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side is left open to allow the gun and cradle to swing in elevation. The cradle is fitted with trunnions, and the gun works axially through it on recoiling. The recoil is controlled as usual by a recoil cylinder containing a fluid and a piston with a gradually restricted port.

The gun is run out after firing, either by springs or by pneumatic recuperators. The elevating arc is attached to the centre of the lower part of the cradle (instead of to one side as in the P. mount- ings), and into it gears a pinion carried on a shaft working through bearings in the side transoms. This shaft is geared to the elevating control wheel, which is fitted in the gunlayers' position. The mount- ing is trained by a pinion which works in the circular rack on the inner side of the lower roller path, and which is geared to training wheels at the gunlayers' and trainers' positions. All the voice pipes and electrical cables are brought on to the mounting through the central pivot. In this particular the C.P. mountings are much more convenient than the P. mountings, as the number of these leads has been much increased during recent years. An extreme elevation of 30 or more is obtainable on the latest C.P. mountings, and the breech of the gun is between 50 and 60 in. off the deck when the gun is horizontal. To facilitate loading a swinging loading tray, having a motion parallel to the axis of the gun, is usually attached to the left rear end of the cradle. Special platforms are provided for the load- ing numbers for use when the gun is being loaded at moderate angles of elevation.

FIG. 48. British 6-in. B.L. Mk. XII. gun on a Mk. XIV. C.P. mounting.

Typical mountings of this pattern are the British 6-in. C.P. XIV. and 5-5 C.P. II. The former is mounted in modern light cruisers and the latter is used in H.M.S. " Hood." Fig. 48 illustrates the 6-in. C.P. XIV. mounting.

Guns of Lesser Calibre. The gun mountings used for the 4-in. and 4-7-in. guns have undergone a change from the P. to the C.P. type, similar to that which has taken place with the heavier guns, and for the same reasons. Guns of these calibres were used in large numbers during the war for two main purposes: (a) for the armaments of destroyers and other small craft ; (b) for the defensive armament of merchant ships and auxiliaries.

For the destroyer armaments the guns that were used in the British service were the 4-in. Q.F. Marks IV. and V. and the 4'7-in B.L. Mark I. The two 4-in. guns are of the semi-automatic type, in which the recoil of the gun opens the breech and ejects the fired cartridge leaving the breech open, and the insertion of a new car- tridge automatically closes the breech and puts the gun in the firing position. With these guns a rate of fire of from 15 to 20 rounds per min. can be obtained with a well-drilled crew. The 4-in. Q.F. Mark IV. gun was originally mounted on the P. IX. mounting, which is of the usual pedestal type with a maximum elevation of 20 degrees. The C.P. Mark III. mounting, which was subsequently introduced for this gun, is constructed on the same general principles as the C.P. mountings for the heavier guns, and admits of an elevation of 30 degrees. Certain modifications are introduced to suit the particular type of gun, and there are alterations in detail to meet the severe conditions that gun mountings are bound to be subjected to in destroyers. Both these mountings and all others designed for use in destroyers allow of a very long recoil, usually approaching 36 in. This is in order to minimize the deck stresses, which become serious when guns of this size are mounted in such lightly built craft. The 4-in. Q.F. Mark V. gun, which is heavier and more powerful than the Mark IV., is mounted on the C.P. Mark II. mounting, which is heavier than, but very similar in general design to, the C.P. III. and admits of an elevation of 30 degrees. The 4-7-in. B.L. Mark I. gun is mounted on the C.P. VI. mounting, which is a central pivot mounting very much like a small edition of the 5-5 C.P. II. The

4-7, being a B.L. gun, has its cartridges made up bare, with no brass cartridge case. A considerable saving in the weight of the ammuni- tion is thus made but the rate of fire of this gun is less than that of the 4-in. Q.F. guns.

The very large numbers of guns required for the arming of mer- chant ships at the beginning of the war at first taxed the resources of the British navy to their utmost; in fact, at one period it became necessary to mount obsolete army guns on improvised naval mount- ings in order to provide some sort of armament. In the first two years of the war any guns of 6-in. calibre or smaller, that could be spared from other services, were adapted for defensively arming merchant ships. Subsequently the production, in bulk, of the 4-7-in. Q.F. Mark V. and the 4-in. B.L. Mark IX. guns provided a standard armament for this purpose. Both the mountings for these guns were made as simple as possible, as they had to be handled to a great extent by unskilled men. The 4'7-in. gun is mounted on the P.V. mounting, a simple mounting of the pedestal type, without a shield, which gives the gun an elevation of 20 degrees. The 4-in. B.L. Mark IX. gun is mounted on the C.P.I, mounting upon which an elevation of 30 can be obtained. The gun on this mounting can be protected by a shield, but when it was first used in merchant ships this shield was not used. Subsequently, however, the shield was added in these ships, partly for moral effect and partly for protec- tion against the weather, but the mounting was shorn of all other complications (see fig. 49).

The usual control of fire fittings and a more elaborate sight than was found necessary in the merchant ships can be fitted to this mounting, and in this form it was used for arming sloops and other small ships. Large numbers of these two guns were produced in the last year of the war and they were used to replace the less efficient weapons that had been mounted in merchant ships. A triple mounting was made for the 4-in. B.L. Mark IX. gun and was used in the secondary armament of the battle-cruisers of the " Re- nown " class. In this mounting the guns are carried side by side in cradles which move together in elevation, on a mounting of the C.P. type. A few special mountings for 4-in. guns have been made for arming submarines. These are usually of the pedestal type, are constructed of non-corrosive metals and are specially designed to offer small resistance to the water when the submarine is submerged.

With regard to the smaller guns, the 3-pdr. and 6-pdr. may be considered to be obsolete except in very small craft. It is true that large numbers of these guns were used in the early part of the war because they were in existence and there was nothing at the time to take their place. Later they were replaced, almost entirely, by the l2-pdr_ Q.F., large numbers of which were used for arming patrol, craft, small merchant ships and auxiliaries. Several different pattern mountings were used for 12-pdr. guns, but all are of the pedestal type and most of them admit of an elevation of 30 degrees. The 12-pdr. ,

FIG. 49. British 4-in. B.L. Mk. IX. gun on a Mk. I. C.P.

mounting.

gun is usually laid, trained and fired by one man, elevating gear being fitted and the training being controlled by a shoulder-piece.

High-Angle Mountings. The rapid development of aircraft has called for a new type of armament in the form of a high-angle gun. The commencement of the war found all nations unprepared to meet the new forms of attack that were quickly developed by the aircraft; and although the menace had been realized none of the belligerent nations had advanced much beyond the trial stages in the development of an anti-aircraft armament. The problem of hitting an airship or aeroplane is a difficult one, since the target is moving in 3 planes and at great speed. A vast amount of experience was obtained on shore during the war, but the problem is still far from being entirely solved. It is true that the high-angle gunfire succeeded in making the aircraft fly at a greater height, and therefore the attainment of their objectives has been rendered more difficult. At sea, much less experience has been gained and the problem is a much more difficult one, since the platform upon which the guns are mounted is a moving and unstable one and this adds immensely to the complications. The attack of aircraft necessitates the use of special shell and very accurate fuzes, and it is with the latter that a large number of difficulties have occurred. At the outbreak of the