was
seen to rise, and that as fast as a Body of 12 feet Diameter, with a
force only of 39 Pounds, could be suppos’d to remove the resisting Air
out of its Way. There was some Wind, but not very strong. A little
Rain had wet it, so that it shone, and made an agreeable appearance.
It diminished in Apparent Magnitude as it rose, till it enter’d the
Clouds, when it seem’d to me scarce bigger than an Orange, and soon
after became invisible, the Clouds concealing it.

The multitude separated, all well satisfied and delighted with the
Success of the Experiment, and amusing one another with discourses of
the various uses it may possibly be apply’d to, among which many were
very extravagant. But possibly it may pave the Way to some Discoveries
in Natural Philosophy of which at present we have no conception.

A Note secur’d from the Weather had been affix’d to the Globe,
signifying the Time & Place of its Departure, and praying those who
might happen to find it, to send an account of its state to certain
Persons at Paris. No News was learned of it till the next Day, when
information was received that it fell a little after 6 o’clock, at
Gonesse, a Place about four Leagues Distance, and that it was rent
open, and some say had ice in it. It is suppos’d to have burst by the
Elasticity of the contain’d Air when no longer compress’d by so heavy
an Atmosphere.

One of 38 feet Diameter is preparing by Mr. Montgolfier himself, at the
Expence of the Academy, which is to go up in a few days. I am told it
is constructed of Linen & Paper, and is to be filled with different
Air, not yet made public, but cheaper than that produc’d by the Oil of
Vitriol, of which 200 Paris Pints were consum’d in filling the other.

It is said that for some Days after its being fill’d the Ball was found
to lose an eighth Part of its Force of Levity in 24 Hours; Whether this
was from Imperfection in the Tightness of the Ball, or a Change in the
Nature of the Air, Experiments may easily discover....

M. Montgolfier’s Air to fill the Globe has hitherto been kept secret;
some suppose it to be only common Air heated by passing thro’ the Flame
of burning Straw, and thereby extreamly rarefied. If so, its Levity
will soon be deminish’d by Condensation, when it comes into the cooler
Region above....

P. S. I just now learned that some observers say, the Ball was 150
Seconds in rising, from the cutting of the Cord till hid in the Clouds;
that its height was then about 500 Toises, but, being moved out of
the Perpendicular by the Wind, it had made a Slant so as to form a
Triangle, whose base on the Earth was about 200 Toises. It is said the
Country People who saw it fall were frightened, conceiv’d from its
bounding a little, when it touched the Ground, that there was some
living Animal in it, and attack’d with Stones and Knives, so that it
was much mangled; but it is now brought to Town and will be repair’d.

The great one of M. Montgolfier is to go up, as is said, from
Versailles, in about 8 or 10 days. It is not a Globe but of a different
Form, more convenient for penetrating the Air.

It contains 50,000 cubic Feet, and is supposed to have Force of Levity
equal to 1,500 pounds weight. A Philosopher here, M. Pilâtre du Rozier,
has seriously apply’d to the Academy for leave to go up with it, in
order to make some experiments. He was complimented on his Zeal and
Courage for the Promotion of Science, but advis’d to wait till the
management of these Balls was made by Experience more certain & safe.
They say the filling of it in Montgolfier’s Way will not cost more
than half a Crown. One is talk’d of to be 110 feet Diameter. Several
gentlemen have ordered small ones to be made for their Amusement.
One has ordered four of 15 feet Diameter each; I know not with what
Purpose; but such is the present Enthusiasm for promoting and improving
this Discovery, that probably we shall soon make considerable Progress
in the art of constructing and using the Machines.

Among the Pleasanteries Conversation produces on this subject, some
suppose Flying to be now invented, and that since Men may be supported
in the Air, nothing is wanted but some light handy instrument to give
and direct Motion. Some think Progressive Motion on the Earth may
be advanc’d by it, and that a Running Footman or a Horse slung and
suspended under such a Globe so as to have no more of Weight pressing
the Earth with their Feet, then Perhaps 8 or 10 pounds, might with a
fair Wind run in a straight Line across Countries as fast as that Wind,
and over Hedges, Ditches & even Waters. It has been even fancied that
in time People will keep such Globes anchored in the Air, to which by
Pullies they may draw up Game to be preserved in the Cool & Water to be
frozen when Ice is wanted. And that to get Money, it will be contriv’d
to give People an extensive View of the Country, by running them up in
an Elbow Chair a Mile high for a Guinea, &c., &c.

                                                         B. FRANKLIN.


                                               PASSY, Nov. 22d, 1783.

... Enclosed is a copy of the Proces verbal taken of the Experiment
yesterday in the Garden of the Queen’s Palace la Muette, where the
Dauphin now resides, which being near my House I was present. This
Paper was drawn up hastily, and may in some Places appear to you
obscure; therefore I shall add a few explanatory Observations.

This Balloon was larger than that which went up from Versailles and
carried the Sheep, &c. Its bottom was open, and in the middle of the
Opening was fixed a kind of Basket Grate, in which Faggots and Sheaves
of Straw were burnt. The Air rarefied in passing thro’ this Flame rose
in the Balloon, swell’d out its sides, and Fill’d it.

The Persons who were plac’d in the Gallery made of Wicker, and attached
to the Outside near the Bottom, had each of them a Port thro’ which
they could pass Sheaves of Straw into the Grate to keep up the Flame,
& thereby keep the Balloon full. When it went over our Heads, we could
see the Fire which was very considerable. As the Flame slackens, the
rarefied Air cools and condenses, the Bulk of the Balloon diminishes
and it begins to descend. If those in the Gallery see it likely to
descend in an improper Place, they can by throwing on more Straw, &
renewing the Flame, make it rise again, and the Wind carries it farther.

One of these courageous Philosophers, the Marquis d’Arlandes, did me
the honour to call upon me in the Evening after the Experiment, with
Mr. Montgolfier, the very ingenious Inventor. I was happy to see him
safe. He informed me that they lit gently, without the least Shock, and
the Balloon was very little damaged.

This method of filling the Balloon with hot Air is cheap and
expeditious, and it is supposed may be sufficient for certain
purposes, such as elevating an Engineer to take a view of an Enemy’s
Army, Works, &c., conveying Intelligence into, or out of a besieged
Town, giving Signals to distant places, or the like.

The other method of filling a Balloon with permanently elastic
inflammable Air, and then closing it is a tedious Operation, and
very expensive; Yet we are to have one of that kind sent up in a few
days. It is a Globe of 26 feet diameter. The Gores that compose it
are red and white Silk, so that it makes a beautiful appearance. A
very handsome triumphal Car will be suspended to it, in which Messrs.
Roberts, two Brothers, very ingenious Men, who have made it in concert
with Mr. Charles, propose to go up. There is room in this Car for a
little Table to be placed between them, on which they can write and
keep their journal, that is, take Notes of everything they observe, the
State of their Thermometer, Barometer, Hygrometer, &c., which they will
have more leisure to do than the others, having no fire to take care
of. They say they have a contrivance which will enable them to descend
at Pleasure. I know not what it is. But the Expence of this machine,
Filling included, will exceed, it is said, 10,000 Livres.

This Balloon of only 26 feet diameter, being filled with Air ten times
lighter than common Air, will carry up a greater Weight than the other,
which tho’ vastly bigger, was filled with an Air that could scarcely be
more than twice as light. Thus the great Bulk of one of these Machines,
with the short duration of its Power, & the great Expence of filling
the other will prevent the Inventions being of so much Use as some may
expect, till Chemistry can invent a cheaper light Air producible with
more Expedition.

But the Emulation between the two Parties running high, the Improvement
in the Construction and Management of the Balloons had already made
a rapid Progress; and one cannot say how far it may go. A few Months
since the idea of Witches riding thro’ the Air upon a Broomstick, and
that of Philosophers upon a Bag of Smoke, would have appeared equally
impossible and ridiculous.

These Machines must always be subject to be driven by the Winds.
Perhaps Mechanic Art may find easy means to give them progressive
Motion in a Calm, and to slant them a little in the Wind.

I am sorry this Experiment is totally neglected in England, where
mechanic Genius is so strong. I wish I could see the same Emulation
between the two Nations as I see between the two Parties here. Your
Philosophy seems to be too bashful. In this Country we are not so
much afraid of being laught at. If we do a foolish thing, we are the
first to laugh at it ourselves, and are almost as much pleased with
a Bon Mot or a Chanson, that ridicules well the Disappointment of a
Project, as we might have been with its Success. It does not seem to me
a good reason to decline prosecuting a new Experiment which apparently
increases the power of a Man over Matter, till we can see to what use
that power can be applied. When we have learnt to manage it, we may
hope some time or other to find Uses for it, as men have done for
Magnetism and Electricity, of which the first Experiments were mere
Matters of Amusement.

This Experience is by no means a trifling one. It may be attended with
important Consequences that no one can foresee. We should not suffer
Pride to prevent our progress in Science.

Beings of a Rank and Nature far superior to ours have not disdained
to amuse themselves with making and launching Balloons, otherwise we
should never have enjoyed the Light of those glorious objects that rule
our Day & Night, nor have had the Pleasure of riding round the Sun
ourselves upon the Balloon we now inhabit.

                                                         B. FRANKLIN.

                                                 PASSY, Dec. 1, 1783.

In mine of yesterday I promised to give you an account of Messrs.
Charles & Roberts’ Experiment, which was to have been made this Day,
and at which I intended to be present. Being a little indispos’d, &
the Air cool, and the Ground damp, I declin’d going into the Garden
of the Tuilleries where the Balloon was plac’d, not knowing how long
I might be oblig’d to wait there before it was ready to depart; and
chose to stay in my Carriage near the Statue of Louis XV, from whence I
could well see it rise, & have an extensive View of the Region of Air
thro’ which, as the Wind sat, it was likely to pass. The Morning was
foggy, but about one o’clock the Air became tolerably clear; to the
great satisfaction of spectators, who were infinite. Notice having been
given of the intended Experiment several days before in the Papers,
so that all Paris was out, either about the Tuilleries, on the Quays
& Bridges, in the Fields, the Streets, at the Windows, or on the Tops
of Houses, besides the inhabitants of all the Towns & Villages of the
Environs. Never before was a philosophical Experiment so magnificently
attended. Some Guns were fired to give Notice that the departure of
the great Balloon was near, and a small one was discharg’d which went
to an amazing height, there being but little Wind to make it deviate
from its perpendicular Course, and at length the Sight of it was lost.
Means were used, I am told, to prevent the great Balloon’s rising so
high as might endanger its Bursting. Several Bags of Sand were taken
on board before the Cord that held it down was cut, and the whole
Weight being then too much to be lifted, such a Quantity was discharg’d
as to permit its Rising slowly. Thus it would sooner arrive at that
Region where it would be in equilibrio with the surrounding Air, and
by discharging more Sand afterwards, it might go higher if desired.
Between One & Two o’Clock, all Eyes were gratified with seeing it
rise majestically from among the Trees and ascend gradually above the
Buildings, a most beautiful Spectacle! When it was about 200 feet high,
the brave Adventurers held out and wav’d a little white Pennant, on
both sides their Car, to salute the Spectators, who return’d loud Claps
of Applause. The Wind was very little, so that the Object, tho’ moving
to the Northward, continued long in View; and it was a great while
before the admiring People began to disperse. The persons embark’d
were Mr. Charles, Professor of Experimental Philosophy, & zealous
Promotor of that Science; and one of the Messieurs Robert, the very
ingenious Constructors of the Machine. When it arrived at its height,
which I suppose might be 3 or 400 Toises, it appeared to have only
horizontal Motion. I had a Pocket Glass, with which I follow’d it,
till I lost Sight first of the Men, then of the Car, and when I last
saw the Balloon, it appear’d no bigger than a Walnut. I write this at
7 in the evening. What became of them is not yet known here. I hope
they descended by Day-light, so as to see and avoid falling among
Trees or on Houses, and that the Experience was completed without any
mischievous Accident, which the Novelty of it & the want of Experience
might well occasion. I am the more anxious for the Event, because I am
not well informed of the Means provided for letting themselves gently
down, and the Loss of these very ingenious Men would not only be a
Discouragement to the Progress of the Art, but be a sensible Loss to
Science and Society.

Tuesday Morning, December 2,—I am reliev’d from my Anxiety by hearing
that the Adventurers descended well near l’Isle Adam, before Sunset.
This Place is near 7 Leagues from Paris. Had the Wind blown fresh, they
might have gone much farther.

P.S. Tuesday Evening ... I hear farther that the Travellers had perfect
Command of the Carriage, descending as they pleas’d by letting some of
the inflammable Air escape, and rising again by discharging some Sand;
that they descended over a Field so low as to talk with Labourers in
passing and mounted again to pass a Hill. The little Balloon falling at
Vincennes shows that mounting higher it met with a Current of Air in a
contrary Direction; an Observation that may be of use to future aërial
Voyagers.

                                                         B. FRANKLIN.




                             APPENDIX III

                SUCCESSFUL MILITARY DIRIGIBLE BALLOONS

                                FRANCE


                      _The Clément-Bayard II_[80]

The _Clément-Bayard II_ may be classed among the airships usually
called “flexible.” The shape of its hull is preserved not by any rigid
framing, but by internal gas pressure maintained by ballonets fed by
ventilating fans. Moreover, the suspension which binds envelope and car
together as one solid is composed wholly of flexible elements, without
any rigid intermediary structure.

The general plan, then, of the craft comprises three prominent
features, well marked and distinct in character:

(_a_) The fish-shaped envelope with major section well forward, a form
favorable to both speed and stability.

(_b_) The trussed girderlike car whose length allows the load to be
distributed over the hull, thus preserving its nicety of outline.
The most minute and technical and mechanical details were studied
for eighteen months by M. Clément and his devoted collaborator, the
engineer Sabathier. The girder car, as will be seen presently, is
particularly well designed to serve as car, sustainer and stiffener. No
stabilizing device is attached to the envelope; all are fixed to the
car, on which is mounted also the complete propulsion plant.

(_c_) The suspension which binds the buoyant envelope to the car serves
no other purpose. Note also the ingenious arrangement of two motors
and two propellers, forming two independent systems, yet unitable
under certain conditions. The placement of the propellers, rudders and
stabilizing surfaces well above the bottom of the car, insures them
against dangerous contact on landing, or while maneuvering near the
ground.

The envelope is of rubberized Continental cloth. Its volume is 7,000
cubic meters, length 76.5 meters and major diameter 13.22 meters, or
an elongation of 5.76 diameters. Inside the gas envelope is an air bag
of 2,200 cubic meters. It is divided into two compartments, _Q_ and
_Q´_, which can be filled with air together or separately through the
air duct, _Q_, joined to a blower, _P_, run by the two motors, or by
hand when so desired. The balloon proper comprises two gas valves, _R_.
Each compartment of the ballonet has one air valve, _S_. The valves of
the type Clément-Bayard-Chauvière are automatic. Their construction is
so perfect that for the first time in France, at least on a balloon of
so large bulk, the blower runs continuously in constant communication
with the ballonet, the pressure in the envelope remaining invariable,
due to the regular play of the valves, which yield at the pressure for
which they are set. They may also be Worked by hand from the pilot’s
bridge in case of emergency. The envelope has on its upper side three
ripping seams, one in the middle, the others toward either end. These
rip panels can be worked together or separately, and permit the rapid
deflation of the balloon.

The long car is attached to the hull by hempen duck feet fastened to
a bolt rope running along the envelope below the equator; these duck
feet terminate below in steel suspension cables fixed to the car. Below
the principal bolt rope are others to which are fastened the duck
feet of the oblique cords, which assure the perfect solidarity of the
envelope and car. The steel cable sustainers have an ingenious patented
regulating windlass. The girder car consists of a latticed girder,
built of steel tubes united with cast-iron joints and steel-tie wires.
Its whole length is 45 meters, of which 14.5 meters constitute the car
proper. It is divided into segments which are easily demountable, thus
rendering it easily transportable by truck or railway. The forward
segment, _A_, tapers toward the front to a sharp point and is of
triangular cross-section. The mid segment, _B_, constituting the car,
has a quadrangular section of variable size. The rear segment, _D_, is
of triangular section, diminishing progressively toward the rear, which
rises to a sort of tail supporting the empennage and the direction
rudders. The entire girder car when resting on the ground is supported
by two pneumatic shock absorbers, _U_, _U_, projecting from its floor.

The car proper comprises three parts: in front, the motor and machine
room, 2.5 meters wide; in the middle, the elevated bridge, _N_, for
the pilot and his aide; in the rear, the passenger cabin, 8 meters
long, 1.3 meters wide and 2 meters high for the observers and wireless
telegraphy plant. The two reservoirs of essence, _M_, _m_, are placed
above the passenger about the center of pressure. The blower _P_, for
the ballonets, and the guide ropes _T_, are placed above the pilot’s
bridge.

In the motor room are symmetrically arranged two Bayard-Clément
engines, _G G_, separated enough to allow free passage between them.
Each motor is elastically supported to obviate vibrations, and connects
with the transmission shaft by a variable speed gear. The engines
can be run separately or together by a connecting sprocket chain, and
develop 100 to 130 horse-power each. The cooling of each motor is
effected by an aluminum radiator, _L L_, of large surface.

The Chauvière propellers, _K K_, six feet in diameter, are driven by
shafting and gear wheels at a normal speed of 250 rotations per minute.
A special recording device serves to show their thrust at each instant,
as also the torque of the motors.

The pilot, standing on the bridge where he enjoys a clear view, has
immediate charge of the vessel’s movements. Before him are the various
controls which he must operate, and the divers indicators which he must
consult. These are the direction wheel, the manometers, the aneroid
and registering barometers, the clinometer, the blower control to
regulate the amount and distribution of pressure, the elevating-rudder
wheel, the spark control, the ripping cord, the release string of the
guide-rope, and the system of transmitting orders to the mechanicians
whereby he can control the engines and the blowers which furnish air to
the radiator and ballonet.

The direction and poise of the vessel in flight are controlled by the
rudders and empennage at the rear, and its altitude from minute to
minute is governed by the elevating biplane _E´_, of 30 square meters
above the car in the mid region of the vessel.


                           The _Patrie_[81]

The _Patrie_, the third of its type, was first operated in 1906. The
gas bag of the first balloon was built by Surcouf at Billancourt,
Paris. The mechanical part was built at the Lebaudy Sugar Refinery.
Since then the gas bags have been built at the Lebaudy balloon shed at
Moisson, near Paris, under the direction of their aëronaut, Juchmes.
The gas bag of the _Patrie_ was 197 feet long with a maximum diameter
of 33 feet, 9 inches, situated about 2/5 of the length from the front;
volume 111,250 cubic feet; length approximately six diameters. This
relation, together with the cigar shape, is in accordance with the
plans of Colonel Renard’s dirigible, built and operated in France in
1884; the same general shape and proportions being found in the Ville
de Paris.

The first Lebaudy was pointed at the rear, which is generally admitted
to be the proper shape for the least resistance, but to maintain
stability it was found necessary to put a horizontal and vertical plane
there, so that it had to be made an ellipsoid of revolution to give
attachment for these planes.

The ballonet for air had a capacity of 22,958 cubic feet or about 1/5
of the total volume. This is calculated to permit reaching a height of
about one mile and to be able to return to the earth, keeping the gas
bag always rigid. To descend from a height of one mile, gas would be
released by the valve, then air pumped into the ballonet to keep the
gas bag rigid, these two operations being carried on alternately. On
reaching the ground from the height of one mile, the air would be at
the middle of the lower part of the gas bag and would not entirely fill
the ballonet. To prevent the air from rolling from one end to the other
when the air ship pitches, thus producing instability, the ballonet
was divided into three compartments by impermeable cloth partitions.
Numerous small holes were pierced in these partitions, through which
the air finally reached the two end compartments.

In September, 1907, the _Patrie_ was enlarged by 17,660 cubic feet
by the addition of a cylindrical section at the maximum diameter,
increasing the length but not the maximum diameter.

_The Gas Bag._—The gas bag is cut in panels; the material is a rubber
cloth made by the Continental Tire Company at Hanover, Germany. It
consists of four layers arranged as follows:

                                                          Weight oz. per
                                                           square yard.
  _a._ Outer layer of cotton cloth covered with lead chromate  2.5
  _b._ Layer of vulcanized rubber                              2.5
  _c._ Layer of cotton cloth                                   2.5
  _d._ Inner layer of vulcanized rubber                        2.21
                                                             ------
        Total weight                                           9.71

A strip of this cloth one foot wide tears at a tension of about 934
pounds. A pressure of about one inch of water can be maintained in the
gas bag without danger. The lead chromate on the outside is to prevent
the entrance of the actinic rays of the sun, which would cause the
rubber to deteriorate. The heavy layer of rubber is to prevent the
leaking of the gas. The inner layer of rubber is merely to prevent
deterioration of the cloth by impurities in the gas. This material
has the warp of the two layers of cotton cloth running in the same
direction and is called straight thread. The material in the ballonet
weighs only about 7¾ ounces per square yard, and has a strength of
about 336 pounds per running foot. When the _Patrie_ was enlarged in
September, 1907, the specifications of the material allowed a maximum
weight of 10 ounces per square yard, a minimum strength of 907 pounds
per running foot, and a loss of 5.1 cubic inches of hydrogen per square
yard in twenty-four hours at a pressure of 1.18 inches of water. Bands
of cloth are pasted over the seams inside and out with a solution of
rubber to prevent leaking through the stitches.

_Suspension._—One of the characteristics of the _Patrie_ is the “short”
suspension. The weight of the car is distributed over only about 70
feet of the length of the gas bag. To do this, an elliptical-shaped
frame of nickel-steel tubes is attached to the bottom of the gas
bag; steel cables run from this down to the car. A small hemp net
is attached to the gas bag by means of short wooden cross-pieces,
or toggles, which are let into holes in a strong canvas band which
is sewed directly on the gas bag. The metal frame, or platform, is
attached to this net by means of toggles, so that it can be quickly
removed in dismounting the air ship for transportation. The frame can
also be taken apart, 28 steel cables about 0.2 inches in diameter run
from the frame down to the car, and are arranged in triangles. Due
to the impossibility of deforming a triangle, rigidity is maintained
between the car and gas bag.

The objection to the “short” suspension of the _Patrie_ is the
deformation of the gas bag. A distinct curve can be seen in the middle.

_The Car._—The car is made of nickel-steel tubes (12 per cent nickel).
This metal gives the greatest strength for minimum weight. The car is
boat-shaped, about 16 feet long, about 5 feet wide and 2½ feet high.
About 11 feet separate the car from the gas bag. To prevent any chance
of the fire from the engine communicating with the hydrogen, the steel
framework under the gas bag is covered with a noncombustible material.

The pilot stands at the front of the car, the engine is in the
middle, the engineer at the rear. Provision is made for mounting a
telephotographic apparatus, and for a 100-candle-power acetylene
searchlight. A strong pyramidal structure of steel is built under the
car, pointing downward. In landing the point comes to the ground first
and this protects the car, and especially the propellers, from being
damaged. The car is covered to reduce air resistance. It is so low,
however, that part of the equipment and most of the bodies of those
inside are exposed, so that the total resistance of the car is large.

_The Motor._—The first Lebaudy had a 40-horse-power Daimler-Mercedes
benzine motor. The _Patrie_ was driven by a 60 to 70-horse-power
4-cylinder Panhard and Levassor benzine motor, making 1,000 r. p. m.

_The Propellers._—There are two steel propellers 8½ feet in diameter
(two blades each) placed at each side of the engine, this giving the
shortest and most economical transmission. To avoid any tendency to
twist the car, the propellers turn in opposite directions. They are
“high speed,” making 1,000 to 1,200 r. p. m.

The gasoline tank is placed under the car inside the pyramidal frame.
The gasoline is forced up to the motor by air compression. The exhaust
is under the rear of the car pointing down and is covered with a metal
gauze to prevent flames coming out. The fan which drives the air into
the ballonet is run by the motor, but a dynamo is also provided so
that the fan can always be kept running even if the motor stops. This
is very essential as the pressure must be maintained inside the gas
bag so that the latter will remain rigid and keep its form. There are
five valves in all, part automatic and part both automatic and also
controlled from the car with cords. The valves in the ballonet open
automatically at less pressure than the gas valves, so that when the
gas expands all the air is driven out of the ballonet before there is
any loss of gas. The ballonet valves open at a pressure of about O.78
inches of water, the gas valves at about 2 inches.

_Stability._—Vertical stability is maintained by means of fixed
horizontal planes. One having a surface of 150 square feet is attached
at the rear of the gas bag and due to its distance from the center of
gravity is very efficient. The elliptical frame attached under the gas
bag has an area of 1,055 square feet, but due to its proximity to the
center of gravity, has little effect on the stability. Just behind
the elliptical frame is an arrangement similar to the feathering of
an arrow. It consists of a horizontal plane of 150 square feet, and a
vertical plane of 113 square feet. To maintain horizontal stability,
that is, to enable the air ship to move forward in a straight line
without veering to the sides, fixed vertical planes are used. One runs
from the center to the rear of the elliptical frame and has an area of
108 square feet.

In addition to the vertical surface of 113 square feet at the rear of
the elliptical frame, there is a fixed plane of 150 square feet at the
rear of the gas bag. To fasten the two perpendicular planes at the
rear of this gas bag, cloth flaps are sewed directly on the gas bag.
Nickel-steel tubes are placed in the flaps, which are then laced over
the tubes. With these tubes as a base, a light tube and wire framework
is attached and waterproof cloth laced on this framework. Additional
braces run from one surface to the other and from each surface to the
gas bag. The rudder is at the rear under the gas bag. It has about 150
square feet and is balanced.

A movable horizontal plane near the center of gravity, above the
car, is used to produce rising or descending motion, or to prevent
an involuntary rising or falling of the air ship due to expansion or
contraction of the gas or to other causes. After the adoption of this
movable horizontal plane, the loss of gas and ballast was reduced to a
minimum. Ballast is carried in 10- and 20-pound sandbags. A pipe runs
through the bottom of the car from which the ballast is thrown.

There are two long guide-ropes, one attached at the front of the
elliptical frame and the other on the car. On landing, the one in front
is seized first so as to hold the air ship with the head to the wind.
The motor may then be stopped and the descent made by pulling down on
both guide-ropes. A heavy rope 22 feet long, weighing 110 pounds, is
attached at the end of a 164-foot guide-rope. This can be dropped out
on landing to prevent coming to the ground too rapidly. The equipment
of the car includes a “siren” speaking trumpet, carrier pigeons, iron
pins and a rope for anchoring the air ship, reserve supply of fuel and
water, and fire extinguisher.

After being enlarged in September, 1907, the _Patrie_ made a number of
long trips at an altitude of 2,500 to 3,000 feet. In November, 1907,
she went from Paris to Verdun, near the German frontier, a distance of
about 175 miles, in about 7 hours, carrying four persons. This trip was
made in a light wind blowing from the northeast. Her course was east,
so that the wind was unfavorable. On Friday, November 20, 1907, during
a flight near Verdun, the motor stopped due to difficulty with the
carburetor. The air ship drifted with the wind to a village about 10
miles away, where she was safely landed. The carburetor was repaired on
the 20th. Soon after, a strong wind came up and tore loose some of the
iron pickets with which it was anchored. This allowed the air ship to
swing broadside to the wind; it then tilted over on the side far enough
to let some of the ballast bags fall out. The 150 or 200 soldiers who
were holding the ropes were pulled along the ground until directed by
the officer in charge to let go. After being released, it rose and was
carried by the wind across the north of France, the English Channel
and into the north of Ireland. It struck the earth there, breaking off
one of the propellers, and then drifted to sea.


                           The _République_

This is the latest of the French military dirigible balloons, and
differs but slightly from its predecessor, the _Patrie_. The volume has
been increased by about 2,000 cubic feet. The length has been reduced
to 200 feet and the maximum diameter increased to 35½ feet. The shape
of the gas bag accounts for the 2,000 additional cubic feet of volume.
The motor and propeller are as in the _Patrie_. The total lifting
capacity is 9,000 pounds, of which 2,700 pounds are available for
passengers, fuel, ballast, instruments, etc. Its best performance was a
125-mile flight made in 6½ hours against an unfavorable wind.

The material for the gas bag of the new air ship was furnished by the
Continental Tire Company. It is made up as follows:

                               Weight oz. per
                                square yard.
  Outer yellow cotton layer         3.25
  Layer of vulcanized rubber        3.25
  Layer of cotton cloth             3.25
  Inner layer of rubber             0.73
                                  ------
      Total weight                 10.48

It is interesting to note the changes which this type has undergone
since the first one was built. The _Jaune_, constructed in 1902-3, was
pointed at the rear and had no stability plane there; later it was
rounded off at the rear and a fixed horizontal plane attached. Finally
a fixed vertical plane was added. The gas bag has been increased in
capacity from 80,670 cubic feet to about 131,000 cubic feet. The
manufacturers have been able to increase the strength of the material
of which the gas bag is made, without materially increasing the weight.
The rudder has been altered somewhat in form. It was first pivoted on
its front edge, but later on a vertical axis, somewhat to the rear of
this edge. With the increase in size, has come an increase in carrying
capacity and, consequently, a greater speed and more widely extended
field of action.


                           _Ville de Paris_

This air ship was constructed for Mr. Deutsch de la Meurthe, of
Paris, who has done a great deal to encourage aërial navigation. The
first _Ville de Paris_ was built in 1902, on plans drawn by Tatin,
a French aëronautical engineer. It was not a success. Its successor
was built in 1906, on plans of Surcouf, an aëronautical engineer and
balloon builder. The gas bag was built at his works in Billancourt,
the mechanical part at the Voisin shop, also in Billancourt. The plans
are based on those of Colonel Renard’s air ship, the _France_, built
in 1884, and the _Ville de Paris_ resembles the older air ship in many
particulars. In September, 1907, Mr. Deutsch offered the use of his air
ship to the French Government. The offer was accepted, but delivery was
not to be made except in case of war or emergency. When the _Patrie_
was lost in November, 1907, the military authorities immediately took
over the Deutsch air ship.

_Gas Bag._—The gas bag is 200 feet long for a maximum diameter of 34½
feet, giving a length of about 6 diameters, as in the _France_ and
the _Patrie_. Volume, 112,847 cubic feet; maximum diameter at about
⅜ of the distance from the front, approximately, as in the _Patrie_.
The middle section is cylindrical with conical sections in front
and rear. At the extreme rear is a cylindrical section with eight
smaller cylinders attached to it. The ballonet has a volume of 21,192
cubic feet or about ⅕ of the volume, the same proportion found in
the _Patrie_. The ballonet is divided into three compartments from
front to rear. The division walls are of permeable cloth, and are not
fastened to the bottom so that when the middle compartment fills with
air, and the ballonet rises, the division walls are lifted up from
the bottom of the gas bag, and there is free communication between
the three compartments. The gas bag is made up of a series of strips
of perpendicular to a meridian line. These strips run around the
bag, their ends meeting on the under meridian. This is known as the
“barchistode” method of cutting out the material, and has the advantage
of bringing the seams parallel to the line of greatest tension. They
are therefore more likely to remain tight and not allow the escape
of gas. The disadvantage lies in the fact that there is a loss of
33⅓ per cent of material in cutting. The material was furnished by
the Continental Tire Company, and has approximately the same tensile
strength and weight as that used in the _Patrie_. It differs from the
other in one important feature—it is diagonal thread, that is, the warp
of the outer layer of cotton cloth makes an angle of 45 degrees with
the warp of the inner layer of cotton cloth. The result is to localize
a rip or tear in the material. A tear in the straight thread material
will continue along the warp, or the weave, until it reaches a seam.

_Valves._—There are five in all, made of steel, about fourteen inches
in diameter; one on the top connected to the car by a cord, operated by
hand only; two near the rear underneath. These are automatic but can
be operated by hand from the car. Two ballonet valves directly under
the middle are automatic and are also operated from the car by hand.
The ballonet valves open automatically at a pressure of 2/3 inches of
water; the gas valves open at a higher pressure.

_Suspension._—This air ship has the “long” suspension. That is, the
weight is distributed along practically the entire length of the gas
bag. A doubled band of heavy canvas is sewn with six rows of stitches
along the side of the gas bag. Hemp ropes running into steel cables
transmit most of the weight of the car to these two canvas bands and
thus to the gas bag. On both sides and below these first bands are
two more. Lines run from these to points half way between the gas
bag and the car, then radiate from these points to different points
of attachment on the car. This gives the triangular or nondeformable
system of suspension, which is necessary in order to have the car and
gas bag rigidly attached to each other. With this “long” suspension,
the _Ville de Paris_ does not have the deformation so noticeable in the
gas bag of the _Patrie_.

_The Car._—This is in the form of a trestle. It is built of wood with
aluminum joints and O.12 inch wire tension members. It is 115 feet
long, nearly 7 feet high at the middle and a little over 5½ feet wide
at the middle. It weighs 660 pounds and is considered unnecessarily
large and heavy. The engine and engineer are well to the front, the
aëronaut with steering wheels is about at the center of gravity.

_Motor._—The motor is a 70 to 75-horse-power _Argus_, and is
exceptionally heavy.

_Propeller._—The propeller is placed at the front end of the car. It
thus has the advantage of working in undisturbed air; the disadvantage
is the long transmission and difficulty in attaching the propeller
rigidly. It has two blades and is 19.68 feet long with a pitch of
26.24 feet. The blades are of cedar with a steel arm. The propeller
makes a maximum of 250 turns per minute when the engine is making 900
revolutions. Its great diameter and width compensate for its small
speed.

_Stability._—This is maintained entirely by the cylinders at the rear.
Counting the larger one to which the smaller ones are attached, there
are five, arranged side by side corresponding to the horizontal planes
of the _Patrie_, and five vertical ones corresponding to the _Patrie’s_
vertical planes. The volume of the small cylinders is so calculated
that the gas in them is just sufficient to lift their weight, so they
neither increase nor decrease the ascensional force of the whole. The
horizontal projection of these cylinders is 1,076 square feet. The
center of this projection is 72 feet from the center of gravity of the
gas. The great objection to this method of obtaining stability, is the
air resistance due to these cylinders, and consequent loss of speed.
The stability of the _Ville de Paris_ in a vertical plane is said to be
superior to that of the _Patrie_, due to the fact that the stability
planes of the latter do not always remain rigid. The independent
velocity of the _Ville de Paris_ probably never exceeded 25 miles an
hour.

_The Rudder._—The rudder has a double surface of 150 square feet placed
at the rear end of the car, 72 feet from the center of gravity. It is
not balanced, but is inclined slightly to the rear so that its weight
would make it point directly to the rear if the steering gear should
break. Two pairs of movable horizontal planes, one at the rear of the
car having 43 square feet, and one at the center of gravity (as on the
_Patrie_) having 86 square feet, serve to drive the air ship up or down
without losing gas or ballast.

_Guide-Ropes._—A 400-foot guide-rope is attached at the front end of
the car. A 230-foot guide-rope is attached to the car at the center of
gravity.

About thirty men are required to maneuver the _Ville de Paris_ on the
ground. The pilot has three steering wheels, one for the rudder and
two for the movable horizontal planes. The instruments used are an
aneroid barometer, a registering barometer giving heights up to 1,600
feet, and an ordinary dynamometer, which can be connected either with
the gas bag or ballonet by turning a valve. A double column of water
is also connected to the tube to act as a check on the dynamometer.
Due to the vibration of the car caused by the motor, these instruments
are suspended by rubber attachments. Even with this arrangement, it is
necessary to steady the aneroid barometer with the hand in order to
read it. The vibration prevents the use of the statoscope.


                                GERMANY

Three different types of air ships are being developed in Germany. The
_Gross_ is the design of Major Von Gross, who commands the Balloon
Battalion at Tegel near Berlin. The _Parseval_ is being developed by
Major Von Parseval, a retired German officer, and the _Zeppelin_ is the
design of Count Zeppelin, also a retired officer of the German Army.


                              The _Gross_

The first air ship of this type made its first ascension on July 23,
1907. The mechanical part was built at Siemen’s Electrical Works in
Berlin; the gas bag by the Riedinger firm in Augsburg.

_Gas Bag._—The gas bag is made of rubber cloth furnished by the
Continental Tire Company similar to that used in the _Ville de Paris_.
It is diagonal-thread, but there is no inner layer of rubber, as they
do not fear damage from impurities in the hydrogen gas. Length, 131¼
feet; maximum diameter about 39⅓ feet; volume, 63,576 cubic feet; the
elongation is about 3⅓. The form is cylindrical with spherical cones at
the ends, the whole being symmetrical.

_Suspension._—The suspension is practically the same as that of the
_Patrie_. A steel and aluminum frame is attached to the lower part of
the gas bag, and the car is suspended on this by steel cables. The
objection to this system is even more apparent in the _Gross_ than in
the _Patrie_. A marked dip along the upper meridian of the gas bag
shows plainly the deformation.

_The Car._—The car is boat-shaped like that of the _Patrie_. It is
suspended thirteen feet below the gas bag.

_Motor._—The motor is a 20- to 24-horse-power, 4-cylinder
Daimler-Mercedes.

_Propellers._—There are two propellers 8³/₁₀ foot in diameter, each
having two blades. They are placed one on each side, but well up under
the gas bag near the center of resistance. The transmission is by belt.
The propellers make 800 r. p. m.

_Stability._—The same system, with planes, is used in the _Gross_ as
in the _Patrie_, but it is not nearly so well developed. At the rear
of the rigid frame, attached to the gas bag, are two fixed horizontal
planes, one on each side. A fixed vertical plane runs down from between
these horizontal planes, and is terminated at the rear by the rudder.
A fixed horizontal plane is attached on the rear of the bags as in the
_Patrie_. The method of attachment is the same, but the plane is put on
before inflation in the _Gross_ air ship, afterwards in the _Patrie_.
The stability of the _Gross_ air ship in a vertical plane is reported
to be very good, but it is said to veer considerably in attempting to
steer a straight course.

The many points of resemblance between this dirigible and the Lebaudy
type are worthy of notice. The suspension or means of maintaining
stability, and the disposition for driving are in general the same. As
first built, the _Gross_ had a volume of 14,128 cubic feet less than
at present, and there was no horizontal plane at the rear of the gas
bag. Its maximum speed is probably fifteen miles per hour. As a result
of his experiments of 1907, Major Von Gross has this year produced a
perfected air ship, built on the same lines as his first, but with
greatly increased volume and dimensions. The latest one has a volume of
176,000 cubic feet, is driven by two 75-horse-power Daimler motors, and
has a speed of 27 miles per hour.

On September 11th of this year, the _Gross_ air ship left Berlin at
10.25 P.M., carrying four passengers, and returned the next day at
11.30 A.M., having covered 176 miles in the period of a little over 13
hours. This is the longest trip, both in point of time and distance,
ever made by any air ship returning to the starting point.


                            The _Parseval_

The _Parseval_ air ship is owned and controlled by the Society for the
Study of Motor Balloons. This organization, composed of capitalists,
was formed practically at the command of the emperor, who is very much
interested in aërial navigation. The society has a capital of 1,000,000
marks, owns the _Parseval_ patents and is ready to construct air ships
of the _Von Parseval_ type. The present air ship was constructed by the
Riedinger firm at Augsburg, and is operated from the balloon house of
this society at Tegel, adjoining the military balloon house.

The gas bag is similar in construction to that of the _Drachen_
balloon, used by the army for captive work. Volume, 113,000 cubic
feet; length, 190 feet; maximum diameter, 30½ feet. It is cylindrical
in shape, rounded at the front and pointed at the rear. The material
was furnished by the Continental Tire Company. It is diagonal-thread,
weighing about 11³/₁₀ ounces per square yard and having a strength of
about 940 pounds per running foot. Its inner surface is covered with a
layer of rubber.

_Ballonets._—There are two ballonets, one at each end, each having a
capacity of 10,596 cubic feet. The material in the ballonet weighs
about 8¼ ounces per square yard, the cotton layers being lighter than
in the material for the gas bag. Air is pumped into the rear ballonet
before leaving the ground, so that the air ship operates with the front
end inclined upward. The air striking underneath exerts an upward
pressure, as on an aëroplane, and thus adds to its lifting capacity.
Air is pumped into the ballonets from a fan operated by the motor.
A complex valve, just under the middle of the gas bag, enables the
engineer to drive air into either, or both ballonets. The valves also
act automatically and release air from the ballonets at a pressure of
about 0.9 inches of water.

In the middle of the top of the gas bag is a valve for releasing the
gas. It can be operated from the car, and open automatically at a
pressure of about 2 inches of water. Near the two ends and on opposite
sides are two rip strips controlled from the car by the cords.

_Suspension._—The suspension is one of the characteristics of the air
ships, and is protected by patents. The car has four trolleys, two on
each side, which run on two steel cables. The car can run backwards
and forwards on these cables, thus changing its position with relation
to the gas bag. This is called “loose” suspension. Its object is to
allow the car to take up, automatically, variations in thrust due to
the motor, and variations in resistance due to the air. Ramifications
of hemp rope from these steel cables are sewed onto a canvas strip,
which in turn is sewed onto the gas bag. This part of the suspension is
the same as in the _Drachen_ balloon. The weight is distributed over
the entire length of the gas bag.

_The Car._—The car is 16.4 feet long and is built of steel tubes and
wire. It is large enough to hold the motor and three men, though four
or five may be taken.

_Motor._—The motor is a 110-horse-power Daimler-Mercedes. Sufficient
gasoline is carried for a run of twelve hours.

_Propeller._—The propeller, like the suspension, is peculiar to this
air ship and is protected by patents. It has four cloth blades which
hang limp when not turning. When the motor is running, these blades,
which are carefully weighed with lead at certain points, assume the
proper position due to the various forces acting. The diameter is 13¾
feet. The propeller is placed above the rear of the car near the center
of resistance. Shaft transmission is used. The propeller makes 500
r. p. m. to 1,000 of the motor. There is a space of 6½ feet from the
propeller blades to the gas bag, the bottom of the car being about 30
feet from the gas bag. This propeller has the advantage of being very
light. Its position, so far from the engine, necessarily incurs a great
loss of power in transmission.

The steering wheel at the front of the car has a spring device for
locking it in any position.

The 1908 model No. 1 of this air ship was constructed for the purpose
of selling it to the government. Among other requirements is a 12-hour
flight without landing, and a sufficient speed to maneuver against a
22-mile wind. A third and larger air ship of this type is now under
construction.


                             UNITED STATES

                    _Signal Corps Dirigible No. 1_

Due to the lack of funds, the United States Government has not been
able to undertake the construction of an air ship sufficiently large
and powerful to compete with those of European nations. However,
specifications were sent out last January for an air ship not over 120
feet long and capable of making 20 miles per hour. Contract was awarded
to Capt. Thomas S. Baldwin, who delivered an air ship last August to
the Signal Corps, the description of which follows:

_Gas Bag._—The gas bag is spindle shaped, 96 feet long, maximum
diameter, 19 feet 6 inches, with a volume of 20,000 cubic feet. A
ballonet for air is provided inside the gas bag, and has a volume of
2,800 cubic feet. The material for the gas bag is made of two layers of
Japanese silk, with a layer of vulcanized rubber between.

_Car._—The car is made of spruce, and is 66 feet long, 2½ feet wide and
2½ feet high.

_Motor._—The motor is a 20-horse-power water-cooled Curtiss make.

_Propeller._—The propeller is at the front end of the car, and is
connected to the engine by a steel shaft. It is built of spruce, has
a diameter of 10 feet, 8 inches, with a pitch of 11 feet, and turns
at the rate of 450 r. p. m. A fixed vertical surface is provided at
the rear end of the car to minimize veering, and a horizontal surface
attached to the vertical rudder at the rear tends to minimize pitching.
A double horizontal surface controlled by a lever and attached to the
car in front of the engine, serves to control the vertical motion and
also to minimize pitching.

The position of the car very near to the gas bag, is one of the
features of the Government dirigible. This reduces the length and
consequently the resistance of the suspension, and places the propeller
thrust near the center of resistance.

The total lifting power of the air ship is 1,350 pounds of which
500 pounds are available for passengers, ballast, fuel, etc. At its
official trials a speed of 19.61 miles per hour was attained over a
measured course and an endurance run lasting two hours, during which
seventy per cent of the maximum speed was maintained.

_Dirigible No. 1_, as this air ship has been named, has already served
a very important purpose in initiating officers of the Signal Corps
in the construction and operation of a dirigible balloon. With the
experience now acquired, the United States Government is in a position
to proceed with the construction and operation of an air ship worthy of
comparison with any now in existence, but any efforts in this direction
must await the action of Congress in providing the necessary funds.




                              APPENDIX IV

        THE RELATIONS OF WEIGHT, SPEED AND POWER OF FLYERS[82]

                    _By Wilbur and Orville Wright_


The flyer of 1903 carried a four-cylinder gasoline motor of four-inch
bore and four-inch stroke. Complete with magneto, radiators, tanks,
water, fuel, etc., the motor weighed a little over 200 pounds, and at
1,200 revolutions per minute developed 16 horse power for the first 15
seconds after starting. After a minute or two the power did not exceed
13 or 14 horse power. At 1,020 revolutions per minute—the speed of the
motor in the flights at Kitty Hawk on the 17th of December, 1903—it
developed about 12 horse power.

The flyer of 1904 was equipped with a motor similar to the first, but
of 1/8-inch larger bore. This engine at 1,500 revolutions per minute
developed 24 horse power for the first 15 seconds, but only 16 to 17
horse power after a few minutes run. Complete with water, fuel and
other accessories, it weighed 240 pounds.

The same engine with a few modifications in the oiling device and the
carburetor, was used in all the flights of 1905. A test of its power
made soon after the flights of October, 1905, revealed a gain of 3
horse power over tests made just before mounting it on the flyer
in 1904. This gain is attributed to the increased smoothness of the
cylinders and pistons produced by wear. The small output of these
engines was due to lack of experience in building gasoline motors.

During the past year further improvements have been made, and our
latest engines of four-inch bore and four-inch stroke produce about 25
horse power continuously. The improvement in the reliability of the
motor has been even more marked, so that now flights of long distances
can be attempted without danger of failure on account of the stopping
of the motor.

A comparison of the flyers of 1903, 1904 and 1905 show some interesting
facts. The flyer of 1903 weighed, complete with operator, 745 pounds.
Its longest flight was of 59 seconds duration, with a speed of 30 miles
an hour and an expenditure of 12 horse power. The flyer of 1904 weighed
about 900 pounds, including a load of 70 pounds in iron bars. A speed
of more than 34 miles an hour was maintained for a distance of three
miles with an expenditure of 17 horse power. The flyer of 1905 weighed,
including load, 925 pounds. With an expenditure of 19 to 20 horse power
it traveled over 24 miles at a speed of more than 38 miles an hour. The
flights of 1904 and 1905 would have been slightly faster had they been
made in a straight line, as were those of 1903.

In 1903, 62 pounds per horse power were carried at a speed of 30 miles
an hour; in 1904, 53 pounds, at 34 miles an hour; and in 1905, 46
pounds at 38 miles an hour. It will be noted that the weight carried
per horse power is almost exactly in inverse ratio to the speed, as
theory demands—the higher the speed, the smaller the weight carried per
horse power.

Since flyers can be built with approximately the same dynamic
efficiency for all speeds up to 60 miles an hour, a flyer designed to
carry a total weight of 745 pounds at 20 miles an hour would require
only 8 horse power or two thirds of the power necessary for 30 miles an
hour. At 60 miles 24 horse power would be necessary—twice that required
to carry the same weight at 30 miles an hour. At 120 miles an hour 60
to 75 horse power would probably be necessary, and the weight carried
per horse power would be only 10 or 12 pounds. At such high speed
the resistance of the operator’s body and the engine is a formidable
factor, consuming 64 times as much horse power as at 30 miles an hour.
At speeds below 60 miles an hour this resistance is almost negligible.

It is evident that the limits of speed have not as yet been closely
approached in the flyers already built, and that in the matter of
distance, the possibilities are even more encouraging. Even in the
existing state of the art it is easy to design a practical and durable
flyer that will carry an operator and supplies of fuel for a flight of
over 500 miles at a speed of 50 miles an hour.




                              APPENDIX V

          CURTISS’S EXPERIMENTS IN RISING FROM THE WATER[83]


During the past two years Glenn H. Curtiss, who, more than any other
experimenter, has been given to developing the aëroplane for various
uses, has experimented with floats for his biplane that would enable
it to rise from the surface of the water. Something over a year ago he
succeeded in developing a speed of about twenty miles an hour on the
water, but this was insufficient to rise from the surface.

At the beginning of the new year Mr. Curtiss moved to the Pacific Coast
and set about endeavoring to develop suitable floats which would make
it possible for his machine to rise from the surface of the water.
These experiments have been carried on at San Diego, where Mr. Curtiss
is instructing several naval and military officers in the art of flying.

In his first experiments on the Pacific Coast Mr. Curtiss followed
the successful experiments of this sort made by M. Henri Fabre at
Marseilles, France, about a year ago, as far as the design of his
floats was concerned. He constructed one large float six feet wide,
five feet from front to rear, and one foot thick at its central point,
and placed this under the center of the machine. The bottom of this
float was perfectly flat and arranged at an incline of ten or twelve
degrees. Some distance forward of the main float, at about the position
of the front wheel in the land machine, another float six feet wide,
by one foot from front to rear, and six inches deep, was placed; while
at the extreme front end of the machine, on a special outrigger, was
mounted a small elevating hydroplane six feet wide by eight inches
in a fore-and-aft direction, and one and one-half inches thick. This
hydroplane was fixed at an angle of about twenty-five degrees and was
intended to lift the front part of the machine. A spray shield was
fitted back of it, as shown in the diagram, page 333.

The first experiments were made with these new floats on January 26th
last; and although they made a considerable disturbance in the water,
especially at low speed, the aviator was enabled to get up a speed on
the surface of about forty-five miles an hour. He found that at as low
a rate as ten miles the hydroplanes (which normally were submerged)
rose to the surface, while as the speed increased only the rear edges
of the two main planes were required to support the machine. The
aëroplane readily attained sufficient speed to rise in the air, for
as the speed increased and the floats emerged from the water, the
head resistance of the floats diminished and there was only the skin
friction of the water on a few inches of the rear edge of these floats,
plus the air resistance, to be overcome.

At the first try-out, while traveling over the water at high speed,
Mr. Curtiss found himself suddenly nearing the shore, and to avoid
running aground he turned his horizontal rudder sharply upward, with
the result that the machine rose from the water with perfect ease.
He soon alighted again, and in the second flight he made a circle
and remained in the air a minute and twenty-one seconds. Two other
experimental flights were made the first day, and on January 27th he
made a three-and-one-half-minute flight and stated, upon alighting,
that he found no difficulty in remaining aloft as long as he pleased.
The machine showed a speed of fifty miles an hour in the air as against
forty-five miles an hour when skimming over the surface of the water.

PLATE XXXII.

[Illustration: CURTISS STARTING FROM THE WATER.]

[Illustration: CURTISS BIPLANE FOR LAND AND WATER.]

[Illustration: CURTISS TRIPLANE RISEN FROM THE WATER.]

Not satisfied with the several floats with which he had attained
his first success in rising from the water, Mr. Curtiss immediately
constructed a single float twelve feet long by two feet in width
and twelve inches deep. This float is built of wood and resembles a
flat-bottomed boat or scow, the top being covered with canvas to keep
the water from getting in. Three feet from the front end the bottom
is curved upward forming a bow the full width of the float, while at
the same distance from the rear the float slants downward in a similar
manner.

This single float is placed under the aëroplane in such a position that
the main weight of the machine and aviator is slightly to the rear of
the center of the float, which causes the latter to incline upward
slightly and thus gives the necessary angle for hydroplaning on the
surface of the water. The weight of this new float is but fifty pounds,
or less than half as much as that of the two floats that were used
before.

The paint was barely dry on the new float before Mr. Curtiss had it
fitted to his machine and gave it a trial. This was done on February
1st and the trial was thoroughly successful. The machine ran over the
surface of the water with very much less disturbance than before and
rose in the air readily. A glance at the photographs showing the new
and the old floats in action will give one an excellent idea of the
much less commotion caused by the single scow-shaped float. Besides
being much more compact and creating less disturbance, this float or
scow can be used for carrying articles or a passenger.

In order to keep the aëroplane from tilting to one side or the other,
an inclined stick four feet long and three inches wide, to which is
attached on its upper side an inflated rubber tube, is fastened to the
front edge of the lower plane at each end. By the use of these props
the aëroplane does not tip readily when skimming along the surface,
even though the scow-shaped float used is but two feet in width.

After meeting with success with his new float, Mr. Curtiss, on February
17th, made more flights with the motor and propeller placed at the
front of his biplane and with his seat placed at the rear of the main
planes. The chief of these flights was one which he made from North
Island, where he is experimenting, over San Diego harbor to the cruiser
_Pennsylvania_. He alighted upon the surface close beside the cruiser
and his aëroplane was hauled up beside the warship and placed on her
deck.

After a short visit on the cruiser the aviator was again lowered to the
surface in his machine. A sailor started the engine, and Mr. Curtiss
flew back to his starting point in short order. The naval authorities
were greatly pleased with his demonstration and it is probable that the
Navy Department will purchase one of these machines in the near future
and continue the instruction of its officers.

After increasing the surface of his biplane Mr. Curtiss, on February
24th, took up one of his naval pupils, Lieutenant T. G. Ellyson, as
a passenger. He made a flight of one and one-half miles, rising to a
height of one hundred feet and flying as slowly as twenty-five miles an
hour, or as fast as fifty miles an hour, at will. Lieutenant Ellyson
was seated on the pontoon below the aëroplane. He could look down
in the water and see bottom at a depth of twenty-five feet, and he
believes submarines can be easily located by flying over the water.
The slow speed at which it is possible to fly will make the biplane
especially useful for bomb dropping. As we go to press Mr. Curtiss is
about to try his machine fitted with wheels and floats as well.




                                 INDEX


    Abbe, Cleveland, 200, 437.

    Acosta, 10.

    Ader, C. F., 222-226.

    Aërial Experiment Association, 264-267, 305.

    Aëro Club of America, 243, 244, 322, 323.
      of France, 106, 256, 258, 259, 301.
      of Great Britain, 287.

    Aëro Corporation Limited, 322.

    Aërodrome, 111, 194, 240, 292.

    Aëronat, 126.

    Aëronautic meteorology, 347 _et seq._

    Aëronautic Society of New York, 284.

    _Aëronautical Annual_, 215, 227, 427.

    _Aëronautics_, 252.

    _Aërophile_, 130, 166, 340.

    Aëroplanes, Ader’s, 222-226.
      advances in, in 1909, 283, 284.
      Aërial Experiment Association’s, 264-267.
      _Antoinette_, 288, 289, 320, 324.
      Blériot’s, 267-270, 286, 287, 290-292, 299, 300, 309.
      Bréguet’s, 313.
      Chanute and Herring’s, 218-221.
      Cody’s, 305.
      competitive flying of, 283 _et seq._
      cost of, 342.
      Curtiss’, 264-266, 284-286, 294-300, 316, 317, 322, 333.
      Delagrange’s flights with, 261-263.
      _Demoiselle_, 324.
      Deperdussin’s, 399.
      earliest public flight of, 257.
      Esnault-Pélterie’s, 304, 314, 337.
      Etrich’s, 335, 336.
      Fabre’s, 332, 335.
      Farman’s, Henri, 259-264, 298, 303, 305, 321.
      Farman’s, Maurice, 305, 311.
      first tour in, 268-270.
      first town-to-town flight in, 264.
      Grade’s, 304.
      Hanriot’s, 339.
      Herring’s compressed air, 221, 222.
      impossibility of, 12.
      Langley’s, 239-243.
      launching of, 202.
      Le Bris’, 203-205.
      Lilienthal’s, 207-209.
      Mattullath’s, 235-239.
      Maxim’s, 226-228.
      model, 173 _et seq._
      Montgomery’s, 251-255, 282.
      Mouillard’s, 207-209.
      Nieuport’s, 339.
      nineteenth century, 202 _et seq._
      Paulhan’s, 324, 325.
      Pilcher’s, 216-218.
      public flying, 256 _et seq._
      reliability of, 341.
      Santos-Dumont’s, 256-258, 303, 324.
      stability of, 232-234.
      stable and powerful, 235 _et seq._
      Tellier’s, 312.
      utility of, 341.
      Voisin’s, 259, 267, 313.
      Wright brothers’, 245-249, 270-282, 309, 324, 326, 329.
      Zahm’s system of control of, 229-231.

    Aërostal, 22.

    Æschylus, 29.

    Agobard, 22.

    Ailerons, 286.

    Air bag, 83.

    Air friction, 238, 239.

    Airscout, 11, 12.

    Allen, Gen. James, 271.

    Alps, Chavez’s flight across, 318, 319.

    Altitude records, 307-309.

    _American Engineer and Railway Journal_, 229.

    American military dirigible, 138.

    _Antoinette_ monoplane, 288, 289, 309, 320, 324, 340.

    Archdeacon, Ernest, 256.

    Archibald, Douglass, 77.

    Archytas of Tarentum, 198.

    Arlandes, Marquis de, 38-42.

    Ascending trend of wind, 211.

    Assman, Professor, 72.

    Astra Society, 120, 123, 124.

    Atmosphere, composition of, 348-350.
      cyclones, tornadoes, waterspouts, 394 _et seq._
      general circulation of, 376-380.
      general properties of, 347 _et seq._
      permanent and periodic winds, 376 _et seq._
      temperature and pressure, 363 _et seq._
      thunderstorms, windgusts, 422 _et seq._

    Aubrun, Emile, 331.

    Audemars, 324.

    Automobile Club of France, 321.


    Bacon, Roger, 20.

    Balance, complete dynamical, 234.

    Baldwin, F. W., 264, 266.
      Thomas S., 138.

    Ballonets, 95.

    _Ballons sondes_, 72.

    Balloon, dirigible:
        Baumgarten and Wölfert’s, 99.
        _Belgique_, 129.
        Blanchard’s, 79, 80.
        British and American, 130, 131.
        _Clément-Bayard I_, 123.
        _Clément-Bayard II_, 131, 132, 133.
        combined with aëroplane, 123.
        _Colonel Renard_, 124, 126.
        development of rigid, 145 _et seq._
        Dupuy de Lome’s, 19, 92, 93.
        early experiments with Zeppelin, 147-150.
        early gasoline driven, 10 _et seq._
        electric, 92-97.
        _España_, 124, 126, 127.
        first designs for, 78-86.
        general design of _Zeppelin_, 146, 147.
        German aërial fleet, 141, 142.
        German nonrigid, 138.
        Giffard’s, 90, 91, 98.
        Gross type of, 138, 139, 140, 471-473.
        Hänlein’s, 98.
        Hopkinson’s suggestion for, 84.
        Italian, 130.
        _Jaune_, 115, 116.
        Jefferson’s suggestion for, 84.
        Jullien’s model, 88.
        _Lebaudy_, 116, 117.
        Lebaudy’s, 115-120, 134-137.
        _Liberté_, 120.
        maneuvers at Cologne, 143, 144.
        Meusnier’s designs for, 85, 86.
        Miolan and Janinet’s, 81.
        _Morning Post_, 134.
        muscular driven, 80, 82, 85, 92.
        Parseval type of, 138, 139, 140-143, 473-476.
        _Patrie_, 115, 118, 119.
        Porter’s, 86, 87.
        practical development of nonrigid, 115 _et seq._
        practical speed of, 101.
        Renard and Krebs’, 93-97.
        _Republique_, 115, 118, 119, 466.
        Robert’s, 81, 82, 83.
        _Russie_, 120.
        Santos-Dumont’s, 102-114.
        Schwartz’s, 99, 100.
        steam, 87, 89.
        successful military, 456.
        two systems of, 101.
        types of, 122.
        _U. S. Military I_, 138, 476, 477.
        _Ville de Nancy_, 124, 125.
        _Ville de Paris_, 120-123, 467-471.
        voyage of across English channel, 132, 136, 137.
          in _Zeppelin_, 153-156.
        _Zeppelin IV_, explosion, 157, 158.
        _Zeppelin_ passenger service, 167-169.
        _Zeppelin_ type of, 145-169.
        _Zodiac_ type of, 127, 128, 129.
      passive:
        cabinet for lofty ascents in, 71, 72.
        Charles’ passenger, 42, 43.
        cruise of, from London to Weilburg, 54.
        dragon fire-inflated, 20.
        earliest conceptions of, 18, 29.
        earliest experiments with, 30, 31, 32.
        early history of, 29 _et seq._
        first coal gas, 54.
        first human passengers in, 38.
        first hydrogen, 35.
        first passengers in, 37.
        first scientific ascension in, 44, 45.
        Glashier’s observations in, 64-70.
        highest ascent of, 69, 70, 71, 72.
        instruments and adjuncts to, 76, 77.
        largest hot air, 48-50.
        largest gas, 70, 71.
        longest voyage of, 74.
        modern spherical, 75.
        Nadar’s _Geant_, 60, 61.
        practical development of, 54 _et seq_.
        principle of, 18.
        public inauguration of, 33, 34.
        recent improvements in, 76, 77.
        ripping panel of, 74, 75.
        sounding and pilot, 72.
        voyage across the Atlantic in, 74, 75.
          across the English channel in, 50, 52.
          Paris to Meaux in, 61, 62.
          Paris to Nienburg in, 62, 63.

    Balsan, 74.

    Baltimore aviation meet, 319.

    _Baltimore Sun_, 319.

    Barometric pressure, 363 _et seq._
      distribution of, 370-374.
      gradient of, 370.
      high and low areas of, 372.
      hygrometric features of, 373.
      mechanical features of, 373, 374.
      modifying conditions of, 371, 373.
      surfaces and lines of equal, 370, 371.

    Basenach, 138.

    Baumgarten, 99.

    _Belgique_, the, 129.

    Bell, A. G., 194, 244, 264-267.

    Bell, Mrs. A. G., 264.

    Belmont Park, 310, 322.

    Bennett international contests, 75, 292-301, 325, 326.

    Berson, Professor, 70.

    Betheny Plain, 292.

    Bielovucic, Jean, 313.

    Bigelow, Professor, 412, 413.

    Biplane, 174, 220.

    Birds, armed against airships, 11.
      as men carriers, 10, 11, 12.
      major limit of, 11, 12.

    Bishop, Cortlandt Field, 285.

    Black, 29.

    Blanchard, 15, 16, 18, 50, 79, 80.

    Blériot, Louis, 267-270, 286, 287, 290-292, 299-300, 380-382.

    Bréguet, Louis, 313.

    Brookins, Walter, 309, 326.

    Brown, D. S., 193.

    Bubbles, soap and varnish, 30.


    Calm belts, 381.

    Cammerman, Lieutenant, 314.

    Cardan, 10.

    Catapult, 240, 338.

    Cavallo, 30, 31.

    Cavendish, 29.

    Cayley, Sir George, 181, 182.

    Chanute, Octave, 15, 181, 218-221, 245, 250, 256, 260.

    Charles, 35.

    _Charlière_, 42.

    _Chauvière_, 125, 136, 331, 339.

    Chavez, George, 318, 319.

    _Circuit de l’Est_, 339, 331.

    _Clément-Bayard_, the, 123, 131-133, 456-459.

    Cody, S. F., 305.

    _Colonel Renard_, the, 124, 126.

    _Compagnie General Transaerienne_, 124.

    Control, three rudder system of, 229-331.

    Coulomb, 17, 18.

    _Country Life_, 321.

    Coxwell, 64-70.

    Critical temperature and pressure, 351.

    Cross-country records, 311-314.

    Curtiss, Glenn H., 138, 264-266, 282, 284-286, 294-300, 316, 317,
            322, 323, 481 _et seq._

    Cyclone, frequency of, 403, 404.
      motions and pressures in, 395, 400.
      motive power of, 395.
      nature of, 394.
      progression of, 401-403.
      stationary, 403.


    Daedalus, 3, 4, 5, 6.

    _Daily Mail_, London, 314.

    Daimler engine, 99, 150.

    Dante, J. B., 13, 14.

    Dauberck, Dr. W., 403.

    Da Vinci, 8, 9.

    De Bacqueville, 13, 14.

    Delagrange, Leon, 261-263.

    Delcourt, Dupuis, 100.

    De Laland, 16, 18.

    De Lesseps, Count, 327, 328.

    De Lome, Dupuis, 91, 92, 93.

    _Demoiselle_ monoplanes, 324.

    Déperdussin, 339.

    Deutsche de la Meurthe, 120 259.

    Dew point, 358.

    Dientsbach, Carl, vii, 164.

    Distance records, 311-314.

    Doldrums, 381.

    Doubleday, Page & Co., 478.

    Drift, defined, 186.

    Dubonnet, 312.

    Du Cros, Arthur, 131.

    Dutrieu, Helene, 321.

    Dynamic flyers, 174.


    Endurance records, 311-314.

    Engine, Daimler, 99, 150, 163.
      Gnome, 312.
      Körting, 139.
      Mercedes, 140.
      Panhard-Levassor, 136.
      Rénault, 311.
      Vivinus, 129.

    _Engineering News_, 435.

    English Channel flights, 50-53, 56, 137, 289-292.

    English military dirigibles, 130-137.

    _Eole_, 223.

    Equator of balloon, 76.

    Equilibrium, of angels, 7, 8.

    Esnault-Pélterie, Robert, 304, 314, 337, 340.

    _España_, the, 124, 126, 127.

    Espy, 419, 420.

    Etrich, Igo, 335, 336.


    Fabre, 332-335.

    Farman, Henri, 259-264, 298, 303, 305, 321.
      Maurice, 305, 311.

    Federation Aëronautique International, 322, 323.

    Fequant, Lieutenant, 312.

    Ferber, Captain, 256.

    Ferrel, W., 356, 376-379, 397, 413, 436.

    Fin, 229.

    _Flesselle_, the, 48, 49, 50.

    Flexible balloons, 122, 123.

    Fluctuating winds, 427-439.
      cause of, 436-438.
      impact of, 435, 436.

    Flying machine, impossibility of, 12, 17.

    Flying machine models, 173 _et seq._
      Abbe’s proposed, 200.
      Cayley’s aërial glider, 181, 182.
      Da Vinci’s helicopter, 175.
      Da Vinci’s parachute, 177, 178.
      Forlanini’s helicopter, 200.
      Garnerin’s parachute, 179.
      Hargrave’s, 190, 191.
      Helicopter, 198-201.
      Henson’s aëroplane, 182-184.
      Henson and Stringfellow’s, 184, 185, 187.
      Langley’s, 192-197.
      Launoy and Bienvenu’s, 198, 199.
      Lenormand’s parachute, 177, 178.
      Paper traveling parachutes, 180, 181.
      Penaud’s toy, 188.
      Phillips’ aëroplane, 191, 192.
      Phillips’ helicopter, 199.
      Tatin’s aëroplane, 189.
      Veranzio’s parachute, 177, 178.
      Wenham’s aëroplane, 185, 186.
      Zanonia Macrocarpa, 180.

    Forbes, A. Holland, 6.

    Forlanini, Professor, 200.

    Fort Myer flights, 138, 272, 275-281.

    Foulois, Lieutenant Benjamin, 278.

    _France_, the, 93-97.

    Franklin, Benjamin, 48, 446.

    Free air, composition of, 349.
      conditions of precipitation in, 351, 352.
      critical points of constituents of, 351.
      dynamical properties of dry, 353, 356.
      friction of, 239.
      humidity and density of, 358-361.
      kinds of expansion of, 361, 362.
      properties of moist, 357, 361.

    French Academy, 17, 35.

    French dirigibles, 88-129.


    Garnerin, Jacques, 179.

    Garros, 324.

    Gasnier, Réné, 340.

    German Airship Society, 166, 167.

    German dirigibles, 138-169.

    Giffard, Henri, 71, 88, 89, 90, 91.

    Glaisher, James, 68-70.

    Gliding machines, 203-221, 245-248.

    Gnome engine, 312, 331, 340.

    Godard, 62, 74, 129.

    Gold-beater skin balloons, 30, 88.

    Grade, 314.

    Grahame-White, Claude, 315, 316, 319, 325, 327, 328.

    Gravitational stability, 233.

    Green, Charles, 54.

    Gross, Major von, 138.

    Gross dirigibles, 138, 139, 140.

    Guide rope, or drag rope, 56, 76, 111, 114.


    Hailstorms and hailstones, 415-419.

    Hamilton, C. K., 313.

    Hammer, W. J., vii.

    Hangar, 126.

    Hänlein, 98, 99.

    Hann, 365.

    Hanriot, 339.

    Hargrave, Lawrence, 190, 191, 250, 260, 339.

    Harmon, Clifford B., 321.

    Hawley, A. R., 75.

    Hazen, Prof. H. A., 435.

    Hearne, 131, 228.

    Helicopters, 198-201.

    Helmholtz, Prof. Ludvig von, 436-438.

    Henson, 182-184.

    Herring, A. M., 218-222, 245, 271.

    Holland, Robert, 54.

    Hopkinson, Francis, 84.

    Horner, 414.

    Hoxsey, Arch, 309, 324.

    Huffaker, E. C., 247.

    Hull, best forms of, 88, 97, 98, 113.
      stiffening of, by internal pressure, 83, 86.

    Humidity, absolute, 359.
      percentage of, 358.

    Humphreys, Dr. W. J., vii, 349, 370.

    Hydro-aëroplanes, 332-334, 481 _et seq._

    Hydrogen balloon, invention of, 29-31, 35.
      first ascent of, 36.

    Hydrogen bubbles, 29.


    Icarus, 3, 4, 5.

    Ice, launching from, 265.

    Indian seed parachute, 180.

    Inherent stability, 229.

    Insolation, effect on density of air, 364.
      quantity of, received, 364-366.

    Isobaric lines and surfaces, 371.

    Isothermal lines, surfaces, 366, 367.

    Isothermal layer, 370.

    Italian Aviation Society, 318.

    Italian military dirigibles, 130.


    _Jaune_, the, 115, 116.

    Jefferson, Thomas, 84.

    Jeffries, 50.

    Johnstone, Ralph, 309, 324, 329.

    Jullien, 88.

    Julliot, Henri, 115, 134, 136.

    _June Bug_, the, 266, 267.


    Kai Kaoos, 8, 9, 10.

    Kapferer, H., 120, 294.

    Keel surface, 120.

    Kinet, Daniel, 312.

    Kinetic stability, 233.

    Kite balloon, 77.

    Körting, 139.

    Krebs, Captain, 93-97.

    Kress, Wilhelm, 214.


    _La Belgique_, 129.

    _La España_, 124, 126, 127.

    _La Flesselle_, 48, 49, 50.

    _La France_, 93-97.

    Lahm, Lieutenant Frank P., 272, 277.

    _La Liberté_, 120.

    Lambert, Count de, 273, 302.

    Lana, 23, 24.

    _La Nature_, 312.

    Land-and-sea breezes, 392.

    Landelle, G. de la, 203.

    Langley, S. P., 187, 192-197, 211, 231, 232, 239-245, 251, 427,
            433, 434, 439.

    _La Patrie_, 115, 118, 119, 459-465.

    _La République_, 115, 118, 119.

    _La Russie_, 120.

    Latent heat of condensation, 364.

    Lateral balance of aëroplane, 229-231.

    Latham, Hubert, 283, 288-290, 291, 319, 320, 324.

    Launching an aëroplane, 202, 230, 256, 258, 259, 265.

    Launching methods, 202, 240, 258, 259, 265.

    Launoy and Bienvenu, 198, 199.

    Laurens, 314.

    _La Ville de Paris_, 120-123.

    _Lebaudy_, the, 116, 117.

    Le Blanc, Alfred, 273, 290, 310, 313, 326, 331.

    _Le Clément-Bayard_, 123, 131-133, 456-459.

    _Le Colonel Renard_, 124, 126.

    Lefebvre, 293.

    Leganeaux, U. G., 311, 319.

    Lenormand, Sebastien, 177, 178.

    Levino, A. S., vii.

    Lift, defined, 186.

    Lilienthal, Otto, 210-216, 250.

    _London Daily Mail_, 289.

    Loomis, 402, 414.

    Lord Rayleigh, 6, 427.


    McCurdy, J. A. D., 264.

    MacMechen, 164.

    Madison, James, 84.

    Malecot, 123.

    Maloney, D., 251-255.

    Manley, Charles M., 242, 245, 251, 285.

    Marconnet, Captain, 312.

    Marey, Professor, 427.

    Marvin, Prof. C. F., 435.

    Mason, Monck, 55.

    Mattullath, Hugo, 231, 235-239.

    Maxim, Sir Hiram S., 226-228, 245.

    Mendoza, 19.

    Mercedes, 140.

    _Meteorological Journal_, 435.

    Meusnier, General, 85, 86.

    Michelin prize, 273, 303, 311, 314, 321.

    Milton, 7.

    Moisant, John, 31, 328.

    Monaco, Prince of, 111.

    Monge, Marey, 100.

    Monoplane, 174.

    Monsoons, 385-391.

    Montgolfier, 29, 37, 50.

    _Montgolfière_, 42.

    Montgomery, Prof. J. J., 251-255, 282, 339.

    Moore, Willis L., 349, 405, 422.

    Morane, 310.

    _Morning Post_, 131, 134-137.

    Motors, 340.
      Antoinette, 254, 258.
      Clément-Bayard, 458.
      Daimler, 99, 150, 163.
      Electrical, 92, 95.
      Gnome, 312.
      Körting, 139.
      Mercedes, 140.
      Panhard-Levassor, 136.
      Rénault, 311.
      steam, 228, 234.
      Vivinus, 129.

    Mouillard, L. P., 206-209.

    Mountain-and-valley winds, 293.

    Munn & Co., 481.

    Muscular flight, 3-7.


    Nadar’s balloon, the _Geant_, 60.

    _Nassau, Great Balloon of_, 55.

    _Nature_, 217, 427.

    Nieuport, 339.

    Northcliffe, Lord, 305.


    Olieslaegers, Jan, 311.

    Orthopters, 174.

    Ovid, 3.


    Panhard-Levassor, 136.

    Parachutes, 176-81.

    Parseval dirigibles, 138, 140-143.

    Parseval, Major von, 77, 138.

    Passive fliers, 174.

    _Patrie_, the, 115, 118, 119, 459-465.

    Paulhan, Louis, 284, 293-296, 305, 311, 315, 316, 317, 324, 325.

    Peltier, H., 456.

    Pénaud, A., 188.

    Pendular stability, 233.

    _Philadelphia Ledger_, the, 313.

    Phillips, Horatio, 191, 192, 199.

    Picardie military maneuvers, 131.

    Pilcher, 216-218, 246.

    Polignac, Marquis de, 301.

    Porter, Rufus, 86, 87.

    Post, Augustus, 6, 75.

    Power expended in flight, 6, 7.

    Power flyers, 174.

    Pressure, critical, 351.
      atmospheric, 370-374.

    _Preussen_, the, 70.

    Projectile stability, 232.

    Propeller, Chauvière, 125, 136.

    Puy de Dome, 314.

    Pylons, 292.


    Rayleigh, Lord, 6, 427.

    Records, aëroplane,
      altitude, 307-309.
      cross-country, 311-314.
      distance, 311.
      duration, 311-314.
      load, 311-314.
      speed, 310-311.

    _Red Wing_, 265, 266.

    Relative humidity, 358.

    Renard, Captain, 93-97, 210.

    _République_, the, 115, 118, 119.

    Reye, Dr., 414.

    Rheims aviation contests, 292-301.

    Riedinger, August, 140.

    Rigid balloons, 122.

    Robert, 42, 45, 81, 82, 83.

    Roc, 11.

    Rolls, Hon. C. S., 321.

    Romain, 52.

    Rotch, A. Lawrence, 380-382.

    Rougier, 302.

    Rozier, Pilâtre de, 38, 52.

    Rudders, aëroplane, 245, 246.
      three-torque, 229-231, 247, 248.

    Ruskin, John, 7.

    _Russie_, the, 120.

    Ryan, Allan A., 327.
      Thomas F., 327.


    Sabathier, 131, 132.

    Saddle bird, 8.

    Saint-Marcq, Com. Le Clément, 438.

    Sandt, Emile, 153.

    Santos-Dumont, Alberto, 102-114, 303, 324, 356-359.

    Saturation, 358.

    Scaliger, 10.

    Schottus, 19.

    Schwartz, 99, 100.

    _Scientific American_, 86, 153, 443, 481.

    Screw, da Vinci’s, 176.
      metal, 340.
      radial-arm, 129, 242, 340.
      wooden, 339.

    Selfridge, Lieutenant T., 264, 265.

    _Signal Corps Dirigible No. 1_, 138, 476, 477.

    Signal Corps, U. S., vi, 271, 272, 276-281.

    Signal Service, U. S., 417-419.

    Sigsfeld, Captain von, 77.

    _Silver Dart_, 305.

    Skin-friction, 238, 239.

    Soaring, early attempts at, 13.
      winds helpful to, 303, 393, 403, 431, 425-459.

    Society for the Study of Motor Air Ships, 138.

    Sommer, Roger, 284, 293.

    Sopwith, Thomas, 314.

    Speed records, 310, 311.

    Spratt, G. A., 247.

    Squier, Major George Owen, 279, 459.

    St. Louis tornado, 412, 413.

    Stabilizing planes, 86.

    Stability and steadiness, artificial, 229-231.
      automatic, 218, 220, 229.
      three-axial, 229, 234.

    Statoscope, 76.

    Statue of Liberty Prize, 325.

    Stringfellow, 184, 185, 187.

    Surcouf, 115.

    Süring, Dr., 70.


    Tabuteau, Maurice, 311.

    Tasso, 3.

    Tatin, Victor, 189.

    Tellier monoplane, 312.

    Temperature, critical, 351.
      distribution of, 366-370.
      gradient, 367.
      vertical gradient, 367-369.

    Temperature of the air, 363 _et seq._

    Teisserenc de Bort, 380-382.

    _The New York Times_, 313.

    Three-rudder principle, 229-232.

    Thunderstorms, genesis and propagation of, 423, 424.
      nature of, 422 _et seq._

    Tidswell, Ella, 216.

    Tissandier, Gaston, 273, 283, 293.

    Tornadoes, bursting of, 419-420 _et seq._
      destructive power of, 409, 410.
      dry, 420, 421.
      dynamics of, 406-409.
      genesis of, 405-406.
      hail and snow, 415-419.
      misty, 411 _et seq._
      nature of, 404.
      sections of, 409-417.

    Tractional balance, 254.

    Trade-winds and antitrade, 380-383.

    Transatlantic voyages, 74, 75, 381, 383.

    Triplanes, 175.

    Types of flyers, 174.
      balloons, 122.


    United States Signal Corps, vi, 271, 272, 276-281.

    United States War Department, 138, 196, 271, 272, 275-281.

    United States Weather Bureau, iv.


    Vacuum balloon, 18, 24, 25, 443-445.

    Van der Born, 312.

    Varnish bubbles, 30.

    Vaulx, Count de la, 74, 127, 129.

    Veranzio, Fauste, 177.

    _Ville de Nancy_, the, 124, 125.

    _Ville de Paris_, the, 120-123.

    Vivinus, 129.

    Voisin, 259, 267, 313.

    Von Bezold, 424.


    Waterspouts, analysis of St. Louis, 412, 413.
      nature of, 411 _et seq._

    Weiller prize, 314.

    Wellman, Walter, 25, 75, 383.

    Wenham, 185, 186, 245.

    Weyman, 314, 331.

    _White Wing_, the, 266.

    Wilkins, 10.

    Winans, Ross, 320.

    Wind gusts, distribution of, 425, 426.
      energy of, 435, 436.
      instrumental study of, 427-459.
      nature of, 425 _et seq._
      soaring value of, 426, 427, 439.
      sustaining force of, 426.

    Winds, ascending trend of, 211.
      cause of periodic, 383.
      cyclonic, 394 _et seq._
      diurnal, 392-393.
      dry whirl, 420, 421.
      fluctuations of, 427-439.
      general cause of, 363, 364.
      kinds of permanent, 380.
      kinds of periodic, 383.
      monsoon, 385, 391.
      nonperiodic, 394 _et seq._
      nonvortical, 422 _et seq._
      permanent and periodic, 376 _et seq._
      prevailing westerlies, 380, 382, 383.
      trade-winds and antitrade, 380, 381.
      useful for voyages, 381, 383.
        in soaring, 303, 393, 403, 421, 425-439.

    Wise, John, 73, 74, 383, 415, 416.

    Wölfert, 99.

    _World_, the New York, 313, 316.

    Wright brothers, 245-251, 270-282, 309, 324, 326, 329, 338, 478.

    Wynmalen, Henri, 321.


    Zahm, 30, 97, 113, 221, 229-231, 239, 245, 334, 427-432, 443.

    Zanonia Macrocarpa, 180.

    Zeppelin, Count Ferdinand von, 102.

    Zeppelin Airship Construction Co., 158, 161.

    Zeppelin dirigibles, 145, 169.

    Zodiac balloons, 127, 128, 129.




+----------------------------------------------------------------------+
|                                                                      |
|                            FOOTNOTES:                                |
|                                                                      |
| [1] With apologies to the California professor who will ride on      |
|     wings worked by muscular force alone.                            |
|                                                                      |
| [2] Mr. A. Holland Forbes and Mr. Augustus Post, in the              |
|     international balloon race of 1908, used a balloon having too    |
|     long a neck, thus causing such pressure at its top as to burst   |
|     the bag. A dreadful plunge ensued, landing them on a house, but  |
|     without injury, as the netting and collapsed bag dampened their  |
|     speed of fall. It is reported that they crashed through the      |
|     skylight, and that the lady of the house regretted not being     |
|     there to receive them.                                           |
|                                                                      |
| [3] _Mechanical Principles of Flight._                               |
|                                                                      |
| [4] The reader may like to know that the basis of so much confidence |
|     was that ancient Euclidean theorem connecting the surfaces and   |
|     volumes of similar figures with certain powers of their          |
|     homologous linear dimensions.                                    |
|                                                                      |
| [5] The writer has made hydrogen-inflated varnish bubbles a foot     |
|     in diameter which ascended swiftly to the ceiling; also,         |
|     air-inflated varnish bubbles a foot and a half in diameter       |
|     which lasted an hour. These, if suitably heated, may be made     |
|     to ascend; but this experiment is more difficult.                |
|                                                                      |
| [6] Both had studied science in college. Stephen was an              |
|     accomplished architect; Joseph, the author of many important     |
|     inventions, among others the common lamp chimney, the            |
|     hydraulic press, etc.                                            |
|                                                                      |
| [7] A long patch on the balloon that can be ripped open for the      |
|     sudden release of gas.                                           |
|                                                                      |
| [8] The equator of such a balloon is its horizontal great circle.    |
|                                                                      |
| [9] A similar suggestion was made by Thomas Jefferson in a letter    |
|     to Prof. James Madison, and dated from Paris in 1785: “I went    |
|     some time ago to see a machine which offers something new. A     |
|     man had applied to a light boat a very large screw, the thread   |
|     of which was a thin plate, two feet broad, applied by its edge   |
|     spirally around a small axis. It somewhat resembled a bottle     |
|     brush, if you will suppose the hairs of the bottle brush         |
|     joining together, and forming a spiral plane. This, turned on    |
|     its axis in the air, carried the vessel across the Seine. It     |
|     is, in fact a screw which takes hold of the air and draws        |
|     itself along by it; losing, indeed, much of its effort by the    |
|     yielding nature of the body it lays hold of to pull itself on    |
|     by. I think it may be applied in the water with much greater     |
|     effect and to very useful purposes. Perhaps it may be used       |
|     also for the balloon.”                                           |
|                                                                      |
| [10] _La Navigation Aerienne_, Gaston Tissandier.                    |
|                                                                      |
| [11] The motive power equals the product of the speed and            |
|     resistance. But in the assumed case, the speed is doubled and    |
|     the resistance quadrupled; hence, the power required is          |
|     eightfold.                                                       |
|                                                                      |
| [12] Santos-Dumont, _My Airships_.                                   |
|                                                                      |
| [13] m^3 signifies cubic meters. One cubic meter equals 35.3166      |
|     cubic feet.                                                      |
|                                                                      |
| [14] Hangar, an airship harbor, or garage.                           |
|                                                                      |
| [15] Aëronat, an airship of the lighter-than-air kind.               |
|                                                                      |
| [16] Hearne, _Airships in Peace and War_.                            |
|                                                                      |
| [17] _Over Sea by Air-Ship_, MacMechen and Dienstbach, _The          |
|     Century_, May, 1910.                                             |
|                                                                      |
| [18] A mathematical argument against this device is presented in     |
|     Appendix I.                                                      |
|                                                                      |
| [19] It is commonly reported by navigators that the albatross        |
|     “sports in the tempest” on unbeating pinions; but it may be      |
|     questioned whether any bird can make headway against the         |
|     swiftest winds.                                                  |
|                                                                      |
| [20] The “drift” and “lift” are the components of surface            |
|     wind-pressure respectively in the direction of flight and at     |
|     right angles to it.                                              |
|                                                                      |
| [21] The tandem monoplane, or two lifting planes arranged in         |
|     tandem, was invented by D. S. Brown and exhibited to the         |
|     Aëronautical Society of Great Britain in 1873.                   |
|                                                                      |
| [22] This gasoline aëroplane model was previously tested in          |
|     private many times, both with single surface wings, and with     |
|     superposed surfaces.                                             |
|                                                                      |
| [23] Abbe, _Helicopters for Aërial Research_, _Aëronautics_, Feb.    |
|     1909.                                                            |
|                                                                      |
| [24] _L’Empire de l’Air._                                            |
|                                                                      |
| [25] _Progress in Flying Machines_, Chanute.                         |
|                                                                      |
| [26] The air rises with increased temperature, hence with            |
|     increased volume displacement, thus causing the wind in          |
|     general to have a slightly ascending trend.                      |
|                                                                      |
| [27] _Aëronautical Annual, 1897._                                    |
|                                                                      |
| [28] Ella Tidswell, _The Aëronautical Journal_, July, 1909.          |
|                                                                      |
| [29] W. J. S. Lockyer, _Nature_, August 12, 1897.                    |
|                                                                      |
| [30] Wenham used superposed planes, Stringfellow superposed          |
|     planes trussed by vertical rods and diagonal wires, Phillips,    |
|     Lilienthal and Hargrave superposed arched surfaces.              |
|                                                                      |
| [31] See _Aëronautic Annual_, 1896.                                  |
|                                                                      |
| [32] _Aërial Warfare_, Hearne, p. 77.                                |
|                                                                      |
| [33] Published by the _American Engineer and Railway Journal._       |
|                                                                      |
| [34] This kind of automatic stability may be called inherent         |
|     stability.                                                       |
|                                                                      |
| [35] Models embodying the above devices had been made and flown      |
|     by the writer some years previously; but aside from these it     |
|     is obvious that a Phillips’s aëroplane and other kinds can       |
|     be effectively controlled in flight by the above-proposed        |
|     three-torque system.                                             |
|                                                                      |
| [36] This idea was later materialized in Langley’s gasoline          |
|     biplane.                                                         |
|                                                                      |
| [37] The means for balancing here suggested in italics was           |
|     claimed some years later in Mr. Hugo Mattullath’s patent         |
|     application in which the inventor had the assistance of the      |
|     present writer.                                                  |
|                                                                      |
| [38] A nearly equivalent vertical surface was used in Dr.            |
|     Langley’s large “aërodrome.” It was a wind-vane rudder placed    |
|     well below and to the rear of the centroid, to be used in        |
|     turning corners. The pressure on this rudder would tilt the      |
|     aëroplane toward the center of curvature of the path, and turn   |
|     it about the vertical axis, but would conspire with the          |
|     centrifugal force. If placed above and forward, it would give    |
|     the desired moments, but oppose the centrifugal force.           |
|                                                                      |
| [39] He died of apoplexy, January 31, 1902.                          |
|                                                                      |
| [40] The first flights were to be made from the water.               |
|                                                                      |
| [41] It can be shown that the angle of flight requiring the least    |
|     motive power is that which makes the wing resistance, or         |
|     drift, three fourths of the entire resistance to progression.    |
|                                                                      |
| [42] _Atmospheric Resistance on Even Surfaces_, by A. F. Zahm,       |
|     _Phil. Soc. Washington_.                                         |
|                                                                      |
| [43] The term “aërodrome” is now commonly applied to an aviation     |
|     field.                                                           |
|                                                                      |
| [44] On August 25, 1909, Louis Paulhan, in the aviation contest      |
|     at Rheims, flew 82 miles in 2 hours, 43 minutes and 24           |
|     seconds, preserving his lateral balance without the aid of       |
|     torsion-wing mechanism and in a turbulent atmosphere.            |
|                                                                      |
| [45] _Aërial Locomotion_, A. G. Bell, Washington Academy of          |
|     Science, March 4, 1907.                                          |
|                                                                      |
| [46] The Wrights in 1910 adopted the rear horizontal and vertical    |
|     rudder, thus returning to the design of their predecessors.      |
|                                                                      |
| [47] On July 18, 1905.                                               |
|                                                                      |
| [48] These glides were abandoned as too dangerous and roundabout,    |
|     in favor of direct tentative flights with a motor.               |
|                                                                      |
| [49] Falling weights pulling a cord that accelerates the             |
|     aëroplane at starting.                                           |
|                                                                      |
| [50] _Present Status of Military Aëronautics_, _Journal of the       |
|     American Society of American Engineers_, December, 1908.         |
|                                                                      |
| [51] On September 18, 1906, Montgomery received a U. S. patent on    |
|     an aëroplane having curved wings and three-rudder control, the   |
|     Wright brothers having on May 22, 1906, received a patent on     |
|     an aëroplane having normally flat wings and three-rudder         |
|     control.                                                         |
|                                                                      |
| [52] The daring aviator escaped without a scratch, but his           |
|     propeller and running gear were damaged slightly.                |
|                                                                      |
| [53] This was an official record, but Brookins had flown 4939        |
|     feet high, at Indianapolis, on June 17th.                        |
|                                                                      |
| [54] This record was made with an uncalibrated barograph, and        |
|     hence was unofficial and unaccepted as a world’s record.         |
|                                                                      |
| [55] The present writer, in his paper quoted on page 229, pointed    |
|     out the equilibrative and steadying quality of torsionally       |
|     elastic wings, and some years previously had proved this by      |
|     gliding models having sustainers with flexible rear margins.     |
|                                                                      |
| [56] The whole water vapor in the atmosphere of our latitude in      |
|     summer is equivalent to about one inch of rainfall.              |
|                                                                      |
| [57] Computed by W. J. Humphreys for Moore’s _Descriptive            |
|     Meteorology_.                                                    |
|                                                                      |
| [58] Ferrel, _Popular Treatise on Winds_.                            |
|                                                                      |
| [59] Solar radiation received by the earth.                          |
|                                                                      |
| [60] W. J. Humphreys, _Astro. Phys. Journ._, January, 1909.          |
|                                                                      |
| [61] An isobar is a line of intersection of an isobaric surface      |
|     with a water level surface at any altitude.                      |
|                                                                      |
| [62] _A Popular Treatise on the Winds._                              |
|                                                                      |
| [63] _The Conquest of the Air._                                      |
|                                                                      |
| [64] By this current John Wise, in 1870, and Walter Wellman, in      |
|     1910, proposed to voyage across the Atlantic; Wise in a free     |
|     balloon, Wellman in a motor balloon with drag rope. See pp.      |
|     74, 75.                                                          |
|                                                                      |
| [65] It is reported that once during the month of August the         |
|     rainfall totaled thirty-two feet; and it is believed that the    |
|     annual fall exceeds fifty feet.                                  |
|                                                                      |
| [66] The “eye” is most noticeable at sea, where the cyclones are     |
|     more symmetrical, and particularly in lower latitudes, where     |
|     they are more concentrated.                                      |
|                                                                      |
| [67] The destructive one that visited Galveston in 1900 is a         |
|     well-known example.                                              |
|                                                                      |
| [68] _Contributions to Meteorology._                                 |
|                                                                      |
| [69] Dr. W. Dauberck, _Met. Zeitschrift_, April, 1866.               |
|                                                                      |
| [70] Moore’s _Meteorology_, p. 164.                                  |
|                                                                      |
| [71] Von Bezold, on the _Thermodynamics of the Atmosphere_.          |
|                                                                      |
| [72] Chanute, _Aeronautical Annual_, 1897, p. 101.                   |
|                                                                      |
| [73] _Nature_, April 5, 1883.                                        |
|                                                                      |
| [74] _Vol des Oiseaux._                                              |
|                                                                      |
| [75] _Internal Work of the Wind._                                    |
|                                                                      |
| [76] _Engineering News_, December 13, 1890.                          |
|                                                                      |
| [77] _Meteorological Journal_, November, 1891.                       |
|                                                                      |
| [78] On _Atmospheric Movements_ (Abbe’s translation).                |
|                                                                      |
| [79] From _Scientific American_, March 13, 1909, by permission of    |
|     Munn & Co.                                                       |
|                                                                      |
| [80] For a fuller account of this fine airship see H. Peltier’s      |
|     article in _L’Aérophile_, December 1, 1910.                      |
|                                                                      |
| [81] This description and the following are from _Present Status     |
|     of Military Aëronautics_, by Major G. O. Squier.                 |
|                                                                      |
| [82] From _Navigating the Air_, by permission of Doubleday, Page     |
|     & Co.                                                            |
|                                                                      |
| [83] From _Scientific American_ of March 4, 1911, by permission      |
|     of Munn & Co.                                                    |
|                                                                      |
+----------------------------------------------------------------------+


  Transcriber’s Notes:
   - Text enclosed by underscores is in italics (_italics_).
   - Redundant title page has been removed.
   - Blank pages have been removed.
   - Silently corrected typographical errors.





End of Project Gutenberg's Aërial Navigation, by Albert Francis Zahm