Page:The Development of Navies During the Last Half-Century.djvu/211

 12½-in. bore, which would speed an 800 lb. projectile with an initial velocity of 1540 ft. per second, an increase of 200 ft. per second over the 25-ton gun, while the charge of powder had advanced from 85 to 200 lbs.

The 38-ton gun was justly considered a great step, but its projectile, weighing 800 lbs. had passed beyond manipulation by hand or tackle. Then the ingenuity of the great Elswick firm provided us with that admirable system by which all the operations of loading, elevating, and training heavy guns are performed by hydraulic machinery. To describe these in detail would require a volume in itself. It will be sufficient to state that, on the principle of the 'Bramah' press, power is transmitted from an engine by water pressure through a small pipe actuating hydraulic rams. Water is contained in a tank and pumped by a steam engine into pressure pipes, by which it passes to the different hydraulic machines and then returns to the tank. One of the advantages of this system is that fewer men are required round the gun. To work a turret by hand originally took fifty men, now it is effected by a third of the number. Then there is no such danger as the bursting of a steam pipe would involve. The gun does not require a high carriage, but rests in a block on the slide. The recoil is controlled by a solid ram fixed to this block, which on discharge of the gun travels in a cylinder full of water. The pressure of the ram or piston forces the water through a number of weighted valves, the resistance of which gradually brings the gun