Engineering Wonders of the World
Volume I

THE ARMAMENT OF A BATTLESHIP. 411 ture, through holes in which the muzzles of the guns protrude. This revolves on roller bearings around circular steel Turrets channels in the deck, and and . , . , . Barbettes. the guns gO round Wlth The barbette differs in this that it is a fixture, and forms part of the structure of the ship herself—a very im- mense advantage. The guns are placed upon a revolving platform within the armour plates forming the barbette, and it is this inner turn-table, to which is also fixed the barbette shield, that carries the guns round on their various arcs of bearing. (We should note in passing that turret is now the generally accepted term for a gun mounting, including the modern bar- bette.) Beneath this barbette chamber or turn-table is a working-chamber, 9 or 10 feet in height, which forms the intermediate position in the loading system. From this chamber a thick steel tubular trunk descends directly through the decks to the ammunition rooms, or near to them. (See illustrations on page 447.) This encloses the “ am- munition hoist,” up which projectiles and powder charges are sent into Ammunition })art)e^e aiong continuous Hoists. chained “ lifts.” In ships fitted with turrets, the guns had to be brought back to a particular position before reloading could be accomplished. To obviate this ne- cessity, which takes, it need hardly be said, a considerable time, and necessitates the fresh laying of the gun after each discharge, the modern ammunition trunk is attached to and revolves with the gun platform. As a result the weapons can be loaded at any point on the arc of training and at any elevation. The powder charges are arranged to be loaded in cages at the magazine floor, which is, as ä rule, immediately over the shell magazine. Their weight is such that'they can be handled easily. The charges are placed in suitable receptacles attached to the armoured hoist, in readiness to be transferred to the lifts or hoist as they come into position for loading. Where there are two guns in a turret, independent ammunition loading hoists are provided. Tell-tale dials are also fitted in the working chamber beneath the barbette to let the operator in charge of the ammunition supply know where the hoists are at any particular moment. The gear is all interlocked, so that there is no possibility of premature hoisting or of jamming. In the roof of the barbette shields are fitted raised a 12-inch shell weighs 850 lbs., and would COUNTERBALANCE FIVE 12-STONE MEN. I steel “ boils,” with small eye-slits. These are the lookout or sighting hoods. Three sighting positions are usually pro- vided in twin-gun mountings. At the centre position between the guns there is a sight for each gun ; at the side positions a sight is provided for the gun on that side only. The training and elevating of the guns are, of course, under complete control from these positions. The elevation allowed by the gun aperture in a barbette shield of a modern 12-inch gun is 35 degrees, with 5 degrees depression, making 40 degrees in all. Since a bare 15 degrees represents a range of 18,000 yards, the maximum given is more than suffi- cient for any possible need that might arise. The entire weight of a pair of 12-inch guns, barbette, shield, and mounting, exceeds 450 tons.