Page:The Development of Navies During the Last Half-Century.djvu/217

 grain or pellet larger the whole charge took longer to consume. Hence, as the shot travelled down the bore continual increments of gas were generated imparting an augmenting velocity to the projectile, which should reach the muzzle when this was at maximum. If the gun was too short, a large portion of the powder would be blown out unconsumed, and result in wasted energy. Even with considerable addition to the length this occurs in a minor degree, as can be seen by an instantaneous photograph of a gun at the moment of discharge. As guns grew in size so did the grains of explosive composing the charge, first to what was termed pebble powder, and then to cubes of much larger dimensions. At a short distance from the gun unconsumed portions of these are a veritable hail of small projectiles.

In 1880 we appeared to have reached some finality in ordnance. We had advanced from 7 to 80 tons, and found no difficulty in manipulating on board ship the heaviest guns. There had been few accidents of a serious nature. The bursting of a 38-ton gun in the 'Thunderer' owing to the insertion of a double charge was a notable exception. The gun had actually missed fire the previous round without the crew being aware of it. It was then loaded again, and burst with great violence on being discharged. Being one of a pair in a turret, the discharge of the other gun had deceived the crew into a belief that both had gone off. Even spectators watching the target stated that they saw two shot strike the water. Such illusions are not