Fig. 2 represents an air torpedo proposed by the same inventor. The air reservoir, C, revolves along with the gearings under the action of the pneumatic machine, D. The central shaft is hollow, so as to serve as a conduit. The admission of air into the slide valve of the machine is regulated by a clockwork which actuates a slide in an aperture whose form and dimensions are so calculated that the speed remains as constant as possible toward the end of the travel. The trajectory of the two torpedoes is regulated by a cylindrical bellows, F, which gives entrance to the sea water. The springs shown in the figure balance the hydraulic pressure. The tension of these springs is regulated by the rod, H, according to the indications of the scale of depths, I. When the torpedo reaches too great a depth, the action of the springs can no longer balance the increase of the hydraulic pressure, and the accumulation of the charge in the rear causes the front to rise toward the surface. When the torpedo reaches the surface, a contrary action is produced.--_Revue Industrielle._ * * * * * THE FIRST STEAMBOAT ON THE SEINE. [Illustration: FIRST STEAMBOAT BUILT ON THE SEINE.] The accompanying engraving represents the remarkable steamboat that the unfortunate Marquis de Jouffroy constructed at Paris in 1816, after organizing a company for the carriage of passengers on the Seine. De Jouffroy, as well known, made the first experiment in steam navigation at Lyons in 1783, but the inventor's genius was not recognized, and he met with nothing but deception and hostility. With the obstinacy of men of conviction, he did not cease to prosecute his task. He assuredly had an inkling of the future in store for the invention that he was offering to humanity. The paddle wheel boat that he constructed at Paris in 1816 did not succeed any better than its predecessors; it was remarkable nevertheless in appearance and structure. The engine was forward, as shown in the engraving, which is copied from a composition of Dubucourt's. The company organized by the marquis was ruined, and, as well known, the unfortunate inventor himself died in poverty in 1832, at the age of eighty-one years.--_La Nature._ * * * * * THE ELECTRIC MOTOR TESTS ON THE NEW YORK ELEVATED RAILROAD. The American Institute of Electrical Engineers at its last meeting of the season, held June 25, again considered the subject of electrical traction, the paper presented by Mr. Leo Daft being based upon some recent electrical work on the elevated railroads and its bearing on the rapid transit problem. The _Railroad Gazette_ gives the following abstract: