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Achievements Of The 19th Century:
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Physics

( Originally Published Early 1900's )

Discoveries in physics have been most far-reaching in their effects. The truths of nature's laws have been unearthed by careful experiment and knowledge of them has been responsible, more than anything else, for the achievements of the Century in industry. The physicist investigates the general phenomena of inorganic nature, and learns the properties of matter and of what they are capable. This volume is devoted chiefly to a history of the application of these principles, for all the developments of the steam-engine and electricity have been made possible by the discoveries of the physicist, while he has aided every branch of pure science. Evolution and the theory of the conservation of energy are reckoned as the two greatest physical discoveries of the Century. The importance of evolution has warranted the devoting of a special article to the subject. The theory of the conservation of energy, though accounted to be of equal importance, requires less space for its statement, and the history of its application finds a place in every chapter devoted to applied science. Like all great discoveries, it is so simple that the wonder is that it was not known thousands of years ago, yet it was a development of the Century, and only during the last two or three generations has it come to be generally accepted.

This great law owes its existence to the determination of the mechanical equivalent of heat, due to the researches of James Prescott Joule, who, at the age of nineteen, began to astonish the physicists of his day by the publication of his researches on the relation between heat and energy and the final result of these investigations was the discovery of the law of the conservation of energy. He demonstrated experimentally in 1840 the law that the "heating effect of an electrical current is directly proportional to the square of the current flowing," but these researches reached their climax when he presented to the Royal Society his paper "on the calorific effects of magneto-electricity and on the mechanical value of heat." In this paper he showed that "an amount of energy equal to 772 foot-pounds will, if communicated to one pound of water, raise its temperature one degree Fahrenheit." Thus he showed that there is definite relation between heat and energy and that a given amount of energy can be converted into a definite quantity of heat.

Joule was only twenty-five years of age, and scientists received his discovery with incredulity. They surmised that this raw country youth was romancing, and refused to believe that his law was based on exact experiments. The knowledge of the nature of heat was slight at that period. Only a few years before heat was believed to he a form of matter termed phlogoston, whose presence was supposed to render combustion possible. Not until 1802 had Count Rumford discovered that heat consisted in motion among particles of matter and supported it by experiments, one of which was the boring of a brass cannon, the heat developed in which, in 2 1/2 hours, was sufficient to raise 26 1/2 pounds of water from the freezing to the boiling point. No loss in weight of the cannon resulting, he concluded that heat could not be matter, but was due as we know now, to motion among particles of matter. Rumford's discovery had only about secured recognition when Joule advanced his theory which was met with scorn; but Sir William Thomson verified his experiments, and J. Meyer and Von Helmholtz, of Germany, ignorant of his youth, accepted the theories after proof, and they became the basis of the law of the conservation of energy which has placed Joule's name by the side of Newton in the scientific world.

The law of the conservation of energy teaches that the exact amount of energy which a force possesses is conserved (or preserved), even though, losing its original character, it appear in other forms. Power may be trans-formed into velocity, so that what is lost in the latter is gained in the former, and vice versa; or it may be trans-formed on the same principle into heat. No force is there-fore destroyed, but only is transformed into some equivalent, capable of doing exactly the same amount of work which it, unchanged, could have done. The extent of this principle and its force and application, embracing as it does the whole phenomena of the universe, is so vast that it is possible only to give the reader a general notion of it. The practical importance of the discovery has been summarized by Sir John Herschel in these words : "First, in showing us how to avoid attempting impossibilities. Second, in securing us from important mistakes in attempting what is in itself possible, by means either inadequate or actually opposed to the end in view. Third, in enabling us to accomplish our ends in the easiest, shortest, most economical and effectual manner. Fourth, in inducing us to attempt and enabling us to accomplish, objects which but for such knowledge we should never have thought of undertaking."

We are taught then by the principle of the conservation of energy that force, like matter; is indestructible. The first thought of the reader might be that this is incredible, and he might instance the steam engine as a creation of force, while the lever and the pulley might be cited as other instances. But it is hoped that the principle will be so explained that the reader will understand the real nature of these contrivances.

Anyone nowadays understands that the various forces of nature, such as mechanical action, heat, light, electricity, magnetism and chemical action, are so related that any one of them can be made to produce all the rest. By Joule's investigation this teaching was extended until we ascertained as has been verified by repeated experiments that a given amount of force of one kind would produce another kind, as that 772 units of work (foot-pounds) will raise the temperature of water from 32 to 33 Fahrenheit. In the steam-engine there is an inverse action. Here heat produces force work. Careful investigation and experiment has shown that after reckoning the amount of heat generated and subtracting that which is lost by conduction, radiation and condensation (an enormous misapplication of energy) it is always found that for every 772 foot-pounds, a unit of heat has disappeared from the cylinder. Not only has this relation between heat and energy been proved definite, but it is known that equally quantitative relations exist among all other forms of force. So we can express a definite chemical or electrical action in terms of work. We also know that quantitative relations exist between all physical forces, although the exact equivalents have not been found in some cases, such as light and vital action.

The amount of energy in the universe is constant. Some of it may lie dormant, and may be what is known as potential energy. An example of this may be had by a man drawing a cross bow. If he pulls the string back six inches and to do it requires a pull of 50 pounds, he exerts 5ox1/2=25 units of work. As long as the string is kept in the notch from which the trigger may release it, the energy is potential, just as when a ball is dropped to the ground the energy remains potential. But when the trigger is released and an arrow is shot upwards, the experiment proves that it will rise just as many feet as is the equivalent of the original energy exerted. If the arrow weighs 1/4 pound, it will rise exactly 100 feet, making the work done by it exactly that which has been done upon it.* While it may have taken a strong man to bend the bow, it needs only the touch of a child to discharge it. So when gunpowder explodes, the real source of energy is not the man, but the separation of carbon atoms from oxygen atoms, and that has been done by the sun's rays. The energy was potential before released, but it was none the less there.

The practical value of this knowledge is enormous. Thus we know by the principle of conservation of energy that perpetual motion is impossible, and that no man can create force any more than he can create matter. And we also know exactly the amount of energy which we should obtain from the combustion of a ton of coal, and knowing this can direct our experiments to reducing the exertion of that energy in any other direction than the producing of the kind of work we require from it.

The great principle also teaches us that all the forces of nature are interdependent, and all have their origin in the sun. There is no origination on the earth. We learn that the heat of the sun is cause of all of the energy around us winds, thunderstorms, water power, waves, rains and rivers. The inequality of the sun's heat on earth causes the winds; evaporation causes water power of all kinds and that evaporation also produces rivers by transferring water from the ocean to the mountains. The heat of the sun supplies the power that enables plants to build up their issues, and this stored energy is released by the muscular action of the animals who have fed on the plants.

To James Clerk Maxwell, who with Helmholtz had been chiefly responsible for the development of and proof of Joule's principle, the world is indebted for the kinetic or molecular theory of gases. He read a paper in 1860 at the British Association, in which he declared that gases consist of myriads of particles jostling against each other. The theory is consistent with the experimental laws of gases, and gives an insight into their behavior when subjected to various physical conditions. The molecules found by a study in gas are wonderfully minute, there being some hundreds of trillions in a cubic inch at an ordinary temperature, and these collide with each other at something like eight thousand million times a second. Experiment since has shown that any gas may be liquefied or solidified, and in fact it is now possible to draw no sharp line between the various forms of matter. All may be converted into gases, liquids or solids. They are all like ice, which, though solid, may be converted into water and then from water into its component gases.

Much progress has been made in regard to determining the nature and property of light. The corpuscular theory held at the beginning of the Century has given way to the undulatory theory, which is that light is caused by vibrations of the luminiferous ether. It is not yet explained, however, what it is that is moved. The velocity of light has been determined by the experiments of Fizeau in 1849 and Foucault in 1850—two ingenious Frenchmen who found that light travels at the rate of from 186,000 to 187,000 miles a second. It has also been found that color is due to light. With the undulatory theory of light as a basis, it has been discovered that color is to light what pitch is to sound. The agent which produces in our visual organs the impression of color is therefore not in the objects, but in the light which falls upon them. The redness is not in the rose itself, but because the light which falls upon it contains some rays in which there are movements that occur just the number of times per second that gives us the impression we call redness. In short, the color comes not from the flower, but from the light. If the reader choose to prove this he may do so by lighting a spirit lamp, on the wick of which a piece of salt as large as a pea is placed. Then let him exclude all other light from the room, and if he brings the red rose to the light he will see that it appears to be of an ashy hue, with all the redness missing. Science declares that the fresh green tints of early summer, and the golden glow of autumn, the brilliant colors of flowers, insects and of birds, the soft blue of the cloudless sky, the rosy hues of sunset and of dawn, the chromatic splendor of gems—are all due to light and to light alone. The shades are caused by the number of vibrations. If the vibrations of ether are at the rate of 458 trillions in a second, we receive the impression we call red, if at the rate of 727 trillions, violet, and so on with the other colors of the spectrum. These discoveries have been made by the aid of spectrum analysis—a most important physical achievement, of which mention will be made in the article on astronomy.

Physicists have made many similar discoveries in regard to the properties of matter, and the work they have done is so vast, and yet of so technical a nature, that it' would not only require many pages to enumerate them, but it would be tedious to the reader unacquainted with the fundamental principles of physics, while those with such knowledge can recall them with ease. In these the physicist has been aided by many delicate machines of his own contrivance, which are in themselves triumphs of scientific and inventive genius. One such machine is an instrument perfected by Professor Dayton C. Miller, of Cleveland, in January, 1899, which will measure down to the twentieth-millionth part of an inch, and is used for making almost infinitesimal measurements of light waves.

Interesting applications of physical principles are to be found in the work which water and air have been made to do for us. The value of water power and of wind-mills was known in the remote antiquities of time, but by the compression of these two forces many things may be done which it would be difficult to accomplish otherwise. The hydraulic press, which depends on the principle that a pressure exerted on any part of the surface of a liquid is transmitted undiminished to all parts of the mass and in all directions, was invented by Braham in 1785, but many improvements have been made since. The force which may be brought to bear by means of this machine upon substances submitted to its action is limited only by the power of the material of the press to resist the strains put upon them. In the press a piston passes water-tight through a strong metal cylinder. A tube leads from the cylinder to a force pump, and thus water is driven from the tank into the cavity of the metal cylinder, so as to force the cylinder upwards. The bale of cotton, or what-ever other article it may be necessary to compress, is placed on a table supported by the piston, and the rising of the tables impresses the object against an entablature sup-ported by pillars at the top. The hydraulic press, with modifications, is used for pressing oils from seeds, where a powerful, steady and easily regulated pressure is required as well as for pressing more bulky objects. By use of hydraulic pressure cannons and steam-boilers are tested, the water being forced into them by means of a force-pump.

William Armstrong patented his hydraulic crane in 1846, and since then it has come into extensive use, it being possible to employ a pressure greatly in excess of that which may be used in the case of steam. These cranes are so arranged that one man can raise, lower or swing around the heaviest load with a readiness or apparent ease marvelous to behold. One of the simplest forms of the hydraulic crane consists of two upright cheeks between which is fixed a hydraulic ram, occupying the lower half of the upright frame. The upper end of this ram carries a pulley, and a similar pulley is affixed to the upright frame. A chain is secured to the bracket on the upright frame. This chain passes up over one pulley and down and under the other pulley, and then over the pulley on the end of the jib of the crane. The rising and falling of the ram causes the chain to ascend and descend with its load. An ingenious device by Armstrong is the accumulator, which acts as a reservoir of power, which is being always stored into that vessel. The principle of the hydraulic crane is largely used by elevators, though it is being supplanted by electricity.

Water engines are sometimes used. They are operated where water under a high pressure may be obtained, and are worked on the same principle as the steam engine.

Compressed air is a new force which is coming into general use, and is regarded by some people as likely to become a rival to electricity. At present, however, they have been rather brothers, working side by side in the industrial field; each can do many things which the other does, but each has its own field of labor. Electrical energy can be produced and converted into power with far less loss than is possible with compressed air, but much more delicate and expensive appliances are necessary, while experts must be employed for the use. On the other hand, compressed air is a rougher workman. It can be set to work in swamps and ditches and quarries digging mud, battering rocks to pieces, and loading or unloading cars, and the men who handle it may be rough-handed, too.

Although authentic records show that as long ago as 250 B. C., Ctesibius of Alexandria applied the air as the force for an airgun, yet little progress had been made in its application until the present Century. Its first real use as power was on the drills in the famous Mount Cenis tunnel to which allusion is made in the article in this volume on engineering. In America the first practical use to which it was put was on the Hoosac tunnel. These were the rock drills that have revolutionized the modern work of quarrying.

One of the most useful applications of compressed air is the air-brake, invented in 1869 by George Westing-house, the use of which has reduced the danger of accident in railroad travel. The present quick-acting air-brake, known as the Westinghouse, was not constructed until 1887. Compressed air also finds its use in the railway service in the operation of switches and semaphore signals; it is used to signal the engineer, ring the bell, to sand the track, dust the cushions, clean the hangings, raise water, and it performs many other rougher duties in the railway machine shops. There are crevices which the feather-duster would not reach in cleaning cushions, but a jet of air one-tenth of an inch in diameter will reach every place and, projected with force, will carry away every particle of dust.

The principle on which these tools is operated is this : The air is compressed, and on its release it rushes forth with great force. Joule calculated in his researches on the compression of air that, assuming the whole of the energy was converted into heat, when air was compressed under a pressure of 21.5 atmospheres, the mechanical equivalent of heat was 848.24 foot-pounds, and when the pressure was 10.5 atmospheres was 796.6 foot-pounds. The work is really done by the steam-engine or another prime mover in compressing the air. In the construction of the Mount Cenis tunnel the air was first compressed by water power and then carried through pipes into the heart of the tunnel, to work the rock-boring machines.

The same principle as that used in the rock-boring ma-chine is employed in the little tool with which the dentist compacts the films of gold-leaf in a tooth. In these ma-chines the part which holds the actual tool is not operated directly by the air, but just above it lies a plunger, which is vibrated back and forward by the air, and this strikes blows on the head of the working tool when the tool is pressed back against it. Tools moved in this manner are used to set up the rivets which hold together steam boilers, the iron-work of bridges and sky-scrapers, and in many shops hand-riveting has been abolished by their use.

One of the advantages possessed by tools of this type is their delicacy. An automatic facing tool used in the marble and stone-yard will prepare the surface for the hand-worker, while another takes the place of the mallet and chisel in fine work. The operator grasps a hand piece and presses the tool to the face of the stone. Air is admitted to the plunger in response to his pressure, and 20,000 blows a minute may be struck; while a man cannot swing a heavy hammer continuously more than thirty times per minute. A pneumatic breast-drill, weighing 18 pounds, with 80 pounds air-pressure, will drill a 5-16 inch hole through cast iron one inch thick in one minute. The tools are of varying size, and a great shear will cut off the end of the big steel beams that are used in ships and buildings as easily as so much tinfoil. Punches and jacks worked in this way will do all sorts of things, from forming the top of a tin can to putting car wheels on their axles.

Compressed air operates hoists and traveling cranes in the foundries. One man in a foundry can lift heavy loads and place them on a wagon in less time than could be done by many men employing less modern methods. The advantage of its use was well shown during the excavating of the great Chicago drainage canal, when fifty air-compressors were used to excavate the channel 160 feet wide and 35 feet deep, which contained over 12,000,-000 cubic yards of solid rock. Those who have witnessed the operation of these machines have an uncanny feeling as they see the great drills and hoists worked apparently without use of motive power the noise and dust of the steam-engine being absent.

Moving air is able to pick up and carry other things with ease. An interesting application of this principle was at the World's Columbian Exposition, when the problem of painting the huge buildings seemed a Herculean task, almost impossible of accomplishment. Frank D. Millet devised a painting machine, by which the great manufactures building was kalsomined inside of a month by a double-spray machine, which covered 31,500 square feet of surface a day. The machine is like one of the atomizers that women use, but a continuous supply of compressed air is used to squirt the stream of paint. With one of these machines one man can paint thirty-two coal cars in a day or one car in fifteen minutes, and not a crack or crevice of the wood will escape the paint. The artist's air-brush is an application of the same principle on a smaller scale. When sharp sand is substituted for paint in such a machine, the result is a tool which will destroy the most stubborn of substances, and which is used to clean steel ships of barnacles and rust, or to polish great surfaces.

It is by the aid of compressed air that the foundations of the great office buildings are sunk, and in wrecking operations it is used to force out the water from numerous barrels or bags attached by the divers, thus furnishing sufficient buoyancy to bring the vessel to the surface. It is also used for ice-making, and in compressing the bundles of kindling that are sold at the groceries. It is used in mixing in breweries, and instead of yeast by some bakers.

Compressed air has reached its greatest development abroad. It was there that the idea of pneumatic dispatch originated, it being introduced in 1853, when the force was used by Latimer Clark to transfer written dispatches through tubes between two of the stations of the Electric and International Telegraph Company. Since then its use has spread until it is used by firms and corporations for the transfer of small parcels, while nearly every post-office in an important European capital city is connected with its sub-stations by pneumatic tubes. During the past few years, such tubes have been introduced in the post-offices as a part of the postal system of Boston, New York and Philadelphia, while it is largely employed in American shops and offices for intercommunication.

In Paris compressed air is put to the most varied uses. Victor Popp, of Vienna, who exhibited his processes at the Paris Exposition, is responsible for its introduction in the French metropolis on a large scale. His first application was to what is now known far and wide as the pneumatic clocks of Paris, and of which there are now fully 10,000. He has a factory with four compressors of 2,000 horse-power each, and from this factory compressed air is conveyed around the city by means of pipes of 1.64 feet in diameter. The force is used largely to operate electric motors. The compressed air attachment may be put into a space so small that it need not be considered, and it re-quires no other manipulation than the turning of a stop-cock. It is applied to printing presses and other machinery in Paris, is used to operate elevators, and for practically any purpose. The advantage of the system in force by Popp is the ease of transportation. All that is necessary is to attach a rubber pipe hose to the stop-cock of the sup-ply, and this hose may be lengthened by the addition of other pieces of hose.

Compressed air has been used as a motive power in the mechanical traction of surface roads for nearly fifty years in France. From the mid-forties until 1859, a pneumatic way seized the train from Paris to St. Germain when it reached a steep grade, and pulled it up the mile and a half to the latter town in three minutes. As it was called into use only once during each hour of the daytime, it was finally abandoned on account of the cost. But as various methods reduced the cost of air-compression by one-half, it came into more general use. A compressed air motor has been used since 1879 to propel street railways in Nantes, and in 1894 compressed air-motors were introduced for traction purposes on the line from St. Augustin to Vincennes, at the extremity of Paris. There are three or four other lines near Paris that now use compressed air as a motive power.

In America compressed air is about to be used for the motive power of railways. Early in 1899 a plant was built for the use of the Twenty-eighth and Twenty-ninth Street lines of the Metropolitan Street Railway Company, of New York, and, if successful, the company will probably extend it. Engineers believe that the cable and trolley may be superseded by the new force. The locomotive must be charged, as is the case with the so-called storage battery of the electrician, but a charge will propel a vehicle for from fifteen to twenty-five miles. The cost is less than a cent a mile for power sufficient to carry a weight of ten tons up a five per cent grade. So great a charge is rendered possible by the construction of air chambers of extreme strength. Early in 1899 experiments in the use of compressed air were made by the New York Central Rail-road. In addition to greater speed and economy, superior advantages to the steam-engine are claimed for it in the retention of power, and in the even and regular manner in which the power is freed. With the compressed air engine a speed of sixty miles for one hour is quite as easy as a speed of twenty miles an hour for three hours.

With the end of the Nineteenth Century, and the dawn of the Twentieth, has come the discovery of a new force, more marvelous in its possibilities than either steam or electricity, although as yet it has been put to no practical use. Its development will probably be the work of the Twentieth Century, just as the Nineteenth Century has perfected and applied discoveries of the Eighteenth. Who can imagine what wondrous stories the historian of the achievements of the Twentieth Century may have to tell of liquefied air? That air might be liquefied if the temperature were made low enough has been known to chemists and scientists for years. As long ago as December and January, 1877-78 air was liquefied by Raoul Pictet, of Geneva, and by Calletet, of Paris, while on June 5, 1885, Professor James Dewar exhibited liquid air obtained at a temperature of 316 degrees below zero, Fahrenheit, be-fore the Royal Institution, London. But the possibilities of its commercial use were not conceived until twenty years later. In March, 1897, a mysterious explosion occurred at the Endicott Hotel, in New York, which, being inquired into, developed the fact that Professor Tripler, of that place, had been experimenting with the new force for several years, with a view to its manufacture upon a scale and at a price which would allow of its use for practical purposes. Almost simultaneously, Professor Linde, of Berlin, announced that he had succeeded in producing liquefied air at a cost which would allow of its use as a motive power for engines of different kinds.

The two methods are probably similar, although Mr. Tripler has not made public either his method of producing the air, nor its cost, as he has organized a company which he hopes will secure a monopoly of the new force. Professor Linde makes no secret of his process, and states the cost as 10 pfennigs (2 1/4 cents) for five cubic metres. Consul-General DeKay, in a report to the state department, dated Berlin, March 11, 1897, describes the machine which he uses as a most ingenious piece of mechanism, which yields the product either in fluid or gaseous form, as may be desired. Its most striking feature is its economy of working, since, once charged, the machine uses the air of the surrounding atmosphere to produce liquid air, and so goes on working indefinitely, without expense for fresh fuel. After the pump has been in operation for a certain length of time, the operator turns a cock and the liquid air runs out at a temperature of 273 degrees below zero. In Professor Linde's method an air-pump of five horse-power condenses air to a pressure of 200 atmospheres: This air passes down a spiral tube and is let out into a chamber, producing intense cold; then it rises, and, passing on the outside of the same tube through which it was conducted, bathes it and cools the fresh supply of air which has been pumped into the tube to take its place. This air, thus cooled, follows down into the chamber, and, expanding again, lowers its atmosphere, then passes up around the same spiral tube; but as its temperature has become much lower, the new air now in the tube is still further refrigerated. This circulating process is repeated again and again, until the new air pumped into the tubes reaches a temperature of 273 degrees below zero, when it drops into the chamber as a liquid. Thus the air, steadily cooled, is made to refrigerate the newly pumped air more and more, until the necessary degree of cold for liquefaction is attained.

For transportation the liquid air can be packed in a tin can, and sent to any distance when protected by a thick layer of felt. All that seems necessary is to preserve it from the surrounding atmosphere, as is done with any other ice. There is no danger in handling it, provided it is kept away from fire and the expanding gases are allowed to escape. For this purpose Professor Tripler places felt over the mouth of the can, which keeps out the air, with-out confining the gases. It can be ladled out with an ordinary tin dipper; but if the dipper, while in use, is let fall, it will shatter like thin glass, the intensity of cold rendering iron and steel extremely brittle. Neither cop-per, aluminum, silver, gold nor platinum are so affected. Fortunately, leather is not affected either, and so can be used for valves. Rubber, however, in contact with it, be-comes as fragile as porcelain. If a tumbler is filled with the liquid air, it will boil hard, and in half an hour will evaporate completely, leaving the tumbler coated with frost. But if the air is placed in a glass bulb, and the bulb set in a larger one, with half an inch vacuum between the two, so that the fluid is protected from the air outside, it vaporizes very slowly, and the tumblerful will last for several hours. In one of Professor Tripler's public experiments, he partly fills a teakettle with the liquid, and pours a few ounces of water upon it. Instantly the kettle bubbles and boils over, sending up from the spout a long jet of steam, mingled with a spray of spurting drops. The water is frozen hard almost as soon as it touches the liquid air, and if the kettle be turned upside down, lumps of ice fall out, hard-frozen and as dry as chalk. Power enough has been generated in the process to run an engine.

The value of the liquid for refrigerating purposes can hardly be overestimated. Meat may be frozen so hard by its use that it rings like metal when struck with a hammer, and may be pounded into powder. Mercury may be frozen into a solid bar, as hard as iron, and so cold that to touch it will blister the flesh. Indeed, nothing has yet been found which will not freeze by contact with it, and Mr. Tripler predicts that it is destined to supersede frozen water for this purpose. Liquid air furnishes a clean, dry cold, which produces no dampness, and renders the transportation of meats, fruit, etc., to any distance an easy matter. In a large hotel, where the liquid air is used as the motive power for driving the dynamos and running the elevators, it might be made to serve for all kinds of refrigeration. Its discoverers claim that by its use it is quite as easy to cool a house in summer as to heat it in winter, and much less expensive, while the gas produced would purify the air, being equivalent to the purest mountain air. The temperature of an hospital ward could at any time be lowered, even in the tropics, to any desired degree, and in cases of yellow fever the "white gift of the frost" might be had at any moment. It can be handled as a motive force with perfect safety, in an ordinary engine, without requiring the intense heat which makes the duties of the engineers and stokers, on an ocean steamer, so arduous, and in submarine boats the motor itself would, in place of exhausting the air, furnish all that was needed for healthy respiration. Moreover, it is claimed that it will render the problem of aerial navigation a simple one, since all that is needed is a motor, strong, light in weight, and safe. Indeed, if one-tenth of what is claimed for the new force be true, its possibilities are revolutionary.

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