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.