in the future. In fact, it seems not improbable that future naval actions will be fought between fleets at extreme ranges and out of sight of one another, either on account of smoke screens or of the prevailing limit of visibility on the surface. This will produce an entirely new set of conditions, both from the point of view of the effects of gunfire and of the methods by which the guns are used.
Let us consider first the effects of gunfire. At extreme ranges the angle of descent of the projectile is very steep, and the target presented by the vertical armour of a ship becomes small in proportion to that offered by the thinner horizontal armour. Again, the large angle of descent means that the vertical armour will be hit at a considerable angle to the normal and is therefore more difficult to pierce. An excessively thick belt of side armour, therefore, tends to become so much deadweight. In the long race for supremacy between gun and armour, the gun had forged a long way ahead when the attack was made so that the pro- jectile would hit at right angles or normal to the surface of the plate. Modern armour-piercing shells are now capable of piercing the heaviest armour carried afloat, even when fired at long range and striking at moderate angles to the normal. Moreover, these shells can carry their bursting charge of H.E. through the armour in a condition to explode and so do the desired damage to the vitals of the enemy. Moderately thick horizontal armour is, however, capable of keeping out the heavi- est projectile, even at the steep angles of descent which occur at very long ranges, since the angle to the normal at which the armour is hit is very much increased when the plates are pre- sented horizontally to the line of fire. It therefore appears cer- tain that a considerable increase in the horizontal protection must be one of the features of the designs of future warships, with a corresponding decrease in the area covered by the thick vertical armour. Again, the development of attacks upon ships by aircraft with bombs must lead to a desire for increased hori- zontal protection. The great destructive effect of H.E. points to the necessity of a more extensive subdivision of the ships internally, in order to localize the effects of shell bursts; and protection against torpedoes will have the same tendency.
The problems with which the control officers are faced become much more complicated as the range is increased. At ranges that approach the limits of visibility, the observation of the fall of the shot becomes very difficult, and it is practically impossible to decide whether the shot are falling over or short, unless they are directly in line with the target. As the range increases, errors caused by the roll, yaw and pitch of the ship, which are not so serious at moderate ranges, become accentuated, and have to be taken into account. The trajectory reaches a very high altitude, and the conditions of wind in the upper atmosphere cannot be known with sufficient accuracy to enable a correct forecast to be made of the effect on the projectiles. The effects of the variations in muzzle velocity of the guns, due to the wear of the guns, changes in the temperature of the charges, and other more obscure causes, become more pro- nounced. Range observation, even with the best-trained observers, becomes unreliable when the visibility is poor, and the errors in the range-finders themselves become greater as the range increases. From all these considerations it is evident that it is a matter of great difficulty to make an accurate forecast of the initial gun range and deflection. It has become the practice to obtain the hitting range by a process of " trial and error," using the gun as its own range-finder and obtaining what assist- ance is possible, under the prevailing conditions, from the avail- able " instruments of observation." This can be done as long as the fall of the shot can be observed, but becomes impossible as soon as this condition ceases to exist. The use of aircraft to assist the spotter, or to carry out the whole of the observa- tion of fire, naturally suggests itself; and it is in this direction, followed by the possible introduction of some form of indirect fire, that future developments are to be looked for. This must inevitably lead to complication and to the introduction of new instruments and methods of working. The increasing of the range must very much reduce the percentage of hits to be ex-
pected. This reduction in the probable number of hits, together with the increasing horizontal armour protection to be defeated, form the main arguments in favour of carrying larger guns.
Recent years have brought about a steady increase in the calibre of the guns that are mounted in capital ships; and in all the naval actions fought during the war experience has been in favour of the larger gun. There is still a trend towards further increasing the calibre of the guns, since victory will always rest with the side that can hit the harder at the longest range. The heavier the gun the greater the damage done by its shell, and the better its accuracy at extreme ranges. A limit in the size of the gun must, however, be reached when the weight of the ammu- nition begins to interfere seriously with the rapidity of fire. When this happens the call comes for an increased number of guns, and a limit is then imposed by the size of the ship.
The size of the guns in the secondary armaments has gener- ally increased to meet the development of the destroyer and sub- marine. To obtain the necessary rapidity of fire, these guns must be hand-worked, and this fact places a limit on their size. It appears therefore that no increase in calibre is likely beyond the 6-in. and 5- 5-in. guns that are now in general use in all navies.
In the decade before the war the i2-in. gun, firing a shell weighing between 800 and ooo lb., was the heavy gun that was almost universally mounted in the battleships of the world. The hitting power of these guns had been gradually increased by improving their ballistics, and no increase in calibre was made until after 1911. By this date the i2-in. gun had reached the limit of its development in the British navy in the i2-in. Mark XI. (50 cal.) gun.
The following summary shows how the gun armaments of warships of all classes gradually became heavier during 1910-20. The battle- ships of the " Colossus " class were armed with 10 12-in. Mark XI. guns, and 8 of the same guns were mounted in some of the con- temporary battle-cruisers of the " New Zealand " class. The " Colos- sus ' class were the last of the so-called " 12-in. Dreadnoughts," and the midship turrets were placed en echelon, so that all the guns could be used on either broadside. This disposition of the main ar- mament marks the transition stage to the centre-line arrangement, which by 1921 had been adopted in the capital ships of all navies. The secondary or anti-torpedo-boat armament in all these ships consisted of from 12 to 14 4-in. Q.F. or B.L. guns. The mam armament of contemporary ships in foreign navies also consisted of 12-in. guns, but both the United States and Japan increased the num- ber of the guns in their battleships to 12 as against the 10 in British ships. The secondary armament of the foreign ships was, at this period, usually heavier than the British, the Japanese having a mixed armament of 6-in. and 4'7-in. guns and the United States employing the 5-in. gun.
In 1912, the B.L. 13-5 Mark V. gun became the standard heavy gun for the capital ships of the British navy. It was introduced in order to increase the hitting power and also to obtain greater range, the demand for which was already being felt. This gun weighs 68 tons, and originally fired a shell of 1,250 lb. with a velocity of about 2,700 f.s. This was afterwards altered to a l,4OO-lb. shell, with which a velocity of about 2,500 f.s. was obtained. Ten of these 13-5 guns formed the main armament of the battleships of the " Orion " and " King George V." classes, which were completed in 1912 and 1913 respectively. The battle-cruisers of the " Lion " class, which were completed at the same time, mounted 8 13-5 guns, and in both the battleships and the battle-cruisers all the guns were mounted on the centre line of the ships, so that all could be used on either broadside. As a secondary armament all these ships carry 14 or 16 4-in. B.L. guns. In the battleships of the " Iron Duke" class and the battle- cruiser " Tiger," which were completed in 1914, the main armament remained the same as in the previous ships, but an advance was made by increasing the secondary armament to 12 6-in. guns in the place of the 4-in. guns.
In both the U.S. and Japanese navies the 14-in. gun was mounted in all ships completed since 1914. This gun remained the standard weapon, in both navies, up to the ships that were building or pro- jected in 1921, wherein a i6-in. gun was being adopted. The United States had retained a secondary armament of 5-in. guns, but in the American ships building in 1921 the 6-in. gun was to be mounted. Japan on the other hand, after having adhered to the 6-in. gun as the standard secondary-armament weapon for her later ships, was in 1921 adopting a 5'5-in. gun.
The year 1915 marked further progress by the introduction of the 15-in. gun into the British navy. This gun weighs 100 tons and fires a i,920-lb. shell with a muzzle velocity of about 2,500 f.s. These guns were used for the main armament of the 10 battleships of the " Queen Elizabeth " and " Royal Sovereign " classes. These ships mount 8 is-in. guns and have a secondary armament of 12 to 14
