through the door on to the projectile tray of the main cage. In the
shell room the shell are stowed in bins, lying 6n their sides with their
axes fore and aft. They thus start from rest in nearly the same posi-
tion in which they are required for loading into the gun, and remain
in this position during the whole of their course to the gunhouse.
This is an important point when the shell that are being dealt with
are over 5 ft. in length and weigh nearly a ton. Throughout the
mounting elaborate interlocking gear is fitted between the working
levers and the moving parts or the working valves of the different
machines. This is to ensure that the various operations shall only
take place in their proper sequence. Accidents are thus prevented,
which, on account of the high speeds at which the heavy weights are
worked, would be serious.
American Varieties. The Japanese turrets follow generally upon the British model, but in the American designs there are essential differences, amongst which the following are the most noticeable. Electric power with hydraulic transmission is almost entirely used for working the machines, and no power other than the electric supply is brought into the turrets from outside. Inside the gun- house the arrangement of the guns and slides is generally similar to that of the turrets of other navies, but the methods by which the various operations are performed are different. For instance, springs are almost invariably used for returning the guns to the firing posi- tion, and a large screw is used for elevating instead of an hydraulic cylinder. The breech is usually worked entirely by hand, and in the loading arrangements there are considerable differences from those of other turrets. The shell and cartridges are sent up to the guns separately : the former vertically in tubes on the outsides of the guns, and the latter by a central hoist placed in rear of and between the guns. The shell are transferred by hand to the horizontal position on arrival at the top of the vertical tubes, and are then rolled on to loading trays in rear of the guns. The cartridges are transferred by hand from the cartridge hoist to the same loading trays. Power- worked rammers are used for loading, which operation can only be carried out at a fixed elevation. The central part of the turret below the gunhouse is occupied by the arrangements for passing up the cartridges. This operation is carried out, to a great extent, by hand, and complete precautions against the passage of flash are fitted between the different compartments.
The shell arrangements differ entirely from those adopted by any other navy. The shell rooms consist of circular compartments which are built into the ship, just below the level of the lower part of the barbettes. The shells are stowed standing on their bases, instead of horizontally as is the custom in the turrets of other navies. The shell chamber in the turret, which is in the same relative position as the working chamber in British turrets, forms a revolving platform in the centre of the circular shell room. The shells are passed, still standing on their bases, from the fixed to the revolving part of the floor. From the shell chamber to the gunhouse the shells are carried up the vertical tubes in buckets. These buckets when loaded are balanced about their centres of gravity. On arrival at the top of the tubes the buckets are turned by hand into a horizontal position, and the shells are thus placed in the position required for loading into the gun. A noticeable feature of these turrets is the number of operations for which alternative hand gear is provided, and also the large number of small compartments into which the structure below the gun- house is divided. .
German Varieties. The German turrets did not differ very greatly, in their main essentials, from the British, but were noticeable for their large gunports and for the somewhat cramped space inside the gunhouse. The loading arrangements differed, because, except in the case of the ships with 15-in. guns, the Krupp type of breech mechan- ism is used. With this type of mechanism the obturation entails the use of a brass cylinder for the rear cartridge of the charge. The projectile is supplied separately from the charge, in a cage on the outer side of each gun, whilst the cartridges come up to the gun- house in cages between the guns. Both shell and cartridge cages are loaded in a working chamber under the gunhouse, the ammunition being supplied to the working chamber by cages working in a revolving trunk. The system of placing the rear cartridge in a brass cylinder has the disadvantage that, owing to their heat, the cylinders are heavy and difficult to handle after firing, and special arrange- ments have to be made for passing them out of the turret. These disadvantages are partially compensated for by the increased pro- tection from flash which is given to the ammunition ; and a very noticeable feature in the German turrets was the absence of flash- tight doors and other such arrangements for the prevention of the passage of flash to the magazines. The loading operation is carried out at a fixed angle of elevation. In the earlier German turrets ramming was carried out by hand only, but in the more modern designs a power rammer is fitted. The rate of fire that could be obtained with the German turrets appears to have been slightly greater than that with the British for short periods, but for prolonged firing the British system is surer and probably the quicker. The power used in the German turrets is hydraulic, supplemented by electrical gear to a greater extent than in the British service.
Triple Turrets. In most foreign navies the triple turret has appeared, but the British navy has been slow to adopt this innova- tion. This development is due to the desire to increase the gun power of the capital ships, without unduly increasing the size of the
ships themselves. Six guns mounted in 2 triple turrets occupy less of length of the ship, which is the important factor, than do the same number of guns mounted in 3 twin turrets. Designs of quadruple turrets have been produced, but it does not appear likely that the number of guns in a single turret will exceed three. It is not clear that economy of space would result from mounting more than 3 guns in one turret, on account of the large space that must be found immediately below the guns for the stowage of the ammunition. In the existing designs of triple turrets, the guns are placed side by side on the same level, and the loading and working of the breech of the centre gun present difficulties which must be solved if the rate of fire of this gun is to be the same as that of the other two. The methods of firing the guns mounted in multiple turrets, and the control of the fire, also present new problems which need investiga- tion, but there seems little doubt that in the near future the triple turret will be adopted by all navies, for economy in space.
Medium-heavy Guns. Few modern ships now mount a medium- heavy gun in either their main or their secondary armament. Guns of from 10 to 7 in. in calibre are not powerful enough to be of any real use as long-range weapons against armoured ships, and since their ammunition is too heavy to be man-handled they cannot be used for rapid fire and are consequently out of place in secondary armaments. The lo-in. gun has never been much used in the British navy, but at one period the g-2-in. B.L. gun attained a high degree of favour. It formed the main armament of the armoured cruisers that immediately preceded the battle-cruisers, supplemented in some cases (e.g. the " Minotaur " class) by the 7'5-in. B.L. gun. The 9-2 B.L. gun also formed the secondary armament of the battleships of the " Lord Nelson " class, which was designed just before the " Dreadnought." Ships having a mixed armament of heavy and medium-heavy guns appeared in foreign navies at the same time as the " Lord Nelson," but since that time guns of medium calibre have not appeared in the armament of any capital ship. During the war, therefore, the lO-in. gun was scarcely used at all, and 9-2 and 7-5 in. guns were only mounted in a number of ships that were rapidly becoming obsolete, and also in a few small monitors, in which they were specially mounted for bombarding at moderate ranges. The relative weakness of the medium-calibre gun was well illustrated at the battle of the Falkland Is. when the German ships, armed with 8-in. guns, speedily fell victims to the greater range and hitting-power of the 12-in. guns of the British battle-cruisers.
The 7'5-in. gun has, however, been revived as the main armament of the " Hawkins " class, which is the largest type of modern British light cruiser. It was originally intended that the guns in these ships should be entirely hand-worked, and special arrangements were made for handling the 2OO-lb. projectiles. In the trial stage, however, it was found necessary to add power for working the elevating and training gear, in order to compete with the rapid motion of the ships. The gun is carried in a cradle through which it recoils, and the usual recoil cylinders and spring or pneumatic running-out arrangements are fitted. The trunnions of the cradle are carried in trunnion bearings on 2 side transoms built up on the floor of the mounting. The turntable is carried on a roller ring, and there is no vertical communication between the mounting and the lower part of the ship. All the ammunition arrangements are entirely separate and in general follow the usual practice for 6-in. guns. The shell and cartridges are brought up in separate hoists from below and from the tops of the hoists are carried to the guns by hand. A swinging loading tray is fitted on the rear part of the cradle and on to this the projectile is placed and the whole of the loading operation is carried out by hand. This is most fatiguing work with projectiles of this weight and there is little doubt that the mounting for any gun larger than 6 in. must be largely power-worked to be entirely satisfactory.
As the result of war experience, the mountings for the 6-in. and 5'5" m ' guns have undergone a change in design, from the old pedestal (P.) mounting to the central pivot (C.P.) type. This has been caused by the necessity for increasing the elevation in order to obtain greater range. Also, mountings of the C.P. type have the added advantage that the base, which is fixed to the deck, is larger in diam. than is the case with P. mountings, and the severe stresses on firing are thus more evenly distributed to the structure of the ship. In the P. mountings the elevation was limited to from 15 to 20, as the bot- tom of the cradle fouled the carriage and the breech of the gun hit the deck when firing at higher elevations. The elevation in this type of mounting can be increased either by lengthening the arms of the carriage or by raising the whole pedestal off the deck on a packing ring. Both these methods are objectionable, as they tend to raise the breech of the gun so far off the deck as to make loading a difficult matter when firing at moderate angles of elevation. But many such alterations were made to P. mountings during the war.
In the C.P. mountings a circular plate is bolted to the deck which has a low pivot in its centre. The circumference of the plate is shaped to form the lower roller path of the mounting, and inside this roller path a fixed circular training rack is fitted. Working round the pivot and carried on the rollers is the revolving platform of the mounting. The whole of the weight of the gun and mounting is taken on the rollers, the pivot being used only to prevent any lateral motion. Two side transoms are built up on the revolving platform, and at the top of these transoms are the trunnion bearings. Strength- ening plates are built across the front of the transoms, but the rear
