does not seem to have been approached by any preceding artist, was the contrivance of what are called indenting cylinders. These are rollers two or three inches in diameter, and made of steel, decarbonized so as to be very soft. In this state they are made to roll backward and forward, under a powerful pressure, over the surface of one of the hardened plates, until all the figures, letters, or indentations are communicated with exquisite precision in sharp relief upon the cylinder, which being carefully hardened and tem pered, becomes, by this means, fitted to communicate an impres sion to other plates, by an operation similar to that by which is was originally figured. It will be obvious that one advantage gained by this method must be the entire saving of the labor and expense of recutting, in every case, on different plates, ornaments, borders, emblematical designs, &c.; as these can now be impressed, with little trouble, on any number of plates, or in any part thereof, by the application of the cylinder. At first sight, the performance of such an operation as the one now alluded to may appear difficult, if not impracticable. Many persons, on its first announcement, were disposed to doubt or deny its possibility altogether. With a proper and powerful apparatus, however, this method of transferring engravings from plates to cylinders, and vice versa, is every day performed with facility and success in works exhibiting even very elaborate engraving. By this means the most delicate designs, which would occupy an engraver many months to effect by hand, can be completed in a few days. Of course the cylinders are produced at a much less price, and they may be executed in a very superior manner. Mr. Perkins has attracted a great deal of attention by his experiments in steam artillery, and in this has far distanced all his predecessors in this mode of warfare. Watt, it appears, once projected something of the kind, but this man of peace did not proceed to much extent with the warlike project. Jonathan Hornblower also constructed what he called a steam rocket; and the French general Chasseloup proposed, some years later, (1805,) a similar plan for the defence of besieged places. M. Gerard, a French officer of engineers, is stated to have carried this idea into practice in 1814, for the purpose of defending Paris at the approach of the allies. In this apparatus the boiler was moved on a carriage, and supplied steam for propelling balls from six gun-barrels, the breeches of which were opened at pleasure; on turning a handle, the six guns received each a ball and the steam at the same time, by a mechanism like what is seen in magazine air-guns. The longest shots were made by turning the handle slowly, and one hundred and eighty balls were thrown in a minute. A wagon at. tended the machine, to supply fuel and bullets. The capitulation of Paris prevented this novel artillery from being brought into action; and shortly afterwards the apparatus was taken to pieces. The experiments of Perkins were on a far more daring and extensive scale. The sounds produced by his steam-guns are said to resemble a rapid running fire of musketry, accompanied by a rustling sound or roar that quite deafened the unaccustomed In his experiments before the duke of Wellington and a numerous party of engineer officers, the balls at first were discharged at short intervals, in imitation of artillery firing against an iron target, at the distance of thirty-five yards, and such was the intensity of the propelling force, that they were completely shattered to atoms. In the next trial the balls were fired at a framing of wood, and they actually passed through eleven planks, each one inch thick, of the hardest deal, placed at a distance from each other. Balls, also, which were fired against an iron plate, one quarter of an inch in thickness, passed through it; yet the pressure of steam required to produce this was estimated not much to exceed sixty-five atmospheres, or nine hundred pounds on each square inch. To demonstrate the rapidity with which musket balls might be thrown, he screwed on to a gun-barrel a tube filled with balls, which falling down by their own gravity into the barrel, were projected one by one with such extraordinary velocity, as to demonstrate that, by means of a succession of tubes filled with balls, fixed in a wheel, a model of which was exhibited, nearly one thousand balls per minute might be discharged. The next experiments were of a more interesting kind. To the gun-barrel was attached a moveable joint, a lateral direction was then given to it, and the balls perforated a lineal series of holes in a plank nearly twelve feet long. Thus, had the musket or gun been opposed to a regi ment in extended line, it might have been made to shoot down each soldier in succession. A similar plank was then placed perpendicularly, and in like manner there was a string of shot holes throughout its whole length and it was thus demonstrated that steam-guns could be made to shoot round a corner! Mr. Perkins thus calculated this new mode of warfare :-Suppose two hundred and fifty balls are discharged in a minute by a single-barrelled gun, or fifteen thousand per hour; this, for sixteen hours, would require about fifteen thousand pounds of powder, which, at seventy shillings per hundred weight, would cost five hundred and twenty pounds, (about two thousand three hundred dollars.) But the same number of balls can be thrown in suc 1 cession, and in the same time, for the price of five bushels of coa per hour, or about ten or twelve dollars for fifteen hours. After the experiments Perkins made at Greenwich before Prince Polignac, and some French engineers whom the Duke d'Angouleme had sent to make a report to him concerning them, he receivea instructions to form a piece of ordnance to throw sixty balls, of four pounds each, in a minute. This he guarantied should be done with the correctness of a rifle musket, and to a proportionate distance. A musket was also attached to the same generator for throwing a stream of lead from the bastion of a fort, and which he engaged to make so far portable as to be capable of being moved from one bastion to another. Both the French and English engineers before whom these experiments were made condemned the steam-gun as being of no real utility. The practical difficulties of working steam under such an enormous pressure were evident; it being impossible to make it as powerful as gunpowder. Besides, all engines of war should be as simple as possible, for in the heat of action it is rarely that men are found to act with the self-possession necessary in the management of even the simplest machinery, no matter how well drilled they may previously have been in its management. It is not intended in derogation of the talents and ingenuity of Mr. Perkins, when we say his inventions have not all been as useful in practice as his friends might have wished. The merit, however, awarded to him is sufficient to establish his reputation as one of the most ingenious and philosophical citizens of the union; and his exertions throughout have been of that laudable and meritorious kind, that, even in failure, ought to bring honor |