12-in. Gun Mountings.
The 12-in. guns are mounted forward and aft on the midship line, as shown in the sketch on the ship. Owing to the powerful nature of the guns, these mountings are necessarily stronger than any hitherto manufactured in this or any other country. The design is arranged with a view to occupying the least possible space in the ship, and, at the same time, to give ample room for working the machinery. The general features of the design are the turn-table proper containing the mountings for the gun, the working chamber underneath into which the ammunition is received from the magazine and shell-rooms in preparation for sending up into the secondary or loading hoist, the trunk connecting the working chamber with the magazines and shell-rooms, and the hoist connecting the working chamber and the gun. This latter hoist is so arranged that a gun can be loaded at any angle of elevation or training. The charge for each gun, consisting of the projectile and the cordite charge, the latter in two halves, is brought up at one time in a loading cage, which is automatically stopped in its proper position in line with the breech opening of the gun. It is then rammed home by means of a chain rammer actuated by a hydraulic motor. The breech-block of the gun is opened or closed by a hydraulic motor, thus enabling this operation to be performed with great rapidity. In the working chamber, by an ingenious arrangement, the projectile and the two halves of the cordite charge are simultaneously transferred from the cage which works in the trunk connecting the shell-rooms and magazines with the working chamber, to the cage working in the hoist connecting the working chamber with the gun position. The ammunition trunk is of a new design, which enables the ammunition cage always to come to the same position in the magazines and shell-rooms; but when it is brought up to the top of the trunk the cage is in its proper position with respect to the ammunition loading hoist, although the turret may be revolving at a quick rate; or, in other words, the ammunition trunk does not revolve at the bottom, but revolves with the turn-table at the top. The guns are protected by 10-in. hard armour in the front, and 8-in. at the sides and back. The feature of the turret is that it is quite balanced, thus enabling it to be readily trained by hand, although the ship may have a heel at the time.
There are three systems for performing the operation of training, primarily by hydraulic power, and should this fail through any of the piping being shot away, electric training gear can be quickly put into operation; and finally, should this be disabled, the turret can be trained by hand. Similarly the operation of elevating and depressing the gun can be performed by working primarily by hydraulic power, and then either by electric or hand. The operations of loading can also be performed by hand should the hydraulic system be disabled. To safeguard against accident by freezing in the intense cold which is found in the China seas during the winter months, heating apparatus is fitted throughout the turret installation. The gun mountings are so arranged as to give the gun 18 deg. elevation and 3 deg. depression, a greater range of elevation than has hitherto been provided for mountings of this description. The training angle is arranged for 270 deg., that is to say, from right ahead or right astern to 45 deg. before or abaft the beam. The turret can be trained at the rate of one complete revolution (viz. 360 deg.) per minute. In the shell-room, suitable overhead hydraulic lifting and traversing arrangements are made for lifting the shell out of the bays and placing them in the cage, but this operation can also be done by hand should necessity require it.
The sighting of the guns is provided for by a central sighting station and two side sighting stations, one on the left and the other on the right. By an ingenious arrangement the captain of the turret is enabled by working one lever to train or elevate the gun or to perform both these motions at the same time. Voice-pipes and other apparatus are fitted to enable the officer in charge of the turret to communicate his orders to the magazines and shell-rooms. A complete system of electric circuits enables the guns to be fired from any one of the eight positions either simultaneously or independently. Percussion firing arrangements are also provided.