_The Disappearing Gun._--The importance of secreting the location of the battery in coast defences, and the better protection of the gunners, have suggested a species of gun carriage which would permit the gun to be normally hidden behind and under the protection of the parapet, and be only temporarily elevated to a position above the parapet while firing. Various forms of this have been devised. General R. E. De Russy, Corps Engineers, U. S. A., devised such a carriage in 1835. Moncrieff, of England, was one of the first to put in practice such a form of carriage. United States patents covering this invention were granted him as follows: No. 83,873, November 10, 1868; No. 115,502, May 30, 1871, and No. 144,120, October 28, 1873. Its principle of operation was to utilize the force of the recoil as a power to raise the gun into firing position. The gun is fulcrumed in a lever frame provided with a counterpoise which more than balances the gun. When the gun is fired the recoil raises the counterweight, and the gun descends and is locked in its lower position. When loaded and released the counterpoise raises the gun again to firing position. Among later gun carriages of this type of American construction may be mentioned those devised by Spiller, Gordon, Howell, and others, but the one most generally known is the Buffington-Crozier, covered by patents No. 555,426, February 25, 1896, and No. 613,252, November 1, 1898. This carriage, sustaining the 8 and 10 inch breech-loading rifles at Fort Wadsworth for the defence of New York harbor, is shown in Figs. 272 and 273, Fig. 272 representing it in its lowered position, and Fig. 273 in its elevated position for firing. The trunnions of the gun rest in bearings at the upper ends of the pair of levers, which latter are fulcrumed near the middle to horizontally sliding carriages connected to hydraulic cylinders that move backward as the gun recoils. These cylinders move over stationary pistons which have orifices that allow the liquid to pass from one side of the piston to the other. As the gun recoils and the levers turn to the horizontal position, the forward ends of the levers are made to raise vertically an immense leaden counterweight, weighing 32,000 pounds, which ordinarily over-balances the weight of the gun on the levers. This cylindrical counterweight is seen raised on the left of Fig. 272. In firing, the energy of the recoil is absorbed partly by raising the counterweight, and partly by the resistance of the hydraulic cylinders, and when the gun reaches its lowest position it is caught and retained by pawls. After loading the pawls are tripped, and the greater gravity of the counterweight raises the gun to firing position again. Ten shots from an 8-inch gun on this carriage have been fired in 12 minutes 21 seconds. [Illustration: FIG. 272.--BUFFINGTON-CROZIER DISAPPEARING GUN, LOWERED.] [Illustration: FIG. 273.--BUFFINGTON-CROZIER DISAPPEARING GUN, ELEVATED FOR FIRING.]