The Cut, Fig. 1, and the series to Fig. 6, represent one of our high pressure Engines, which, regarded These details, Figs. 1, 2, 3 and 6, being similar to those of other engines, need no special notice; but the The inside piece (D) is a hub, which exactly fits in the hollow of the cylinder (C), and has a socket (e) When the several pieces are put together, the cam is complete as shown in Fig. 5, and it operates as fol It is unnecessary to insist on the great economy attained by using steam with a well-regulated cut-off, for EXHAUST PIPL engine, which is, in turn, a perfect copy of an properly-constructed one would use to do old pump taken from Serviere's collection. the work of twenty. As an instance of the It may be thus described: two cog-wheels truth of this statement, we will take the fitted accurately to each other are inclosed engines built by Messrs. Corliss & Nightenin a case; each cog is grooved and fitted with packing, bringing it into steam-tight contact with the circumference and sides of the case. The axles of the cog-wheels are continued through the sides of the case, and geared together at each end to prevent friction upon the centre cogs; now, if revolved, each cog will act as a piston, but as the cogs in contact in the centre lap each other, the piston surface at each extreme of the case will be just double that of the centre, and this surplus of force gives motion to the two axles. The pump of which this engine is a copy was invented as long ago as the sixteenth century. A patent was obtained in England in 1825 by Mr. J. Eve, an American. Within a cylindrical case a hollow drum was so constructed as to fit closely to the case; floats, or pistons, were cast upon its periphery, and packed to fit the cylinder; on one side of the main cylinder was a small recess filled with a small drum, that revolved in contact with the main drum, this small drum having a segment removed to receive each piston as it passed, and having its diameter so proportioned to the main drum as to revolve once between the passage of each piston or float. Other rotary engines, on a plan analogous to the above, differing only in the manner of opening the valve, have been invented, and copied from the ancients, some of which are exceedingly complicated, but they have always been unsuccessful in practice, principally from the fact that it is exceedingly difficult to pack them. If they could overcome this fault without adding friction, the rotary engine would be very valuable on account of the small space it occupies. The demand for stationary engines, from one horse power upward, during the last twenty-five years, has been so great that now almost any machine shop is prepared to build them, and of course, while such is the case, thousands of engines are annually built that would better bear the name of steam eaters than steam engines. In some of the small engines that flood the market, the first principles of steam are practically ignored, and there are at this moment running in the United States engines that consume more coal to do the work of ten horses than a gale, of Providence, over an engine that was working to good advantage in the James Mills, Newburyport, but was removed on the representation of the builders of the new machine, that they would take five times the saving of the first year's fuel as sole payment of their engine. The James Steam Mills contained 17,024 spindles, and, including the weaving and all the preparations for making sheeting and shirtings, required a hundred and ninety horse power; their engines were condensers; cylinders, twenty-four inches by four feet length of stroke. Ten thousand four hundred and eighty-three pounds of coal per day was the average amount used during five years previous to the contract for the new engines; this included the coal used for dressing, heating, and all other purposes for which steam is used in such an establishment. The new engines were high-pressure cylinders, eighteen inches by four feet stroke. By the terms of contract under which the change of engines was made, it was at the option of the company to pay for the new arrangement the sum of ten thousand five hundred dollars cash in lieu of the saving of coal; but the choice was to be made before the new engines were put in operation. In view of the favorable results obtained by the former engines, they decided to pay in the saving of fuel. The new engines were run one year from December 3d, 1855, and the average amount of coal used per day was found to be five thousand six hundred and ninety pounds. The coal being reckoned at six dollars per ton, Messrs. Corliss & Nightengale received nineteen thousand seven hundred and thirty-four dollars and twenty-two cents. Thus it will be seen that the builders received nearly double price for their engine, and yet it cost the owners of the mill nothing for a machine that was destined to be a source of great saving in their future expenses. The singular character of Mr. Corliss' bargains attracted much attention to his engines, as they showed conclusively the advantages thereof over the old plans. The above experiment was a comparison between his engine and what had been considered a good machine; in the following, however, we see its great advantages over a more or dinary engine. In March, 1852, Mr. Corliss double-nay, triple-that for which they contracted with Crocker Brothers & Co., of Taunton, Massachusetts, to furnish them with an engine that would do the same work they were then doing with five tons of coal per day, and yet only consume two; agreeing to forfeit one dollar per pound, for every pound per day used above that amount. This contract was successfully filled without taking out the old boilers. Mr. Corliss' engines possessed, as may be readily supposed, several important improvements, one of which was the manner by which its speed was regulated. Watt regulated by connecting the governor with the throttle-valve; Corliss used no throttlevalve, but connected the governor direct to the cut-off. This connection of the governor was not of itself the improvement of Mr. Corliss, as that had already been done by others; but it was the manner by which this connection was made, which was at once simple and efficacious, for which he deserves credit. The use of the throttle-valve was always attended with a wire-drawing of the steam. This wire-drawing is a reduction of the expansive force of the steam, and is always attended with more or less condensation; so that every form of cut-off, used with a throttle, is more or less imperfect. By thus dispensing with the throttle-valve altogether, and opening the steam-valve suddenly, the pressure of steam in the cylinder approximates very closely to the boiler pressure. The valves in the Corliss engine are circular; and by his automatic method of varying the point of cut-off, he gains a great advantage, as he cuts off suddenly without danger of slamming, as in the use of the puppet-valve. were intended; the safety (?) valve weighted down by old pieces of iron, stones, etc., to such an extent that the runner no more knows what pressure he is using, than does the stranger who is passing his door. In thousands of cases the steam-gauge, which, at least, gives the pressure when in order, is not used, or never tested; and what was intended as a preventive, becomes, by a stoppage in the connecting pipe or a derange ment of its machinery, a source of treacherous security. Many a man, on being asked why he does not use a steam-gauge, will reply that they are not reliable, or that the safety-valve is good enough; and yet that same man is perhaps employing an engineer that could not calculate, to save his life, the amount of pressure he was carrying, or, the size of his safety-valve being given, tell its area in square inches. "We can point out places where the engines, beautifully designed and executed in their details, are nothing but a mass of slime and grease from bed-plate to cylinder-head, the deposit of no one knows how many weeks of inattention and neglect, while a stolid runner sits calmly by, as though rather admiring the state of things than otherwise. When such is the case where every thing is visible, where is the necessity of looking among the usually unsearched portions of the machine for safety and economy." One of these steam boilers blew up in Brooklyn, in 1859, and Mr. J. C. Merriam, a scientific practical engineer, was sent for to examine it. He found that in this case, as in many others, the engineer did not understand his business, as was sufficiently evident from the following reasons: his The Corliss engines are manufacturea with pump was small, but sufficiently large if in extreme care; and Mr. Corliss, in 1869, re- good order-which it certainly was not; he ceived the great Rumford medal for the took out the piston with ease, and put it back greatest improvement in the construction of again readily, although it was entirely covsteam-engines; a medal which has been ered with the coarse gravel and sand thrown awarded but twice in more than sixty years. about by the explosion. The safety-valve When we add the fact that one-half of the was held in its place by a rod passing through stationary engines in the United States are a plate; this rod, originally a good fit, was run by boys or men not capable of manag- so firmly rusted in its place, that all the force ing a modern cooking-stove, the reader can he could exert on the end of the lever was realize to some extent the economy of cheap not sufficient to move it. He unscrewed (?) engines and cheap (?) engineers. Steam this plate, and it required two or three smart is a good slave but a bad master; and the blows of the hammer to drive the rod out. fearful loss of life in the United States In his opinion, it would have taken not less during the past forty years, from the explosion of steam boilers, is mainly due to bad management. Boilers are in constant use all over the country, carrying a pressure than twelve hundred pounds in the boiler to have started that valve, allowing that it had the weight upon it that he saw. The owner stated that the valve always leaked more or less; but on looking at it he was convinced that if it rested upon its seat, it never could have leaked, as it was a ground joint and a good one. He consequently came to the conclusion that the valve was not held in its place by the weight on the lever, but simply by the rust on the valve-rod or stem, the weight at the end having nothing to do with it. The safety-valve was bolted on to the steam dome with four 5-8 bolts, and was evidently blown off at the same instant as the flue collapsed, as it was found in the shop near the engine, while the boiler was thrown at least seventy-five feet against a house. We might name scores of other accidents resulting from similar causes, of which the above is a fair sample; but it is evident enough, from what we have already said, that there is a want in the community yet unfilled-one that should receive the careful attention of every public man. What we need is a law compelling the owners of steam boilers to have them inspected at least once a year, and properly provided with safetyvalves and other trustworthy appliances; it also should be imperatively their duty to employ engineers, and not mere runners. A law framed upon the United States steamboat inspection plan would be of incalculable benefit to the owners themselves, as well as the community at large. The gradual introduction of the stationary engine has been of infinite value to our country as it is, but if rendered safe as it might be, its value would be increased fourfold. It is now no longer necessary that the manufacturer should locate beside a waterfall, and transport his manufactured goods for miles to a market; he can establish himself beside the railroad, the steamboat, nay, in the city itself, where his customers dwell. Thus, the stationary engine tends to centralize manufactures, while the locomotive and steamboat lengthen the arms of trade. The portable engine has lately come into general use, and, like the stationary, is made of various forms, in all of which it resembles the latter, with the exception of placing the engine directly upon, or against the boiler. These engines are used wherever it is necessary to do work sufficiently great to pay for them, but not for permanent business, such as pile driving, excavating, etc. Among the simplest of this class of engines, may be mentioned Reed's oscillator, and the Wood & Mann steam-engine Co.'s. A portable engine manufactured at the Washington Iron Works, contains all the safety and economic appliances of the best stationary engines; a description of this will answer for this class of machines. The boiler is tubular, commonly called a locomotive boiler, and is mounted upon two large wheels at the fire-box end, and two small wheels at the smoke-box end, so fitted as to turn beneath the barrel. The steam dome is over the firebox, and is fitted with safety-valve and steam gauge. The cylinder is fastened to a hollow frame that serves as a feed-water heater, and is placed very near the steam dome, thereby preventing radiation in the steam pipe. Upon the top of the steam chest is placed the governor. On the front of the boiler we find the smoke pipe, and, directly behind it, the main shaft and a pair of balance wheels. The next matter of interest is the arrangement of the main slide-valve of the engine, which is well known to cause much loss of power, in the ordinary construction, by the friction caused by the pressure of steam on its back. This is entirely relieved by a very simple method in this engine. The valve, which is an ordinary one, has a solid protection at each end, which rests on a roller. These rollers are made at first slightly too small, but the grinding away of the valve on its seat soon causes the projections to rest on the rollers, when all the sliding friction at once ceases, and the valve works free from friction except that caused by the stuffing-box around its rod. It is evident that this arrangement will not readily get out of order, for when the rollers wear, it brings the valve on the seat, which at once begins to wear, and the pressure once more is brought on the rollers; hence, it is selfadjusting. The rollers being removed, reduces it to the usual slide-valve. The force pump has been a fruitful source of trouble to all those who have ever had charge of a small steam engine having a quick motion; indeed, it frequently gives trouble in larger engines, from the accumulation of air in the chamber, which prevents its suction. It is usual to have attached to the lower part of the pump, or valve chamber, a small air-cock, and, when the pump is to start, the attendant places his finger on its extremity as soon as the plunger reaches the bottom of the pump, thus expelling the air; then, on the rise of the plunger, a vacuum is formed, and the pump fills with water; the cock is then closed, and the pump left to itself. As soon, however, as air collects from any defect of packing, or otherwise, the pump ceases to work, and has to be again started as before. This difficulty is entirely got rid of by the simple contrivance of an air-trap, whose valve, opening outward at each downward stroke of the pump, allows the air to escape, accompanied with a little water, and closes by the atmospheric pressure as the plunger rises. Within the last five years, the labor of loading and unloading vessels at our wharves has been performed by hoisting engines. These are all run at high pressure, and do the work with economy and dispatch. One of the best of these machines is made at the shop of Hittinger & Cook. Several of the ocean steamers carry them to use at the other end of the route. The hoisting so much resembles the portable engine, as not to require especial explanation. stand this subject, it is necessary that we should look closely into the nature of steam itself. It would defeat the purpose of this article if we were to go into a lengthy argument upon the relative merits of the various theories that have been advanced by scientific men upon steam, and, consequently, we shall merely give our own opinions upon the subject-opinions at which we have arrived by careful study and experience, it being understood that the laws of steam are at best comparatively unknown. The analyzation of simple steam is yet to be made; we will, however, call it water converted into an aëriform state by the electrization of its particles by caloric. Simple steam does not, however, in the present construction of boilers, come into use as a motor, from the following reason: steam has the same affinity for liquids that all fluids have, forming an electro-magnetic combination to which there is no barrier; it will then absorb and hold in suspension particles of water whenever in In most of the steam sawmills in the direct contact therewith, and, consequently, United States, the fuel consists of the saw-all steam formed in the boiler will hold in dust made at the mills, and thus the cost of suspension a portion of water, and become, running is greatly reduced; in other en- in lieu of simple, surcharged steam. Thus, gines, coal is almost exclusively used. In steam at 20 lbs. to the square inch holds fact, the enormous amount of wood con- in suspension nearly double its weight of sumed by steam engines throughout the water. What is the effect of this? First, United States, has so called the attention of the water thus carried off in suspension is mechanics to coal-burning engines, that it is at the maximum temperature, or equal to not probable we shall use wood as fuel that of the steam containing it, and the inmany years longer. One of the greatest vested heat of this water is not only wasted fields for economy in the use of steam, now to a great extent, but these water particles open, is the waste of combustible gases by become a very serious tax upon the real the chimney, commonly spoken of under the steam with which they are admixed, as fol term smoke, but often consisting of the best lows: having been heated under the maxipart of the fuel, unconsumed from the lack of mum pressure of the steam with which they oxygen, and, in some cases, lack of caloric. are incorporated, they have a corresponding Tubes, to conduct atmospheric air to the sur-temperature, and as the latter, the steam, face of the fire, have been in use some time, also the perforation of the fire door; but the tubes being exposed to an intense heat, soon become of no value, and the openings at the door and sides of the fire-box only partially supply the oxygen. A Mr. Pierce, of Troy, has patented a plan for surrounding the air tubes with water, thus protecting a passage direct to the middle of the fire; we have not seen this plan tried, but think it would be a source of economy. Stationary engines being the most plenty, it is upon them that are tried nearly all the new experiments. At the present time, the use of super-heated steam is attracting a great deal of attention. In order to under expands in the steam pipes, on its way to the cylinder, and in the cylinder itself, the pressure becoming correspondingly less, these particles flash partially into steam, but not containing the total amount of heat necessary to their constitution as clastic vapor, they absorb into the "latent" form a quota of heat from the surrounding particles of true steam, thus condensing them; for steam, be it remembered, can part with no portion of its legitimate heat without condensation (unless it be super-heat, of which presently), it being understood that the absorption of sensible heat (temperature) into the "latent" form, and which is the exact measure of the force exerted by steam under all circum |