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[Illustration]




SCIENTIFIC AMERICAN SUPPLEMENT NO. 803




NEW YORK, May 23, 1891

Scientific American Supplement. Vol. XXXI., No. 803.

Scientific American established 1845

Scientific American Supplement, $5 a year.

Scientific American and Supplement, $7 a year.


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TABLE OF CONTENTS.


I.    ASTRONOMY.--The Great Equatorial of the Paris Observatory.--
      The new telescope recently put in use in Paris.--Description of
      the instrument and of its effects.--3 illustrations

II.   CHEMISTRY.--An Apparatus for Heating Substances in Glass
      Tubes under Pressure.--By H. PEMBERTON, Jr.--A simple apparatus
      for effecting this purpose, avoiding risk of personal injury.--
      2 illustrations

      Table of Atomic Weights.--A revised table of atomic weights,
      giving the results of the last determinations, and designed for
      every-day use

      Testing Cement.--A laboratory process for testing Portland cement

III.  CIVIL ENGINEERING.--The Compressed Air System of Paris.
      --An elaborate review of this great installation for the transmission
      of power.--The new compressed air station, with full details
      of performances of apparatus, etc.--10 illustrations

IV.   ENTOMOLOGY.--Report on Insects.--Continuation of this report
      on noxious insects.--Their habits and how to cope with them.
      --18 illustrations

V.    FLORICULTURE.--Lily of the Valley.--Practical notes on the
      cultivation of this popular flower.--How to raise it and force the
      growth

VI.   MATHEMATICS.--The Conic Sections.--By Prof. C.W.
      MACCORD.--Examination of the four conic sections with a general
      definition applicable to all.--6 illustrations

VII.  MECHANICAL ENGINEERING.--The Builders of the Steam
      Engine--The Founders of Modern Industries and Nations.--By Dr.
      R.H. THURSTON.--Prof. Thurston's address before the Centennial
      Celebration of the American Patent System at Washington,
      D.C.--The early history of the steam engine and its present position
      in the world

VIII. MISCELLANEOUS.--The Breeds of Dogs.--Popular description
      of the different breeds of dogs most affected by amateurs.--6
      illustrations

IX.   NAVAL ENGINEERING.--Modern Armor.--By F.R. BRAINARD.--The
      development of modern ship armor, from laminated
      sandwiched and compound types to the present solid armor.--9
      illustrations

X.    PISCICULTURE.--Restocking the Seine with Fish.--The introduction
      of 40,000 fry of California trout and salmon, designed to restock
      the Seine, depopulated of fish by explosions of dynamite
      used in breaking up the ice.--1 illustration

XI.   RAILWAY ENGINEERING.--Improved Hand Car.--A novelty
      in the construction of hand cars, avoiding the production of a
      dead center.--1 illustration

XII.  TECHNOLOGY.--The Tanning Materials of Europe.--The natural
      tanning materials and pathological or abnormal growth tanning
      materials described and classified, with relative power


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THE GREAT EQUATORIAL OF THE PARIS OBSERVATORY.


The great instrument which has just completed the installation of our
national observatory is constructed upon the same principle as the
elbowed equatorial, 11 in. in diameter, established in 1882, according
to the ingenious arrangement devised as long ago as 1872, by Mr.
Loewy, assistant director of the Paris Observatory.

We shall here recall the fact that the elbowed equatorial consists of
two parts joined at right angles. One of these is directed according
to the axis of the world, and is capable of revolving around its own
axis, and the other, which is at right angles to it, is capable of
describing around the first a plane representing the celestial
equator. At the apex of the right angle there is a plane mirror of
silvered glass inclined at an angle of 45 deg. with respect to the
optical axis, and which sends toward the ocular the image coming from
the objective and already reflected by another and similar plane
mirror. The objective and this second mirror (which is inclined at an
angle of 45 deg.) are placed at the extremity of the external part of
the tube, and form part of a cube, movable around the axis of the
instrument at right angles with the axis of the world. The diagram in
Fig. 3 will allow the course of a luminous ray coming from space to be
easily understood. The image of the star, A, toward which the
instrument is directed, traverses the objective, B C, is reflected
first from the mirror, B D, and next from the central mirror, E F, and
finally reaches O, at the ocular where the observer is stationed.

This new equatorial differs from the first model by its much larger
dimensions and its extremely remarkable mechanical improvements. The
optical part, which is admirably elaborated, consists of a large
astronomical objective 24 in. in diameter, and of a photographic
objective of the same aperture, capable of being substituted, one for
the other, according to the nature of the work that it is desired to
accomplish by the aid of this colossal telescope, the total length of
which is 59 ft. The two plane mirrors which complete the optical
system have, respectively, diameters of 34 in. and 29 in. These two
magnificent objectives and the two mirrors were constructed by the
Brothers Henry, whose double reputation as astronomers and opticians
is so universally established. The mechanical part is the successful
work of Mr. Gautier, who has looked after every detail with the
greatest care, and has thus realized a true _chef d'oeuvre_. The
colossal instrument, the total weight of which is 26,400 lb., is
maneuvered by hand with the greatest ease. A clockwork movement, due
to the same able manufacturer, is capable, besides, of moving the
instrument with all the precision desirable, and of permitting it to
follow the stars in their travel across the heavens. A star appearing
in the horizon can thus be observed from its rising to its setting.
The astronomer, his eye at the ocular, is always conveniently seated
at the same place, observing the distant worlds, rendered immovable,
so to speak, in the field of the instrument. For stars which, like the
moon and the planets, have a course different from the diurnal motion,
it is possible to modify the running of the clockwork, so that they
can thus be as easily followed as in the preceding case. Fig. 1 gives
a general view of the new installation, for which it became necessary
to build a special edifice 65 ft. in height on the ground south of the
observatory bordering on the Arago Boulevard. A large movable
structure serves for covering the external part of the instrument.
This structure rests on rails, upon which it slides toward the south
when it is desired to make observations. It will be seen from the
figure how the principal axis of the instrument rests upon the two
masonry pillars, one of which is 49 ft. and the other 13 ft. in
height.

[Illustration: FIG 1.--THE GREAT EQUATORIAL OF THE PARIS OBSERVATORY.]

The total cost of the pavilion, rolling structure, and instrument
(including the two objectives) will amount to about $80,000 after the
new equatorial has been provided with the scientific apparatus that
necessarily have to accompany it for the various and numerous
applications to which the use of it will give rise.

[Illustration: FIG 2.--OCULAR OF THE GREAT EQUATORIAL.]

Fig. 2 shows us the room in the observatory in which the astronomer,
seated in his chair, is completely protected against the inclemencies
of the weather. Here, with his eye applied to the ocular, he can,
without changing position (owing to all the handles that act at his
will upon the many transmissions necessary for the maneuvering),
direct his instrument unaided toward every point of the heavens with
wonderful sureness and precision. The observer has before him on the
same plane two divided circles, one of which gives the right
ascensions and the other the declinations, and which he consults at
each observation for the exact orientation of the equatorial.

[Illustration: FIG. 3.--DIAGRAM SHOWING THE COURSE OF A LUMINOUS RAY
IN THE GREAT EQUATORIAL.]

All the readings are done by the aid of electric lamps of very small
dimensions, supplied by accumulators, and which are lighted at will.
Each of these lamps is of one candle power; two of them are designed
for the reading of the two circles of right ascension and of
declination; a third serves for the reading of the position circle of
the micrometer; two others are employed for the reading of the drums
fixed upon the micrometric screws; four others serve for rendering the
spider threads of the reticule brilliant upon a black ground; and
still another serves for illuminating the field of the instrument
where the same threads remain black upon a luminous ground. The
currents that supply these lamps are brought over two different
circuits, in which are interposed rheostats that permit of graduating
the intensity of the light at will.

Since the installation of the first model of an elbowed equatorial of
11 in. aperture, in 1882, at the Paris Observatory, the numerous and
indisputable advantages of this sort of instrument have led a certain
number of observatories to have similar, but larger, instruments
constructed. In France, the observatories of Alger, Besancon, and
Lyons have telescopes of this kind, the objectives of which have
diameters of from 12 in. to 13 in., and which have been used for
several years past in equatorial observations of all kinds. The Vienna
Observatory has for the last two years been using an instrument of
this kind whose objective has an aperture of 15 inches. Another
equatorial of the same kind, of 16 in. aperture, is now in course of
construction for the Nice Observatory, where it will be especially
employed as a seeker of exceptional power--a role to which this kind
of instrument lends itself admirably. The optical part of all these
instruments was furnished by the Messrs. Henry, and the mechanical
part by Mr. Gautier.

The largest elbowed equatorial is, therefore, that of the Paris
Observatory. Its optical power, moreover, corresponds perfectly to its
huge dimensions. The experimental observations which have already been
made with it fully justify the hopes that we had a right to found upon
the professional skill of the eminent artists to whom we owe this
colossal instrument. The images of the stars were given with the
greatest sharpness, and it was possible to study the details of the
surface of the moon and other planets, and several star clusters, in
all their peculiarities, in the most remarkable manner.

When it shall become possible to make use of this equatorial for
celestial photography, there is no doubt that we shall obtain the most
important results. As regards the moon, in particular, the
photographing of which has already made so great progress, its direct
image at the focus of the large 24 in. photographic objective will
have a diameter of 11 in., and, being magnified, will be capable of
giving images of more than 3 ft. in diameter.--_La Nature_.

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LILY OF THE VALLEY.


There is no flower more truly and universally popular than the lily of
the valley. What can be more delicious and refreshing than the scent
of its fragrant flowers? What other plant can equal in spring the
attractiveness of its pillars of pure white bells half hidden in their
beautiful foliage? There are few gardens without a bed of lily of the
valley, but too often the place chosen for it is some dark corner
where nothing else would be expected to grow, but it is supposed as a
matter of course that "it will do for a lily bed." The consequence is
that although these lilies are very easy things to cultivate, as
indeed they ought to be, seeing that they grow wild in the woods of
this and other countries, yet one hears so often from those who take
only a slight interest in practical gardening, "I have a lily bed, but
I scarcely ever get any lilies." Wild lilies are hardly worth the
trouble of gathering, they are so thin and poor; it is interesting to
find a plant so beautiful and precious in the garden growing wild in
the woods, but beyond that the flowers themselves are worth but very
little. This at once tells us an evident fact about the lily of the
valley, viz., that it does require cultivation. It is not a thing to
be left alone in a dark and dreary corner to take care of itself
anyhow year after year. People who treat it so deserve to be
disappointed when in May they go to the lily bed and find plenty of
leaves, but no flowers, or, if any, a few poor, weak attempts at
producing blossoms, which ought to be so beautiful and fragrant.

One great advantage of this lovely spring flower is that it can be so
readily and easily forced. Gardeners in large places usually spend
several pounds in the purchase of crowns and clumps of the lily of the
valley, which they either import direct from foreign nurserymen or
else procure from their own dealer in such things, who imports his
lilies in large quantities from abroad. But we may well ask, Have
foreign gardeners found out some great secret in the cultivation of
this plant? Or is their climate more suitable for it? Or their soil
adapted to growing it and getting it into splendid condition for
forcing? It is impossible that the conditions for growing large and
fine heads of this lily can be in any way better in Berlin or
elsewhere than they are in our own land, unless greater heat in summer
than we experience in England is necessary for ripening the growths in
autumn.

There is another question certainly as to varieties; one variety may
be superior to another, but surely if so it is only on the principle
of the survival of the fittest, that is to say, by carefully working
on the finest forms only and propagating from them, a strong and
vigorous stock may be the result, and this stock may be dignified with
a special name. For my own part what I want is to have a great
abundance of lily of the valley from February till the out-door season
is over. To do this with imported clumps would, of course, be most
costly, and far beyond what any person ought to spend on mere flowers.
Though it must be remembered that it is an immense advantage to the
parish priest to be able to take bright and sweet flowers to the
bedside of the sick, or to gratify the weary spirit of a confirmed
invalid, confined through all the lovely spring time to the narrow
limits of a dull room, with the fragrant flowers of the lily of the
valley. I determined, therefore, that I would have an abundance of
early lilies, and that they should not be costly, but simply produced
at about the same expense as any other flowers, and I have been very
successful in accomplishing this by very simple means. First of all,
it is necessary to have the means of forcing, that is to say the
required heat, which in my case is obtained from an early vinery. I
have seen lilies forced by pushing the clumps in under the material
for making a hot bed for early cucumbers, the clumps being drawn out,
of course, as soon as the flowers had made a good start. They have
then to be carefully and very gradually exposed to full light, but
often, although fine heads of bloom may be produced in this way, the
leaves will be few and poor.

My method is simply this: In the kitchen garden there is the old
original bed of lilies of the valley in a corner certainly, but not a
dark corner. This is the reservoir, as were, from whence the regular
supply of heads for special cultivation is taken. This large bed is
not neglected and left alone to take care of itself, but carefully
manured with leaf mould and peat moss manure from the stable every
year. Especially the vacant places made by taking out the heads for
cultivation are thus filled up.

Then under the east wall another piece of ground is laid out and
divided into four plots. When I first began to prepare for forcing I
waited four years, and had one plot planted with divided heads each
year. Clumps are taken up from the reserve bed and then shaken out and
the heads separated, each with its little bunch of fibrous roots. They
are then carefully planted in one of the plots about 4 in. or 5 in.
apart, the ground having previously been made as light and rich as
possible with plenty of leaf mould. I think the best time for doing
this is in autumn, after the leaves have turned yellow and have rotted
away; but frequently the operation has been delayed till spring,
without much difference in the result.

Asparagus is usually transplanted in spring, and there is a wonderful
affinity between the two plants, which, of course, belong to the same
order. It was a long time to wait--four years--but I felt there was no
use in being in too great a hurry, and every year the plants
manifestly improved, and the buds swelled up nicely and looked more
plump each winter when the leaves were gone. It must be remembered
also that a nice crop of flowers could be gathered each year. When the
fourth year came, the first plot was divided up into squares about 2
ft. each way, and taken up before any hard frost or snow had made
their appearance, and put away on the floor of an unused stable. From
the stable they are removed as required in the squares to the vinery,
where they grow beautifully, not sending up merely fine heads of bloom
without a vestige of leaf, but growing as they would in spring out of
doors with a mass of foliage, among which one has to search for the
spikes of flower, so precious for all sorts of purposes at that early
season of the year.

The spikes produced in this way do not equal in thickness and
substance of petal the flowers which come from more carefully prepared
clumps imported from Berlin, but they are fine and strong, and above
all most abundant. I can not only supply the house and small vases for
the church, but also send away boxes of the flowers to friends at a
distance, besides the many gifts which can be made to those who are
ill or invalids. Few gifts at such a time are more acceptable than a
fragrant nosegay of lily of the valley. In order to keep the supply of
prepared roots ready year after year, a plot of ground has only to be
planted each autumn, so that in the rotation of years it may be ready
for forcing when its turn shall come.

As the season advances, as every one knows who has attempted to force
the lily of the valley, much less time is taken in bringing the
flowers to perfection under precisely the same circumstances as those
in which the first sods are forced. In February or earlier the buds
are more unwilling to start; there seems to be a natural repugnance
against being so soon forced out of the winter's sleep and rest. But
when the flowers do come, they are nearly as fine and their leaves are
quite as abundant in this way of forcing as from the pieces introduced
much later into heat. It would be easy to preserve the squares after
all the flowers are gathered, but I found that they would not, like
strawberries, kindly furnish forth another crop later on in the year,
and, therefore, mine are flung away; and I have often pitied the
tender leaves in the frost and snow after their short sojourn in the
hot climate of the vinery. But the reserve bed will always supply an
ample quantity of fresh heads, and it is best to take the new plants
for preparation in the kitchen garden from this reserve bed.

This very simple method of forcing lilies of the valley is within the
reach of any one who has even a small garden and a warm house, and
these two things are becoming more and more common among us every
day.--_A Gloucestershire Parson, in The Garden_.

       *       *       *       *       *

[Continued from SUPPLEMENT, No. 802, page 12820.]




REPORT ON INSECTS.

THE ONION MAGGOT.

_Phorbia ceparum_ (Meig.)


Early in June a somewhat hairy fly, Fig. 9, may be seen flying about,
and depositing its eggs on the leaves of the young onion plants, near
the roots, Fig. 10.

[Illustration: FIG. 9.]

Dr. Fitch describes this fly as follows: "It has a considerable
resemblance to the common house fly, though when the two are placed
side by side, this is observed as being more slender in its form. The
two sexes are readily distinguished from each other by the eyes, which
in the males are close together, and so large as to occupy almost the
whole surface of the head, while in the females they are widely
separated from each other. These flies are of an ash gray color, with
the head silvery, and a rusty black stripe between the eyes, forked at
its hind end. And this species is particularly distinguished by having
a row of black spots along the middle of the abdomen or hind body,
which sometimes run into each other, and then forming a continuous
stripe.

"This row of spots is quite distinct in the male, but in the female is
very faint, or is often wholly imperceptible. This fly measured 0.22
to 0.25 inch in length, the females being usually rather larger than
the males." The eggs are white, smooth, somewhat oval in outline, and
about one twenty-fifth of an inch in length. Usually not more than
half a dozen are laid on a single plant, and the young maggot burrows
downward within the sheath, leaving a streak of pale green to indicate
its path, and making its way into the root, devours all except the
outer skin.

[Illustration: FIG. 10.]

The maggots reach their full growth in about two weeks, when they are
about one-third of an inch long, white and glossy, tapering from the
posterior end to the head, which is armed with a pair of black,
hook-like jaws. The opposite end is cut off obliquely and has eight
tooth-like projections around the edge, and a pair of small brown
tubercles near the middle. Fig. 11 shows the eggs, larva, and pupa,
natural size and enlarged.

[Illustration: FIG. 11.]

They usually leave the onions and transform to pupæ within the ground.
The form of the pupa does not differ very much from the maggot, but
the skin has hardened and changed to a chestnut brown color, and they
remain in this stage about two weeks in the summer, when the perfect
flies emerge. There are successive broods during the season, and the
winter is passed in the pupa stage.

The following remedies have been suggested:

Scattering dry, unleached wood ashes over the plants as soon as they
are up, while they are wet with dew, and continuing this as often as
once a week through the month of June, is said to prevent the deposit
of eggs on the plants.

Planting the onions in a new place as remote as possible from where
they were grown the previous year has been found useful, as the flies
are not supposed to migrate very far.

Pulverized gas lime scattered along between the rows has been useful
in keeping the flies away.

Watering with liquid from pig pens collected in a tank provided for
the purpose, was found by Miss Ormerod to be a better preventive than
the gas lime.

When the onions have been attacked and show it by wilting and changing
color, they should either be taken up with a trowel and burned, or
else a little diluted carbolic acid, or kerosene oil, should be
dropped on the infested plants to run down them and destroy the
maggots in the roots and in the soil around them.

Instead of sowing onion seed in rows, they should be grown in hills,
so that the maggots, which are footless, cannot make their way from
one hill to another.


THE CABBAGE BUTTERFLY.

_Pieris rapae_ (Linn.)


In the New England States there are three broods of this insect in a
year, according to Mr. Scudder, the butterflies being on the wing in
May, July, and September; but as the time of the emergence varies, we
see them on the wing continuously through the season.

[Illustration: FIG. 12.]

The expanded wings, Fig. 12, male, measure about two inches, are white
above, with the base dusky. Both sexes have the apex black and a black
spot a little beyond the middle, and the female, Fig. 13, has another
spot below this. The under side of the fore wings is white, yellowish
toward the apex, and with two black spots in both sexes corresponding
to those on the upper side of the female. A little beyond the middle
of the costa, on the hind wings, is an irregular black spot on the
upper surface, while the under surface is pale lemon yellow without
marks, but sprinkled more or less with dark atoms. The body is black
above and white beneath.

[Illustration: FIG. 13.]

The caterpillars of this insect feed on the leaves of cabbage,
cauliflower, turnip, mignonette, and some other plants.

The female lays her eggs on the under side of the leaves of the food
plants, generally, but sometimes on the upper sides or even on the
leaf stalks. They are sugar loaf shaped, flattened at the base, and
with the apex cut off square at the top, pale lemon yellow in color,
about one twenty-fifth of an inch long and one fourth as wide, and
have twelve longitudinal ribs with fine cross lines between them.

The eggs hatch in about a week, and the young caterpillars, which are
very pale yellow, first eat the shells from which they have escaped,
and then spin a carpet of silk, upon which they remain except when
feeding. They now eat small round holes through the leaves, but as
they grow older change to a greenish color, with a pale yellow line
along the back, and a row of small yellow spots along the sides, and
eat their way down into the head of the cabbage.

[Illustration: FIG. 14.]

Having reached its full growth, the caterpillar, Fig. 14, a, which is
about an inch in length, wanders off to some sheltered place, as under
a board, fence rail, or even under the edge of clapboards on the side
of a building, where it spins a button of silk, in which to secure its
hind legs, then the loop of silk to support the forward part of the
body.

It now casts its skin, changing to a chrysalis, Fig. 14, b, about
three-fourths of an inch in length, quite rough and uneven, with
projecting ridges and angular points on the back, and the head is
prolonged into a tapering horn. In color they are very variable, some
are pale green, others are flesh colored or pale ashy gray, and
sprinkled with numerous black dots. The winter is passed in the
chrysalis stage.

After the caterpillar changes to a chrysalis, their minute parasites
frequently bore through the outside and deposit their eggs within.
These hatch before the time for the butterflies to emerge, and feeding
on the contents, destroy the life of the chrysalis.

Birds and spiders are of great service in destroying these insects.

The pupæ should be collected and burned if the abdomen is flexible;
but if the joints of the abdomen are stiff and cannot be easily moved,
they should be left, as they contain parasites.

Several applications of poisons have been used, the best results being
obtained from the use of pyrethrum as a powder blown on to the plants
by a hand bellows, during the hottest part of the day, in the
proportion of one part to four or five of flour.

As the eggs are laid at different times, any application, to be
thoroughly tested, must be repeated several times.


THE APPLE TREE TENT CATERPILLAR.

_Clisiocampa Americana_ (Harr.)


Large, white, silken web-like tents, Fig. 15, are noticed by the
roadsides, in the early summer, on wild cherry trees, and also on
fruit trees in orchards, containing numerous caterpillars of a
blackish color, with fine gray hairs scattered over the body.

This well known pest has been very abundant throughout the State for
several years past, and the trees in many neglected orchards have been
greatly injured by it, some being entirely stripped of their leaves.
The trees in these orchards and the neglected ones by the roadsides
form excellent breeding places for this insect, and such as are of
little of no value should be destroyed. If this were well done, and
all fruit growers in any given region were to destroy all the tents on
their trees, even for a single season, the work of holding them in
check or destroying them in the following year would be comparatively
light.

[Illustration: FIG. 15.]

The moths, Fig. 16, appear in great numbers in July, their wings
measuring, when expanded, from one and a quarter to one and a half
inches or more. They are of a reddish brown color, the fore wings
being tinged with gray on the base and middle, and crossed by two
oblique whitish stripes.

[Illustration: FIG. 16.]

The females lay their eggs, about three hundred in number, in a belt,
Fig. 15, c, around the twigs of apple, cherry, and a few other trees,
the belt being covered by a thick coating of glutinous matter, which
probably serves as a protection against the cold weather during
winter.

The following spring, when the buds begin to swell, the egg hatch and
the young caterpillar seek some fork of a branch, where they rest side
by side. They are about one-tenth of an inch long, of a blackish
color, with numerous fine gray hairs on the body. They feed on the
young and tender leaves, eating on an average two apiece each day.
Therefore the young of one pair of moths would consume from ten to
twelve thousand leaves; and it is not uncommon to see from six to
eight nests or tents on a single tree, from which no less than
seventy-five thousand leaves would be destroyed--a drain no tree can
long endure.

As the caterpillars grow, a new and much larger skin is formed
underneath the old one, which splits along the back and is cast off.
When fully grown, Fig. 15, a and b, which is in about thirty-five to
forty days after emerging from the eggs, they are about two inches
long, with a black head and body, with numerous yellowish hairs on the
surface, with a white stripe along the middle of the back, and minute
whitish or yellowish streaks, which are broken and irregular along the
sides; and there is also a row of transverse, small, pale blue spots
along each side of the back.

As they move about they form a continuous thread of silk from a fleshy
tube on the lower side of the mouth, which is connected with the
silk-producing glands in the interior of the body, and by means of
this thread they appear to find their way back from the feeding
grounds. It is also by the combined efforts of all the young from one
belt of eggs that the tents are formed.

These caterpillars do not feed during damp, cold weather, but take two
meals a day when it is pleasant.

After reaching their full growth, they leave their tents and scatter
in all directions, seeking for some protected place where each one
spins its spindle-shaped cocoon of whitish silk intermingled with
sulphur colored powder, Fig. 15, d. They remain in these cocoons,
where they have changed to pupæ, from twenty to twenty-five days,
after which the moths emerge, pair, and the females lay their eggs for
another brood.

Several remedies have been suggested, a few of which are given below.
Search the trees carefully, when they are bare, for clusters of eggs;
and, when found, cut off the twigs to which they are attached, and
burn them.

As soon as any tents are observed in the orchard they should be
destroyed, which may be readily and effectually done by climbing the
trees, and with the hand protected by a mitten or glove, seize the
tent and crush it with its entire contents; also swab them down with
strong soapsuds or other substances; or tear them down with a rounded
bottle brush.

Burning with a torch not only destroys the caterpillars but injures
the trees.

It should be observed, however, since the caterpillars, are quite
regular in taking their meals, in the middle of the forenoon and
afternoon, that they should be destroyed only in the morning or
evening, when all are in the tent.

Another remedy is to shower the trees with Paris green in water, in
the proportion of one pound to one hundred and fifty gallons of water.


THE FOREST TENT CATERPILLAR.

_Clisiocampa disstria_ (Hübner.)


This species, commonly known as the forest tent caterpillar, closely
resembles the apple tree tent caterpillar, but does not construct a
visible tent. It feeds on various species of forest trees, such as
oak, ash, walnut, hickory, etc., besides being very injurious to apple
and other fruit trees. The moth, Fig. 17, b, expands an inch and a
half or more. The general color is brownish yellow, and on the fore
wings are two oblique brown lines, the space between them being darker
than the rest of the wing. The eggs, Fig. 17, c and d, which are about
one twenty fifth of an inch long and one fortieth wide, are arranged,
three or four hundred in a cluster, around the twigs of the trees,
Fig. 17, a. These clusters are uniform in diameter and cut off
squarely at the ends. The eggs are white, and are firmly fastened to
the twigs and to each other, by a brown substance, like varnish, which
dries, leaving the eggs with a brownish covering.

[Illustration: FIG. 17.]

The eggs hatch about the time the buds burst, or before, and the young
caterpillars go for some time without food, but they are hardy and
have been known to live three weeks with nothing to eat, although the
weather was very cold.

[Illustration: FIG. 18.]

As soon as hatched they spin a silken thread wherever they go, and
when older wander about in search for food. The caterpillars are about
one and a half inches long when fully grown, Fig. 18. The general
color is pale blue, tinged with greenish low down on the sides, and
everywhere sprinkled with black dots or points, while along the middle
of the back is a row of white spots each side of which is an orange
yellow stripe, and a pale, cream yellow stripe below that. These
stripes and spots are margined with black. Each segment has two
elevated black points on the back, from each of which arise four or
more coarse black hairs. The back is clothed with whitish hairs, the
head is dark bluish freckled with black dots, and clothed with black
and fox-colored hairs, and the legs are black, clothed with whitish
hairs.

At this stage the caterpillars may be seen wandering about on fences,
trees, and along the roads in search of a suitable place to spin their
cocoons, which are creamy white, and look very much like those of the
common tent caterpillar, except that they are more loosely
constructed.

Within the cocoons, in two or three days they transform to pupæ of a
reddish brown color, densely clothed with short pale yellowish hairs.
The moths appear in two or three weeks, soon lay their eggs and then
die. The insects are not abundant many years in succession, as their
enemies, the parasites, increase and check them.

Many methods have been suggested for their destruction, but the most
available and economical are to remove the clusters of eggs whenever
found, and burn them, and to shower the trees with Paris green in the
proportion of one pound to one hundred and fifty gallons of water.


THE STALK BORER.

_Gortyna nitela_ (Gruen.)


The perfect moth, Fig. 19, 1, expands from one to one and a half
inches. The fore wings are a mouse gray color, tinged with lilac and
sprinkled with fine yellow dots, and distinguished mainly by a white
band extending across the outer part. The moths hibernate in the
perfect state, and in April or May deposit their eggs singly on the
outside of the plant upon which the young are to feed. As soon as the
eggs hatch, which is in about a month, the young larvæ, or
caterpillars, gnaw their way from the outside into the pith.

[Illustration: FIG. 19.]

The plant does not show any sign of decay until the caterpillar is
fully grown, when it dies. The caterpillar, Fig. 19, 2, is about one
and one-fourth inches long, of a reddish brown color, with whitish
stripes along the body. The stripes on the sides are not continuous,
and the shading of the body varies, being darker on the anterior than
on the posterior portion. When fully grown, Fig. 20, the color is
lighter and the stripes are broader. At this stage of life it burrows
into the ground just beneath the surface, and changes into the pupa
state. The pupa is three-fourths of an inch long, and of a mahogany
brown color. The perfect moth appears about the first of September,
and there is only one brood in a season.

[Illustration: FIG. 20.]

The caterpillars feed in the stalks of corn, tomatoes, potatoes,
dahlias, asters, and also in young currant bushes, besides feeding on
many species of weeds. By a close inspection of the plants about the
beginning of July, the spot where the borer entered, which is
generally quite a distance from the ground, may be detected, and the
caterpillar cut out without injury to the plant. This plan is
impracticable for an extensive crop, but by destroying the borers
found in the vines that wilt suddenly, one can lessen the number
another year.


THE PYRAMIDAL GRAPEVINE CATERPILLAR.

_Pyrophila pyramidoides_ (Guen.)


This caterpillar, Fig. 21, is generally found on grapevines early in
June, but also feeds on apple, plum, raspberry, maple, poplar, etc. It
is about an inch and a half in length, with the body tapering toward
the head; of a whitish green color, darker on the sides; with a
longitudinal white stripe on the back, broader on the last segments.
Low down on each side is a bright yellow stripe, between this and the
one on the back is another less distinct, and the under surface of the
body is pale green.

[Illustration: FIG. 21.]

The caterpillar is fully grown about the middle or last of June, when
it descends to the ground, draws together some of the fallen leaves,
and makes a cocoon, in which it soon changes to a mahogany brown pupa.

[Illustration: FIG. 22.]

In the latter part of July the perfect moth, Fig. 22, emerges,
measuring, when its wings are expanded, about one and three-fourths
inches; the fore wings are dark brown shaded with lighter, with dots
and wavy lines of dull white. The hind wings are reddish, or of a
bright copper color, shading to brown on the outer angle of the front
edge of the wing, and paler toward the hinder and inner angle.

The under surface of the wings is lighter than the upper, and the body
is dark brown, with its posterior portion banded with lines of a paler
hue.

This pest may be destroyed by hand picking, or by jarring the trees or
vines on which they are feeding, when they will fall to the ground and
may be crushed or burned.


THE GRAPE BERRY MOTH.

_Eudemis botrana_ (S.V.)


The moths emerge and fly early in June, and are quite small,
measuring, when the wings are expanded, only two-fifths of an inch,
Fig. 23, a, enlarged. The fore wings are purplish or slate brown from
the base to the middle, the outer half being irregularly marked with
dark and light brown.

[Illustration: FIG. 23.]

These insects are two-brooded and the first brood feeds not only on
the leaves of the grape, but on tulip, sassafras, vernonia and
raspberry. The caterpillars of the second brood emerge when the grapes
are nearly grown, and bore in them a winding channel to the pulp,
continuing to eat the interior of the berry till the pulp is all
consumed, Fig. 23, d, when, if not full grown, they draw one or two
other berries close to the first and eat the inside of those.

The mature caterpillar, Fig. 23, b, measures about half an inch in
length, is dull greenish, with head and thoracic shield somewhat
darker; the internal organs give the body a reddish tinge. It then
leaves the grape and forms its cocoon by cutting out a piece of a
leaf, leaving it hinged on one side; then rolling the cut end over,
fastens it to the leaf, thus making for itself a cocoon in which to
pupate. The pupa is dark reddish brown.

The second generation passes the winter in the pupa state, attached to
leaves which fall to the ground; therefore, if all the dead and dried
leaves be gathered in the fall and burned, also all the decayed fruit,
a great many of these insects would be destroyed. As the caterpillars
feed inside of the berry, no spraying of the vines with poisons would
reach them. The caterpillar makes a discolored spot where it enters
the berry, Fig. 23, c. Therefore the infested fruit may be easily
detected and destroyed.

There is a small parasite that attacks this insect and helps to keep
it in check. The insect has been known in Europe over a hundred years.
It is not certain when it was introduced into America, but it is now
found from Canada to the Gulf of Mexico, and from the Atlantic to the
Pacific Ocean.


THE CODLING MOTH.

_Carpocapsa pomonella_ (Linn.)


This well known insect has a world-wide reputation, and is now found
wherever apples are raised.

[Illustration: FIG. 24.]

The moths are on the wing about the time the young apples are
beginning to set, and the female lays a single egg in the blossom end
of each apple. The fore wings of the moths when expanded, Fig. 24, g
(f, with the wings closed), measure about half an inch across, and are
marked with alternate wavy, transverse streaks of ashy gray and brown,
and have on the inner hind angle a large tawny brown, horseshoe shaped
spot, streaked with light bronze or copper color. The hind wings and
abdomen are light brown with a luster of satin.

Each female lays about fifty eggs, which are minute, flattened,
scale-like bodies of a yellowish color. In about a week the eggs hatch
and the tiny caterpillar begins to eat through the apple to the core,
Fig. 24, a, pushing its castings out through the hole where it
entered, Fig. 24, b. Oftentimes these are in sight on the outside in a
dark colored mass, thus making wormy apples plainly seen at quite a
distance.

The caterpillar is about two-fifths of an inch in length, of a glossy,
pale yellowish white color, with a light brown head. The skin is
transparent and the internal organs give to it a reddish tinge.

When mature the caterpillars, Fig. 24, e, top of head and second
segment, h, emerge from the apples and seek some sheltered place, such
as crevices of bark, or corners of the boxes or barrels in which the
fruit is stored, where they spin a tough whitish cocoon, Fig. 24, i,
in which they remain unchanged all winter, and transform to pupæ, Fig.
24, d, the next spring, the perfect moths emerging in time to lay
their eggs in the new crop of apples.

One good remedy is to gather all the fallen apples, and feed them to
hogs; another is to let swine and sheep run in the orchard, and eat
the infested fruit.

It has been recommended to place bands of cloth or hay around the
trunks of the trees for the caterpillars to spin their cocoons
beneath, and to remove them at the proper time, and put them in
scalding water to destroy the worms.

By far the most successful method as yet adopted is to shower the
apple trees with Paris green in water, one pound to one hundred and
fifty gallons of water, when the apples are about the size of peas,
and again in about a week.


THE CABBAGE LEAF MINER.

_Plutella cruciferarum_ (Zell.)


The cabbage leaf miner is not a native of this country, but was
imported from Europe.

[Illustration: FIG. 25.]

The perfect moth, Fig. 25, f, with the wings expanded (h, with the
wings closed, g, a dark variety), measures three-quarters of an inch.
The fore wings are ashy gray, and on the hinder margin is a white or
yellowish white stripe having three points extending into the gray,
thus forming, when the wings are closed, three diamond-shaped white
spots. Generally there is a dark brown stripe between the white and
the gray. There are also black dots scattered about on the anterior
part of these wings.

The hind wings are leaden brown, and the under side of all the wings
is leaden brown, glossy, and without any dots.

The antennæ are whitish with dark rings, and the abdomen white. There
are two broods of this insect in this region, the moths of the first
appearing in May, and those of the second in August. They hibernate in
the pupa stage.

The caterpillars, Fig. 25, a (b, the top and c, the side of a
segment), appear in June or July and September; they are small and
cylindrical, tapering at both ends, pale green, and about one-fourth
of an inch long. The head has a yellowish tinge, and there are several
dark stiff hairs scattered over the body.

When ready to transform, this caterpillar spins a delicate gauze-like
cocoon, Fig. 25, e, made of white, silken threads, on the under side
of a cabbage leaf. The pupa, Fig. 25, d, and i, the end of a pupa, is
commonly white, sometimes shaded with reddish brown, and can be
distinctly seen through the silken case.

The first brood is more injurious than the second, as it feeds on the
young cabbage leaves before the head is formed, and this must surely
stunt the growth and make weak, sickly plants; while the second brood
feeds only on the outside leaves. The caterpillars are very active,
wriggling violently when disturbed, and falling by a white silken
thread.

Hot dry weather is favorable to them and enables them to multiply
rapidly. Advantage has been taken of this fact, and spraying the
plants thoroughly with water is strongly recommended. Prof. Riley
states that the insects are very readily destroyed by pyrethrum. There
are two species of spiders and a species of ichneumon fly that destroy
them.


THE GARTERED PLUME MOTH.

_Oxyptilus periscelidactylus_ (Fitch.)


The caterpillars of this species draw together the young grape leaves,
Fig. 26, a, in the spring, with fine silken threads, and feed on the
inside, thus doing much damage in proportion to their size. These
caterpillars, Fig. 26, a, and e, a segment greatly enlarged, are full
grown in about two weeks, when they are about one-fourth of an inch
long, pale green with whitish hairs arising from a transverse row of
warts on each segment.

Early in June they transform to pupæ, Fig. 26, b, which are pale green
at first and change to dark brown. The surface is rough and the head
is cut off obliquely, while on the upper side near the middle are two
sharp pointed horns, Fig. 26, c. They remain in this stage from a week
to ten days, when the moths emerge.

[Illustration: FIG. 26.]

The moths, Fig. 26, d, belong to the family commonly known as plume
moths or feather wings (Pterophoridæ), from having their wings divided
into feather-like lobes. When the wings are expanded they measure
about seven-tenths of an inch across. They are yellowish brown with a
metallic luster, and have several dull whitish streaks and spots. The
fore wings are split down the middle about half way to their base, the
posterior half having a notch in the outer margin. The body is
somewhat darker than the wings.

It is not known positively in what stage the winter is passed, but it
is supposed to be the perfect, or imago stage. The unnatural grouping
and spinning of the leaves together leads to their detection, and they
can be easily destroyed by hand picking and then crushing or burning
them.

       *       *       *       *       *




THE BREEDS OF DOGS.


The dog exhibitions that have annually taken place for the last eight
years at Paris and in the principal cities of France have shown how
numerous and varied the breeds of dogs now are. It is estimated that
there are at present, in Europe, about a hundred very distinct and
very fine breeds (that is to say, such as reproduce their kind with
constant characters), without counting a host of sub-breeds or
varieties that a number of breeders are trying to fix.

Most of the breeds of dogs, especially those of modern creation, are
the work of man, and have been obtained by intercrossing older breeds
and discarding all the animals that departed from the type sought. But
many of these breeds are also the result of accident, or rather of
modifications of certain parts of the organism--of a sort of rachitic
or teratological degeneration which has become hereditary and has been
due to domestication; for it is proved that the dog is the most
anciently domesticated animal, and that its submission to man dates
back to more than five thousand years. Such is the origin of the
breeds of terriers, bulldogs, and all of the small house dogs.

Man has often, designedly or undesignedly, aided in the production of
breeds of this last category by submitting the dog to a regimen
contrary to nature, or setting to work to reproduce an animal born
monstrous, either for curiosity or for interest. As well known, the
accidental characters and the spontaneous modifications which work no
injury to the essential functions of life became easily hereditary,
and the same is the case with certain artificial modifications pursued
for a long series of generations.

It was the opinion of Buffon that the breeds of dogs, which were
already numerous in his time, were all derived from a single type,
which, according to him, was the shepherd's dog. Other scientists have
insisted that the dog descended from the wolf, and others from the
jackal. At the present time, it is rightly admitted that several
species of wild dogs have concurred in the formation of the different
breeds of dogs as we now have them.

In the lacustrine habitations of the stone age in Sweden, and in the
_kjoekkenmoedding_ (kitchen remains) of Denmark, of the same epoch, we
find the remains of a dog, which, according to Rutymeyer, belongs to a
breed which is constant up to its least details, and which is of a
light and elegant conformation, of medium size, with a spacious and
rounded cranium and a short, blunt muzzle, and a medium sized jaw, the
teeth of which form a regular series.

This dog, which has been named by geologists _Canis palustris_, fully
resembles in size, slenderness of the limbs, and weakness of the
muscular insertions, the spaniel, the brach hound, or the griffon.

This dog of the stone age is entirely distinct from the wolf and
jackal, of which some regard the domestic dog as a descendant, and as
it has appeared in Denmark as well as in Sweden, there is no doubt
that this species, peculiar to Europe, was subjugated by man and used
by him, in the first place, for hunting, and later on for guarding
houses and cattle. Later still, in the age of metals, we observe the
appearance, both in Denmark and Sweden, of larger and stronger breeds
of dogs, having in their jaws the character of mastiffs, and probably
introduced by the first emigrants from Asia.

There are, moreover, historic proofs that the dogs of the strongest
breeds are indigenous to Asia, where we still find the dog of Thibet,
the most colossal of all; in fact, in Pliny we read the following
narrative: Alexander the Great received from a king of Asia a dog of
huge size. He wished to pit it against bears and wild boars, but the
dog remained undisturbed and did not even rise, and Alexander had it
killed. On hearing of this, the royal donor sent a second dog like
the first, along with word that these dogs did not fight so weak
animals, but rather the lion and the elephant, and that he had only
two of such individuals, and in case that Alexander had this one
killed, too, he would no longer find his equal. Alexander matched this
dog with a lion and then with an elephant, and he killed them both.
Alexander was so afflicted at the premature death of the first dog,
that he built a city and temples in honor of the animal.

Did the mountainous province of Epirus called Molossia, in ancient
Greece, give its name to the _molossi_ that it produced, or did these
large dogs give their name to the country? At all events, we know that
it was from Epirus that the Romans obtained the molossi which fought
wild animals in the circuses, and that from Rome they were introduced
into the British islands and have became the present mastiffs.

Although our hunting and shepherd's dogs have a European and the
mastiffs an Asiatic ancestry, the ancestry of the harriers is African,
and especially Egyptian; in fact, in Upper Egypt we find a sort of
large white jackal (_Simenia simensis_) with the form of a harrier,
and which Paul Gervais regarded with some reason as the progenitor of
the domestic harrier, and a comparison of their skulls lends support
to this opinion.

A study of the most ancient monuments of the Pharaohs shows that the
ancient Egyptians already had at least five breeds of dogs: two very
slim watch dogs, much resembling the harrier, a genuine harrier, a
species of brach hound and a sort of terrier with short and straight
legs. All these dogs had erect ears, except the brach, in which these
organs were pendent, and this proves that the animal had already
undergone the effects of domestication to a greater degree than the
others. The harrier of the time of the Pharaohs still exists in great
numbers in Kordofan, according to Brehm.

Upon the whole, we here have, then, at least three stocks of very
distinct dogs: 1, a hunting or shepherd's dog, of European origin; 2,
a mastiff, typical of the large breed of dogs indigenous to Asia; and
3, a harrier, indigenous to Africa.

We shall not follow the effects of the combination of these three
types through the ages, and the formation of the different breeds; for
that we shall refer our readers to a complete work upon which we have
been laboring for some years, and two parts of which have already
appeared.[1]

[Footnote 1: Les Races des Chiens, in La Bibliotheque de l'Eleveur.]

We shall rapidly pass in review the different breeds of dogs that one
may chance to meet with in our dog shows, beginning with the largest.
It is again in mountainous countries that the largest dogs are raised,
and the character common to all of these is a very thick coat. The
largest of all, according to travelers, is the Thibetan dog. Buffon
tells of having seen one which, when seated, was five feet in height.
One brought back by the Prince of Wales from his voyage to the Indies
was taller in stature, stronger and more stocky than a large mastiff,
from which it differed, moreover, in its long and somewhat coarse
hair, which was black on the back and russet beneath, the thighs and
the tail being clothed with very long and silky hair.

In France, we have a beautiful mountain dog--the dog of the
Pyrenees--which is from 32 to 34 inches in height at the shoulders,
and has a very thick white coat, spotted above with pale yellow or
grayish fox color. It is very powerful, and is capable of
successfully defending property or flocks against bears and wolves.

The Alpine dog is the type of the mountain dog. It is of the same size
as the dog of the Pyrenees, and differs therefrom especially in its
coloring. It is white beneath, with a wide patch of orange red
covering the back and rump. The head and ears are of the same color,
with the addition of black on the edges; but the muzzle is white, and
a stripe of the same color advances upon the forehead nearly up to the
nape of the neck. The neck also is entirely white. There are two
varieties of the Alpine or St. Bernard dog, one having long hair and
the other shorter and very thick hair. We give in Fig. 1 a portrait of
Cano, a large St. Bernard belonging to Mr. Gaston Leonnard.

[Illustration: FIG. 1--LARGE ST. BERNARD DOG BELONGING TO MR. LEONARD.]

Although this breed originated at the celebrated convent of St.
Bernard, it no longer exists there in a state of purity, and in order
to find fine types of it we have to go to special breeders of
Switzerland and England. The famous Plinnlimon, which was bought for
$5,000 by an American two or three years ago, and about which there
was much talk in the papers, even the political ones, was born and
reared in England. It appears that it is necessary, too, to reduce the
number of life-saving acts that it is said are daily performed by the
St. Bernard dogs. This is no longer but a legend. There was, it is
true, a St. Bernard named Barry, now exhibited in a stuffed state in
the Berne Museum, which accomplished wonders in the way of saving
life, but this was an exception, and the reputation of this animal has
extended to all others of its kind. These latter are simply watch dogs
kept by the monks for their own safety, and which do not go at all by
themselves alone to search for travelers that have lost their way in
the snow.

The Newfoundland dog, which differs from the preceding in its wholly
black or black and white coat, was, it appears, also of mountain
origin. According to certain authors, it is indigenous to Norway, and
was carried to Newfoundland by the Norwegian explorers who discovered
the island. Adapted to their new existence, they have become excellent
water dogs, good swimmers, and better life savers by far than the
majority of their congeners.

Is it from descending to the plain that the mountain dogs have lost
their long hair and have become short haired dogs like the English dog
or mastiff and the German or large Danish dogs? It is very probable.
At all events, it is by this character of having short hair that
mastiffs are distinguished from the mountain dogs. Again, the large
breed of dogs are distinguished from each other by the following
characters: The mastiff is not very high at the shoulders (30 inches),
but he is very heavy and thick set, with powerful limbs, large head,
short and wide muzzle and of a yellowish or café-au-lait color
accompanying a black face; that is to say, the ears, the circumference
of the eyes and the muzzle are of a very dark color. The German or
large Danish dogs constitute but one breed, but of three varieties,
according to the coat: (1) those whose coat is of a uniform color, say
a slaty gray or isobelline of varying depth, without any white spots;
(2) those having a fawn colored coat striped transversely with black
like the zebra, but much less distinctly; (3) those having a spotted
coat, that is to say, a coat with a white ground strewed with
irregular black spots of varying size. These, like those of the first
variety are generally small-eyed. Whatever be the variety to which
they belong, the German or large Danish dogs are slimmer than, and not
so heavy as, the mastiffs. Some, even, are so light that it might be
supposed that they had some heavier blood in their veins. They have
also a longer muzzle, although square, and are quicker in gait and
motions.

The largest dogs are to be met with in this breed, and the beautiful
Danish dog belonging to Prof. Charcot (Fig. 2) is certainly the
largest dog in France and perhaps in Europe. It measures 36 inches at
the shoulders and has an osseous and muscular development perfectly in
keeping with its large stature, and at the same time has admirable
proportions and lightness, and its motions are comparable to those of
the finest horse.

[Illustration: FIG. 2--DR. CHARCOT'S LARGE DANISH DOG.]

Among the English dogs or mastiffs, we very frequently meet with
individuals in which the upper incisors and canines are placed back of
the corresponding ones in the lower jaw, this being due to a slight
shortening of the bones of the upper jaw, not visible externally. This
is the first degree of an artist of teratological development, which,
since the middle ages, has become very marked in certain subjects, and
has given rise to a variety in which this defect has become
hereditary. Such is the origin of the breed of bulldogs. The latter
were originally as large as the mastiffs. Carried to Spain under
Philip II., they have there preserved their primitive characters, but
the bulldogs remaining in England have continued to degenerate, so
that now the largest are scarcely half the size of the Spanish
bulldog, and the small ones attain hardly the size of the pug,
although they preserve considerable width of chest and muscular
strength.


POINTERS.

Man hunted for ages with dogs that he united in a pack; but these
packs were of a very heterogeneous composition, since they included
strong dogs, light dogs very swift of foot, shepherds' dogs, and
others noted for acuteness of scent, and even mongrels due to a
crossing with the wolf. It is from the promiscuousness of all these
breeds that has arisen our ordinary modern dog.

The pointer is of relatively recent creation, and is due to the
falconers. In our western countries, falconry dates from the fourth
and fifth centuries, as is proved by the capitularies of Dagobert.
This art, therefore, was not brought to us from the East by the
crusaders in the twelfth and thirteenth centuries, as stated by Le
Maout in his Natural History of Birds.

The falconer soon saw the necessity of having a dog of nice scent
having for its role the finding or hunting up of game without pursuing
it, in order to permit the falcons themselves to enter into the sport.
This animal was called the bird dog, and was regarded as coming from
various countries, especially from Spain, whence the name of spaniel
that a breed of pointers has preserved. It is quite curious to find
that for three or four centuries back there have been no spaniels in
Spain. From Italy also and from southern climes comes what is called
the _bracco_, whence doubtless is derived the French name _braque_ and
English brach. Finally the _agasse_ of the Bretons was certainly also
one of the progenitors of our present pointers. It was, says Oppian, a
breed of small and very courageous dogs, with long hair, provided with
strong claws and jaws, that followed hares on the sly under shelter of
vine-stocks and reeds and sportively brought them back to their
masters after they had captured them. We have certainly here the
source of our barbets and griffons.

Finally the net hunters of the middle ages also contributed much to
the creation of the pointer, for it is to them that we owe the setter.
It is erroneously, in fact, that certain authors have attributed the
creation of this dog to hunters with the arquebuse, since this weapon
did not begin to be utilized in hunting until the sixteenth century.
Gaston Phoebus, who died in 1391, shows, in his remarkable work, that
the net hunters made use of Spanish setters and that it was they who
created the true pointer--the animal that fascinates game by its gaze.
By the same pull of their draw net they enveloped in its meshes both
the setter and the prey that it held spellbound.

Upon the whole, we see that at the end of the middle ages there
existed three types of pointers: spaniels, brachs and very hairy dogs,
that Charles Estienne, in his Maison Rustique, of the sixteenth
century, calls barbets. It is again with these three types that are
connected all the present pointers, which we are going to pass rapidly
in review.

_The Brach hounds_.--To-day we reserve the name of brachs for all
pointers with short hair. The type of the old brach still exists in
Italy, Spain, the south of France and in Germany. It is characterized
by its large size, its robust form, its large head, its long, flat
ears, its square muzzle separated from the forehead by a deep
depression, its large nose, often double (that is to say, with
nostrils separated by a deep vertical groove), its pendent lips, its
thick neck, its long and strong paws provided with dew claws, both on
the fore and the hind feet, and its short hair, which is usually white
and marked with brown or orange-yellow spots. The old brach breed has
been modified by the breeders of different countries, either by
hygiene or by crossing with ordinary dogs, according to the manner of
hunting, according to taste, and even according to fashion. Thus in
England, where "time is money" reigns in every thing and where they
like to hunt quickly and not leisurely, the brach has been rendered
lighter and swifter of foot and has become the pointer. In France,
while it has lost a little in size and weight, it has preserved its
moderate gait and has continued to hunt near its master, "under the
gun," as they say. The same is the case in Spain, Italy and Germany
even. In France there are several varieties or sub-breeds of brach
hounds. The old French brach, which is nothing more than the old type,
preserved especially in the south, where it is called the Charles the
Tenth brach, is about twenty-four inches in height, and has a white
and a maroon coat, which is somewhat coarse. It often has a cleft nose
and dew-claws on all the feet. The brach of the south scarcely differs
from the preceding except in color. Its coat has a white ground
covered with pale orange blotches and spots of the same color. The St.
Germain brach is finer bred, and appears to be a pointer introduced
into France in the time of Charles X. It has a very fine skin, very
fine hair of a white and orange color. The Bourbon brach has the
characters of the old French brach, with a white coat marked here and
there with large brown blotches, and the white ground spotted with the
same color; but what particularly characterizes this dog is that it is
born with a stumpy tail, as if three-quarters of it had been chopped
off. The Dupuy brach is slender and has a narrow muzzle, as if it had
some harrier blood in its veins. It is white, with large dark maroon
blotches. The Auvergne brach resembles the southern brach, but has a
white and black coat spotted with black upon white. The pointer, or
English brach (Fig. 3), descends from the old Spanish brach, but has
been improved and rendered lighter and much swifter of foot by the
introduction of the blood of the foxhound into its veins, according to
the English cynegetic authors themselves. The old pointer was of a
white and orange color, and was indistinguishable from our St.
Germain. The pointer now fancied is white and maroon and has a
stronger frame than the pointer of twenty years ago. The Italian
brachs are heavy, with lighter varieties, usually white and orange
color, more rarely _roan_, and provided with dew-claws, this being a
sign of purity of breed according to Italian fanciers. The German
brachs are of the type of the old brach, with a stiff white and
maroon coat, the latter color being so extensively distributed in
spots on the white as to make the coat very dark.

[Illustration: FIG 3.--POINTER.]

_Spaniels_.--The old type of spaniel has nearly disappeared, yet we
still find a few families of it in France, especially in Picardy and
perhaps in a few remote parts of Germany. The old spaniel was of the
same build as the brach, and differed from it in that the head, while
being short-haired, was provided with ears clothed with long, wavy
hair. The same kind of hair also clothed the whole body up to the
tail, where it constituted a beautiful tuft. The Picard spaniel is a
little lighter than the old spaniel. It has large maroon blotches upon
a white ground thickly spotted with maroon, with a touch of flame
color on the cheeks, over the eyes, and on the legs. The Pont-Andemer
spaniel is a Norman variety, with very curly hair, almost entirely
maroon colored, the white parts thickly spotted with a little color as
in the Picard variety, and a characteristic forelock on the top of the
head.

[Illustration: FIG 4.--ENGLISH SETTERS.]

In England, the spaniel has given rise to several varieties. In the
first place there are several sub-breeds of setters, viz.: The English
setter, still called laverack, which has large black or orange-colored
blotches on the head, the rest of the body being entirely white, with
numerous spots of the same color as the markings on the head (Fig. 4);
the Irish setter, which is entirely of a bright yellowish mahogany
color; and the Gordon setter, which is entirely black, with orange
color on the cheeks, under the throat, within and at the extremity of
the limbs (Fig. 5). Next come the field spaniels, a group of terrier
spaniels, which includes the Clumber spaniel, which is white and
orange color; the Sussex spaniel, which is white and maroon; the black
spaniel, which is wholly black; and the cocker, which is the smallest
of all, and is entirely black, and white and maroon, or white and
orange-colored, or tricolored.

[Illustration: FIG 5.--GORDON SETTER.]

_Barbets and Griffons_.--To this latter category belong the dogs, _par
excellence_, for hunting in swamps. The barbets are entirely covered
with long curly hair, like the poodles, which are directly derived
from them. They are white or gray, with large black or brown blotches.
The griffons differ from the poodles in their coarse and stiff hair,
which never curls. They have large brown blotches upon a white ground,
which is much spotted or mixed, as in the color of the hair called
roan. There is an excellent white and orange-colored variety. The
griffons, neglected for a long time on account of the infatuation that
was and is still had for English hunting dogs, are being received
again with that favor which they have never ceased to be the object of
in Germany and in Italy (where they bear the name of _spinone_).
Breeders of merit, such as Mr. Korthals, in Germany, and Mr. E.
Boulet, in France, are endeavoring to bring them into prominence (Fig.
6). Finally, we reckon also among hunting dogs some very happy
crosses between the spaniels and the barbets, which in England are
called retrievers or water spaniels.--_P. Megnin, in La Nature_.

[Illustration: FIG 6.--COARSE HAIRED GRIFFON.]

       *       *       *       *       *




RESTOCKING THE SEINE WITH FISH.


A few days ago, at Bougival, a short distance below the dam of the
Marly machine, there were put into water 40,000 fry of California
trout and salmon, designed to restock the Seine, which, in this
region, has been depopulated by the explosions of dynamite which last
winter effected the breaking up of the ice jam that formed at this
place.

[Illustration: RESTOCKING THE SEINE WITH FISH.]

The operation, which is quite simple in itself, attracted a large
number of inquisitive people by reason of the exceptional publicity
given to the conflict provoked by a government engineer, who, under
the pretext that he had not been consulted, made objections to the
submersion of the little fish. As well known, the affair was
terminated by a sharp reprimand from Mr. Yves Guyot, addressed to his
overzealous subordinate.

It would have been a great pity, moreover, if this interesting
experiment had not taken place, and had not come to corroborate the
favorable results already obtained.

In three years the California salmon reaches a weight of eleven
pounds, and, from this time, is capable of reproduction. Its flesh is
delicious, and comparable to that of the trout, the development of
which is less rapid, but just as sure.

The fry put into the water on Sunday were but two months old. The
trout were, on an average, one and a half inches in length, and the
salmon two and three-quarter inches. They were transported in three
iron plate vessels, weighing altogether, inclusive of the water, 770
lb., and provided with air tubes through which, during the voyage, the
employes, by means of pumps, assured the respiration of the little
fish.

Our engraving represents the submersion at the moment at which
the cylinders (of which the temperature has just been taken and
compared with that of the Seine, in order to prevent too abrupt a
transition for the fry) are being carefully let down into the
river.--_L'Illustration_.

       *       *       *       *       *




Figures show that the consumption of iron in general
construction--other than railroads--in this country has grown from a
little more than a million and a half of tons in 1879 to more than six
million tons in 1889. Much of this increase has gone into iron
buildings. By using huge iron frames and thin curtain walls for each
story supported thereon, as is done in a building going up on lower
Broadway, New York city, a good deal of space can be saved.

       *       *       *       *       *




MODERN ARMOR.

By F.R. BRAINARD, U.S.N.


The building of a navy, which has been actively going on for the past
few years, has drawn public attention to naval subjects, and recent
important experiments with armor plates have attracted large
attention, hence it may not be amiss to give a description of the
manufacture and testing of armor. It would be interesting to wade
through the history of armor, studying each little step in its
development, but we shall simply take a hasty glance at the past, and
then devote our attention to modern armor and its immediate future.

Modern armor has arrived at its present state of development through a
long series of experiments. These experiments have been conducted with
great care and skill, and have been varied from time to time as the
improvements in the manufacture of materials have developed, and as
the physical laws connected with the subject have been better
understood. There has been very little war experience to draw from,
and hence about all that is now known has been acquired in peaceful
experiments.

The fundamental object to be obtained by the use of armor is to keep
out the enemy's shot, and thus protect from destruction the vulnerable
things that may be behind it. The first serious effort to do this
dates with the introduction of iron armor. With this form of armor we
have had a small amount of war experience. The combat of the Monitor
and Merrimac, in Hampton Roads, in May, 1862, not only marked an epoch
in the development of models of fighting ships, but also marked one in
the use of armor. The Monitor's turret was composed of nine one-inch
plates of wrought iron, bolted together. Plates built in this manner
form what is known as laminated armor. (See Fig. 1.) The side armor of
the hull was composed of four one-inch plates. The Merrimac's casemate
was composed of four one-inch plates or two two-inch plates backed by
oak. The later monitors had laminated armor composed of one-inch
plates. The foregoing, with the Albemarle and Tennessee rams under the
Confederate flag, are about the sum of our practical experience in the
use of armor.

[Illustration: Fig. 1.]

European nations took up the subject of armor and energetically
conducted experiments which have cost large sums of money, but have
given much valuable data. For a long time wrought iron was the only
material used for armor, and the resisting power depending on the
thickness; and the caliber and penetration of guns rapidly increasing,
it was not long before a point was reached where the requisite
thickness made the load of armor so great that it was impracticable
for a ship to carry it. The question then arose as to what were the
most important parts of a ship to protect. The attempted solutions of
this question brought out various systems of distributions.

Armored ships were formerly of two classes; in one the guns were
mounted in broadside, in the other in turrets. Every part of the ship
was protected with iron to a greater or less thickness. In more modern
ships the guns are mounted in an armored citadel, in armored barbettes
or turrets, the engines, boilers and waterline being the only other
parts protected. There may be said to be three systems of armor
distribution. The belt system consists in protecting the whole
waterline by an armored belt, the armor being thickest abreast of the
engines and boilers. The guns are protected by breastworks, turrets or
barbettes, the other parts of the ship being unprotected. The French
use the belt system, and our own monitors may be classed under it. The
central citadel system consists in armoring that part of the waterline
which is abreast of the engines and boilers. Forward and aft the
waterline is unprotected, but a protective deck extends from the
citadel in each direction, preventing the projectiles from entering
the compartments below. The hull is divided into numerous compartments
by water-tight bulkheads, and, having a reserve of flotation, the
stability of the ship is not lost, even though the parts above the
protective deck, forward and aft, be destroyed or filled with water.
The guns are protected by turrets or barbettes. The deflective system
consists in inclining the armor, or in so placing it that it will be
difficult or impossible to make a projectile strike normal to the face
of the plate. A plate that is inclined to the path of a projectile
will, of course, offer greater resistance to penetration than one
which is perpendicular; hence, when there is no other condition to
outweigh this one, the armor is placed in such a manner as to be at
the smallest possible angle with the probable path of the projectile.
This system is designed to cause the projectile to glance or deflect
on impact. Deflective armor should be at such an angle that the
projectiles fired at it cannot bite, and hence the angle will vary
according to the projectile most likely to be used. In the usual form
of deflective deck the armor is at such a small inclination with the
horizon that it becomes very effective. Turret and barbette armor may
be considered as deflective armor. The term inclined armor denotes
deflective armor that is inclined to the vertical. The kinds of armor
that are in use may be designated as rolled iron, chilled cast iron,
compound, forged and tempered steel, and nickel steel. Iron armor
consists of wrought iron plates, rolled or forged, and of cast iron or
chilled cast iron, as in the Gruson armor. Compound armor consists of
a forged combination of a steel plate and an iron plate. Steel armor
consists of wrought steel plates. Nickel-steel armor consists of
plates made from an alloy of nickel and steel.

I have spoken above of laminated armor. To secure the full benefit of
this kind, the plates must be neatly fitted to each other; the
surfaces must make close contact. This requires accurate machining,
and hence is expensive. To overcome this point sandwiched armor was
suggested. This consists in placing a layer of wood between the
laminations, as shown in Fig. 2. It was found that laminated and
sandwiched armor gave very much less resisting power than solid rolled
plates of the same thickness. Wrought iron armor is made under the
hammer or under the rolls, in the ordinary manner of making plates,
and has been exhaustively studied and experimented with--more so than
any other form of armor.

[Illustration: Fig. 2.]

Chilled cast iron armor is manufactured by Gruson, in Germany, and is
used in sea coast defense forts of Europe.

In 1867 several compound plates were made by Chas. Cammell & Co., of
Sheffield, England, and were tested at Shoeburyness, in England, and
at Tegel, in Russia. These plates were made by welding slabs of steel
to iron; but the difficulties were so great that the idea was
abandoned for the time.

[Illustration: Fig. 3.]

[Illustration: FIG. 4.]

Compound armor, as now manufactured, is of two types: Wilson's patent,
a backing of rolled iron, faced with Bessemer steel; Ellis' patent, a
backing of rolled iron, faced with a plate of hard rolled steel,
cemented with a layer of Bessemer steel. Both these kinds are
manufactured in England and France in sizes up to fifty tons weight.
The Wilson process is used at the works of Messrs. Cammell & Co., of
Sheffield, England, and the Ellis process at the Atlas Works of Sir
John Brown & Co., of the same place. These are the two leading
manufacturers of compound plate.

[Illustration: Fig. 5.]

The method employed by Wilson in making compound plate is to first
make a good wrought iron plate. To the surface of this and along each
side of the length of the plate are fixed two small channel irons, as
shown in Fig. 5. The plate is then raised to a welding heat in a gas
furnace, and transferred to an iron flask or mould. Wedges are driven
in between the back of the plate and the side of the mould, thus
forcing the channel irons up snug against the opposite side of the
mould. Moulding sand is then packed around the back and sides of the
plate (see Fig. 6). The mould is lowered in a vertical position into a
pit. Molten steel, manufactured by either the Siemens-Martin or
Bessemer process, is then poured in through a trough that forms
several streams, and forms the hard face of the plate. The molten
steel as it runs down cleans the face of the wrought iron plate,
scoring it in places, and, being of much higher temperature, the
excessive heat carbonates the iron to a depth of one-eighth to
three-sixteenths of an inch, forming a zone of mild steel between the
hard steel and soft iron. The mould is placed in a vertical position
to insure closeness of structure and the forcing of gases out of the
steel. After solidifying, the whole plate is pressed, and passed
through the rolls to obtain thorough welding. It is then bent, planed,
fitted, tempered, and annealed to remove internal strains.

[Illustration: Fig. 6.]

In 1887, Wilson took out a patent for improvements in his process of
making compound plates. In this method of manufacture he takes a
wrought iron, fibrous plate, fifteen inches thick, built up from a
number of thin plates. While hot from the forging press, he places
this plate in an iron mould (see Fig. 7) about 28 inches deep, and
upon it runs "ingot iron" or very mild steel to a depth of thirteen
inches. In this form of mould the plate rests on brickwork, and is
held in place by two grooved side clamps or strips which are caused to
grip the plate by means of screws which extend through the sides of
the mould. After solidifying, the plate, which is twenty-eight inches
thick, is reheated and rolled down to eighteen inches. This is the
iron backing of the finished plate, and it is again put in the iron
mould and heated, when a layer of hard steel is run on the exposed
surface of the original wrought iron plate to a depth of eight inches.
This makes a plate about twenty-eight inches thick. It is taken from
the mould, reheated, rolled, hammered or pressed down to twenty
inches. After cooling, it is bent, planed, and fitted as desired, then
tempered and annealed to relieve internal strains.

[Illustration: Fig. 7.]

The method employed by Ellis in making compound plates is to take two
separate plates, one of good wrought iron and one of hard forged
steel, placing the forged steel plate on the wrought iron plate,
keeping them separate by a wedge frame or berm of steel around three
sides, and placing small blocks of steel at various points near the
middle of the plates (see Fig. 8). These blocks are called distance
blocks. After covering all the exposed steel surfaces with ganister,
the plates are put in a gas furnace and heated to a welding heat. They
are then lowered into a vertical iron pit with the open side
uppermost. The plates are held in position by hydraulic rams, which
also prevent bulging. Molten steel of medium softness is then poured
into the space between the plates, by means of a distributing trough
having holes in the bottom, and after this has solidified, the whole
plate is placed under the hydraulic press and reduced about twenty per
cent. in thickness. The plate is then passed through the rolls, bent,
planed, fitted, tempered, and annealed to reduce internal strains.

[Illustration: Fig. 8.]

In heating the compound plates for rolling, the plate is placed in the
furnace with the steel face down, so that the iron part gets well
heated and the steel does not become too hot. Great care must be taken
not to overheat the plate, and in working, many passes are given the
plate with small closings of the rolls. The steel part of a compound
plate is usually about one third of the full thickness of the plate.

Forged steel armor, tempered in oil, is fabricated at Le Creusot,
France, by Schneider & Co., using open-hearth steel, and forging under
the 100 ton hammer. The ingots are cast, with twenty-five per cent.
sinking head and are cubical in form. The porter bar is attached to a
lug on one side of the ingot. By means of a crane with a curved jib
which gives springiness under the hammer, the ingot is thrust into the
heating furnace. On arriving at a good forging heat it is swung around
to the 100 ton hammer, under which it is worked down to the required
shape. A seventy-five ton ingot requires about eight reheatings before
being reduced to shape. Having been reduced to shape, the plate is
carefully annealed, then raised to a high tempering heat, and the face
tempered in oil. It is reannealed to take out the internal strains,
care being taken not to reduce the face hardness more than necessary.
The Schneider process of tempering is based upon the utilization of
the absorption of heat caused by the fusing or melting of a solid
substance, and of the fact that so long as a solid is melting or
dissolving in a liquid substance, the liquid cannot get appreciably
hotter, except locally around the heating surface. The body to be
hardened is plunged at the requisite temperature into a bath
containing the solid melting body, or is kept under pressure in the
solid material of low melting point until the required extraction of
heat has taken place, more solid material being added if necessary as
that originally present melts and dissolves.

Nickel steel armor is made in a similar manner to the steel plates,
the material used in casting the ingot being an alloy of nickel and
steel containing between three and four per cent. of nickel.

The Harvey process of making armor consists in taking an all-steel
plate and carbonizing the face. This carbonizing process is very
similar to the cementation process of producing steel, and by it the
face of the plate is made high in carbon and very hard.

The system invented by Sir Joseph Whitworth, of Manchester, England,
consists in what might be called scale armor. A section of a sample of
the armor represents four plates. The outer layer, one inch thick, is
composed of steel of a tensile strength of 80 tons per square inch;
the second layer, one inch thick, of steel whose tensile strength is
40 tons per square inch; the third and fourth layers, each one-half
inch thickness, of mild steel. The outer layer is in small squares of
about ten inches on a side, and is fastened to the second layer by
bolts at the corners and one in the middle of each square. The surface
is flush. (See Fig. 9.) The end sought by the above system is to break
up the shot by the hard steel face and to restrict any starring or
cracking of the metal to the limit of the squares or scales struck.
The bolts are of high carbon and are extremely hard steel.

[Illustration: Fig. 9.]

Armor plates must often be bent or curved to single or double
curvature and sometimes to a warped surface to fit the form of the
ship. There are several methods of bending plates. One method employs
a cast iron slab of the required form, which is placed on the piston
of a hydraulic press. The armor plate is placed face down on this
slab, and on top of the plate are laid packing blocks of cast iron, of
such sizes and shapes as to conform to the required curve. These
blocks take against the upper table of the press, when the piston is
forced up, and the hot plate is thus dished to the proper form.

In the French method of bending, an anvil or bed plate of the required
curve is used, and the armor plate is forced to take the curve by
being hammered all over its upper surface with a specially designed
steam hammer.

The edges of the plate are trimmed by large, powerful slotting
machines or circular saws; the latter, however, operate in exactly the
same manner as a slotter, except that there is no return motion to the
tool. Each tooth of the saw is but a slotting tool, and these teeth
are, by screws, rendered capable of being nicely adjusted in the
circumference of the saw.

The plates are fastened to the hulls and backing by heavy bolts,
varying in size according to the weight of the individual plate. For
the 6,000 ton armored ships, these bolts are from 2.75 to 3.1 inches
in diameter and from 18.45 to 23 inches in length. They are tapped two
or three inches into the armor and do not go through the plate. They
pass through wrought iron tubes in the backing and set up with cups,
washers and nuts against the inner skin of the ship.

At steel works where plates for our new navy are being manufactured,
there are inspectors who look after the government's interests.
Officers of the navy are detailed for this work, and their duty is to
watch the manufacture of plates through each part of the process and
to see that the conditions of the specifications and contract are
complied with.

The inspection and testing of armor plates consists in examining them
for pits, scales, laminations, forging cracks, etc., in determining
the chemical analysis of specimens taken from different parts, in
determining the physical qualities of specimens taken longitudinally
and transversely, and the ballistic test. Specifications for these
different tests are constantly undergoing change, and it would be
impossible to state, with exactness, what the requirements are or will
be in the near future. The ballistic test is the important one, and is
made by taking one plate of a group and subjecting it to the fire of a
suitable gun. The other tests are simply to insure, as far as
practicable, that all the other plates of the group are similar to and
are capable of standing as severe a ballistic test as the test plate.

The following will give an idea of the ballistic test as prescribed by
the Bureau of Ordnance, Navy Department. The test plate, irrespective
of its thickness, is to be backed by thirty-six inches of oak or other
substantial wood. Near the middle region of the plate an equilateral
triangle will be marked, each side of which will be three and one-half
calibers long. The lower side of the triangle will be horizontal.
Three shots will be fired, the points of impact being as near as
possible the extremities of the triangle. The velocity of the shot
will be such as to give the projectile sufficient energy to just pass
through a wrought iron plate of equal thickness to the test plate, and
through its wood backing. The velocity is calculated by the Gavre
formula:

              a
       V² =  --- { 3507 E² × 2265464 e^{1.4} }
              w

[TEX: V^2 = \frac{a}{w} \{ 3507 \ E^2 \times 2265464 \ e^{1.4} \}]

  V = the velocity of the projectile in feet per second.
  a = the diameter of the projectile in inches.
  w = the weight of the projectile in pounds.
  E = the thickness of the backing in inches.
  e = the thickness of the plate in inches.

Using the above formula we can make out a table as follows:

-------+-------+-------------+-------+-------+------+---------+
Plate. |Backi'g| Gun, service|  w,   |  a,   |  V.  | Energy, |
Inches.|Inches.| shot.       |Pounds.|Inches.| f. 8.| Impact. |
       |       |             |       |       |      | f. tons.|
-------+-------+-------------+-------+-------+------+---------+
  6    |  36   |   6" B.L.R. |  100  |  5.96 | 1389 |  1337   |
  7    |  36   |   6"   "    |  100  |  5.96 | 1528 |  1619   |
  8    |  36   |   8"   "    |  250  |  7.96 | 1213 |  2550   |
  9    |  36   |   8"   "    |  250  |  7.96 | 1308 |  2966   |
 10    |  36   |   8"   "    |  250  |  7.96 | 1399 |  3390   |
 11    |  36   |   8"   "    |  250  |  7.96 | 1489 |  3839   |
 12    |  36   |  10"   "    |  500  |  9.96 | 1247 |  5386   |
 13    |  36   |  10"   "    |  500  |  9.96 | 1315 |  5987   |
 14    |  36   |  10"   "    |  500  |  9.96 | 1381 |  6608   |
 15    |  36   |  12"   "    |  850  | 11.96 | 1215 |  8699   |
 16    |  36   |  12"   "    |  850  | 11.96 | 1269 |  9710   |
 17    |  36   |  12"   "    |  850  | 11.96 | 1332 | 10454   |
 18    |  36   |  12"   "    |  850  | 11.96 | 1374 | 11124   |
 19    |  36   |  12"   "    |  850  | 11.96 | 1425 | 11965   |
 20    |  36   |  12"   "    |  850  | 11.96 | 1476 | 12837   |
-------+-------+-------------+-------+-------+------+---------+


No projectile or fragment of the plate or projectile must get wholly
through the plate and backing. The plate must not break up or give
such cracks as to expose the backing, previous to the third shot.

The penetration of projectiles of different forms into various styles
of armor has been very thoroughly studied and many attempts have been
made to bring the subject down to mathematical formulæ. These formulæ
are based on several suppositions, and agree very closely with results
obtained in actual experiments, but there are so many varying
conditions that it is extremely doubtful if any formulæ will ever be
written that will properly express the penetration.

Many different forms have been given to the heads of projectiles, as
flat, ogival, hemispherical, conoidal, parabolic, blunt trifaced, etc.

The flat headed projectile has the shape of a right cylinder, and acts
like a punch, driving the material of the armor plate in front of it.
These projectiles are especially valuable when firing at oblique
armor, for they will bite or cut into the armor when striking at an
angle of thirty degrees.

The ogival head acts more as a wedge, pushing the metal aside, and
generally will give more penetration in thick solid plates than the
flat headed projectile. The ogival head is usually designed by using a
radius of two calibers.

The hemispherical, conoidal, parabolic and blunt trifaced all give
more or less of the wedging effect. The blunt trifaced has all the
good qualities of the ogival of two calibers. It bites at a slightly
less angle, and the three faces start cracks radiating from the point
of impact.

Forged steel is the best material for armor-piercing projectiles, but
many are made of chilled cast iron, on account of its great hardness
and cheapness.

The best weight for a projectile is found by the formula

    w = d³ (0.45 to 0.5)

w being the weight in pounds, d the diameter in inches and 0.45 to 0.5
having been determined by experiment.

With a light projectile we get a flat trajectory, and accuracy at
short ranges is increased. With a heavy projectile the resistance of
the air has less effect and the projectile is advantageously employed
at long ranges.

In the following formulæ, used in calculating the penetration of
projectiles in rolled iron armor,

  g = the force of gravity.
  w = the weight of projectile in pounds.
  d = the diameter of projectile in inches.
  v = the striking velocity in feet per second.
  P = the penetration in inches.


Major Noble, R.A., gives

              _________________
         1.6 /      w v²
   P =  /\  /  ----------------
          \/   [pi] g d 11334.4

[TEX: P = \sqrt[1.6]{\frac{w \ v^2}{\pi \  g \  d \ 11334.4}}]

U.S. Naval Ordnance Proving Ground uses

              ________________
        2.035/      w v²
   P =  /\  /  ---------------
          \/   [pi] g d 3852.8

[TEX: P = \sqrt[2.035]{\frac{w \ v^2}{\pi \  g \  d \ 3852.8}}]

Col. Maitland gives

            w v²
   P =  ------------
        g d² 16654.4

[TEX: P = \frac{w \ v^2}{g \  d^2 \ 16654.4}]

Maitland's latest formula, now used in England, is

                 _
          v     /w
    P = ----- \/ - - 0.14 d
        608.3    d

[TEX: P = \frac{v}{608.3} \sqrt{\frac{w}{d}} - 0.14 \ d]

General Froloff, Russian army, gives

         w v
    P = ------
        d² 576

[TEX: P = \frac{w \ v}{d^2 \ 576}]

for plates less than two and one-half inches thick, and

         w v
    P = ------ - 1.5
        d² 400

[TEX: P = \frac{w \ v}{d^2 \ 400} - 1.5]

for plates more than two and one-half inches thick.


If [theta] be the angle between the path of the projectile and the
face of the plate, then v in the above formulæ becomes v sin [theta].

When we come to back the plates, their power to resist penetration
becomes greater, and our formula changes. The Gavre formula, given
above, is used to determine the velocity necessary for a projectile to
pass entirely through an iron plate and its wood backing.

Compound and steel armor are said to give about 29 per cent. more
resisting power than wrought iron, but in one experiment at the
proving ground, at Annapolis, a compound plate gave over 50 per cent.
more resisting power than wrought iron.

The Italian government, after most expensive and elaborate comparative
tests, has decided in favor of the Creusot or Schneider all-steel
plates, and has established a plant for their manufacture at Terni,
near Rome.

The French use both steel and compound plates; the Russians, compound;
the Germans, compound; the Swedes and Danes use both. Spain has
adopted and accepted the Creusot plate for its new formidable armored
vessel, the Pelayo; and China too has recently become a purchaser of
Creusot plates.

Certain general rules may be laid down for attacking armor. If the
armor is iron, it is useless to attack with projectiles having less
than 1,000 feet striking velocity for each caliber in thickness of
plate. It is unadvisable to fire steel or chilled iron filled shells
at thick armor, unless a normal hit can be made. When perforation is
to be attempted, steel-forged armor-piercing shells, unfilled, should
be used. They may be filled if the guns are of great power as compared
to the armor. Steel and compound armor are not likely to be pierced by
a single blow, but continued hammering may break up the plate, and
that with comparatively low-powered guns.

Wrought iron must be perforated, and hard armor, compound or steel,
must be broken up. Against wrought iron plates the projectile may be
made of chilled cast iron, but hard armor exacts for its penetration
or destruction the use of steel, forged and tempered. Against
unarmored ships, and against unarmored portions of ironclads, the
value of rapid-firing guns, especially those of large caliber, can
hardly be overestimated.

The relative value of steel and compound armor is much debated, and at
present the rivalry is great, but the weight of evidence and opinion
seems to favor the all-steel plate. The hard face of a compound plate
is supposed to break up the projectile, that is, make the projectile
expend its energy on itself rather than upon the plate, and the
backing of wrought iron is, by its greater ductility, to prevent the
destruction of the plate. It seems probable that these two systems
will approach each other as the development goes on. An alloy of
nickel and steel is now attracting attention and bids fair to give
very good results.

The problem to be solved, as far as naval armor is concerned, is to
get the greatest amount of protection with the least possible weight
and volume, and this reduction of weight and volume must be
accomplished, in the main, by reducing the thickness of the plates by
increasing the resisting power of the material. In the compound plate
great surface hardness is readily and safely attained, but it has not
yet been definitely determined what the proper proportionate thickness
of iron and steel is.

A considerable thickness of steel is necessary to aid, by its
stiffness, in preventing the very ductile iron from giving back to
such an extent as to distort the steel face and thus tear or separate
the parts of the plate. The ductile iron gives a very low resisting
power, its duty being to hold the steel face up to its work. If now we
substitute a soft steel plate in the place of the ductile iron, we
will get greater resisting power, but our compound plate then becomes
virtually an all-steel one, only differing in process of manufacture.
The greatest faults of the compound plate are the imperfect welding of
the parts and the lack of solidity of the iron. When fired at, the
surface has a tendency to chip.

In the all-steel plate we have the greatest resisting power
throughout, but there are manufacturing difficulties, and surface
hardness equal to that of the compound plate has not been obtained.
The manufacturing difficulties are being gradually overcome, and
artillerists are in high hopes that the requisite surface hardness
will soon be obtained.

The following may be stated as well proved:

1. That steel armor promises to replace both iron and compound.

2. That projectiles designed for the piercing of hard armor must be
made of steel.

3. That the larger the plate, the better it is able to absorb the
energy of impact without injury to itself.

4. That the backing must be as rigid as possible.

       *       *       *       *       *

[FROM ENGINEERING.]




THE COMPRESSED AIR SYSTEM OF PARIS.


The demand for compressed air as a motive power is constantly
increasing in Paris; the company, according to its official reports,
is financially prosperous, and it seems difficult to understand how it
should continue as an actively going concern, unless it at all events
paid its way. The central station of St. Fargeau, originally started
on modest lines, for maintaining a uniform time by pneumatic pressure
throughout Paris, has grown rapidly to very large proportions, though
it has never been able to supply the demand made on it for power; and
at the present time a second and still larger station is being
constructed in another part of Paris. We confess that we do not
understand why such large sums of money should continue to be spent if
the enterprise is not commercially a sound one, nor how men of such
eminence in the scientific world as Professor Riedler should, without
hesitation, risk their reputation on the correctness of the system, if
it were the idle dream of an enthusiast, as many persons--chiefly
those interested in electric transmission--have declared it to be.

[Illustration: Fig. 1.--MAP OF PARIS WITH ST. FARGEAU STATION]

In describing the developments that have taken place during the last
two years, we shall confine ourselves entirely to the details of a
report recently made on the subject by Professor Riedler. As soon as
it became evident that a very largely increased installation was
necessary, it was determined that the new central station should be as
free as possible from the defects of the first one. These defects,
which were the natural results of the somewhat hasty development of an
experimental system, were of several kinds. In the first place, so
large a growth had not been contemplated, and the extensions were
made more or less piecemeal, instead of being on a regular plan; the
location of the central station itself was very unfavorable, both as
regards the facilities for obtaining coal and other supplies; the cost
of water was excessive, and the amount available, inadequate.

This evil was partly remedied by elaborate arrangements for cooling
the injection water so that it could be repeatedly used, a device
costly and ineffective, and resulting in extravagant working, to say
nothing of the high charges made by the Paris company for supplying
water. To these drawbacks had to be added others of an even more
serious character. The engines first laid down were not economical,
and the compressors employed gave but a very inferior result; with
each extension of the plant, the efficiency of both engines and
compressors was increased, the most satisfactory, we believe, having
been those supplied by the Societe Cockerill, and one of which was
exhibited at the Paris exhibition in 1889. Still it was clearly
recognized that much better results were possible, results which
Professor Riedler claims have been attained and which will be embodied
in the new installation now in progress.

This central station is located on the left bank of the Seine, close
to the fortifications, opposite Vincennes and not far from the
terminal stations of the Orleans and the Paris, Lyons, and
Mediterranean Railways; the plan, Fig. 1, shows the position. The
works are separated from the river by the quay, over which a bridge
will be constructed for the transfer of coal from the landing stages
belonging to the company, into the works; as will be readily seen from
the plan, it would be quite easy to run junction lines to the two
adjacent railways, but with all the advantages given by water
carriage, it was considered unnecessary to incur the expense. The
river also affords a constant and unlimited water supply, so that none
of the difficulties existing at St. Fargeau Station in imperfect
condensation and cooling will be met with.

The new installation, called the Central Station of the Quai de la
Gare, is laid out on a very large scale, the total generating energy
provided for being no less than 24,000 horse power; of this it is
intended that 8,000 horse power will be in operation this year, and an
extension of 10,000 horsepower in 1892; the power now in course of
completion comprises four engines of 2,000 horse power each. Four
batteries of boilers will provide steam for these engines. Figs. 2, 3,
and 4 show the first section of the installation now in progress; the
four groups of engines (three-cylinder condensing) are shown at 1, 2,
3, and 4; the four groups of boilers ranged behind them at F, F; the
feed water heaters belonging to each group at V V.

[Illustration: COMPRESSED AIR STATION ON THE QUA DE LA GARE, PARIS.
(FIG. 2,3,4)]

The end of the building abuts against the Seine, and the position of
the water conduits for inlet and discharge are indicated at C and A
respectively. The installation, when completed, will include very
extensive arrangements for transporting and storing coal, and the
interior of the boiler houses will be furnished with an overhead
system of rails and carriers for handling the coal automatically, as
far as possible. All the principal mains and steam pipes are made in
duplicate, not only for greater security, but in order that each set
of engines and boilers may be connected interchangeably without delay.
The Seine supplies an ample quantity of water, but not in a condition
either for feeding the boilers, for condensation, or for the air
compressors.

[Illustration: THE NEW COMPRESSED AIR STATION AT PARIS. (FIG. 5, 6)]

Special provisions have therefore to be made to filter the water
efficiently before it is used. For this purpose the water is led to a
group of four filters (see L, Fig. 4); from them it passes into the
tanks, JJ, and is pumped into the heaters. The filters can be rapidly
and automatically cleaned by reversing the flow of water through them.
Figs. 5 and 6 show the general form of the type of engine adopted, as
well as the engine house, some of the mains, etc. They are vertical
triple-expansion engines, and are being constructed by MM. Schneider
et Cie, of Creusot, with a guarantee of coal consumption not to exceed
1.54 lb. per horse power per hour, with a penalty of 2,000 francs for
every 100 grammes in excess of this limit. It is evident that with
this restricted fuel consumption, a large margin for economy will
exist at the new works, as compared with the St. Fargeau station,
where the best engines cannot show anything like this result, while
some of the earlier ones are distinctly extravagant, and the whole
installation is handicapped with imperfect means of condensation.

Moreover, according to Professor Riedler, the consumption of steam by
the new Schneider engines will be only 5.3 kilos. per horse power and
per hour as compared with some of the large engines requiring 9
kilos., and the Cockerill engines--using 8 kilos. per hour, not to
speak of the older motors that are very extravagant in the use of
steam. The St. Fargeau station is worked under a further disadvantage.
The constantly increasing demand from subscribers taxes the resources
of the station to their fullest extent, so that practically there is
no reserve power.

In the new installation the work will be equally constant, but care
will be taken always to have a sufficient reserve. Electric lighting
will form a considerable part of the duty to be done from this
station, and in all cases it is intended to work with accumulators, so
that the resistance to be overcome by the engines, so far as this part
of the duty is concerned, will be well known and uniform. The
engineers of the Compressed Air Co., of Paris, have during the last
five years acquired an experience which could only be attained at a
high price and at the expense of a certain amount of failure; this
period, it is claimed, is now passed, and in the new installation it
is possible to put into practice all the valuable lessons learned at
St. Fargeau, to say nothing of the more favorable natural conditions
under which the extension is being started and the improvements in the
compression of the air made by Mr. Popp and Professor Riedler, and to
which we shall refer later.

Chiefly in consequence of the high value of the ground, vertical
engines were adopted at the new station; the proximity to the river
made the foundations somewhat costly, and the risk of occasional
floods rendered it desirable to set the level of the engine bedplates
20 inches above the floor of the building; the foundations of the
engines are continuous, but are quite independent of the building.
There are three compressing cylinders in each set of engines, one
being above each steam cylinder. Two of these are employed to compress
the air to about 30 lb. per square inch, after which it passes into a
receiver and is cooled; it is then admitted into the third or final
compressing cylinder and raised to the working pressure at which it
flows into the mains. In the illustrations, h, m, and b are the high,
intermediate, and low pressure cylinders of one set of engines; as
will be seen, each cylinder is on a separate frame connected by
girders; directly above the cylinders are the two low and the one high
pressure air cylinders, b¹, m¹, and h¹ respectively. The former
deliver the air compressed to the first stage into the receiver, T¹
(see Fig. 5), whence it passes into the third compression cylinder,
and thence by a main into the cylinders, R R, which are in direct
communication with the delivery mains; these mains terminate in the
subway, T. The water for condensation is brought into the engine house
by the channel, C, and the condenser pumps, a, draw direct from this
supply; the discharge main back to the river is shown at A. The
relative positions of the engine and boiler houses are indicated in
Figs. 2 to 5, where F shows the end of one group of boilers; the air
supply for the compressors is led from the central raised portion, S,
of the roof.

Professor Riedler's first experiments in improving the efficiency of
air compressors were made with one of the Cockerill compressors in use
at the St. Fargeau Station, and considerable difficulty attended this
work, because the machinery was necessarily kept almost in constant
operation. These compressors were designed by MM. Dubois and Francois,
of Seraing. Two of their leading features were the delivery of the
compressed air at as low a temperature as possible, and with a
relatively high piston speed of about 400 ft. a minute. The former
object is attained by the injection of a very fine water spray at each
end of the air cylinder, and its rapid removal with each stroke; the
free as well as the compressed air flows through the same passages,
one at each end of the cylinder; the inlet valves being placed at the
side of these passages, and the outlet or compressed air valves at the
top, the compressed air, entering a chamber above the cylinder, common
to both valves, and passing thence to the reservoir. The compressed
air valves, which are seven in. in diameter, are brought back sharply
to their seats at each stroke, by a small piston operated by
compressed air flowing through a by-pass from the chamber. The
illustrations published by us on page 686 of our forty-seventh volume
show the construction of these compressors. The engravings on page 683
of the same volume illustrate the compressors used in a somewhat older
part of the installation; they were made by M. Blanchod, of Vevey, and
a passing reference may be made to them. The air is admitted through
valves in the cylinder, and is forced out through spring-loaded
valves; water is admitted into the cylinder to cool the air.

Fig. 7 indicates the modification made by Professor Riedler in one of
the Cockerill compressors: a receiver, A, was placed under the two
compressing cylinders, B and C. The first stage is completed in the
large cylinder, B, the air being compressed to about 30 lb. per square
inch; from this it is discharged into the receiver, A, through the
pipe, B¹, where it meets with a spray injection that cools it to the
temperature of the water. The final stage is then effected in the
smaller cylinder, C, which, drawing the air from the receiver through
the pipe, C¹, compresses it to about 90 lb. and delivers it through
the pipe, d, to the mains. We hope shortly to publish drawings of this
compressor in its final form; in its elementary stage Professor
Riedler claims to have obtained some very remarkable results. He says
that the waste spaces in his modification were much smaller than in
the Cockerill compressor, while the efficiency of the apparatus was
largely increased. The actual engine duty per horse power and per hour
was raised, as a maximum, to 384 cubic feet of air at atmospheric
pressure, and compressed to 90 lb. per square inch, a marked increase
on the duty of the compressors in use at the St. Fargeau station. The
Cockerill compressors experimented on at the same time showed a
maximum duty of 306 cubic feet of air. A considerable advantage is
claimed in drawing clean and cool air from the outside of the
building, and beyond the main feature of carrying out the compression
in two stages, Mr. Riedler appears to have shown great skill in
introducing several minor alterations and improvements in the plant.

[Illustration: EFFICIENCY CURVES FOR THREE TYPES OF COMPRESSORS. (Fig.
8, 9, 10)]

Figs. 8, 9 and 10 are diagrams showing the comparative efficiency of
the three types of compressors at St. Fargeau--Fig. 10 being a diagram
of the Riedler compressor--and indicate the gain derived from the
intermediate cooling. The loss is shown to be only 12 per cent., as
compared with a loss of 43 per cent. in a large part of the plant, and
of 105 per cent. in the earlier compressors of the St. Gothard type.
The table given herewith contains a summary of trials made by
Professor Gutermuth, and are intended to show the comparative results
of an extended trial with three kinds of compressors at St. Fargeau.

  PERFORMANCES OF COMPRESSORS AT THE ST. FARGEAU CENTRAL STATION.

--------------+-------+--------+------+-------+--------+--------+---------+
              | R   p |        |  E   |       |        |        |         |
              | e o e | Horse- |  f   |Amount |Quantity| Cubic  |         |
Compressors.  | v f r | Power  |  f   |of Air | of Air |Feet of |Final Air|
              | o     |Absorbed|  i   |Passing| Passing|Air per |Pressure.|
              | l E m |   by   |  c   |through| through| Horse- |         |
              | u n i |Compres-|  i   | Inlet | Valves | Power  |         |
              | t g n | sors.  |  e   | Valves| per    | and per|         |
              | i i u |        |  n   | each  | Hour.  |  Hour. |         |
              | o n t |        |  c   |Revolu-|        |        |         |
              | n e e |        |  y   | tion. |        |        |         |
              | s   . |        |  .   |       |        |        |         |
--------------+-------+--------+------+-------+--------+--------+---------+
              |       |        |      | cubic |  cubic |        |lb. per  |
1.            |       |        |      | feet  |  feet  |        |sq. in.  |
_Sturgeon_    |       |        |      |       |        |        |         |
_Compressor_  |  37   |   302  | .87  | 41.67 |  91,507| 261.3  | 90      |
Diameter of   |  37   |   258  | .87  | 38.13 |  84,650| 276.1  | 90      |
cylinder,     |       |        |      |       |        |        |         |
23.62 in.     |       |        |      |       |        |        |         |
and 21.66 in.;|       |        |      |       |        |        |         |
stroke,       |       |        |      |       |        |        |         |
48.63 in.     |       |        |      |       |        |        |         |
              |       |        |      |       |        |        |         |
2.            |       |        |      |       |        |        |         |
_Cockerill_   | 40    |   337  | .83  | 46.61 | 111,864| 281.83 | 90      |
_Compressor._ | 45    |   353  | .83  | 46.61 | 125,844| 302.66 | 90      |
Diameter of   | 40    |   342  | .88  | 49.43 | 118,632| 296.65 | 90      |
cylinder,     | 46    |   377  | .85  | 48.02 | 132,534| 298.77 | 90      |
25.98 in.;    | 38.67 |   324  | .89  | 50.14 | 116,434| 306.19 | 90      |
stroke,       | 38.5  |   337  | .89  | 50.14 | 115,818| 294.18 | 90      |
47.24 in.     | 38.6  |   329  | .91  | 50.84 | 117,740| 305.13 | 90      |
              |       |        |      |       |        |        |         |
              |       |        |      |       |        |        |         |
3.            |       |        |      |       |        |        |         |
_Riedler_     | 52    |   615  | .985 | 77.34 | 241,300| 353.50 | 90      |
_Compressor._ | 60    |   709  | .985 | 76.98 | 277,128| 353.50 | 90      |
Diameter of   | 38    |   422  | .985 | 77.34 | 176,330| 376.12 | 90      |
low-pressure  | 39    |   424  | .985 | 77.34 | 181,030| 384.60 | 90      |
cylinder,     |       |        |      |       |        |        |         |
42.91 in.;    |       |        |      |       |        |        |         |
diameter of   |       |        |      |       |        |        |         |
high-pressure |       |        |      |       |        |        |         |
cylinder,     |       |        |      |       |        |        |         |
26.38 in.;    |       |        |      |       |        |        |         |
stroke,       |       |        |      |       |        |        |         |
47.24 in.     |       |        |      |       |        |        |         |
--------------+-------+--------+------+-------+--------+--------+---------+


The results thus obtained were so satisfactory that the designs were
prepared for the great compressors to be operated at the new central
station on the Quai de la Gare by the 2,000 horse power engines.

The transmission of the compressed air through the mains is
unavoidably attended with a certain percentage of loss, which, of
course, increases with the length of the transmission, the presence of
leakage at the joints, etc. Professor Riedler has devoted considerable
time to the investigation of this source of waste, and we shall
presently refer to the results he has recorded; in the first place,
however, we propose to consider what he has to say on the subject of
utilizing the air at the points of delivery, and the means employed
for obtaining a relatively high efficiency of the motor.

In the earliest stages of the Popp system in Paris it was recognized
that no good results could be obtained if the air were allowed to
expand direct into the motor; not only did the formation of ice due to
the expansion of the air rapidly accumulate and choke the exhaust, but
the percentage of useful work obtained, compared with that put into
the air at the central station, was so small as to render commercial
results hopeless. The practice of heating the air before admitting it
to the motor is quite old, but until a few years ago it never seems to
have been properly carried out; in several mining installations where
this motive power had been long used, more or less imperfect attempts
had been made to heat the air; in one instance only, recorded by
Professor Riedler, was an efficient means employed. In this case a
spray of boiling water was injected into the cylinder and mixed with
the air at each stroke, with the result that a very marked economy was
obtained.

After a number of experiments, Mr. Popp arrived at the conclusion that
the simplest mode of heating, if not the most efficient, was at all
events the most suitable, as it was a matter of the first importance
that subscribers should not be troubled with the charge of any
apparatus involving complication or careful management; he therefore
adopted a simple form of cast iron stove lined with fireclay, heated
either by a gas jet or by a small coke fire. It was found that this
apparatus, crude as it was, answered the desired purpose, until some
better arrangement was perfected, and the type was accordingly adopted
throughout the whole system. It was quite recognized that this method
still left much to be desired, and the economy resulting from the use
of an improved form was very marked.

From a large number of trials very carefully carried out by Professor
Gutermuth, it was found that more than 70 per cent. of the total
number of calories in the fuel employed was absorbed by the air and
transformed into useful work. Whether gas or coal be employed as the
fuel, the amount required is so small as to be scarcely worth
consideration; according to the experiments carried out, it does not
exceed 0.09 kilo. per horse power and per hour, but it is scarcely to
be expected that in regular practice this quantity is not largely
exceeded. Professor Weyrauch has also carefully investigated this part
of the subject and fully confirms, if he, indeed, does not go beyond
Professor Gutermuth. He claims that the efficiency of fuel consumed in
this way is six times greater than when burnt under a boiler to
generate steam. He goes so far as to assert that with a good method of
heating the air, not only can all the losses due to the production and
the transmission of the compressed air be made good, but also that it
will actually contain more useful energy at the motor than was
expended at the central station in compressing it.

According to Professor Riedler, from 15 to 20 per cent. above the
power at the central station can be obtained by means at the disposal
of the power users, and it has been shown by experiment that by
heating the air to 250 deg. Cent. an increased efficiency of 30 per
cent. can be obtained. Better results than those heretofore obtained
may, therefore, be confidently expected with a more perfect and
economical application of the fuel in heating the air, and a better
means of regulation in admitting it to the motors. In his report
Professor Riedler indicates a method by the use of which he considers
considerable advantages may be secured. This is the heating the air in
two stages instead of at one operation, and passing it through two
motors, to the first of which the air is admitted heated only to a
moderate extent; the exhaust from this motor then passes into a second
heater and thence into the second motor. A series of experiments with
this arrangement were recently carried out.

The consumption of air per brake horse power was reduced from 812
cubic feet per hour, a favorable duty in the single motor, to 720, and
in the best result to 646 cubic feet with the two motors and double
heaters. It should be added that these trials were carried out with
steam engines but ill adapted for the purpose. It is to be regretted
that the experiments of Professor Riedler could not have been
conducted with more perfect appliances, but it must be borne in mind
that the utilization of compressed air, especially as regards the
motors, is still in a very imperfect stage, and that a great deal
remains to be done before the maximum power available at the motor can
be obtained. Investigations in this direction for a considerable time
to come must be directed, therefore, toward improving the design and
construction of the motors and the treatment of the air at the point
of delivery into the engine.

A large number of motors in use among the subscribers to the
Compressed Air Company, of Paris, are rotary engines developing one
horse power and less, and these in the early times of the industry
were extravagant in their consumption, to a very high degree. To some
extent this condition of things has been improved, chiefly by the
addition of better regulating valves to control the air admission.

As altered, the two horse power rotary motors, when employed as cold
air engines, a method often desired in special industries, consume
1,059 cubic feet per hour and per indicated horse power; with a
moderate degree of heating, say to 50 deg. Cent., this consumption
falls to 847 cubic feet. The efficiency of this type of rotary motors
with air heated to 50 deg. may now be assumed at 43 per cent., not a
very economical result, it is true, and one that may be largely
improved, yet it is evident that with such an efficiency the use of
small motors in many industries becomes possible, while in cases where
it is necessary to have a constant supply of cold air, economy ceases
to be a matter of the first importance.

Some useful results were obtained with compressed air used in crank
engines; it is to be regretted that with this, also, apologies have to
be made for the imperfect design and construction; they were old steam
engines, some of those of two horse power losing from 25 to 30 per
cent. by their own friction; some of the others tried, however, were
far better, a newer type losing only from 8 to 10 per cent., while the
80 horse power referred to below showed an efficiency of 91 per cent.
From these trials Prof. Riedler deduces--assuming 85 per cent.
efficiency--a consumption of 611, 752, and 720 cubic feet per brake
horse power. It is very evident from the foregoing that the Compressed
Air Company, of Paris, will never do itself justice until as much
thought and care has been devoted to the economical use of the motive
power as has been expended in the means of producing it, and Professor
Riedler's recent investigations should be especially useful in this
respect. The question has indeed attracted the attention of more than
one manufacturer, and reference is made to a particular type of small
rotary motors which are being constructed by MM. Riedinger & Co., and
which is stated have given very excellent results. These engines were
specially used for working sewing machines and developed on the brake
an efficiency of 34.07 and 51.63 foot pounds per second. Trials were
made with a half horse power variable expansion Riedinger engine.


  TRIALS OF A SMALL ROTARY RIEDINGER ENGINE.
 ______________________________________________________________
                                               |       |
  Number of trials.                            |   I.  |   II.
 ______________________________________________|_______|_______
                                               |       |
 Initial air pressure.     lb. per square inch |    86 | 71.8
      "      temperature.           deg. Cent. |   +12 |  +170
 Ft. pounds per second  measured on the brake. | 51.63 | 34.07
 Revolutions per minute.                       |   384 |  300
 Consumption of air for one horse power per    |       |
    hour.                                      | 1,377 |  988
 ______________________________________________|_______|_______


  TRIALS OF A 0.5 HORSE POWER RIEDINGER ROTARY ENGINE.
 _____________________________________________________________________
                                           |      |      |      |
  Number of trials.                        |  I.  |  II. | III. |  IV.
 __________________________________________|______|______|______|_____
                                           |      |      |      |
 Initial pressure of air.  lb. per sq. in. |   54 | 69.7 |   85 | 71.8
      "  temperature of air.    deg. Cent. |  170 |  180 |  198 |    8
 Final        "        "            "      |   25 |   20 |  ... |   25
 Revolutions per minute.                   |  335 |  350 |  310 |  243
 Foot pounds per second measured on        |      |      |      |
    brake.                                 |  271 |  477 |  376 |  316
 Consumption of air per horse power        |      |      |      |
    and per hour.                          |  883 |  791 |  900 |1,148
 __________________________________________|______|______|______|______

  TRIAL OF AN 80 HORSE POWER (NOMINAL) FARCOT STEAM ENGINE.
 ___________________________________________________________________
                  | R p  |      |                  |
                  | e e  | I    |                  | Consumption of
                  | v r  | n    |   Temperature    |  air per horse
                  | o    | d h p|      of air.     |  power and per
                  | l m  | i o o|                  |      hour.
                  | u i  | c r w|__________________|________________
                  | t n  | a s e|         |        |       |
    Motor.        | i u  | t e r|Admission|Exhaust.|Nominal| Brake
                  | o t  | e   .|         |        | horse | horse
                  | n e  | d    |         |        | power.| power.
 _________________|_s_.__|______|_________|________|_______|________
                  |      |      |  deg. C | deg. C |       |
 Nominal 80 horse | 54.3 | 72.3 |    129  |   21   |  469  |  517
 power single     | 54.3 | 72.3 |    152  |   29   |  437  |  475
 cylinder Farcot  | 54.0 | 72.3 |    160  |   35   |  424  |  465
 engine.          | 40   | 65.0 |    170  |   49   |  438  |  477
 _________________|______|______|_________|________|_______|________


These motors, it may be assumed, represent the best practice that has
been obtained up to the present time in the construction of compressed
air motors; with the smallest of them, indicating about one-tenth of a
horse power, the consumption of air, when admitted cold, was 1377
cubic feet and 988 cubic feet when the air was heated before
admission. The half horse power engine consumed 1148 cubic feet of
cold air, and of heated air 791 cubic feet per horse power and per
hour. It should be mentioned that these, the most valuable and
suggestive of all the trials carried out by Professor Riedler, were
conducted with the greatest care, two distinct modes of measuring the
air supplied being followed on two occasions for each test; it may
therefore be considered that the results given are absolutely correct.
The trials were made with an old single cylinder Farcot engine,
nominally of 80 horse power, but indicating over 72.3. With this
engine the consumption of air varied from 465 to 517 cubic feet, the
larger consumption being due to the lower temperature (129 deg. Cent.)
to which the air was raised before admission; in the most economical
result the temperature was 160 deg. Cent. The volumes of air referred
to are, of course, in all cases taken at atmospheric pressure.

Among the important losses that have to be reckoned with in every
system of distributing motive power from a central station--whether by
steam or by electricity, water, or compressed air--losses must occur
in the mains by which the power generated is transferred from the
point of production to that of consumption. In the case we are now
considering very careful tests were conducted in 1889 by Professor
Kennedy, to whose report we have already referred. Since that time
important changes have been made by the Compressed Air Company, at
Paris, in the details of distribution, and on this account the later
investigations of Professor Riedler on the losses due to this cause
are of special interest.

Before its admission into the mains a certain loss occurs at the St.
Fargeau station, in the large reservoirs to which the air is delivered
from the compressors. This question of preliminary storage was one
that received considerable attention when the designs of the new
station on the Quai de la Gare were being considered. It was intended
to construct very large receivers in the basement of the station, and
the foundations for these were even commenced. It was decided,
however, that for the 10,000 horse power which is to form the first
section of the new station, and for which the complete system of mains
has already been laid down, storage reservoirs would be unnecessary,
and a saving both in first cost and subsequent loss of air would be
effected. The length of mains of 19.69 in. diameter is so considerable
that they will contain at all times a sufficient reserve of air to
prevent any irregularities in pressure at the motors.

With reference to these mains it may be mentioned that, unlike the
11.81 in. conductors of the St. Fargeau system, of which 17 kilometers
are laid in the Paris subways, the new mains are entirely laid in the
streets, it having been found impossible to make room for these large
pipes in the subways already crowded with telegraph and telephone
wires, water mains, etc.

Professor Riedler investigated the two causes of loss in the
mains--leakage and resistance. It was superficially evident that the
mains of the old system were so well laid, and the joints so well
designed, that the loss from leakage was never a serious one. In
order, however, to ascertain the amount accurately, a series of
careful experiments were carried out by Professor Gutermuth with the
11.81 in. mains of the St. Fargeau system.


  EXPERIMENTS ON LEAKAGE IN MAINS.

---------------------------------------------------------------------
| |                 |         |               |             | L P A |
| |                 |         | Air Pressure  |   Loss of   | o e i |
| |                 |         |  in Mains.    |  Pressure.  | s r r |
| |                 |         |---------------|-------------| s     |
| |                 |         |  B    |       |      |      |   C D |
| |System of Mains  | Length. |  e   T|       |      |      | o e e |
|N|    Tried.       |         |  g   r|  At   |      |      | f n l |
|u|                 |         |A i o i| End   |During| Per  |   t i |
|m|                 |         |t n f a|  of   |Trials|Hour. | A . v |
|b|                 |         |  n   l|Trials.|      |      | i   e |
|e|                 |         |  i   s|       |      |      | r o r |
|r|                 |         |  n   .|       |      |      |   f e |
| |                 |         |  g    |       |      |      |     d |
--+-----------------+---------+-------+-------+------+------+-------|
| |                 | yards.  | atm.  |  atm. |      |      |       |
|1|Southern reseau  |         |       |       |      |      |       |
| | to Place de la  |         |       |       |      |      |       |
| | Concorde.       |  9,980  | 6.5   |  6.0  | 0.5  | 1.5  |  3    |
|2| Total reseau    | 18,500  | 6.9   |  5.9  | 1.0  | 1.5  |  6.3  |
|3|To Place de      |         |       |       |      |      |       |
| | la Concorde     |  9,980  | 7.0   |  6.43 | 0.57 | 0.75 |  2.16 |
|4|Total reseau     | 18,500  | 6.7   |  5.28 | 0.88 | 1.32 |  5.5  |
|5|Northern reseau  |         |       |       |      |      |       |
| | to Rue de Belle-|         |       |       |      |      |       |
| | ville.          |  1,530  | 6.0   |  5.0  | 1.0  | 0.6  |  2.3  |
|6|To the Rue des   |         |       |       |      |      |       |
| | Pyrenees.       |    600  | 6.1   |  3.7  | 2.4  | 0.56 |  2.2  |
---------------------------------------------------------------------


These trials refer to the mains running from the St. Fargeau station
to the Place de la Concorde, a length of 9.142 kilometers; to the
whole system of mains, 16.5 kilometers; to the northern mains running
from St. Fargeau to the Rue de Belleville, 1.4 kilometers; and from
St. Fargeau to the Rue des Pyrenees, 6.5 kilometers. It will be seen
from the figures given in the table that the actual loss is small, and
it is stated that this is due chiefly to the elastic joint employed
throughout the system, excepting in the Rue de Belleville, where rigid
couplings are used, and continual trouble is experienced from loss by
leakage. In all cases the losses given are the maximum, which only
occur under the most unfavorable conditions.

It was found, during the first, second, and fourth tests, that
considerable leakage occurred between the St. Fargeau central station
and the Rue de Belleville. During the trials two and four, an
uncertain amount of loss occurred from the consumption of air required
to work the pneumatic clocks, and also motors in the circuit, that
could not be stopped. The tests two and four include all losses in the
service pipes, as well as the mains.

The production of compressed air at the central station is assumed at
30,000 cubic feet per hour (atmospheric pressure), and in all cases
the loss in the mains is taken as a percentage of the total
production.

The losses due to resistance in the mains were also examined with
great care, over independent sections, as well as through the complete
_réseau_. During the early part of these trials, an unusual and
excessive loss was recorded, the cause of which could not be at first
ascertained. At intervals along these mains are placed a number of
water reservoirs which receive the water injected into the mains; in
addition to these the direct flow of the air is interrupted by
numerous siphons, the stop valves to branches, etc. Investigation
showed that the presence of these reservoirs created considerable
resistance on account of an increased and subsequently reduced
section. The exact loss from this cause was, therefore, carefully
measured, as well as the losses existing in the mains not so
interrupted. The results show that the loss by expansion at one
reservoir, when the speed of the air flow was 23 ft. per second, was
equal to 0.15 atmosphere; with a speed of 29 ft. 6 in. per second, it
amounted to 0.2 atmosphere.

Therefore, the presence of five such reservoirs would cause a loss in
pressure equal to one atmosphere. This very undesirable arrangement is
not repeated in the new system, the sumphs being connected in such a
way as not to modify the section of the tube, nor consequently the
pressure of the air. The presence of the siphons and stop valves did
not seem to affect the pressure to any measurable extent. The
following table contains a list of the more important mains tested,
and it may be mentioned that the resistance, due to the reservoirs,
was at first partially included. The trials were carried out while the
mains were not being drawn upon by subscribers.


-----------------------------------------------------------------------
                                                   |            |
Section of Mains Tested.                           |  Length.   |No. of
                                                   |            |Tests.
                                                   |            |
---------------------------------------------------+------------+------
                                                   |  yards.    |
From the central station to the end of reseau and  |            |
  back to central station by return circuit        |  18,100    |   7
From the central station to the Rue Fontaine au    |\ 14,600    |/  3
  Roi                                              |/  9,900    |\  4
From the central station to the Rue de la          |            |
  Charonne                                         |   9,490    |   5
From the Rue de la Charonne to Fontaine au         |            |
  Roi                                              |   4,770    |   3
From the central station to the Avenue de la       |            |
  Republique                                       |   1,860    |   8
Various trials on different lengths of mains       |770 to 8,000|  11
-----------------------------------------------------------------------


Over the whole system of 16.5 kilometers, which was also tested when
no air was being taken off, there were four reservoirs of considerable
size, and which offered a large resistance with a corresponding loss
of pressure; on the line there were also 23 siphons and 42 stop
valves.

These trials were repeated several times to secure accuracy, and the
speed of the air was brought to 49 ft. a second. The results obtained
in one of these trials may be taken as an example. The main between
the Rue St. Fargeau and the Fontaine au Roi, on which there are no
collecting reservoirs, but three siphons and eight stop valves, gave,
with an average speed of 21 ft. 3 in., a loss in pressure of 0.05
atmosphere for each kilometer of main.

From these experiments it would appear that, assuming a speed of 21
ft. per second, a loss in pressure of one atmosphere would correspond
to a distance of 20 kilometers; that is to say, a central station
could extend its mains on all sides with a radius of 20 kilometers,
and the motors at the ends of the lines would receive the air at a
pressure 15 lb. less than at the central station. Professor Riedler
states that as an actually measured result, the velocity of the air
through the mains of the St. Fargeau system is 19 ft. 8 in. per
second, and that the loss in pressure per kilometer is 0.07
atmosphere. From this it follows that including the resistances due to
the four reservoirs, and other obstructions actually existing, an
allowance of one atmosphere loss on a 14 kilometer radius is ample. By
increasing the initial pressure of the air, much better results can be
obtained, and future attention in practice should be devoted to this
point. The amount of work required to compress air does not increase
in the same ratio as the pressure, and for this reason considerable
economy can be effected at the first stage, and the loss in the mains
will be reduced.

Passing to another point of the same subject, Professor Riedler
considers the best dimensions that should be given to the mains.
Resistance decreases with an increase in the diameter of these and in
direct ratio to their diameter; for this reason--still assuming a
pressure corresponding to a velocity of 20 ft. per second--with a fall
of one atmosphere, a length of 40 kilometers could be succesfully
worked.

The mains of the new _réseau_ for the Quai de la Gare station are
19.69 in. in diameter; they are built up of steel plates riveted, and
this Professor Riedler considers to have been a serious error on
account of the extra resistance offered by the large number of rivet
heads.

The following may be taken as a brief summary of Professor Riedler's
conclusions: Recent improvements in central station practice have
resulted in an increased efficiency of about 30 per cent. in the
compressors, but this benefit can only be realized when the new
station is in operation. That the small and very imperfect air engines
in use on the system give an efficiency of 50 per cent., while with
ordinary steam engines driven by air an efficiency of 80 per cent. can
be reached with a very small expenditure of fuel for heating the air
before admitting it into the motor. That special attention should be
given to the improvement of air engines, and that with increased
initial pressures at the central station the distance of the
transmission can be very considerably augmented. Finally, Professor
Riedler claims that power can be transmitted by compressed air more
conveniently and more economically than by any other means.

       *       *       *       *       *

[Continued from SUPPLEMENT, No. 802, page 12810.]




THE BUILDERS OF THE STEAM ENGINE--THE FOUNDERS OF MODERN INDUSTRIES
AND NATIONS.[1]

[Footnote 1: An address delivered at the Centennial Celebration of the
American Patent System, Washington, April, 1891.]

By Dr. R.H. THURSTON, Director of Sibley College, Cornell University.


Papin, Worcester, Savery, were the authors of the period of
application of the power of steam to useful work in our later days.
The world was, in their time, just waking into a new life under the
stimulus of a new freedom that, from the time of Shakespeare, of
Newton, and of Gilbert, the physicist, has steadily become wider,
higher, and more fruitful year by year. All the modern sciences and
all the modern arts had their reawakening with the seventeenth
century. Every aspect of freedom for humanity came into view in those
days of a new birth. Both the possibility of the introduction of new
sciences and of new arts and the power of utilizing all new
intellectual and physical forces came together. The steam engine could
not earlier have taken form, and, taking form, it could not have
promoted the advance of civilization in the earlier centuries. The
invention becoming possible of development and application, the
promotion of the arts and of all forms of human activity became a
possible consequence of its final successful introduction into the
rude arts that it was to so effectively promote and improve.

But the work of these inventors was in itself but little more
important than that of the Greek inventor of the steam ælopile, for
each brought forward a machine which was, from a business point of
view, utterly impracticable, and which, in each case, only served to
show that a better device might prove useful and lead the way to its
introduction. The merit of the inventors of the eighteenth century was
that they were _able_ to lead the way, to point out the path to
success, to furnish evidence of the value of the coming, crowning
invention. The "fire engines," as they were then called, of these now
famous men were merely contrivances by the use of which the pressure
of confined steam of high tension could be brought to act on the
surface of a mass of confined water, forcing it downward into pipes
through which it was led off and upward to a higher level; and thus a
mine could be drained, ineffectively and expensively to be sure, but
vastly more satisfactorily than by the animal power of the time. The
machine of Savery was the best of all; but that was only a somewhat
improved and manageable rearrangement of the engines of Papin and
Worcester. And, after all, Papin, the greatest man of science perhaps
of his time, died in poverty; Worcester languished in prison his whole
life, and the later efforts of his widow brought nothing by way of a
return for his invention; nor did either they or their successor,
Morland, make the introduction of the engine either general or
remunerative.

Savery, coming on the stage at more nearly the right time to seize
upon an opportunity, gained more than either of his predecessors; but
we have no evidence that he ever acquired any large compensation or
met with any remarkable business success in the introduction of the
rude engine which bore his name; nor did Desaguliers, the great
philosopher, or even Smeaton, the great engineer, of the later years
of that century, make any great success of it. It was reserved for
Watt to reap the harvest. But, though he so effectively reaped where
his predecessors had sown, Watt is not the greatest of the inventors
of the steam engine, if we rate his standing by the magnitude of the
improvement which marked his reconstruction of the engine.

It was NEWCOMEN who made the modern steam engine.

When Newcomen came forward the labors of Worcester in Great Britain
had sufficed to attract the attention of all intelligent men to the
character of the problem to be solved, and to convince them of its
importance and promise. The work of Savery had shown the
practicability of the solution of the problem, both in mechanics and
finance. He succeeded, though under great disadvantages and
comparatively inefficiently. Once the task had been performed, though
ever so rudely, the rest came easily and promptly. The defects of the
Savery system were at once recognized; its great wastes of heat and of
steam were noted, and the fact that they were inherent in the system
itself was perceived. A complete change of type of machine was
obviously requisite; it was this which constituted the greatest
invention in the whole history of the steam engine, from Hero's time
to our own; and to Newcomen we owe more than to any other man who ever
lived, the value of the invention itself being considered, and the
importance of the services of its introducer being left out of
consideration. No such complete and vital improvement and modification
of the machine has ever been effected by any other man, Watt and
Corliss not excepted. Newcomen and his comrade Calley--we do not know
how the honors should be divided--produced the modern steam engine.
Its predecessor, the Savery engine, had been a mere steam "squirt."
Newcomen constructed an engine. Savery built a simple combination of
cylindrical or ellipsoidal vessels which wastefully and at once
performed all the several offices of engine, pump, condenser, and
boiler; Newcomen divided the several elements among as many parts,
each especially adapted to the performance of its task in the most
effective manner--the condenser excepted; for that was Watt's
principal invention--and thus produced the first steam engine in the
modern sense of that term.

It was Newcomen, not Watt, who gave us the train of mechanism that we
now call the steam engine. It is to Newcomen, rather than Watt, that
we owe the highest honors as an inventor in this series of the most
important of all the products of the inventive genius of mankind.
Newcomen brought into existence a new, the modern, type of engine, and
effected the greatest revolution that has been recorded in the history
of the arts. Without Newcomen, there might have been no Watt; without
Watt, there very possibly may not even yet have been brought into
existence that giant of our time, whose mighty powers are employed
more effectively than ever those of Aladdin's genii, in building
palaces, in transporting men and material, in doing the work of the
whole world; promoting the welfare of the race, in a single century,
more than had all the forces of matter and mind together in the whole
previous history of the world. Newcomen laid down a foundation beneath
our whole economic system, out of sight, almost, but the essential
base, nevertheless, on which Watt and his successors have carried up
the great superstructure which seems to us to-day so imposing; which
is so tremendous in magnitude, importance, and result. If to any one
man could be assigned the credit, it is Newcomen who is to be
considered the inventor of the steam engine.

James Watt, indisputably the great inventor that he was, found the
steam engine ready to his hand, applied himself to its improvement,
and made it substantially what it is to-day. His most important work,
the most unique service performed by him, was, however, that of its
adaptation and introduction to do the work of the world. James Watt
was the inaugurator of the era of refinement of the machine already
invented, and the greatest of its builders and distributors. His
inventions were all directed to the improvement of its details, and
his labors to its introduction and its application to the myriad tasks
awaiting it. By the hands of Watt it was made to pump water, to spin,
to weave, to drive every mill; and he it was who gave it the form
demanded by Stephenson, by Fulton, by the whole industrial world, for
use on railway and steamboat, and in mill and factory, throughout the
civilized countries of the globe. It was this great mechanic who
showed how it might be made to do its work with least expense, with
highest efficiency, with greatest regularity, with utmost
concentration of power.

The grand secret of his success was historical and economic, as much
as scientific and mechanical. He brought out his inventions just when
the world was economically and historically ready for them. The age of
authority was past, that of freedom was come; the period of political
and ecclesiastical tyranny was gone by, and that of the spontaneous
development of man was arrived. The great invention was offered to a
world ready and needing it, and, more than all, competent, for the
first time in history, to make and use it.

James Watt was himself a product of the modern scientific spirit. He
was a man so constituted mentally that he could apply scientific
methods to problems which his logical and clairvoyant mind could
readily and exactly formulate the instant he was led to their
consideration in the natural course of his progress. He was the ideal
great inventor and mechanic. With inventive genius he combined strong
common sense--not always a quality distinguishing the inventor--clear
perception, breadth of view, and scientific method and spirit in the
treatment of every question. His natural talent was re-enforced by an
experience and an environment which led him to develop these ways and
this mental habit. His trade was that of an instrument maker, his
position was that of custodian and repairer of the apparatus of
Glasgow University. He had for his daily companions and stimulus the
great men and ozonized atmosphere of that famous institution. He kept
pace with advancing science, and was imbued, both naturally and
through contact with its promoters, with that ambition and those
aspirations which are the life element of all progress, whether
scientific or other. He was aware of the nature of the problems
seeking solution at the time, and familiar with the state of his own
art and that of the great mechanicians about him. Everything was
favorable to his progress, so soon as he should be given an
opportunity to take a step in advance and to come into sight at the
front. The man and the time were both ready, and all conditions,
internal and external, social and personal, were favorable to his
development.

The invention upon which Watt was to improve was at his hand. A word
in regard to its status at the moment will throw some light upon that
of Watt and his creation. Newcomen had, as we have seen, produced the
modern type of steam engine as an original and wholly novel invention.
But this machine, marvelous as an advance upon pre-existing forms of
the steam engine, was still, as seen in the light of recent knowledge
and experience, exceedingly defective. The purpose of a steam engine
is to convert into usefully applicable power the hidden energy of
fuel, stored ages ago in the earth, by transformation, through the
action of vegetation, from the original form, the heat of the sun,
into an available form for reconversion, through thermodynamic
operations. In this process of reconversion, whatever the nature of
the machine used in the operation, there are invariably wastes, both
of heat required for conversion into power and of the power thus
produced. That machine which effects the most complete transmutation
of the heat supplied it into mechanical power, which wastes the least
amount of heat supplied and of power produced, is the best engine, and
constitutes an advance over every other.

It was this reduction of wastes that made the Newcomen engine so much
superior to that of Savery. The latter was by far the simpler and less
costly construction; but its enormous losses, both of heat and of
power, mainly the former, however, made it an extravagant expenditure
of money to buy and use it. The Newcomen engine, costly and cumbrous,
comparatively, nevertheless wasted so much less heat and steam and
fuel that no one could afford to buy the cheaper machine. Before
considering what Watt accomplished, we may find it profitable to
examine into the nature of the wastes which characterized this later
and better machine on which he effected his improvements.

The Newcomen engine consisted of a steam boiler, a steam cylinder, a
beam and a set of pumps. By making the boiler do its work separately,
the engine acting independently, and the pumps as a detached portion
of the mechanism, this inventor had reduced to an enormous extent
those wastes of heat and of steam and of fuel which were unavoidable
in the older machines in which all these parts were represented by a
single vessel, or by two at most, in each element. In the Savery
engine, the steam entering first heated up the interior of the working
vessel to its own temperature, and held it at that temperature in
spite of the cooling influence of the water present. This consumed
large quantities of heat. It then was compelled to surrender probably
much greater quantities still to the water itself, coming in direct
contact as it did with its surface. If the water was agitated, either
by the currents produced during its ingress or by the impact of the
steam entering the vessel, this heating action penetrated to
considerable depths and perhaps even warmed the whole mass very far
above its initial temperature. This constituted another and a very
serious loss. Then, again, as the water was gradually driven out of
the containing vessel by the steam pressing on its surface, new
portions of the vessel and new masses of water were continually
brought in contact with the hot steam, taking its full temperature,
and thus, often, probably, finally heating the whole mass of the
forcing vessel, and a large proportion of the water as well, up to the
temperature, approximately at least, of the steam itself. Thus in many
instances, if not always, vastly more heat and steam were wasted, in
this undesirable heating of water and forcing vessel, than were
usefully employed in the legitimate work of raising the water to a
higher level. In fact, in some cases in which these quantities were
measured, the wastes were one hundred times as much as the work done.
One per cent. of the heat supplied did the work; while ninety-nine per
cent. was thrown away. One dollar or one shilling expended for fuel to
do the work was accompanied by an expenditure of ninety-nine dollars
or shillings thrown away, because of the imperfections of the system
and machine. The whole history of the development of the steam engine
has been one of gradual reduction of these wastes; until to-day, our
best engines only compel us to spend five dollars for wastes to each
dollar paid out for useful work. A business man would think that amply
extravagant, however, and the man of science is continually seeking
methods of evading these losses, a large proportion of which are now
apparently unavoidable in heat engines, by finding some new system of
heat and energy transformation.

Watt was the instrument maker and repairer at Glasgow University in
the year 1763. His companions were, among others, the professors of
natural philosophy and of mathematics in the university. Their
conversation and their frequent presentation of practical and
scientific questions and problems stimulated his naturally inquiring
and inventive mind to the pursuit of a thousand interesting and
promising schemes for the improvement of existing methods and
machinery. Dr. Robison, then a student, suggested the invention of a
steam carriage for use on common roads, and the young mechanician at
once began experiments that, resulting in nothing at the time, were
nevertheless continued, in one or another form, until all modern
applications of steam came into view. Dr. Black taught Watt chemistry,
then a newly constructed science, and led him on to the discovery,
finally made by them independently, of the fact and the magnitude of
the latent heat of steam; the discovery coming of a series of
scientifically planned and accurately conducted investigations, such
as the man of science of to-day would deem creditable. The treatises
of Desaguliers and others on physics gave Watt a knowledge of that
domain of natural phenomena which stood him in good stead later, when
he attempted to apply its principles to the reduction of the wastes of
the steam engine.

It was while at Glasgow University, working under such influences and
in such an atmosphere of intellectual activity, that the accident of
the Newcomen model engine needing repair brought to the mind of Watt
the opportunity which, availed of at once, made him famous and gave
the world its greatest aid, its most powerful servant. The observing
mind of the great mechanic immediately noted its defects, sought their
causes, found their remedy. He discovered, at once, that the quantity
of steam entering the cylinder of the little engine has four times the
volume of the cylinder receiving it: in other words, three-fourths of
that steam must be condensed immediately on entrance. This meant,
evidently, that only one-fourth of the steam supplied was utilized,
and even then inefficiently, in doing its work. The reason of this was
as easily seen, immediately the fact was revealed. As Watt himself
expressed it, the causes of this loss, causes which would obviously be
exaggerated in a small engine, were: "First, the dissipation of heat
by the cylinder itself, which was of brass and both a good conductor
and a good radiator. Secondly, the loss of heat consequent upon the
necessity of cooling down the cylinder at every stroke in producing
the vacuum. Thirdly, the loss of power due to the pressure of vapor
beneath the piston, which was a consequence of the imperfect method of
condensation." This much determined, the next step looked toward the
confirmation of his conclusions and the remedy of the defects.

To meet the first difficulty he made a cylinder of wood, soaked in oil
and baked, a non-conducting and non-radiating material. Then he was
able to determine with some accuracy the quantities of steam and
injection water used in the engine; and a comparison with the original
cylinder and its operation showed that not only four times the
quantity of steam, but also four times the amount of injection water
was used as was necessary, assuming wastes checked. Further scientific
research on the part of Watt gave him measures of specific heats of
the metals and of wood, the specific volumes of steam at various
working pressures, the evaporative efficiency of boilers, the
pressures and temperatures of steam in the boiler under specified
conditions, the quantities of steam and of water required for the
operation of his little condensing engine.

Then came his enunciation of the grand principle of economy in the
construction and operation of the steam engine: "Keep the cylinder as
hot as the steam which enters it," as he expressed it. This was Watt's
guiding principle, as it has been that of all his successors in the
improvement of the economic performance of the steam engine and of all
other heat engines. The great source of waste is the dispersion of
heat, uselessly, which should be applied to the production of work by
its transformation, thermodynamically, into the latter form of energy.
The second form of waste is that of power thus produced in the
unprofitable work of moving the parts of the engine itself; and the
third is that of heat by transfer, without transformation, by
conduction and radiation to surrounding bodies. In modern engines, the
latter is but three or five per cent., in the best cases; the second
waste constitutes perhaps ten per cent.; while the first of these
losses amounts very usually to seventy per cent., of which last
one-third or one-fourth is of the kind discovered by Watt, the rest
being the thermodynamic waste incident to all known methods of
operation of heat engines, and apparently unavoidable. In our very
best and largest engines, the waste found by Watt to constitute three
fourths of all heat supplied has been brought down to ten per cent., a
fact which well exemplifies the advances made since his time of
apprenticeship by himself and his successors of this nineteenth
century. The steam engine of to-day, in its most successful operation,
gives us twenty-five times as much power from a pound of coal as did
the engine that the great inventor sought to improve: this is the
magnificent fruit of that one discovery of James Watt, and of
application of the simple principle which he so concisely and clearly
stated.

The method adopted by Watt to secure a remedy, so far as practicable,
of this defect of the older machine was as simple and as perfect as
was the principle which it embodied. He first removed from the
cylinder the prime source of its wastes; providing a separate
condenser, and thus avoiding the repeated chilling of its surfaces by
the cold water used in condensing the steam at exhaust, and also
permitting its strokes to be made with far greater frequency, thus
giving less time for cooling by the influence of the remaining vapors
after condensation. He next went still further, and provided the
cylinder with a closed top, keeping out the air, and a "jacket" of hot
boiler steam to _keep_ it as hot as the steam which entered it. These
were the two great improvements which converted the first real steam
engine into an economical form of heat engine and essentially finished
the work so grandly begun by Newcomen and Calley. These changes gave
us the modern steam engine; and these are Watt's first and greatest,
but by no means only, contributions to the production of the modern
world with all its comforts, its luxuries and its opportunities for
material, intellectual and moral advancement of individual and of
race. His work was to this extent complete in 1765.

But Watt did not stop here. There still remained for him the no less
important and the, in some senses, still more imposing, work of
finding employment for the new servant of mankind and of setting it at
its work of giving the human arm a thousand times greater strength, to
the mind of man uncounted opportunities to promote the advancement of
knowledge, of civilization, of every good of the race. His was still
the task of adapting the new machine to all the purposes of modern
industry. It had been hitherto confined to the task of raising water
from the depths of the mine; it was now to be harnessed to the railway
train; to be made to drive the machinery of the mill, to apply its
marvelous power to the impulsion of the river boat and ocean steamer;
to furnish energy, through endless systems of transfer and use, to
every kind of work that man could devise and should invent. All this
meant the giving of the machine forms as various as the purposes to
which it was to be devoted. It had previously only raised and
depressed a rod; it must now turn a shaft. It had then only operated a
pump; it must now turn a mill, grind our grain, spin our threads,
weave our cloths, drive our shops and factories, supply the powerful
blast of the iron furnace. It must be made to move with the utmost
conceivable regularity, and must, with all this, do its work in the
development of the hidden energy of the fuel, with the greatest
possible economy, through the expansion of its steam. All this was
achieved by James Watt.

The invention of the double-acting engine, in which the impulsion of
the steam is felt both in driving the piston forward and in forcing it
backward, both upward and downward, the application of its force
through crank and fly wheel, the creation of an automatic system of
governing its speed, and the discovery of the economy due to its
complete expansion, were all improvements of the first magnitude, and
of the greatest practical importance; and all these were in rapid
succession brought into existence by the creative mind that had
apparently been brought into the world for the express purpose of
giving to the hand of man this mighty agent, to perfect the mightiest
power that mind of man has yet conceived.

But to do the rest required more than inventive genius and mechanical
skill. It demanded capital and the stored energy of labor and genius
in other fields, directed by the mind of a great "captain of
industry." This came to Watt through Matthew Boulton, a manufacturer
of Birmingham, whose father and ancestors had gradually and
toilsomely, as always, accumulated the property needed for the
prosecution of a great business. The combination of genius and capital
is always an essential to success in such cases; and good fortune, a
Providence, we may well say, brought together the genius and the
capitalist to do their work, hand in hand, of providing the world with
the steam engine. Hand in hand they worked, and all the world to-day,
and the race throughout its future life, must testify gratitude for
the inexpressible obligations under which these two men have placed
them, doing the work of the world.

Boulton & Watt, the capitalist with the inventor, gave the world the
steam engine, finally, in such form and in such numbers that its
permanent establishment as the servant of man was insured. The
capitalist was as essential an element of success as was the inventor,
and, in this instance, as in a thousand others, the race is indebted
to that much-abused friend of the race, the capitalist, for much that
it enjoys of all that it desires. The industry and patience, the skill
and the wisdom required for the accumulation of this energy stored for
future use in great enterprises is as important, as essential, as
inventive power or any other form of genius. Talent and genius must
always aid each other. This firm was established in 1764 and its main
resources, aside from the bank account, were Watt's patent, about
expiring, and Watt's genius, and Boulton's talent as a man of
business. The patent was extended for twenty-four years, the new
inventions of Watt, now beginning to pour from his prolific brain in a
wonderful stream, were also patented, and the whole works were soon
employed upon the construction of engines for which numerous orders
soon began to pour in upon the now prosperous builders. The patent law
established Boulton and Watt and the firm paid back the nation with
handsome usury, giving it unimaginable profits indirectly through its
control of the work of the world and large profits directly through
the business brought them from all parts of the then civilized globe.
There has never, in the history of the world, been a more impressive
illustration of the value to a nation of that generous public policy,
that simply just legislation, which gives to the man of brain control
of the products of his mind. For a hundred years, Great Britain has,
largely through her encouragement of the inventor and her protection
of his mental property by securing the fruits of his labors, in fair
portion, to him, gained the power of dictating to the world and has
gained an advance that cannot be measured. Watt and Arkwright and
Stephenson and Crompton and their ilk, protected by their government
and its patent laws, made their country the peaceful conqueror of the
world. The story of the work of the inventor is a poem of mighty
meaning and of wonderful deeds. The inventor proved himself a mightier
magician than ever the world had seen.

    "A creature he called to wait on his will,
    Half iron, half vapor--a dread to behold;
    Which evermore panted, and evermore rolled,
    And uttered his words a millionfold."

Such was the outcome of this grand modern "trust," a combination of
the wisest legislation, the most brilliant invention, and the most
wisely applied capital. There are "trusts" of which the outcome is
most beneficent.

Since the days of Watt, the improvement of the steam engine and the
work of inventors has been confined to matters of detail. All the
fundamental principles were developed by Watt and his predecessors and
contemporaries and it only was left to his successors to find the best
ways of carrying them into effect. But these matters of detail have
been found to involve opportunities to make enormous strides in the
direction of securing improved efficiency of the machine. The further
application of the principle which led Watt to his greatest
inventions; of the principle, keep the cylinder as hot as the steam
which enters it, of that which he enunciated relative to the advantage
of expanding steam, and of that affecting the regulation of the
machine; have reduced the costs of steam and of fuel to a small
fraction of their earlier magnitude. One ton of engine to-day does the
work of eight or ten in the time of Watt: one pound of fuel or of
steam gives to-day ten times the power then obtained from it. A
steamship now crosses the Atlantic in one-eighth the time required by
the famous "liner" of the "Black Ball Line." The wastes of the engine
have been brought down from above eighty per cent. to eight; and a
half-ounce of fuel on board ship will now transport a ton of cargo
over a mile of ocean.

FREDERICK E. SICKELS gave us the first practicable form of expansion
gear in 1841; GEORGE H. CORLISS gave a new type of engine of marvelous
perfection and economy in 1849; Noble T. Green, Wm. Wright and many
less well known but no less meritorious inventors have since done
their part in the transformation of the old engine of Watt into the
modern wonder of concentrated and economical power, and marvel of
accurate and beautiful design and workmanship. The "trip cut-off,"
with reduced clearances, increased boiler pressure, higher rates of
expansion, accelerated speeds of engine, better construction in all
respects, as well as improved design, have enabled us to avail
ourselves to the utmost of the principles of Watt, and our mills, our
railways, our steamers and our fields, even, have gained almost as
extraordinarily by these advances, since the days of the great
inventor, as through his immediate labors.

With the introduction of the new form of older energy, electricity,
with the reduction of the lightning into thraldom, has now come a new
impulse affecting all the industries. Through its mysterious, its
still unknown action, steam now reaches out far from its own place,
driving the electric car along miles of rail; giving light throughout
all the country about it, turning night into day, and repressing crime
while encouraging legitimate labor, reaching into distant chambers and
every little workshop, to offer its powerful aid in all the
distributed work of cities. Without the steam engine there would be
little work available for electricity, but the appearance of this, the
latest and most useful handmaid of steam, has given the engine work to
do in an uncounted number of new fields, has called in the inventor
once more to adapt steam to its new work. The "high-speed engine" is
the latest form of the universal helper. And such has been the
readiness and the intelligence of the contemporary inventor that we
now have engines capable of turning their shafts three hundred
rotations a minute and without a perceptible variation of velocity,
whatever the change of load or the suddenness with which it is varied.
In the days of Watt a fluctuation of five per cent. in speed was
thought wonderfully small; in those of Corliss, the variation was
restricted to two per cent. and we wondered at this unanticipated
success. To-day, thanks to Porter and Allen, to Hartnell, to Hoadley,
to Sims, to Thomson, to Sweet, to Ide, and to Ball, we have seen the
speed fluctuation restricted to even less than one per cent. of its
normal average.

The inventors of the steam engine are, through their representatives
of to-day, according to the statisticians, doing the equivalent of
twelve times the work of a horse, for every man, woman and child on
the globe. We have not less, probably, than a half million of miles of
railway, transporting something over 150,000,000,000 of tons a mile a
year. A horse is reckoned to haul a ton weight about six and a half
miles, day by day, by the year together. In the United States, it is
reckoned that the steam engine, on the railways alone, hauls a
thousand tons one mile, for every inhabitant of the country, every
year, or, if it is preferred to so state it, a ton a thousand miles.
This is the way in which the East and the West are, by the inventors
of the steam engine, enabled to help each other. This costs about $10
each individual; it would require some 25 millions of horses to do the
work, and would cost about $1,000 a family, which is more than twice
the average family earnings.

Dr. Strong, in that remarkable book, "Our Country," says: "One man, by
the aid of steam, is able to do the work which required two hundred
and fifty men at the beginning of the century. The machinery of
Massachusetts alone represents the labor of more than 100,000,000 men,
as if one-half of all the workmen of the globe had engaged in her
service." And again: "Some thirty years ago, the power of machinery in
the mills of Great Britain was estimated to be equal to 600,000,000
men, or more than all the adults, male and female, of all mankind."
Mr. Gladstone estimated that the aggregation of wealth on the globe
during the whole period from the birth of Christ to that of Watt was
equaled by the production in twenty years, at the middle of this
century, with the aid of machinery driven by the fruit of the brain of
the inventors of the steam engine. We may probably now safely estimate
the former quantity as rivaled in less than five years, while, since
the birth of Watt and his engine, and the production of the spinning
mule, the power loom, the cotton gin and our own patent system and its
marvelous mechanism, all events of a century ago, we may estimate that
they have, together, accomplished more in this period which we now
celebrate than could have been done in a millenium of milleniums
without these now subjected genii. But the power behind all these
curious inventions and their work is that of steam. The steam engine
even supplies power to the telegraph and transports words and thought
as well as cotton bales and coal.

And now what has this combination of legislation for private
protection and public good, of a genius producing great inventions,
and of the accumulated capital of earlier years, brought about?

It has given us the best fruits of science in permanent possession.
The study of science invariably aids, in a thousand ways, the progress
of mankind. It gives us new conceptions of nature and of the
possibilities of art; it promotes right ways of work and of study; it
teaches the inventor and the discoverer how most surely and promptly
to gain their several ends, it gives the world the results of all
acquired knowledge in concrete form. This one instance which we are
now especially interested in contemplating has performed more
wonderful miracles than ever Aladdin's genii attempted. One man, with
a steam engine at his hand, turns the wheels of a great mill, drives
forty thousand spindles, applies a thousand horse power to daily work
in the spinning of threads, the weaving of cloth, the impulsion of a
steamboat, or the drawing of great masses of hot iron into finest
wire. This puny creature, his mind in his finger tips, exerts the
power of ten thousand men, working with muscle alone, and, aided by a
handful of women, boys and girls, clothes a city. A half dozen men in
the engine room of an ocean steamer, with a hundred strong laborers in
the boiler room and on deck, transports colonies and makes new
nations, brings separated peoples together, unites countries on
opposite sides of the globe, brings about easy exchanges between pole
and equator. One man on the footboard of the locomotive, one man
shoveling into the furnaces the black powder that incloses the energy
stored in early geological ages, a half dozen men mounted on the long
train of following vehicles, combine to bring to the mill girl in
Massachusetts, the miner in Pennsylvania, the sewing woman, and the
wealthy merchant, her neighbor in New York, the flour made in
Minnesota from the grain harvested a few weeks earlier in Dakota. All
the world is served faithfully and efficiently by this unimaginable
power, this product of the brain of the inventor, protected by the
law, stimulated and aided by the capital that it has itself almost
alone produced.

And thus have the inventors of the steam engine set in motion and
placed at the disposal of mankind for every form of useful work all
the great forces of nature; thus Hero of Alexandria touched the then
concealed spring which called all the genii of earth, fire, water and
air to do the bidding of the race. Thus Papin, Worcester, Newcomen,
Watt, and Corliss and others of our own contemporaries, have applied
the genii to their task of leveling mountains, traversing seas,
continents, and the depths of the earth, building ships, locomotives,
hamlets and cities, cottages and palaces, turning the spindle,
operating the loom, and setting motion and giving energy to every
machine, doing the work of thousands of millions of men, converting
barbarism into civilization, giving necessaries of life in profusion,
comforts in plenty, and luxuries in superabundance.

Aiding and working hand in hand with those other genii of progress,
the inventors of the printing press and of the telegraph, the
telephone, and the electric railway, of the modern system of textile
manufactures, of iron and steel making, of the mowing machine and the
harvester, they have compressed into two centuries the progress of a
millennium, destitute of their aid. Every step taken under their
stimulus, and with their help, is a step toward a higher life for all,
intellectually and morally as well as physically; every advance in the
improvement of their work is a gain to every man, woman, and child;
every improvement of the steam engine is a help to the whole world.
This progress makes the day of the extinction of the system now
grinding the populations of the earth into the ground, the day of the
abolition of armies and the restoration to the people of that freedom
which characterized the times of the patriarchs, and of the
restoration of the rights of the citizen to his own time and strength
and producing power, perceptibly nearer.

When this final revolution shall have been accomplished, and when all
the world has settled down to the steady and undisturbed work of
production by daily and regular labor, aided by the genii of steam, of
electricity, of all nature, combined for good, the results of the
intellectual activity of the inventors of the steam engine will be
fully seen. Then no monument will be required to keep green the memory
of Watt, Corliss, or any other of these great men, but it will be said
of them, as of Sir Christopher Wren in the epitaph in St. Paul's:
"Seek you a monument, look about you!" Every wreath of steam rising to
the heavens from factory, mill or workshop will be a reminder of Hero
of Alexandria, every mine will possess a memorial to Papin, Worcester
and Savery; every steamship will bring into grateful memory Fitch and
Stevens, and Bell and Fulton; thousands of locomotives, crossing the
continents, will perpetuate the thought of the Stephensons and their
colleagues in the introduction of the railway; the hum of millions of
spindles and the music of the electric wire will tell of the work of
Corliss and his contemporaries and successors who made these things
possible, and all kingdoms and races, all nations, will revere the
name of James Watt, the genius to whom the world is most indebted for
the beginnings of all this later and grander civilization which has
converted the slow progress of earlier centuries into the meteor-like
advance of to-day toward a future as grand and as mighty and as noble
as humanity shall choose to make it.

       *       *       *       *       *




IMPROVED HAND CAR.


[Illustration]

In the accompanying illustration we show a new design of hand car,
being introduced by the Courtright Manufacturing Co., of Detroit. It
will be seen that the apparatus for propelling the car is very
different from the mechanism generally used. An upright framework
secured to the platform carries a large sprocket wheel, which is
connected to a smaller one upon one of the axles by means of a chain.
The larger sprocket wheel is rotated by means of a triangular shaped
lever attached at the lower corner to the crank of the sprocket wheel
and having a handle at each of its upper corners. It is hinged upon a
fulcrum which slides upon the two vertical rods shown in the
illustration. It will be seen that this gives a peculiar movement to
the handles by which the operators propel the car, but it has been
found that the motion is an excellent one, and it is claimed that a
higher speed can be obtained with the mechanism here shown than with
any other now in use. There is practically no dead center, as in the
case where the ordinary crank and lever is used. A number of leading
roads have given the car a trial, and being well satisfied it, have
given orders for more. The company claim that a car with 20 in. wheels
can easily be made to attain a speed of 15 miles an hour by two
men.--_Railway Review_.

       *       *       *       *       *




THE CONIC SECTIONS.

By Prof. C.W. MACCORD, Sc.D.


In Fig. 1 let D be a given point, and O the center of a given circle,
whose diameter is FG. Bisect DF at A. Also about D describe an arc
with any radius DP greater than DA, and about O another arc with a
radius OP = DP + FO, intersecting the first arc at P, then draw PD,
and also PO, cutting the circumference of the given circle in L. Since
PD = PL, and DA = AF, it is evident that by repeating this process we
shall construct a curve PAR, which satisfies the condition that _every
point in it is equally distant from a given point and from the
circumference of a given circle_. Since PO-PD = LO, and AO-AD = FO,
this curve is one branch of the hyperbola of which D and O are the
foci.

[Illustration: FIG. 1]

Bisect DG at B, then about D describe an arc with any radius DQ
greater than DB, and about O another are with radius OQ = DQ-FO; draw
from Q the intersections of these arcs, the line QD, and also QO,
producing the latter to cut the circumference in E. By this process we
may construct the curve QBZ, each point of which is also equally
distant from the given point D, and from the concave instead of the
convex arc of the given circumference. The difference between QD and
QO being constant and equal to FO, and AB being also equal to FO, this
curve is the other branch of the same hyperbola, whose major axis is
equal to the radius of the given circle.

The tangent at P bisects the angle DPL, and is perpendicular to DL,
which it bisects at a point I on the circumference of the circle whose
diameter is AB, the major axis, the center being C, the middle point
of D O. As P recedes from A, it is evident that the angles P D L, P L
D, will increase, until D L assumes the position D T tangent to the
given circle, when they will become right angles. P will therefore be
infinitely remote, and the point I having then reached t, where D T
touches the smaller circle, C t S will be an asymptote to the curve.
This shows that the measurements from the convex arc, for the
construction of A P, are made only from the portion F T of the given
circumference.

In the diagram the point Q is so chosen that D L produced passes
through E, so that Q J, the tangent at Q, is parallel to P I. It will
thus be seen that the measurements from the concave arc, for the
construction of B Q, are confined to the portion G T of the given
circumference. As D L E rises, the points P and Q recede from A and B,
the points L and E approach each other, finally coinciding at T; at
this instant I and J fall together at t, so that S S is the common
asymptote to A P and B Q.

In Fig. 2 the given point D lies within the circumference of the given
circle. Bisect D F at A, and D G at B; about D describe an arc with
any radius D P greater than D A, and about O another, with radius O P
= O F--D P, these arcs intersect in P, and producing O P to cut the
circumference in L, we have P D = P L. Similarly E D = E H, U D = U W,
etc. And since P D + P O = L P + P O, D E + E O = H E + E O, and so
on, the curve is obviously the ellipse of which the foci are D and O,
and the major axis is A B = F O, the radius of the given circle.

[Illustration: FIG 2.]

If, as in Fig. 3, the given point be made to coincide with the center
of the circle, the ellipse becomes a circle with diameter A B = F O.
But if the point be placed upon the circumference, as in Fig. 4, the
ellipse will reduce to the right line A B coinciding with F O.

[Illustration: FIGS 3, 4, 5, 6.]

In this case we may also apply the same process as in Fig. 1; D T
becomes a tangent at D to the circumference, and the asymptotes
coincide with the axis of the hyperbola, of which one branch reduces
to the right line A P extending from A to infinity on the left, and
the other reduces to the right line B G Q, extending from B to
infinity on the right.

If the circle be reduced to a point, as in Fig. 5, the resulting locus
is a right line perpendicular to and bisecting D O. If on the other
hand the diameter of the given circle be infinite, the circumference,
as in Fig. 6, becomes a right line perpendicular to the axis at F, and
the curve satisfies the familiar definition of the parabola, D E being
equal to E H, D P equal to P L, and so on.

In Fig. 7, as in Fig. 1, DT is tangent at T to the given circle whose
center is O, and at t to the circle about C whose diameter is AB, the
major axis. Since DTO is a right angle, T lies upon the circumference
of the circle whose center is C, and diameter DO; this circle cuts the
asymptote SCS at M and N. The semi-conjugate axis is a mean
proportional between D A and AO; now drawing TM and TN, it is seen
that Tt is that mean proportional; and a circle described about C with
that radius will be tangent to TO. DT, then, is the radius of the
circle to be described about the focus of the conjugate hyperbola for
its construction according to the enunciation first given: and we
observe that DT and TO are supplementary chords in the circle about C
through D and O. The conjugate foci must therefore lie upon this
circumference, at D' and O'; and since D'O' is perpendicular to DO,
D'T will be perpendicular and T'O' will be parallel to SCS.

[Illustration: FIG 7.]

Now as TO increases, T'O' will diminish, until, when TO equals DO,
T'O' will vanish and with it Ct'; and at this crisis, the case is the
same as in Fig. 4; but the conjugate hyperbola logically reduces to
_two_ right lines, extending from C to infinity on the right and left.
As indeed it should from the familiar construction, since the
distances from D' and O' to any point on the horizontal axis being
equal, their difference is constant and equal to zero.

It appears, then, that a conic section may be defined as the locus of
a point which is equally distant from a given point and from the
circumference of a given circle. Boscovich defines it as the locus of
a point so moving that its distances from a given point and from a
given right line shall have a constant ratio.

The latter definition involves the conceptions of a rectilinear
directrix, and a varying ratio in the cases of the different curves,
this ratio being unity for the parabola, less for the ellipse, and
greater for the hyperbola. The former involves the conception of a
circular directrix with a ratio equal to unity in all cases; and the
two definitions become identical in the construction of the parabola,
which is in fact the only curve of which a clear idea is given by
either of them. That of Boscovich has been given a prominence far in
excess of its merits, being made the foundation for the discussion of
these important curves, and this in a textbook whose preface contains
the following true and emphatic statement, viz.:

    "The abstract nature of a ratio, and the fact that it is a
    compound concept, peculiarly unfit it for elementary
    purposes."

The definition herein set forth has not been given in any treatise on
the subject, so far as we have been able to ascertain. And it is
presented with the distinctly expressed hope that it never will be,
except as a mere matter of abstract interest.

Of this it may, like the other, possess a little, but both have the
great disadvantage that, except in relation to the parabola, the idea
which they convey to the mind of the curves to which they relate, if
indeed they convey any at all, is most obscure and indirect; and of
practical utility neither one can claim a particle.

       *       *       *       *       *




TABLE OF ATOMIC WEIGHTS.

(Issued December 6, 1890.)


By request of the Committee of Revision and Publication of the
Pharmacopoeia of the United States of America, Prof. F.W. Clarke,
chief chemist of the United States Geological Survey, has furnished a
table of atomic weights, revised upon the basis of the most recent
data and his latest computations. The committee has resolved that this
table be printed and furnished for publication to the professional
press. The committee also requests that all calculations and
analytical data which are to be given in reports or contributions
intended for its use or cognizance be based upon the values in the
table. It would be highly desirable that this table be adopted and
uniformly followed by chemists in general, at least for practical
purposes, until it is superseded by a revised edition. It would only
be necessary for any author of a paper, etc., to state that his
analytical figures are based upon "Prof. Clarke's table of atomic
weights of December 6, 1890," or some subsequent issue.

This table represents the latest and most trustworthy results, reduced
to a uniform basis of comparison, with oxygen=16 as starting point of
the system. No decimal places representing large uncertainties are
used. When values vary, with equal probability on both sides, so far
as our present knowledge goes, as in the case of cadmium (111.8 and
112.2), the mean value is given in the table.

The names of elements occurring in pharmaceutical, medicinal,
chemicals, are printed in italics[1]:

[Transcriber's Note 1: ITALICS represented by surrounding with "_".]


  Name.           Symbol.  Atomic Weight.

_Aluminum_.        _Al_        27.
_Antimony_.        _Sb_       120.
_Arsenic_.         _As_        75.
_Barium_.          _Ba_       137.
_Bismuth_.         _Bi_       208.9
_Boron_.           _B_         11.
_Bromine_.         _Br_        79.95
Cadmium.            Cd        112.
Caesium.            Cs        132.9
_Calcium_.         _Ca_        40.
_Carbon_.          _C_         12.
_Cerium_.          _Ce_       140.2
_Chlorine_.        _Cl_        35.45
_Chromium_.       _Cr_         52.1
Cobalt.             Co         59.
Columbium.[1]       Cb         94.
_Copper_.          _Cu_        63.4
Didymium.[2]        Di        142.3
Erbium.             Er        166.3
Fluorine.           F          19.
Gallium.            Ga         69.
Germanium.          Ge         72.3
Glucinum.[3]        Gl          9.
_Gold_.            _Au_       197.3
_Hydrogen_.        _H_          1.007
Indium.             In        113.7
_Iodine_.          _I_        126.85
Iridium.            Ir        193.1
_Iron_.            _Fe_        56.
Lanthanum.          La        138.2
_Lead_.            _Pb_       206.95
_Lithium_.         _Li_         7.02
_Magnesium_.       _Mg_        24.3
_Manganese_.       _Mn_        55.
_Mercury_.         _Hg_       200.
_Molybdenum_.      _Mo_        96.
Nickel.             Ni         58.7
_Nitrogen_.        _N_         14.03
Osmium.             Os        191.7
_Oxygen_.[4]       _O_         16.
Palladium.          Pd        106.6
_Phosphorus_.      _P_         31.
Platinum.           Pt        195.
_Potassium_.       _K_         39.11
Rhodium.            Rh        103.5
Rubidium.           Rb         85.5
Ruthenium.          Ru        101.6
Samarium.           Sm        150.
Scandium.           Sc         44.
Selenium.           Se         79.
_Silicon_.         _Si_        28.4
_Silver_.          _Ag_       107.92
_Sodium_.          _Na_        23.05
Strontium.          Sr         87.6
_Sulphur_.         _S_         32.06
Tantalum.           Ta        182.6
Tellurium.          Te        125.
Terbium.            Tb        159.5
Thallium.           Tl        204.18
Thorium.            Th        232.6
Tin.                Sn        119.
Titanium.           Ti         48.
Tungsten.           W         184.
Uranium.            U         239.6
Vanadium.           V          51.4
Yterbium.           Yb        173.
Yttrium.            Yt         89.1
_Zinc_.            _Zn_        65.3
Zirconium.          Zr         90.6

--_Am. Jour. Pharm._

[Footnote 1: Has priority over niobium.]

[Footnote 2: Now split into neo-and praseo-didymium.]

[Footnote 3: Has priority over beryllium.]

[Footnote 4: Standard, or basis of the system.]

       *       *       *       *       *




THE TANNING MATERIALS OF EUROPE.


The tanning materials of Europe are of an altogether different type
from those of the United States. The population is so dense that the
quantity of home materials produced is not nearly proportionate to the
amount consumed, and consequently they must draw upon surrounding
lands for their supply. The vegetation of these adjacent countries is
of a much more tropical nature, and it naturally follows that the
tanning materials are also of a different species.

Tanning materials may be divided into two great classes, viz.:
Physiological and pathological.


PHYSIOLOGICAL.

The first class includes those tannins which are the results of
perfectly natural or normal growth, and a growth necessary to the
development of vegetation, for instance, bark, sumac, etc., whereas
the second class contains those which are the results of abnormal
growth, caused by diseases, stings of insects, etc. An example of this
is the gall. Both of these classes are used to a great extent in
Europe, while only the first division is in general use in the United
States. We will first consider the physiological tannins.


_Oak Bark._--This material was, is, and will be for some time to come
the main tanning material in use here in Europe. The advantages of the
oak tannage are as fully appreciated here as in the United States. The
European oak gives a light colored, firm leather, with good weight
results, is comparatively cheap and of an excellent quality. The
varieties are numerous, each country having its own kind. Those in
most general use are:

_Spiegel Rinde_ (mirror bark).--This bark is well distributed
throughout Europe, and is peeled when the tree has attained a growth
of from 12 to 24 years. It is marketed in three grades.

_Reitel Rinde_--Is obtained from the same tree as the spiegel rinde,
but after the tree has attained a growth of from 25 to 40 years.

_Alte Pische_ (old oak).--Obtained from the aged tree. It is not as
valuable as the younger bark, and consequently brings a much lower
price.

Spiegel rinde may be judged by small warts which appear on the shining
surface of the bark. The presence of a great number of these, as a
rule, indicates a high tannin percentage.

Bosnia has fine oak trees, the bark containing 10 to 11 per cent.
tannin.

Bohemia has the _trauben eiche_ (grape oak).

France uses the kirmess oak, which grows in the south of that country
and in northern Africa. Two grades are made, viz., root and trunk.

Tyrol has the evergreen oak--12 to 13 per cent. tannin.

Sardinia possesses a cork oak, which yields 13 to 14 per cent.

White oak is found throughout Europe, yielding 10 per cent. The price
of oak bark varies a great deal. The assortment is much more strict
than in the United States. In Austria it brings 4 to 5 fl., equal to
$1.60 to $2 per kilo. (224 lb.); in Germany, 11 to 16 marks per 100
kilos.[1]

[Footnote 1: In the principal districts in America, removed from the
cities, the price of oak bark is about $4 to $6 per cord or per ton
of 2,240 lb. The hemlock bark, which gives a sole leather just as
thoroughly tanned, but of a darker and reddish color, costs the
larger tanners from $3 to $4 a cord.]

The above mentioned varieties are all used for both upper and sole
leather. In Germany a great deal of upper leather is pure oak tannage,
but one seldom finds a pure oak tanned sole leather; it is almost
always in combination with other tannics.


_Pine Bark_--Is well distributed and is a very important tanning
material. It bears the same relation to oak bark here as does hemlock
in America, but its effects are quite different from hemlock. The best
Austrian sorts are those of Styria and Bohemia, but that of Karuthen
is also of good quality. The German pine comes from Thuringia to a
great extent. The countries that consume the greatest amount of pine
bark are Austria, Germany, Russia and Italy. The tannin contained
varies from 5 to 16 per cent. Its use is almost wholly confined to the
handlers, as its weight returns are not so satisfactory as oak or
valonia. In case it should be used for layers it is always in
combination with some better weight-giving tannic. For upper leather
its use is limited.

The bark is always peeled from the felled tree, and often the woodman
accepts the bark in part payment for his labor; he then sells the bark
to the tanner or agents who go about the country collecting bark. It
is generally very nicely cleaned. I would here like to correct a
mistake which tanners often make in their estimations of the value of
barks. A tanner usually buys the bark of southern-grown trees in
preference to that of trees grown in northern countries, as it is a
common idea that southern vegetation contains more tannin than that of
the north. This is a fallacy, as has not only been proved by careful
analyses, but may also be found to be an incorrect conclusion after a
moments' thought. Those trees which flourish in southern countries
grow very rapidly, and as tannin is necessary to the development of
leaf structure, etc., it is absorbed to a greater extent than is the
case with the slower-growing tree of the north. The tannin contained
in the sap does not increase in the same ratio as does the rapid
growth, and it follows that the remainder in the bark is less than in
the tree of slower growth.


_Birch Bark_--Is at home in Russia, Norway, and Sweden. It is used for
both upper and sole leather, but seldom alone. The bark is usually
peeled from the full grown tree, and contains 4 to 9 per cent. tannin.


_Willow Bark_--May also be found in the above mentioned countries and
also in Germany. This material is used for both upper and sole
leather, and contains 6 to 9 per cent. tannin. It is a very delicate
material to use, as its tannin decomposes rapidly.


_Erlen Rinde_--Is also a native of Germany, but is not used to any
great extent. The same may be said of the larch, although this variety
is also to be met with in Russia.


_Mimosa Bark_--Is obtained from the acacia of Australia. It is a
favorite in England. The varieties are as follows: Gold wattle, silver
wattle (blackwood, lightwood), black wattle, green wattle. The gold
wattle is a native of Victoria. Its cultivation was tried as an
experiment in Algeria and met with some success. The trees are always
grown from seeds. These seeds are laid in warm water for a few hours
before sowing. The acacia may be peeled at eight years' growth and
carries seeds. The Tasmania bark is very good; that from Adelaide
likewise good.

Sydney does not produce so good an article, but Queensland better. The
bark is marketed in the stick, ground or chopped.

Madagascar and the Reunion Islands have also a mimosa bark.

The mimosa barks give a reddish colored leather, pump well and contain
a high tannin percentage, 10 to 35 per cent.


Now we will consider the fruit tanning materials.

Valonia may truly be called one of the most generally used tanning
agents at present employed in Europe. All countries consume it more or
less. Valonia was first used in England about the beginning of this
century. A few years later Germany began using it, and still later
Austria introduced it. It is the fruit of the oak tree and is
obtainable in Asia Minor and the adjacent islands. In form it
resembles the American acorn, but in size it nearly trebles it. The
fruit may be divided into two parts, namely, the cup and acorn, and
the cup again divided into trillor and inner cup. The acorn only
contains 10 per cent. tannin, whereas the cup contains from 25 to 40
per cent.

The percentage depends altogether upon the time of harvesting and the
place of growth. The best valonia is derived from Smyrna, and is
naturally the highest priced article. Valonia is worth from 22 to 28
florins ($9 to $11) per 100 kilos. (224 pounds) at present. The other
provinces and islands from which it is obtainable are Demergick,
Govalia, Idem, Ivalzick, Troy (this is the best); Metelino Island, the
vicinity of Smyrna. The material sold in three grades--prime, mazzano;
seconds, una aqua; thirds, skart.

The product of Smyrna generally averages:

                       Tons.           Price.
    Prime.        2,000 to  3,000      28 florins.
    Seconds.      5,000 to 10,000      25    "
    Thirds.      20,000 to 30,000      22    "

The _Metilino_ valonia is a product of a neighboring island, and is a
very good article. It may be easily distinguished by its thin cup. It
is harvested in September.

The _Candia_ valonia is nearly as long as it is wide, in contrast to
the Smyrna, which is much wider than long. The recent harvest showed a
return of 800 to 1,000 tons, but no assortment is made. A grade called
the Erstlige is sold, this being the first which has fallen to the
ground before maturing.

A peculiarity of the valonia is that it often strikes out a sort of
sugar sweat, which gives the cup a less attractive appearance, but
denotes the presence of large quantities of tannin.

Valonia is used almost wholly for sole leather, either alone or in
combination with pine or oak bark or knoppern and myrabolams. The
union of valonia and knoppern is that in most general use. Valonia
gives the leather a yellowish appearance, as it deposits a great deal
of yellow bloom. The leather is very firm and of good wearing
qualities. The weight results are also excellent, as will be seen
below. To sole leather there are usually given from one to three
layers of valonia. The demand for valonia is increasing more and more
every year, and the present outlook does not indicate any relaxation
of its popularity. Its use for upper leather is very limited.

Myrabolams are mainly used in England and Austria, and give a nice
light-colored leather, both upper and sole, although rarely used
alone. Their main use is for dyeing purposes. They are indigenous to
the East Indies.

Sumac is so well known that treating of it is superfluous. Its use is
very extensive, and it is a general favorite for light, fine leather,
which is mostly used for colors.

_Gambier_--Is in general use in England and to some extent in Germany.

_Catechu_.--Obtained from India, resembles gambier greatly. Its use is
almost wholly confined to England. It is also consumed by the silk
manufacturers in preference to gambier, for weighting purposes.


PATHOLOGICAL.

We now leave the physiological class and take up those tanning
materials included in the pathological class, or those of abnormal
growth.


_Galls_.--These are not consumed to any great extent at the present
period, but formerly they were used quite extensively. The galls are
found upon the leaves of the oak or sumac, etc. The direct cause of
their growth is that a certain wasp (cynips galles) stings into the
leaf and after depositing its egg, flies away. The egg develops into a
larva and then into a full-fledged wasp, boring its way out of the
gall which has served as a protection and nourisher. This accounts for
the hole noticed in almost every gall. The different varieties include
Aleppo. It is found upon the same trees as the valonia and contains 60
to 75 per cent. tannin; Istrian galls, 32 per cent. tannin; Persian,
28 to 29 per cent. tannin. Chinese galls, giving 80 to 82 per cent.
tannin, are the results of the sting of a louse, and make a very
light-colored leather. The dyers also use this material for coloring.


_Knoppern_--Belongs to the family of galls, and is a most important
factor of commerce in Austria. The knopper is generally found on the
acorn or leaf of the oak tree. The greatest quantity is derived from
the steel oak of Hungary. The tannin contained varies from 27 to 33
per cent. Knoppern are not being used so much now as formerly, and
consequently the amount harvested lessens from year to year. Its main
use was and is in combination with valonia as layers for sole leather.
Valonia gives better weight results than knoppern, and is replacing
knoppern more and more every year. The combination of knoppern,
valonia and myrabolams is also quite popular, and gives good results.
Knoppern are seldom used alone, being generally combined with some
other tannin. Austria is almost the only consumer at present, but
Germany used it extensively formerly.


_Bark and Wood Extracts_--Are becoming general favorites throughout
Europe, partly because of their weight-giving qualities and partly as
the transportation costs so little; they can be used to strengthen
weak bark liquors.

_Oak Extracts_--Are well liked, both wood and bark, and are used
extensively. Slavonia furnishes a great deal of it.

_Chestnut Oak Wood Extract_--Is manufactured in quantities, and easily
finds purchasers.

_Pine Bark Extract_--Is also consumed in goodly amounts.

_Quebracho Wood Extract_.--The wood is shipped from Brazil to Hamburg
and other ports, and the tannin extracted there. Hamburg furnishes
quantities of it.

_Hemlock Extract_--Is used in Russia, and seems to have taken a hold
on the shoe buyers' fancies, as they now make imitations of it in
color. The hemlock that is consumed is imported from America.


As most leather is sold by weight in Europe, the leather manufacturers
aim to obtain as good weight results as possible, and often, I am
sorry to say, do so at the sacrifice of quality. This is common to
both upper and sole leather. Sole leather is nine times out of ten
given false weight by forcing entirely foreign substances into the
leather, such as glucose, barium chloride, magnesium chloride, resins,
etc. Glucose and resin are also used for weighting upper leather.
Leather is also weighted with extracts by overtanning. Leather buyers
have become very wary of late and do not purchase large quantities
before an analysis is made of a fair sample.

One more word before I close. The governments and private individuals
in Europe cultivate and raise trees for both lumber and bark purposes.
The forests are excellently cared for by efficient foresters, and the
result is that the tanners obtain much cleaner and better bark, and of
a very even quality. Would it not be a good idea if some individual,
who would certainly earn the everlasting gratefulness of the tanners,
would look into this matter, and see that not only the lumber side of
our forest cultivation is not neglected, but that the bark also is
preserved and cared for? Of course, we can obtain all the bark
necessary at present and for some time to come, but the time will come
when we shall certainly regret not having taken these steps, if the
lumbermen and bark peelers go on devastating magnificent forests.
Below will be found a table of weight results. Sole leather tanned
with these materials gives for every 100 lb. green hide the following
quantities of finished leather:

                                     lb.
  Oak bark                          48 to 54
  "   extract                       55 to 56
  Pine bark                         44 to 46
  "   extract                       48 to 50
  Willow                            45 to 46
  Birch bark and oak extract        49 to 51
  Quebracho wood and extract        48 to 49
  Valonia                           52 to 56
  Knoppern                          51 to 53
  Myrabolams                        50
  Knoppern, myrabolams and valonia  52 to 53
  Hemlock                           55

Specification of tanning materials used in different countries:

_France_.
Oak bark (kirmess).
Sumac.
Chestnut wood extract.
Quebracho "     "
Some gambier.

_Italy_.
Oak bark.
Pine "
Sumac.
Valonia.

_England_.
Oak bark.
Divi divi.
Myrabolams.
Valonia.
Mimosa.
Extracts { Oak bark and wood hemlock.
Gambier.
Cutch.

_Germany and Austria_.
Oak bark.
Pine "
Willow bark.
Valonia.
Knoppern.
Myrabolams.
         { Oak bark and wood.
Extracts { Pine bark and wood.

_Russia._
Birch bark.
Willow "
Oak    "
Pine   "
Hemlock extract.


_Norway and Sweden_.
Birch bark.
Willow "
Oak    "

                                      WALTER J. SALOMON.
--_Shoe and Leather Reporter_.

       *       *       *       *       *




AN APPARATUS FOR HEATING SUBSTANCES IN GLASS TUBES UNDER PRESSURE.[1]

[Footnote 1: Read at the meeting of the Chemical Section of the
Franklin Institute held March 17, 1891.]

By H. PEMBERTON, Jr.


Chemists who do not happen to have in their laboratories oil or air
baths for heating closed tubes can make an air bath at short notice
from materials furnished by all dealers in steam fittings.

_Order_:

(1) One four-inch wrought iron pipe, eighteen inches out to out, with
usual thread on each end. At about nine inches from either end this
pipe is drilled and tapped for a one-inch nipple, in such a manner
that a pipe introduced would pass, not on a line with the radius, but
about half way between the axis of the four-inch pipe and its walls;
in other words, it would be on a line with a chord of the circle.

(2) One one-inch wrought iron nipple, two inches long, one-inch thread
on one end.

(3) Two four-inch malleable iron caps, drilled and tapped for a
one-inch pipe.

(4) One one-inch wrought iron pipe, twenty-four inches out to out,
with a three-inch straight thread on each end.

(5) Two one-inch iron caps. A hole, one-eighth of an inch in diameter,
is drilled in the end of one of these caps.

The above order can be given _literatim_, and will be understood by
the dealer, who will furnish, at a trifling cost, the materials, cut
and tapped as ordered.

Fig. 1 shows how the whole is put together. The numbers on the figure
correspond also to the numbers of the paragraphs of the order as given
above.

[Illustration: FIG. 1.]

[Illustration: FIG. 2.]

Fig. 2 is an end section. A cork is inserted in 2 and through it a
thermometer, the bulb of which is on a level with the interior pipe.
The whole is supported on a few bricks at either end, and is kept
steady and in place by a couple of weights or half bricks. It is
heated by one or two Bunsen burners, according to the temperature
desired.--_Jour. Fr. Institute_.

       *       *       *       *       *




TESTING CEMENT.


An improved method of testing Portland cement has been adopted by M.
Deval, Chief Superintendent of Bridges and Roads, who has charge,
under M. Saele, of the Public Works Laboratory of the City of Paris.
The principal difference in M. Deval's method consists in the use of
hot water for the period of hardening. The briquettes are made in the
usual way, and of the ordinary size; and the cement to be tested is
gauged with three times its weight of normal sand, and the smallest
quantity of water possible. After preparation, the briquettes are
allowed to harden in air for a period ranging from 24 hours for
Portland cement to 30 days for certain slow-setting hydraulic limes.
After this period, the samples are immersed in water kept at a
temperature of 80° C., in which they remain for from two to seven
days. The briquettes are then broken in the ordinary way. After
careful comparisons of many varieties of cement hardened hot and cold,
M. Deval finds that cold tests are fallacious, inasmuch as they may
fail to detect bad material. Portland cement of good quality will not
only stand water at 80° C., but will attain in seven days about the
same strength as is reached in the cold after 28 days. The hot test
therefore saves time. The hot test is an unfailing proof for free
lime; cements containing this constituent betraying weakness, and
cracking, swelling, and disintegrating in a very significant manner.
This last result is regarded as a valuable quality of the new method
of testing cement, the general effect of which appears to be to
enhance the test value of really good cements, while depreciating
those of an inferior character.

       *       *       *       *       *


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A NEW CATALOGUE OF VALUABLE PAPERS

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sent _free of charge_ to any address. MUNN & CO., 361 Broadway, New
York.

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USEFUL ENGINEERING BOOKS

Manufacturers, Agriculturists, Chemists, Engineers, Mechanics,
Builders, men of leisure, and professional men, of all classes, need
good books in the line of their respective callings. Our post office
department permits the transmission of books through the mails at very
small cost. A comprehensive catalogue of useful books by different
authors, on more than fifty different subjects, has recently been
published, for free circulation, at the office of this paper. Subjects
classified with names of author. Persons desiring a copy have only to
ask for it, and it will be mailed to them. Address,

    MUNN & CO., 361 Broadway, New York.

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PATENTS!

MESSRS. MUNN & CO., in connection with the publication of the
SCIENTIFIC AMERICAN, continue to examine improvements, and to act as
Solicitors of Patents for Inventors.

In this line of business they have had _forty-five years' experience_,
and now have _unequaled facilities_ for the preparation of Patent
Drawings, Specifications, and the prosecution of Applications for
Patents in the United States, Canada, and Foreign Countries. Messrs.
Munn & Co. also attend to the preparation of Caveats, Copyrights for
Books, Labels, Reissues, Assignments, and Reports on Infringements of
Patents. All business intrusted to them is done with special care and
promptness, on very reasonable terms.

A pamphlet sent free of charge, on application, containing full
information about Patents and how to procure them; directions
concerning Labels, Copyrights, Designs, Patents, Appeals, Reissues,
Infringements, Assignments, Rejected Cases. Hints on the Sale of
Patents, etc.

We also send, _free of charge_, a Synopsis of Foreign Patent Laws,
showing the cost and method of securing patents in all the principal
countries of the world.

  MUNN & CO., Solicitors of Patents,
  361 Broadway, New York.

BRANCH OFFICES.--No. 622 and 624 F Street, Pacific Building, near 7th
Street, Washington, D.C.