The latest Paris fashion is powdering the hair with gold dust and filings of silver. This fashion will suit California and-Australia; but the expensiveness of the powder is likely to , speedily explode the fehion. ."We will now present a " History, of the Caloric Engine," accompanied with sucli remarks as our readers expect us to make.' ? Figure 1 is a longitudinal vertical section of Capt. Ericsson's first Caloric Engine, patented in England in 1833, and described in Sir Rich-ard Phillips': "Arts of Life," published the same year. " A is the regenerator,, consisting of a cylindrical vessel,.closed at the ends by the plates, B B ; through.these plates a number of small tubes, C,;pass from end to end, terminating in the caps, D and E, thus forming a -free conf-munication between them, but not communicating with the body of the regenerator. A number of division plates, b, divide the regenerator into as many chambers, and these are made to communicate with each other, by segments being cut out alternately fwm the tops and bottoms of the division plates. The tubes, C, are also provided with division plates, or small metallic discs, placed in opposite directions to each other. F is the working cylinder of the engine, called the hot cylinder. G is a smaller cylinder, called the cold cylinder, which receives the air that escapes from the former, and then forces it back again, for every stroke of the piston, thereby keeping up a constant circulation of the impelling medium and promoting a constant transfer of heat. The pistons of the two cylinders are connected by a beam, H, side-rods, and cross-heads, similar to a common marine-engine, and the cylinders are provided with slide-valves, nearly of the common construction, moved by suitable gear from eccentrics fixed on the crank shaft, I. t J is one of a series of pipes inclosed in a stove, K, acted upon by a fire, L, the combustion being supported by ordinary draught, caused to circulate round the regenerator, and passing off from M, into a chimney. The pipes, J, in the stove, all terminate at one end, in the cap, D, and at the other end in the pipe, N, which communicates with the slide-box, 0, of the hot cylinder. P represents a cooler, and consists of one or more pipes, exposed to sotfle,-cooling medium, these being, like the longitudinal pipes ia .the regenerator, provided .with "a numbef of metallic discs. Previous to describing the action of the engine, let us suppose that the stove with its pipes and the working cylinder, have been brought to some considerable temperature, and likewise the regenerator with its tubes' brought to the same temperature nearest to the stoVe, gradually lessening so as to be, at the opposite- end, equal in temperature With the surroundmg atmosphere. By examining the positions of the slide-valves, as represented in figure-l,it becomes evident that if air be, by some means, forced or pumped into the caps pf Ihe regenerator, such air will on the one hand,4nd its, way through the stope-pipes, &c, into the top-part of the hot cylinder, and on the other hand, .through the connecting-pipe, Q,intathe'to'p-part of the cold cylinder. Now, since the hot cylinder is larger, say double thesizs of the cold cylinder, it follows that the power of the piston, f, will vanquish the -power of the piston, g and make it ascend, at the same time itself descending: thus motion will be produced, and the crank-shaft begin to revolve, and, by reversing the position of the slide-valves, when the pistons have performed their lull strokes, that motion will be continued. ' By further examining figure 1, it will be seen that the cold cylinder receives its supply of air from the body of the regejierator through the cooler, P, and the pipe, p, entering under.the slide valves, it will also be seen that the hot-air from the hot cylinder escapes under the slide-valves, through the pipe, , into the body of the regenerator,—hence the same air that escapes from the hot cylinder supplies the cold one. In like manner it will be found, by referring to fig. 1, that the air forced from the cold-cylinder into the cap, E, must pass through the pipes of the regenerator, stsve-pipes, &c, to supply the hot cylinder. From what has been already said, the action of the engine, and the transfer of the heat be- come almost self-evident; it need, therefor only be briefly stated, that the hot-air, in escaping from the hot-cylinder, will, during its passage through the body of the regenerator, give out its heat to the tubes, C, being, by the peculiar arrangement of the division plates, b, compelled to ply round those tubes. And the cold air, coming from the cold cylinder, will, in its passage through the tubes, C, naturally take up the heat imported to them, its particles being kept in a constant state of change by the .small metallic discs. A transfer of heat being thus effected, it becomes evident that the office of the cooler will be that of carrying away any heatjrom the air which has not been taken up1, in the regenerator, and that the office of the stove will be to give an additional quantity of heat to the circulating air, previous'to its entering the hot cylinder, in order to make up for a small deficiency which will always be unavoidable in the transferring process, besides the losses caused by radiation. The pomier of the engine will mainly depend on the density of the circulating medium, —accordingly, by ..having a small pump attached to the engine, the power and pressure may be varied at pleasure. High pressure will, of course, produce the greatest proportionate effect; since the losses, by radiation, will remain the same under whatever pressure. The trial engine, which has been erected by the inventor, and the action of which has been found in every respect satisfactory, may be fairly estimated at five horse-power; it makes fifty-six revolutions per minute, having a break wheel fixed on the fly-wheel shaft, loaded with upwards of five thousand pounds weight. The working cylinder is fourteen inches in diameter, and the cold cylinder ten and a quarter inches in diameter, both.making eighteen inches stroke, working under a pressure of thirty-five pounds to the square inch. The regenerator, in this trial engine, is eight inches-and a half in diameter, and seven feet six inches long, containing seventubes, of two inches diameter each; and its operation is go 154 perfect that all the heat lost, that is, heat not returned to the engine, does not amount to moie than three pounds of fuel per hour. The total consumption of fuel is nearly two pounds per horse-power in the hour, owing to the great radiating surfaces unavoidable in an engine on a small scale, while these surfaces have not, in this first instance, been properly protected by any imperfect conductors. The principle of this new engine consists in this, that the heat which is required to give motion to the engine at the commencement, is returned by a peculiar process of transfer, and thereby made to act over and over again, instead of being, as in the steam engine, thrown into a condenser, or into the atmosphere as so much waste fuel. And the well-known phenomenon that temperature, or quality of heat, is always equalized between substances, however unequal they may be in density, forms the basis of this new application of heat. The most accurate experiments prove that the combustion of one pound of the best coal is only capable of raising the temperature of 9000 lbs. of water one degree. So that an engine, in giving motion to the shaft of a mill, will consume from 7| to 8 lbs. of fuel in the hour for every horse-power constantly imparted to that shaft." Thus writes Sir Richard Phillips, a most inordinate admirer of the then Caloric Engine. Let us point out its fallacious principles : it is stated that it only uses so much coal to make up the loss of radiation, therefore, if there were no loss of heat by radiation, it would use no coal at all, after the first fire; it would go on for ever—a perpetual motion surely. Capt. Ericsson is also, or has been, laboring under a wrong impression of the value of " Forces," as applied to machinery. Thus this engine is constructed upon the principle of heat force that is, if a certain amount of heat can be retained, it will produce repeated effects upon innumerable quantities of matter—a thing totally at variance with Mechanical Philosophy. It is like this : 900 of heat will give a certain velocity to 900 cubic feet of air, during one stroke of a piston, then the same velocity to another 900 cubic ieetof air during the next stroke of the piston, and so on ad infinitum. If there were no loss by radiation, and none by exhaustion, upon this principle of reasoning, 500 of heat will give rapid motion to z cubic feet of air, and, by so doing, give motion to machinery for ever. It is a great mistake to suppose that this can be done, for action and re-action are equal —"A'e are no believers in motion derived from static pressure. What is heat 1 It is the effect of the disturbance of chemical equilibrium like the lightning from the positive seeking the negative cloud. The amount of this disturbance is exactly in proportion to the quantity of fuel used to produce the effect—the fire is just like the electric battery. The amount of this force is more economically employed or directed in some machines or engines than others, but a certain quantity of action cannot produce an infinite amount of reaction. It is, however, upon this principle, that the Caloric Engine is built, and that it is fallacious, we leave to the judgment of every mechanical philosopher. Thus, for example, take this first engine of Capt. Ericsson, and let us cover up all the metallic parts, so that there will be no loss by radiation, and what will we have then, but this engine (by its author's reasoning), going on continually, giving out force without any expenditure of fuel at all, after a certain amount of heat has been imparted to a certain amount of air. But if there were no loss of heat by radiation, the engine would soon stop, and thus we hold, that what some people would call loss, is nececessary to gain; this loss of heat is the value of the power gained, just like the escape of water from tke buckets of the water wheel. Let a millwright build a wheel so that the inlet water will not be able to escape, and how many revo. lutions will the wheel make, by thus saving the water? Only one. All machine force, is reaction, the result of action and its equal, and was the doctrine which enabled D'Alembert to make a number of beautiful mathematical discoveries. If we cover up all this first engine of Capt. Ericsson, with a good nonconducting substance and keep the fire under it, the hot air after a certain length of time, will impart its heat to every portion of the Regenerator, and the pressure of the air will be alike in both cylinders, therefore the engine must stop, for the pressure will be alike on both sides of the pistons. The radiation ol the heat therefore, what is called the loss, is the real value of the power given out by machinery. The quantity of heat required to produce a certain effect in velocity to air, may well be compared to the quantity of fuel required to make a vessel move through water, in other words, give a certain quantity of water a certain rate of mo- the engravings to point out the transformations which this caloric engine has undergone, and we trust we shall make its operation and construction clearly understood. We wish particular attention directed to spherical furnaces which are now used by Erricsson, also to the using of the same air over and over again, both in the original engine, and this one of 1850, but notin the one he now employs. A B are two cylinders of unequal diameter, but nearly alike in all points; a, and 6, are their pistons; A is the supply, and B the working cylinder : a' is the piston rod; C is a cylinder with a spherical bottom, called the expansion heater, and is affixed to the working cylinder. D D are braces which connect the pistons, a b. E is a self-acting valve opening inwards to the supply cylinder. F is a similar valve, opening outwards from the said cylinder and contained within the valve box, c, which is connected by a pipe with a cylindrical vessel, G. H is a cylindrical vessel with an inverted spherical bottom, called the heater. L and M are two vessels of cubical form filled to their utmost capacity (excepting small spaces at the top and bottom), with discs of wire net or straight wires, closely packed, or with other small metallic or mineral substances, such as asbestos, so arranged as to have minute channels running up and down ; the vessels L and M are named regenerators. OPERATION.—Fire having been kindled in the furnaces, R, and the air chamber heated up, air is forced in by a hand air pump into the receiver until it is about 12 lbs. pressure to the square inch. The conical valve at the lower end of stem, /, is then opened, and the air enters under the piston, 6, which as heat is imparted to the air, ascends, and the air in cylinder A, is forced into the receiver, G, by piston, o. Before the piston, b, has completed its stroke, the valve of /, is closed (this is the cut oft); at the end of the stroke, the valve K is opened, and the hot air escapes through the passages, eAP and g, into the pile of wire tion; the greater the quantity to be acted upon, the greater the amount of heat, or fuel required. Thus we have described and philosophised on Capt. Erricsson's first engine, and now in Figs. 2 and 3, we have his engine as improved after 17 years' time to perfect it. Figures 2 and 3 are longitudinal sections of Ericsson's Hot Air Engine, improved and patented in England 1850, in the United States 1851. We do not wish to occupy space in our columns now with a lull description of these figures, we refer to page 60, last Vol., Scientific American, for this,but we re-pablish gauze or regenerator, M, where it parts with its heat and then passes up the pipe indicated by the dotted lines, and into the upper cylinder through the valve, E, there to be forced out into the receiver, G, by the next up stroke of the piston using the same air over and over again. This was certainly a kind of perpetual motion engine; the same heat and the same air being used over and over again. Within two years the engine has undergone a change; the same heat but not the same air is repeatedly used. If we suppose the pipe with the dotted lines to be a chimney operi ing to the atmosphere, and not into the upper cylinder, A, so as to let the spent hot air pass out, we will have the caloric engine as it now is. The cold air is taken from the atmosphere direct into cylinder, A, which is simply a large air feed pump, and compressed into a receiver, and the spent air is sent away into the atmosphere. Figures 2 and 3 are somewhat different, but the principle is the same, the links and crank show how the power is conveyed to drive the shaft of the paddle wheels. If we suppose four of those single acting cylinders to be arranged in line, two on each side of the main shaft, giving it motion by a walking beam, our readers will have a good idea of the engines of the caloric ship. This hot air engine has been denominated " a new motive power," by nearly all our papers. The " New York Daily Times," and "Hunt'sMerchants' Magazine" have specially so termed it. Now we wonder at this, for no person who has received an education at a good seminary or university can be ignorant of the fact that " hot air " is capable in its very nature of moving machinery. It certainly takes away much from the character of any editor for intelligence to have used such language. Hot air engines are very old. In France, hot air was used prior to steam. The great principle of the Ericsson engine, is the regenerator. " Hunt's Merchants'. Magazine" says about the " regenerator ":—the wonderful process of the transfer and re-transfer of heat, is a discovery which justly ranks as one of the most remarkable ever made in physical science. Its author, Captain Ericsson, long since ascertained, and upon this is based the sublimest feature of his caloric engine, that atmospheric air and other permanent gases, in passing through a distance of only six inches, in the fiftieth part of a second of time, are capable of acquiring, or parting with, upwards of lour hundred degrees of heat. He has been the first to discover this marvellous property of caloric." Our readers expect of us correct information on this subject, which has not been given elsewhere. We will therefore endeavor to point out what is new and what is not new, in Ericsson's engine. The principle of robbing the escaping hot air of its caloric by passing it through narrow metal plates having small channels in them, and then using this over again, is the invention of the Rev. Dr. Robert Stirling, a Scotch Presbyterian clergyman of Galston, who took out a patent for his hot air engine in 1827. His engine is illustrated and briefly described on pages 667, 8, 9, 10, of Galloway & Hebert's History of the Steam Engine, published in London in 1832, before Capt. Ericsson took out his first patent. It was asked of the author of the " caloric engine," while he was explaining his engines on the trial trip of the caloric ship, it" there was no danger arising from fracturing the top plates of his furnaces by the expansion and contraction of the metal." His answer was, that" owing to the spherical form of his furnaces, the top plates expanded and contracted without danger of fracture." Figure 4 is a vertical section of Dr. Stirling's hot air furnace ; it is spherical, and of the form now used in the caloric ship. This figure is taken from the book referred to, page 668. a a is the cylinder; b is the hot air chamber; C is a piston packed with thin pieces of metal, perforated with zig zag holes, and pieces of brick and other non-conducting substances below. This piston was moved by the rod, d, in the hot air chamber, and the cold air passed from the top of the piston, through the small holes, and down into the hot air chamber, and from thence to the working cylinder, which was double acting, and had an air vessel for each end, just as the present caloric engine uses two hot air furnaces for two single acting cylinders which amounts to one double acting one. The same air was used over by Stirling continually. A gentleman in this city, a professor of mathematics and languages, and who is well vsrsed in mechanical af, has informed us that Dr. Stirling, while pastor in Kilmarnock, many years before 1827, was to his knowledge blamed by his parishioners, for neglecting his ministerial duties for his hot air hobby. Mr. Steel—called the doctor in this city owing to his extensive acquaintance with science and art—who may be Mechanics' Institute, exhibitedanddescrTBed" a model of Stirling's hot air engine, in his lectures in Glasgow belore he came to New York, and that is many years since. Hebert's history does not give a very clear description of the operation of Stirling's first hot air engine, but we have the words of Dr. Stirling's brother, an engineer of Dundee, Scotland, who was a joint inventor. He, along with his brother, took out a patent for an improvement in 1840, which was described in the " London Times," '? London Mechanics' Advocate," Vol. 4, pages 229 and 230, and in the "Dundee Advertiser," Oct. 1841. This latter paper says " it is now working at the Dundee Foundry, is superior to the steam engine, saves a great deal of fuel, and lor the purposes of navigation, it is invaluable."— This paper thus states its principle of saving heat:—" Of the heat communicated to the air from the furnaces, a very small portion is lost, for by making the air, in its way from the hot to the cold end of the air vessel, pass through a chamber divided into a number of small apertures, the great extent of surface with the hot air extracts the heat temporarily, and restores it to the cold again on its passage back from the cold to the hot end of the vessel." This paper of 1841 uses the following identical language recently used by some of our papers in reference to the caloric engine. It says again :—" In reference to the purposes of navigation, this invention must lead to extraordinary results, and will render a voyage to India round the Cape, by machinery, a matter ol perfectly easy accomplishment." In 1846, J. Stirling, the engineer, read a paper on Stirling's hot air engine, belore the Institution of Civil Engineers, in England. We refer to Vol. 45, page 559, " London Mechanics' Magazine," for an account of the same. The paper elicited a long discussion among such men as Sir George Cayly, Robert Stevenson, C. E., A Gordon, C. E., Smith, of Deanston, J. Jeffreys, &c. Mr. J. Jeffreys said, " the principle of the engine's operation is analogous to that of a respirator. The conducting power of the metals alternately absorb and gives out the caloric." This description is just like that of M. V. Beaumont's, about 155 the Caloric Engine [in the Herald ; some gentlemen on board also called it " the breathing ship." Mr. Stirling said, on page 565 and 566, London Mechanics' Magazine. "In an early patent (1827, his first,) he had specified the arrangement of the respirator, intending to use a series of perforated plates or wire gauze." This was in print four years before Capt. Ericsson obtained his last patent. We quote fairly, and treat the matter candidly, giving our authorities, so that any person can examine for himself, and see that we set down nothing but truth—truth long known to us, but with which our newspaper editors einnot be supposed to be acquainted,—on that very account they should have been more moderate in their language. So much then for the history of the hot air engine. We have only to add that it was stated at the aforesaid meeting, that Stirling's hot air engine, ol 30 horse power, had been ir. operation for two and a-half years, driving all the machinery of the Dundee foundry, and that the iuel it consumed was only 2J lbs. of coal per horse power in an hour. POWER OF THE ENGINES.—In the Caloric Ship, there are four working cylinders, each having 22,300 square inches of piston area (each single acting) and six feet stroke. The supply cylinders (air feed pumps) have each 14,794 square inches of piston area, and the same length of stroke. The horse-power of the caloric engines is set forth in the following extract from the "New York Herald," which was an answer to a correspondent of the " Brooklyn Eagle," and has been sanctioned by Capt. Ericsson as being correct. " Atmospheric air, enclosed in a tight vessel, and elevated to a temperature of 384 degrees, acquires, it is well know, a pressure of 12 pounds per square inch. This happening to be the working pressure of the engines under consideration, it will be quite easy to test the accuracy of the calculation qfthe scientific correspondent, by estimating the force of the working piston, and the resistance of the supply piston, each by itself. The latter deducted from the former will obviously exhibit the theoretical power of the engine. Now, each working piston of the Ericsson contains-22jS#0 square inches, operate *ipon by heated air of 10'96 pounds, mean pressure—the actual pressure of 12 pounds being reduced by cutting oft at three-fourths oi the stroke. The mean force of the working piston will thus be 22,300X10 96=244,408 pounds. The active space passed through by the four working pistons being 6X14X4=336 feet per minute, "the active power developed will be 244,408 X 336=82,121,128-33000=246'88 horse power. The supply pistons, each containing 14,794 square inches, in compressing and forcing the cold air into the receivers, operate against a mean resistance of 9'34 pounds per square inch. The contracting force of these pistons will thus be 14,794 X 9'34X336=46,527,936H-33,000= 1,409 horse-power, which deducted from 2488, leaves 1079 horse-power differential or effective force, losses by friction, &c, being disregarded. Make the liberal allowance of 479 horse-power for such losses, and 600 horsepower remains—a force sufficient to effect far more than the projectors of the Ericsson expect. Some time may yet elapse, it is reasonable to suppose, before the pistons, valves, &c, will be rendered air-tight enough to retain the internal pressure of the machine, which is so essential in bringing out its full power. ENGINEER." There were many typographical errors in the Herald,"—we have corrected some of them so as to state the question as fairly, as viewed by those interested in the " Caloric Ship." The above calculation however is not correct and we will endeavor to point out more than one error. We allow the 384 to be above the common temperature of the air, which if it is 40O+384=424 it will not have a pressure of 121bs on the square inch, but 11.7311bs. Air doubles its volume by an increase of its temperature to 491 according to the latest experiments of Eegnault and Magnus, not 480 as Capt. Ericsson calculates, therefore when air U heated from 40s to 531 it will exert a pressure of 151bs on the square inch thus 491-M5=32'733, therefore 384-r32733= ll'7311bs. pressure on the square inch, not , 12lbs. V The horse power of an engine, is equal t the average pressure on the piston in pounds per square inch multiplied into the velocity of the piston per minute, divided by 33,000. The calculation of Engineer, is not therefore correct, for the air feed pump only allows a certain quantity of air every stroke, and no more; it is not like the steam engine, having a reservoir of power in the boiler; for the pressure of the steam is as the quantity, and so it is with hot air. The pressure then of the hot air in the working cylinder, is not 12 lbs. nor 11-731 lbs., but about 7i lbs. on each square inch. The large cylinder, although it has 22,300 square inches area, surely cannot be filled with more air each stroke than the capacity of the feed cylinder, it it were, it must be fed in by some hidden extraneous steam engine. Well as 384 of heat is imparted to the quantity of air fed in by the feed pump, we will have a pressure equal to 11.731 upon each square inch of 14,794 piston area, but even allowing the pressure to the 121 bs. on the square inch, the average pressure on the working cylinder will be 14,794X 12H-22,300=7.956 pressure on the square inch of the working piston, it has 312 ft. 670 in. of greater cubic capacity; for as is the difference of capacity in the feed pump and working cylinders, so, is the pressure reduced by the expanding. The power of the engines are as follows : 22,350X7.95X54-f-33,000=290X 4=1160, for the power of the four cylinders. We give 54 ft. per minute as the velocity of the piston, or 9 revolutions of the shaft per minute, as we counted them on the trial trip. Now what power do the engines expend in working the pumps; namely an average pressure of 9.341bs on the square inch of 14,974 inches area of piston, therefore 14,974 X 9.34 X 54-f-33,000=228.857 h.-p. X4=915.428—1160 h. p.=244.572 or nearly 250 horse power which the engines have to spare to drive the paddle wheels. We make no allowance for the cut off, for the teed is entirely different from the steam engine; it is forced in, and the quantity of air fed in is the only data for calculation along with the heat imparted. The power required to feed must be very great, for as the molecules of cold air expand While passiSgTErouglTThe "Regenerator they exert a back pressure in proportion to the heat they imbibe. What then is the value of the Hot Air engine in comparison with the steam engine ? It is in its very nature, owing to the element it employs (hot air) very inferior. Its motion must be sluggish for at every stroke, 616 cubic feet of cold air must be heated to 384 and the faster cold air is passed over a heated surface, the slower it takes up heat. In the steam engine, for every 1788 cubic feet of steam, it only requires one cubic foot of cold water fed into the boiler. The Caloric Engine consumes nearly all the fuel used upon itself; it is not so with the steam engine. It has been stated that the Caloric Engine only consumes 1 lb. of coal per horse-power per hour; its speed was no more than seven miles per hour by the Coast Survey measurement j therefore, to double its speed, it would consume eight times more fuel, as calculated by engineers, this is half a pound more per horse-power than the Arctic uses, which has made 18 miles per hour in smooth water. It is said to be more safe than the Marine Steam Engine; but when did we ever hear of a steam ship using low pressure steam, bursting her boiler. The steam engine is a sate machine, under the charge of good men, and so is a ship without steam or hot air, but not otherwise. We would welcome hot air, as a superior and more economical motive power to steam, if it really were so, but it is not. The same amount of fuel applied to a boiler to produce steam from water, will produce a greater mechanical effect than if applied to air, which is a very bad conductor, and absorbs heat so slowly that it must always be sluggish in its motion. A steam engine can be built—boilers and all, which will give out triple the power of the Caloric Engines to the main shaft, and occupy less room. The combustion of fuel in the Caloric Ship is very perfect, and deserves credit, but the amount of leakage must be very great every stroke, as a portion of the fed air must always be lost, and it will be very difficult to keep the pistons air-tight. We therefore cannot have any other belief than that the " Caloric Ship Eri csson" will not be successful. We have used no scoffing language, nor have we such a spirit towards this enterprise. In speaking of the fuel, we have allowed 6 tons of coal per day for the Ericsson, with 600 horse-power engines. We have nothing to add to the remarks we published on page 141.