The enormous force developed in the explosion of gunpowder could hardly fail early to occupy the minds of the ingenious, with the effort to make it available for the uses of industry. Accordingly, we fiad that this problem formed a subject of study with such men as d'Hautfeuille, Huyghens, and Papin. But the intense energy of the force and the suddenness of its action seem to have discouraged the at. tempt to apply it directly as a motive, power. The earlier experimenters occupied themselves with the endeavor to turn it to account by indirect means. The expedient which appeared to them most promising was to use it for the purpose of creating a vacuum. In fact, if a comparatively small charge of gunpowder be exploded- in a closed vessel furnished with valves freely op ming outward, the enormous expansion of the gaseous products of the explosion, an expan. sion due to the exce-s've heat developed, will drive out the atmospheric air through the valves, while the gases, contracting almost as suddenly as they expanded, will leave th vessel nearly void. It was first proposed to apply this principle to the elevation of water. A very simple apparatus Buffices for this purpose. Let there be placed, for instance, such a vessel as has just been supposed, some fifteen or twenty feet above the level of a reservoir ; a tube, open at both ends, communicating between this vessel and the reservoir will be all that is needed. So soon as the air has been expelled from the vessel by whatever means, the water of the reservoir will rise under the pressure of the atmosphere and occupy its place. This water may then be discharged at the superior level, and the apparatus will be ready for the repetition of the operation. In order to prevent the return of the water to the reservoir, when the orifices of discharge of the upper vessel are opened, the tube may have valves in it. op. ning upward but closing under a downward pressure, or, what is simpler, it may be recurved at the upper extremity and enter the explosion chamber by the top. Such was the application of this power suggested by d'Hautfeuille. Huyghens perceived that it was capable of beng turned to more varied uses. He proposed to employ a cylinder with a movable hut air-tight piston to serve as an explosion chamber, with a view to obtain a reciprocating motion. In fact, by blowing out the air contained in such a cylinder through valves properly Ilisposed, the atmospheric pressure could be made to force the piston downward, and thus indirectly to move the arm of a lever to raise a weight or to turn a crank. The valves suggested and perhaps actually used by Huyghens for this purpose were sufficiently rude. They were nothing more than open but flexible leather tubes, which, after allowing the air to escape, were expected to col. lapse under the pressure from without, and prevent it from re-entering. Papin substituted for these a much more ef. ficient and neater contrivance. This was to make an in the middle of the piston sufficiently large for the free escape of the air, and to cover this with a bell. The bell, yielding to the upward pressure, permitted the air to pass out, but, dropping immediately after into its place, eff ctually prevented its return. But none of these expedients sufficed to make a practically useful gunpowder engine. In 1791, John Barber, a British inventor, patented a project for a new motive power, which may perhaps be regarded as embracing the germ idea of the modern inflammable-gas engine. This project. however, for it amounted to nothing more, was of the crudest sort. The motive force was to be derived from the driect action of a powerful current of fhme, which he proposed to create by the combustion of inflammable gas mingled in explosive proportions with common air. The gas was to be generated by the destructive distillation of any combustible substances in It tight vessel. From tht gen- <.lratol' it W9A! to be conducted into another chamber;- ca.lM the “ explosion chamber,” common air being simultaneously introduced into the same vessel by a different channel. Under such circumstances combustion would of course be explosive, generating a powerfully outrushing stream of flame, which might be maintained as long as the gas should continue to be supplied. As the plan was only to employ the “ 1Jis ®i®a “ of this stieam to turn a wheel or a windmill, the unpractical nature of the scheme needs not to be pointed out. In 1794, another British inventor, by name Robert Street, patented a gas engine, founded on principles somewhat more rational than those which seem to have guided Barber, inasmuch as he clearly perceived that if heated gas is to be made .the medium of applying mechanical power, it is through its elasticity, and not through the momentum of its mass, that we must expect to see the useful eflect produced. But inasmuch as Street proposed to make the cylinder of the engine itself the generator of the gas by which the engine was to be driven, his scheme in a practical point of view was not a whit less visionary than that of Barber. These early, and, as they seem to us now, absurd projects, though they bore no fruit, and were probably never even subjected to a serious experimental test,mention in the history of this subject, as marking the progress of an idea destined at length to be successfully wrought out. Indeed, considered as an id«a merely, it was successfully wrought out only a few years later. The gas engine, in every essential particular, such as it is at the present time, that is to say, actually realized in a form available for purposes of industry, was invented as as 1799, and patented in France by an ingenious artisan named Lebon. Nevertheless, this machine was not a success. It attracted no notice in the scientific world, and inspired no confidence in thil industrial. After the lapse of about half a century it was re-invented, and re-in- vente;, doubtless, quite independently; the resemblance of the modern machine to that of Lebon being so c mplete that a description of one of them might easily1 be supposed to have been taken from the other. the date of Lebon's invention illuminating glts had not yet come into general public use, but the mode in which he proposed to prepare the gas for his engine was precisely that which is now in universal use in the works of the great city gas companies. Having thus provided himself with a sufficient reservoir of this essential material, his plan was to introduce a certain charge of this into the cylinder of his engine beneath the piston, and simultaneously through another channel to admit a proper proportion of atmospheric air. The mixed gases were then to be exploded by means of the electric spark, their consequent dilatation furnishing the desired motive power. The inventor seems to have ov rlooked no provision nece ssary to secure the perfect success of his plan. The engine was entirely self.regulating. It operated two pumps, one of them designed to introduce the supply of gas, and the other that of air. According to the descriptions, by which only we know it, it would- seem to have combined every feature important to secure success, and yet, as already stated, it was not successful, Its failure is probably to be attributed to the influence of several causes, which, in the progress of improvement in the industr 11.1 arts, and the sim- ultaneouB advancement of experimental science, have since ceased to exist. In the first place, its just remarked, inflammable gas had not yet been introduced for purposes of general illumination ; and the preparation of gas for the engine must have been troublesome and disproportionately ex pensive. Electrical science, moreover, had not then reached such a state of perfection as to be in condition to suggest an apparatus for producing the spark required to inflame the gases, capable of operating with the unvarying certainty indispensable in such a machine ; and !:nally, the mechanic arts were probably yet unequal to the requisitions of a prob- 1em involving the peculiar difficulties which the construction of this engine presented. In point of fact it can hardly be doubted that mechanical difficulties were among the principal obstacles which prevented the full realization of a project which, abstractly considered, stems to have been entirely feasible. Many other inventors since Lebon, have occupied themselves with gas engines. Until within the past ten years, none have succeeded in establishing their inventions in the confidence of the industrial vlOrld. Of machines of this class which have left no trace except in history, it is unnecessary here to speak with minute detail. There is one of them, however, which deserves a passing mention, as having been distinguished from the rest by a feature which may be characterized as more bold than practical. This consisted in the proposed substitution of oxygen gas instead of atmospheric air in forming the explosive mixture by which the piston was to be driven, and hydrogen instead of coal. gas ; the proportion being that required to form water by combination ; so that after explosion the vacuum of the cylinder might be complete. It is true that immediately after the explosion, the water of combination would exist in the state of vapor, and that this would have a momentary elasticity so great as, by its direct action, to drive the piston to the md of the cylinder. But this vapor would be almost instantaneously conden^d, especially if the cylinder were kept properly cooled; and a vacuum being t ,us formed practically perfect, the piston, on the opening of the valves for the admission of a new charge of gas to the opposite side, would be urged by the full pressure of the atmosphere upon its entire surface. If this idea could be practically realized, it would certainly be attended with very sensible advantage. In the gas-engine as now constructed, there is necessarily a period during each stroke in whith the effective force is zero. This is the case during a great part of the time of admission of each successive charge of gas, which continues for one half the length of the stroke. If during &11 this time there should be a vacuum, in the opposite of the cylinder, the engine, instead of being powerless, would be actuated by positive working force upon the piston equal to one atmosphere ; an advantage which more than doubles the efficiency as yet secured in any motor of this class. The proj ect here described was patented by James Johnson, a Bricish inventor, in 1841. Mr. Tresca, in an interesting article published in the Annals of the Conservatoire, has expressed surprise that subsequent inventors have not occupied themselves more with this idea of Johnson. But in point of fact, the plan is much mOre plausible than feasible, To say nothing of the trouble and expense of generating the gases, which in the case of .oxy, gen, especially, would be sufficient to defeat the economical object; the violence of detonation of the pure gases in thl.l proportions suggested would be such as to endanger the safety of the machine, or to render the power unmanageable, It is also perhaps questionable whether, in practice, the condensation could be determined so as to take place at the moment desired. If the piston were free to take on the velocity of a projectile discharged from a gun, no doubt the pressure would follow it to the end; but if, owing to the connections by which the force is to be utilized, the motion of the piston is comparatively slow, the oollapse may occur before it reaches the limit of its course. In such a case the vacuum would be injurious. In to reduce the violence of the explosion, the quantity of gali! employed in each charge might be diminished, and the charge might be allowed to dilate to some extent, as it would naturally do in consequence of the movement of the piston, before being fired. But these expedients would )leduce correspondingly both the direct t ffect of the gag, and the indirect effect of the vacuum which it is sought to utilize. It is not very surprising, therefore, considering all the difficulties in the way, that no successful gas-eng-ine has yet been constructpd, deriving its power from the explosion of hydrogen with oxygen. Three engines present themselves in the prescnt Exposition which derive their force from the combustion of inflammable gas. Two of these employ the direct pressure ot t e ga'les as dilated hy combustion. The third reverts to the principle which chiefly occupied the earlier inventors, viz., that of using the gases only as a means of clearing the cylinder of air, and rendering available the pressure of the atmosphere. It is to this last, which, though not earliest in the of invention, revives the idea which belongs to the earlier period of this history, that attention will be first directed. This prominence of position may also be considered a, due to this machine, since it was rewarded by the jury with a gold medal, while the other two just mentioned received a less honorable distinction. Sewing Machines Driven by Electricity. It seems that the subtile force of electricity, which has an, nihilated space in intercommunication, is now to be called in to ameliorate the condition of that large and' meritorious class of community, wo nen who support themselves by work with sewing machines, and to make the operation of the sewing machine in the family no longer a task but a luxury. All who have witnessed the operation of Gaume's ElectroMagnetic Engine, ourselves among the number, are convinced that it must eventually be largely employed as a motor this purpose. And all philanthropists must join us in wishing success to an invention so well calculated to do good. As we will shortly illustrate and describe this machine at length, we will not at this time enter intoits details. Suffice it to say that the numerous obstacles which have barred the way to success in this field seem all removed, and that the cheap compact motor so long sought is at last obtained. Although involving well known principles of electric sci, ence, there has been much ingenuity displayed in their application, and in its scientific as well as practical bearings the machine is well worthy of earnest attention. The manufacturers of this machine are represented by Mr, H. C. Covert, 535 Broadway, New York, at which place the ma.hine may be seen in operation. © 1869 SCIENTIFIC AMERICAN, INC312 dewiifo Swntati. [November 13, 1869. Improved Apparatus for Printing Photographic Vignettes. In order that the general reader as well as the professional photographer, may understand the nature and use of this ingenious invention, we will state in as plain a manner as the subject will admit,'the nature oi the difficulty which it is designed to obviate. In the printing of large vignettes which have no definite border in order to secure the delicately-shaded background which gradually grows lighter as it recedes from the outline of the picture, until it finally fades out altogether, a device usually consisting of cloth or . paper painted black on' the Bide toward the blank, to ob-. viate refiection, and having an opening through its center for the transmission of light from the camera, is held by the operator and moved to and fro to intercept the light from the outer parts of the vig nette. These outer parts are therefore less acted upon by the light, and are softened off in the manner desired. The operation is a tedious one, and very trying to the eyes of the operator, as it not unfrequently requires from four to sb: hours to print a large-sized vignette. It is obvious that a machine capable of moving the screen auto, maticaUy and in the manner required, would be a very useful im provement,relieving the operator from a most unwelcome task, and enabling ):tim to devote the timeto execute it,to other more agree- abJe and profitable work. Our engravings exhibit such an improvement, and upon examination we are satisfied ; it will prove a valuable addition to photographic apparatus. The working parts of the machine are inclosed in a wooden case, like the works of a clock. The door of this case has a slide in the center, covering a round opening, which is opened when ill use, an opening in the opposite side of the case being provided with a telescopic tube and a slide. The door is shown thrown open in the figure. In this figure, A is the front plate of the works of an ordinary brass clock, to the axle of the fourth wheel of which is attached the wheel, B. This wheel is shown in detail in Fig. 2. Upon the wheel, B, is attached a plate, C, also shown in detail at Fig. 3. The plate, C, is of concavo-convex form, or what would be called in common parlance, dished ; its concave side beiJlg placed next the wheel, B, and held there by the buttons, D, Fig. 2. A tongue, E, Fig. 2, is pivoted to an arm of the wheel, B, and at its opposite end it has a round stud, F, which projects through the curved slot of the plate, C, Fig. 3. The plate, C, also has a hole in its center, which, when C is placed upon B, fits upon the axle of B It is obvious that when C is thus placed upon B, that partially rotating C, while B is held stationary will carry the stud, F, further from the center or contrari wise, so that anything attached to F, and moved by it will have greater or less motion, according !Ls F is placed further from or nearer to the center of B Now, upon the pivo#, I!', Fig. 1, plays a hole in the end of the bar, G, th'l opposite end of G being pivoted to a rock-bar, H, pivoted at I, H *in its turn imparting motion to another rock-bar, J, pivoted at K, J through the bar, L, imparting motion to M, the latter being a projection from an annular frame, the form of which is shown in the dotted outline on the screen, N, this outline showing the position of the frame behind N. From the top of the annular frame rises another piece of the same form a,s M at the bottom, and is pivoted to F in common with the bar, G. It will now be plain that the motion imparted to the wheel, B, will also be communicated to all the parts described in proportion as F is set near to, or away from the center of B by turning the plate, C, on the axis of B. To the annular. frame, shown in dotted outline on the screen or diaphragm, N, are attached supports, 0, which serve to hold N firmly to the annular frame and to give N all the motion imparted to the annular frame by the top piece pivoted to F, and the bars and rock-bars, G, H, J, and |L. Wings, P, are pivoted upon the screen, N, so that the oval apperture in the center of N, may be reduced to the general contour of the head and shoulders of a figure in a vignette when desired. A wire support, Q, is loosely pivoted to R and M, which preserves the relative distance between the annular frame and the screen when the apparatus is worked in a horizontal position, as well as when it is in the upright position. A weight, S, acts through a lever and suspending wire as a counterpoise to the weight of the annular frame and the screen. It will now be obvious that the revolution of the stud, F, around the center of the wheel, B, will be imparted through th') bars and rock-bars, G, H, J, <ind L, to the annular frame and the screen, N, all the parts of the latter revolving around a center in the oval aperture through the center of N, the exterior edges of which will intercept the light on the exterior edge of the background of the vignette, and soften it, but without some further provision the machine could not imitate handwork, as it is frequently desirable, to soften off the background more at the top than at the bottom, or vice versa. In order to do this the pivot which works in the slot in the lower arm of the rock-bar, II, and through which the rock-bar, H, imparts motion to the rock-bar, J, projects from a slide, T, which is adjustable upon the rock-bar, J, being held at any point desired by a spring pawl, U, which engages with a rack substitute tor many of the implements heretofore used for this purpose. For further information, address W. H. Howland, 26 West, Washington Place, New York city. Steering by Steam. A correspondent who was present at the occasion of a recent trial of the steam steering apparatus with which the. small steamer North Star, of Muskegon, has been supplied, writes to the St. Louis Dillpatch as follows: The experiment was such a complete and marked success' mechanically, and seems in its principle to foreshadow such immense benefits to steam navigation, that it deserves the- earnest and'instant attention of the public. While the arrangement of the machinery connected therewith is simplicity itself, the result on the motions of a vessel are instantaneous,. and as powerful as can be desired. Instead of a cumbrous wheel in the pilot house, a lever like the starter of a locomotive stood up from the floor, which worked either way from side to side by no heavier pressure than could be given by the thumb and finger, but which made the North Star, a long, narrow river boat, almost turn on her centre, and then as instantly reverse with the same promptitude of action on a different application. A doubt having been expressed as to whether, by the same machinery, she could be “ held” on the same steady course for a length of time, the steersman fixed on a mill chimney two miles distant, and made for it. After getting her from the previous violent swayings into true line, he dropped the bar and let her run for it, until all on boardwere satisfied of the truth of her course. Where the steam rudder is left there it stays, and no power less than that able to overcome all the steam force of the boilers can shift it till again manipulated by the lever. Numerous experiments were made in turning, backing, twisting, and all with astonishing results. When standing still the rudder could be put down with such force as to swing the vessel a point or two. I really believe that, had such an JEAN ELIE RICHARD'S cut on the inner side of the lower part of J. When T is slid up near to the pivot, I, upon which the rock-bar, H, plays, very little motion is il1 parted to J and through it and the bar, L, to the lower part of the screen, while the motion of the top remains the same as before. When T is made to approach the pivot, K, on which the rock-bar, J, plays, the motion imparted by II to J is greatly increased, so that the bottom of the screen, N, is moved considerably more than the top. By these ingenious means all the movements required to be made in the printing of a vignette are automatically performed, and with much greater uniformity and accuracy than is possible when they are done by hand. It exhibits great fertility of resource in invention, and its merit eminently consists in the simplicity of the II\eans employed to secure the complicated movements required. Patented through the Scientific American Patent Agency, August 17, 1869. For further information, address, for two weeks, Jean Elie Richard, patentee, Sweeny's Hotel, New York city, after that time, Columbia, S. C.