Scientific American Volume 22, No. 1, January 1, 1870 Part 14

The invention of the magic lantern dates back to 1650, and is attributed to Professor Kircher, a German philosopher of rare talents and extensive reputation. The instrument is simple and familiar. It is a form of the microscope. The shadows cast by the object are, by means of lenses, focussed upon something capable of reflection, such as a wall or screen.

No essential changes in the principles of construction have been made since the time of Kircher; but the modern improvements in lenses, lights, and pictures, have raised the character of the instrument from that of a mere toy to an apparatus of the highest utility. By its employment the most wonderful forms of creation, invisible, perhaps, to the eye, are not only revealed but reproduced in gigantic proportions, with all the marvelous truth of nature itself. The success of some of the most celebrated demonstrations of Faraday, Tyndall, Doremus, Morton, and others, was due to the skillful use of the magic lantern. As an educator, the employment of this instrument is rapidly extending. No school apparatus is complete without it; and now that transparencies are so readily multiplied by photography upon gla.s.s, and upon mica, or gelatin, by the printing press or the pen, it is destined to find a place in every household; for in it are combined the attractive qualities of beauty, amus.e.m.e.nt, and instruction.

The electric light affords, probably, the strongest and best illumination for the magic lantern; then comes the magnesium light; but their use is a little troublesome and rather expensive; next to these in illuminating power is the oxy-hydrogen or Drummond light. The preparation of the gases and the use of the calcium points involve considerable skill.

Need has long been felt for some form of the magic lantern, having a strong light, but more easily produced than any of those just mentioned; and this has at last been accomplished, after several years' study and experiment, by Prof. L.J. Marcy, 632 Arch St., Philadelphia, Pa.

The "Sciopticon," is the name of his new instrument, and from actual trial we find that it possesses many superior qualities. Its lenses are excellent, and in illuminating power its light ranks next to the oxy-hydrogen. The sciopticon light is produced from ordinary coal oil by an ingenious arrangement of double flames, intensifying the heat and resulting in a pencil of strong white light. Prof. Marcy's instrument is the perfection of convenience, simplicity, and safety. Any one may successfully work it and produce the most brilliant pictures upon the screen. It is peculiarly adapted for school purposes and home entertainment. Those who wish to do a good thing for young people should provide one of these instruments. Photographic transparencies of remarkable places, persons, and objects, may now be purchased at small cost; while there is no end to the variety of pictures which may be drawn by hand at home upon mica, gla.s.s or gelatin, and then reproduced upon the screen by the sciopticon.

The Largest Well in the World--Capacity 1,000,000 Gallons of Water per Day.

One of the grand necessities of the Prospect Park, Brooklyn, N.Y., that of providing for a continual supply of water for all the purposes of the Park developed itself, as the Commissioners progressed with their stupendous undertaking. Mr. Stranahan, the President of the Board, after carefully weighing the cost, the practicability, and importance of having an independent water supply for the Park, advised the Commissioners of the plan which had suggested itself, and the calculations which had been made by the engineers relative to the project, and the work was commenced, the first idea being to secure at least a partial supply of water by means of a well constructed in the Park. The subject was thus treated in the last annual report of Mr. C.C.

Martin, the engineer in charge:

"This well has been located on the south side of Lookout Hill, near the lake, and work was commenced upon it late in the season. After a careful consideration of various methods for sinking the well, it was decided to build the wall and then to excavate the material from within, trusting to the weight of the wall to force it down. Sixteen feet of the wall were laid securely bolted together, before the excavation was commenced.

A derrick with a boom fifty-five feet in length was set up near the wall, so that the sweep of the boom commanded the interior of it.

Iron buckets containing fourteen cubic feet each were obtained, and a six-horse power hoisting engine purchased. With these appliances the excavation was commenced, and carried on with slight interruption until the work was suspended on account of the frost."

The well is now completed, and is one of the most important features of the Park. It is worthy to rank as a feat of engineering skill with, any of the great works of modern times. The Commissioners decided to put its powers to the test yesterday afternoon, but owing to the unpropitious weather of the forenoon the trial was postponed. Nevertheless, Commissioners Stranahan, Fiske, and Haynes, with Mr. Martin, engineer in charge, and Mr. John Y. Culyer, his a.s.sistant, were at the well. During the last summer some difficulties were encountered in the sinking of the wall, which were set down by superficial observers as the utter failure of the enterprise. Mr. Stranahan received but little encouragement from his fellow Commissioners, some of whom had never seen greater works of engineering than the construction of street sewers. He a.s.sumed the responsibility of seeing the work through, feeling that the whole thing depended entirely upon the ability of the engineers, in which he had abundant faith. All obstacles were surmounted; the work proceeded and the well is now finished, and so far as is known, is understood to be the largest one in the world.

The outer wall is fifty feet in diameter, two feet thick, and fifty-four feet high. The inner curb, or wall, is thirty-five feet in diameter and two feet thick, having a depth of ten feet. The masonry, as seen from the top of the structure, is a marvel of neatness and solidity. The water surface in the well is thirteen feet above high-tide level, and the depth of water in the well is fourteen feet. The pump foundations are entirely independent of the walls. This plan was adopted so as to obviate any possible difficulty which might arise from displacement. The pump is the Worthington patent, and, with a pressure of forty pounds, is capable of raising one million gallons of water every twenty-four hours a height of 176 feet, and is competent to a lift of 180 feet.

The boiler house is a neat, pressed-brick structure trimmed with Ohio stone, standing on the surface near the mouth of the well. The interior of the well is reached by a spiral stairway built in the wall, and commencing in the boiler house. In this way the engineer is able to reach the pump. It is a fact worthy of notice in connection with the construction of the wall, or rather the sinking of it, that the outer wall rests upon four feet of wooden cribwork, two feet thick, and having an iron s.h.i.+eld. The inner wall is built upon a similar crib only two feet deep, also s.h.i.+elded with iron.

The Commissioners were led to the construction of this well in presence of the danger at any time of some accident taking place in connection with the Brooklyn Water Works which would render it necessary for the Water Board to cut off the Park supply so as to secure the citizens from suffering. This well has more than the necessary capacity to supply the Park abundantly with water, yielding most when most is needed. This is established by the discovery that the time of drought from which the well is, or may be, likely to suffer, occurs in the Fall. Besides these facts, it further appears that in order to furnish the supply of water to the Park the Water Board would have to go through the process of pumping their water twice to convey it to the required elevation, equal to 225 feet from its original level.

The work of the well will be to supply the pools at an elevation of 133 feet. From the pools the water is conducted to the lake. Besides this, there is an independent connection with the lake by which, as necessity may suggest, the water can be directed to the lake, a lift of only seventy feet. The lake, when completed, will occupy an area of fifty acres, which will be kept continually supplied with fresh water, the arrangements being such, or to be such, as will insure a permanent change of water, and prevent any of the evils that may arise from stagnancy. The well is fed from the earth, consisting of a circuit of two miles, with a fall of five feet to the mile. For this reason it does not appear easy to exhaust the supply, as when the water is pumped out to four or five feet from the surface of the well it is replaced at a rate equal to the demand. Every allowance has been made for evaporation from the lake and pools, and the supply is regarded as inexhaustible.

Another important fact here suggests itself; that is, that sufficient rain falls during the season in the area of two miles around the well to make the supply perennial. The Prospect Park well is a credit to Brooklyn.--_New York Times_.

PAPER FOR BUILDING.

Our readers will find in another column an advertis.e.m.e.nt of this new building material which is now attracting much attention in the West, and of which we have received very favorable reports. It has been recently tested in Chicago with the result we are informed of fully establis.h.i.+ng its utility. It is said that a house twenty-two feet long, sixteen wide, and fourteen high, can be covered on the outside for less than $9; and a house thirty-six feet by twenty-two, and twenty feet high, for $20. The building can be done at any season, and can be finished with great speed, and there are said to be numerous other advantages connected with the use of the paper. It differs from ordinary paper in consistency, compactness and solidity. In the manufacture it is subjected to a pressure of hundreds of tuns, which squeezes out the liquid matter, leaving a substance of the right thickness. It is said to be proof against damp and gnawing of vermin, and it being an excellent non-conductor of heat, must make a warm dwelling in winter and a cool one in summer. It is used in the place of plastering for inside walls.

The Prussian Government has military maps of every foot of its territory so complete that every hill, ravine, brooklet, field, and forest is delineated with perfect accuracy. It is a common boast of Prussian military men, that within the s.p.a.ce of eight days 848,000 men can be concentrated to the defense of any single point within the kingdom, and every man of them will be a trained and well-equipped soldier.

Improved Muzzle-Pivoting Gun.

We are indebted for the following able description and criticism of this Prussian gun to our able contemporary, _The Engineer_.

Viewed as a piece of mechanism, nothing can well be more beautiful in mutual adaptation of parts to the fulfillment of given and rather recondite movements, and in point of execution, than this muzzle-pivoting arrangement of Herr Gruson's; but having said this we are compelled to add, as impartial engineering critics, that it is nothing more.

[Ill.u.s.tration: GRUSON'S SYSTEM OF MUZZLE-PIVOTING APPLIED TO MONITORS.]

A very few words of description, aided by the very clear engraving annexed, will suffice to make the arrangement plain to every mechanical reader. The entire structure is metallic, chiefly of cast iron or of steel. Upon the platform of the casemate, or deck of the s.h.i.+p, or turret, is laid the heavy bed or traverse plate, cast hollow in iron, holding the vertical pivot at its forward end, on which the gun slide traverses in azimuth, and at its rear end the segment plate, bolted down and separately adjustable as to position upon the bedplate. The slide is also a ponderous hollow casting, the upper surfaces of which, on which the gun carriage runs forward or recoils, are curvilinear in a vertical plane, so that the inclination to the horizon is greatest at the rear end. At the rear end of the slide it traverses upon two heavy cast-iron turned conical rollers, which are geared together and actuated by the winch handle and spur gear, seen in our engraving; by these the slide is practically held fast in any position on the bedplate. The gun itself--in the model, a steel breech-loader, on the Prussian regulation system, very slightly modified--is sustained between two high and ponderous cheek plates of cast iron, which const.i.tute the sides of the carriage, and which are connected together strongly at the lower edges by a heavy base or bottom plate, and at the top by two light cross distance bolts. The muzzle and breech extremities of the piece project well beyond those cheeks. Along the bottom of the trough of the carriage, directly under the gun, lies a nearly horizontal hydraulic press cylinder, the pump and handle actuating which are seen in the figures to the proper left of the gun, and the supply of water for which is contained in the hollow bottom of the carriage. On each side cheek of the carriage is formed, by curved planing, a circular segmental race, opening inward or toward each other, rectangular in cross section and into each of which is fitted a segmental block just filling it up, and occupying a portion of its length so as to slide easily up or downward through the whole range of the arc or segment.

The center point of the length of each of those blocks carries one side of the gun, which is connected also with the two heavy radius bars seen outside the cheeks, and pivoted close to the segment races on the outside, and with a system of link work between the gun itself and the crosshead of the ram of the hydraulic cylinder, which gives motion to the gun in elevation or depression, through a vertical arc, the imaginary center of which, and of the segments of the side cheeks, is situated in the horizontal diameter across the muzzle of the gun. This is in brief the muzzle-pivoting part of the arrangement, of which, were it worth while to go into its details, we should need some further diagrams to make it quite clear. Nor is it worth while to go into the description of various minor points of refinement about the gun mounting, such as the very exposed long tangent scale seen in the figure, by which the elevation or depression is read off, nor the still more exposed and rather ricketty arrangement by which the rear sight is arranged to rise and fall with the gun, and allowance for dispart avoided. The recoil of the gun is resisted through and by the segment blocks in the side cheeks, and by the heavy radius bars, etc., and thus transferred to the carriage itself. This moves upon four eccentro-concentric rollers, in all respects identical with those brought before the Ordnance Select Committee of Woolwich by Mr. Mallet, in 1858--then rejected, after some time adopted, and brought into use in our own service, where they are now universal, and from which they have been adopted into every artillery in the world, and, we understand, without the slightest recognition of the inventor's rights. On the axle of each of these rollers is keyed a circular eccentric cam plate, those at the same side being connected together by a linking bar so as to move in concert. Adjustable tripping plates attached to the sides of the slide, are so arranged that when the loaded gun has been run forward its carriage base rests hard down, with its full weight upon the top faces of the slide, and thus the recoil is made under the full resistance due to the friction of the entire load. Arrived at the highest point, it rests there until loaded. The cam plates being then given a slight motion of rotation by the help of socket levers--the rectangular projections to be received by which are seen on the top edges of the cam plates in the figure--the carriage, by its own commenced descent, gets again upon its rollers, and runs forward upon these at once into firing position. The two elevated horns which are seen standing up at the rear part of the slide above the roller frame are designed to receive the thump of the two short buffer-blocks--seen at the rear part of each carriage cheek--in the event of the recoil not being wholly expended in raising the weight of gun and carriage, etc., along the curved racers of the slide. These buffer-blocks bear against plugs of vulcanized india-rubber secured in the bottoms of the buffer cylinders.

We have thus, though very briefly, described the whole of this mounting.

As a carefully thought out and elaborated piece of elegant mechanical complication Herr Gruson's muzzle-pivoting carriage attracted much attention at Paris, in 1867, and its merits were regarded as great by those whose thoughts went little further perhaps. We should have been glad had it been in our power to have joined in its praise. We are, however, obliged honestly to say that, however highly creditable to its designer as an ingenious and capable mechanism, it shows that he has never realized to himself as a practical artillerist the primary, most absolute, and indispensable conditions of construction for a serviceable muzzle-pivoting gun for either land or sea service.

As to the general merits, or general conditions, of muzzle-pivoting, however, once in doubt at first, these are admitted now by all; and the latter resolve themselves almost into this--that system of muzzle-pivoting must be best which, while preserving the essential point of leaving the muzzle of the gun free of any direct attachment, i.e., with an imaginary, not an actual, pivot of vertical arc motion, shall be _the simplest possible_ in its parts, have the least details, the fewest parts capable of being struck by splinters or shot, and all its parts of such materials and character as to receive the smallest amount of injury if so struck. In every one of these aspects Herr Gruson's mounting is at fault. With parts and movements far more ingeniously adapted than those of the crude and unskillfully designed muzzle-pivoting carriages of Captain Heathorn, also exhibited at Paris, and much exhibited and exposed since, the Gruson mounting is even more complicated, expensive, and liable to injury of every sort to which a gun carriage can be conceived liable. We may even venture to affirm that ponderous as was the ma.s.s of cast iron, etc., in the Paris model carrying only a 12-pounder gun, were it all enlarged in such ratio as might appear to suit for a 10-inch 25-tun rifled gun of the British type, the almost proverbial relations, between weight, velocity of impulse, and brittleness of cast iron, would show themselves, in the whole machine going to pieces within a very few rounds.

Stock Feeding by Clock Work.

Mr. F. B. Robinson, of North Haven, Conn., has invented a very neat arrangement, whereby horses or stock can be fed at any time required with certainty and without personal attention at the time of feeding.

His invention consists of a hopper with a drop bottom in which the provender is placed. A latch secures the drop bottom, the latch engaging with a spring catch. A simple arrangement of clock work on the principle of the alarm clock, may be set to release the spring at any hour or minute desired, when the drop falls and the provender falls through a chute into the feeding trough. This invention may be adapted to feeding any number of horses or cattle, only one clock being required. We regard the invention as one of much value. By its use much neglect of careless attendants may be obviated, and a farmer without help, might leave home for an evening's entertainment, or absent himself on business, without fear that his stock would suffer. Besides being so convenient the cost of the apparatus is a mere bagatelle.

Milk, and What Comes of It.

Orange County has long been a laud flowing with milk and--b.u.t.ter. Three or four of these most beautiful autumn days were spent by us, says a writer in _Harper's Weekly_, among the farmers which are supposed to b.u.t.ter our New York city bread, and qualify our tea and coffee. Recent mechanical improvements have taken away much of the traditional romance of the farm, but, on the whole, the loss is more than made up by the gain of perfect system and wonderful adaptation. Instead of four or five cows, known by such names as Brindle, Bess, and Sukey, milked by rosy-cheeked maidens, we have now droves of fifty or a hundred, milked by men, who know them only as "good" or "poor milkers."

In some fine farms a large and luxuriant pasture, with running brooks and border of woodlands, affords, with the herd feeding in it, a beautiful picture; and the substantial barns constructed to keep the cattle comfortably cool in summer and warm in winter, with ample drinking troughs and stalls for fastening up at night, are indicative of the good shelter at hand when winter storms drive the cows indoors. To the farmyards the cows are brought night and morning, in summer, to be milked. The strained milk is put into large cans holding forty quarts, such as the milkmen use in distributing it through the city. These cans are then put into tanks made in some cool running stream, where the water comes nearly to the top of the can. Frequent stirring is necessary until the animal heat is quite gone. The milk is then fit to be sent to the cars. This process can never safely be omitted for, paradoxical though it may seem, milk is "fresher" and sweeter when it reaches the consumer if it is delayed at the farm for at least twelve hours. Even in hot weather, it is more certain to keep sweet when twenty-four or thirty-six hours elapse between the milking and the using in the city.

There has been much discussion as to the best means of cooling milk for market, and patent pails have been tried in which the milk pa.s.ses directly from the cow through small, coiled tubes surrounded by ice.

But this rapid cooling does not work well, and practical experience indicates that the old simple process is the best. Every well-appointed farm must have, therefore, a cool and unfailing stream of water. There are two such streams in one of the farms we visited. One pa.s.ses through the barn, furnis.h.i.+ng drinking troughs for the cattle, and a tank for cooling milk in winter. The other, running through the pasture, supplies a trout-breeding pond, and furnishes a tank for summer use. In a little hut under the trees, the milk cans are kept in a stream, which even the severe drought of last summer did not dry, nor the heat raise to a temperature of 60.

We are a.s.sured most positively that none of the spring water finds its way over the mouth of the can into the milk. Its dilution, of which there is so much just complaint, must be done, if at all, in the city, for the wholesale buyer is said to have such means of testing the milk as effectually protects him against the farmer. May the man be busy at work who is to give each family such a protection. We have heard it said that one end of a small piece of common tape placed in a pan of milk will carry from it all the water into another vessel in which the other end of the tape should be placed; but we have never found this a safe test.