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You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: Scientific American Supplement, No. 803, May 23, 1891 + +Author: Various + +Release Date: September 3, 2004 [EBook #13358] + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THIS PROJECT GUTENBERG EBOOK SCIENTIFIC AMERICAN *** + + + + +Produced by Don Kretz, Juliet Sutherland, Victoria Woosley and the +Online Distributed Proofreading Team. + + + + + +[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. + + + * * * * * + + + + +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 + + + * * * * * + + + + +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_. + + * * * * * + + + + +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. + + * * * * * + + +THE SCIENTIFIC AMERICAN Architects and Builders Edition + +$2.50 a Year. Single Copies, 25 cts. + + +This is a Special Edition of the SCIENTIFIC AMERICAN, issued +monthly--on the first day of the month. 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