and so impair his sea-going qualities.

before to 60° abaft the beam, while two guns each side forward | unarmoured portions of his side diminish his reserve of buoyancy and two aft (one forward and one aft in the "Majestic " class) fired through similar arcs to the turret guns, but on their own sides only. Four of these 6-in. guns were mounted on either side of the main deck and two on either side of the upper deck, all being enclosed in casemates.

In the armoured and large protected cruisers built contemporaneously with these classes of battleships, the 9-2-in. gun had been largely mounted, and it was the improvements brought about by practical experience in the rate and accuracy of fire of this gun that suggested its adoption in battleships to replace the whole or a part of the 6-in. armament. During the period in which the battleships referred to above were constructed, the idea of the

12

"Dreadnought"

"Lord Nelson"

"London"

FIG. 90.-Diagrams showing Disposition of Armament in Typical Ships. functions of the respective divisions of the armament was that the 12-in. guns were to injure the enemy's vitals by piercing his armour with armour-piercing shot or shell, while the business of the 6-in. guns was to cover him with a hail of shells of large

These ideas were gradually losing favour; it was realized that the damage done by an armour-piercing shot, whether or not it hit and pierced armour, was limited to its own path, while that done by an armour-piercing shell striking an unarmoured portion of the ship's side was inconsiderable as compared with that effected by a common shell of the same calibre. Further, the area of side, by piercing which an armour-piercing projectile would reach any portion of the propelling machinery or magazines of an enemy, was so small compared with the whole exposed area of his side and upper works that it was scarcely advantageous to fire at it projectiles, the effectiveness of which, if they struck another portion of the enemy, was small in comparison with that of other projectiles which might equally well be fired from the same gun. Again, the lessons of practical experience showed that ships might be and were defeated by shell fire alone, while their armour remained unpierced, and propelling machinery and magazines intact.

All these considerations led to the conclusion that it was to intensity of shell-fire, and especially to the fire of large capacity and high explosive shell, that attention should be directed. At the same time, while the rate of fire of the 6-in. guns, to which great attention had been paid, remained stationary or nearly so, the rate of fire of the 9.2 in. and 12-in. guns had considerably improved, and their ballistic powers rendered possible more accurate firing at long ranges than could be effected with the 6-in. guns. The explosive effect of a shell is said to vary as the square of the weight of its bursting charge. The bursting charge. with shell of the same type, bears a constant proportion to the weight of the shell. Now the weight of the 12-in. shell is 850 lb, that of the 9-2-in. 380 lb, that of the 6-in. 100 lb. Hence it would require fourteen 6-in. shells to produce the same effect as one 9.2-in., and seventy-two to produce the same effect as one 12-in. shell, consequently the 6-in. gun to produce the same shell effect as the 12-in. or 9-2-in. gun must fire 72 times, or 14 times, respectively, faster. The rate of fire of guns in action depends upon a variety of conditions, an important one being that of smoke interference, which tends to reduce the maximum rate of fire of the smaller guns nearer to that practicable with the heavier guns, but the rate of fire of the three guns in question,

under battle conditions, is in the approximate proportions of 1: 154, which would thus produce a shell effect (supposing the hits made by each type of gun to bear a fixed proportion to the rounds fired), in the proportions of 72: 22: 4, for the 12-in., 9.2-in. and 6-in. guns respectively. This argument of course takes no account of the probably greater effect produced by the dispersion of the larger number of hits of the smaller gun over the exposed area of the target, nor, on the other hand, does it take account of the greater armour-piercing power of the 12-in. shell which would have the result that a larger proportion of the hits from the smaller gun would be defeated by the enemy's armour, and so prove innocuous.

The shell effect forms a strong argument for the weight available for the heavy gun armament of a ship being disposed of in the form only of the heaviest gun available. Another strong argument is that deduced from the fact already stated, that, as the calibre of the gun increases, its ballistic powers enable accurate shooting to be made at a longer range.

which is termed "spotting," a duty the performance of which calls for the exercise of the most accurate judgment on the part of the "spotter," and which requires much practice in order that efficiency may be secured. In practice, the first shot is fired with the sights adjusted for the distance of the target given by the range-finder, corrected as far as is practicable for the various conditions affecting the gun range. The first shot is spotted, and the result of the spotting observations governs the adjustment of the sights for the next shot, which is spotted in its turn, and the sights are readjusted until the target is hit. From this time onwards it is (in theory) only necessary to apply the change in range, due to the movements of our own ship and of the enemy, for the interval between successive shots, in order to continue hitting. This change of range, which may be considerable (e.g. 1000 yds. per minute in the extreme case of ships approaching each other directly, and each steaming at the rate of 15 knots), is in practice extremely difficult to estimate correctly, and the spotting is consequently continued in order to rectify errors in estimating the rate of change in range. For various reasons the gun range which has been referred to is not the same for different natures of guns. This is mainly on account of the difference in the height attained by their projectiles in the course of their respective trajectories. While it is possible, by careful calibration (i.e. the firing from the several guns of carefully aimed rounds at a fixed target with known range and under favourable conditions for practice), to make the shots from all guns of the same nature fall in very close proximity to each other when the sights of all are similarly adjusted, it has not been found possible in practice to achieve this result with guns of different natures. Consequently guns of cach nature must be spotted for independently, and it is obvious that this adds considerably to the claboration and complication of the fire control system.

The accuracy of a gun at any range depends mainly, for practical naval purposes, on what is known as the "dangerous" space," or the limit within which the range must be known in order that a target of a given height may be struck. Again, the dangerous space at any range depends upon the remaining velocity of the projectile at that range, which, as between guns of different calibres but with the same initial muzzle velocity, is greater, the greater the calibre of the gun and weight of projectile, the advantage possessed by the larger gun in this respect being much increased at great ranges. As a practical example, for a target 30 ft. high at a range of 8000 yds., the dangerous spaces of modern 12-in., 9-2-in. and 6-in. guns, which do not differ greatly in muzzle velocity, are 75, 65 and 40 yds. respectively. At whatever range a naval action is to be fought, it is evident that there must be a period during which the enemy is within the practical 12-in. gun range, and outside the practical 6-in. gun range, and that during this period the weight allotted to 6-in. guns will be wasted, and this at the outset of an action, when it is more important than at any time during its progress to inflict damage on the enemy as a means of preventing him from inflicting damage on ourselves. But if all the weight available be allotted to 12-in. guns, the whole of the armament which will bear on the enemy will come into action at the same time, and that the earliest, and consequently most advantageous, time possible. This train of argument led to the substitution of 9.2-in. guns in the 8 King Edward VII." class (the first of which was completed in 1905) for the upper deck 6-in. guns, and eventually in the "Lord Nelson" and " Agamemnon" (completed in 1908) to the abolition of the 6-in. armament, which was replaced by ten 9.2-in. guns.

At the beginning of the present century the subject of "fire control" began to receive considerable attention, and a short statement is necessary of the causes which render essential an accurate and reliable system of controlling the fire of a ship if hits are to be made at long range. In the first place, even with the 12-in. gun, the range must be known with considerable nicety for a ship to be hit. At a target 30 ft. high, at 8000 yds., for example, the range on the sights must be correct within 75 yds. or the shot will fall over or short of the target. No rangefinder has yet proved itself reliable, under service conditions, to such a degree, and even if one were found, it could not be relied upon to do more than place the first shot in fair proximity to the target. The reason for this lies in the distinction which must be drawn between the distance of a target and its " gun range," or, in other words, the distance to which the sights must be adjusted in order that the target may be hit.

This gun range varies with many conditions, foremost among which are the wear of the gun, the temperature of the cordite, the force and direction of the wind and other atmospheric conditions. It can only be ascertained with certainty by a process of "trial and error," using the gun itself. The error, or distance which a shot falls short of or beyond the target, can be estimated with a greater approach to accuracy the greater the height of the observer. It is the process of forming this estimate I

This constitutes one of the reasons for the adoption of the uniform armament in the "Dreadnought" and her successors; another important reason lies in the fact that with the weight available for the heavy gun armament disposed of in a small number of very large guns, a greater proportion of these guns can be mounted on the midship line, and consequently be available for fire on either side of the ship (see fig. 90). Thus in the "Dreadnought," eight of her ten 12-in. guns can bear through a considerable arc on either beam, while in the "Lord Nelson," although all her four 12-in. guns can bear on either beam, half at least of her 9.2-in. armament (i.e. that half on the opposite side to the enemy) will be at any moment out of bearing, and consequently be for the time a useless weight. The same principle of a uniform armament of 12-in. guns has been adopted in the Invincible" type, the only large cruisers designed since the inception of the "Dreadnought." Thus the 12-in. gun forms the sole heavy gun armament of all battleships and large cruisers of the " Dreadnought era. The gun so carried is known as the Mark X., it is 45 calibres in length, and fires a projectile weighing 850 lb with a charge of cordite of 260 lb, resulting in a muzzle velocity of 2700 ft. per second. The Mark XI. gun was designed to be mounted in the later " Dreadnoughts." Following the same line of development as resulted in the Mark X. gun, it is longer, heavier, fires an increased charge of cordite, and has a higher muzzle velocity, viz. of 2960 ft. per second. This gun appears to mark the climax of development along the present lines, since the price to be paid in greater weight, length and diminished durability of rifling is out of all proportion to the small increase in muzzle velocity. Further developments would therefore be looked for in some other direction, such as the adoption either of a new form of propellant or of a gun of larger calibre. A modern gun of 10-in. calibre is found in the battleships" Triumph "and" Swiftsure." The next gun in importance to the 12-in. is the 9-2-in., which forms part of the armament of the "Lord Nelson " and "King Edward VII." classes of battleships, and the principal armament of all armoured cruisers (excepting the "County" class) antecedent to the "Invincibles.” The latest gun of this calibre has developed from earlier types in a similar manner to the 12-in., that is to say, it has experienced a gradual increase in length, weight, and weight of charge, with

light craft is one giving 2300 ft. per second muzzle velocity only and has a very long recoil. The 6-pounder and 3-pounder Q.F. guns are no longer being mounted as part of the armaments of modern ships. A very high rate of fire was attained in the "semi-automatic mounting of the 3-pounder, which was last fitted in the " Duke of Edinburgh " class, but for reasons already given guns of this type are no longer required, and the 3-pounder is retained only as a boat gun for sub-calibre practice.

All double-banked pulling boats and all steam-boats are fitted with arrangements for mounting one or two guns, according to the size of the boat; the object of the boat armaments being for use in river operations, for covering a landing, or in guardboats. Three descriptions of gun are used, the 12-pounder 8 cwt. and 3-pounder, light Q.F. guns, and the Maxim rifle-calibre Gun-Mountings.-Gun mountings in the British navy may be divided broadly into two classes, power-worked and handworked mountings. The former class includes the mountings of guns of all calibres mounted in turrets or barbettes, also of 9-2-in. guns mounted behind shields; the latter class includes mountings of guns of all sizes up to the 7.5-in. which are mounted in batteries, casemates or behind shields.

a consequently increased muzzle velocity. The latest type, |
which is known as the Mark XI., and is mounted in the "Lord
Nelson" and "Agamemnon," is 50 calibres in length, weighs 28
tons, and with a charge of cordite of 130 lb gives to a projectile
of 380 lb a muzzle velocity of 2875 ft. per second. The 7.5-in.
gun forms the secondary armament of the "Triumph" and
"Swiftsure," and is mounted in the armoured cruisers of the
"Minotaur," "Duke of Edinburgh" and Devonshire
classes. The 6-in. gun, of which there are a very large number
afloat in modern, though not the most recent, battleships, and
in armoured and first and second class cruisers, is the largest gun
which is worked by hand power alone. For this reason, and on
account of its rapidity of fire, it was for many years popular as
an efficient weapon. It was evolved from the 6-in. 80-pounder
B.L. gun, constructed at Elswick, which was the first breech-machine gun.
loader adopted by the Royal Navy, and whose development has
culminated in the 6-in. Mark XI. gun of the "King Edward
VII" class and contemporary cruisers, which fires a 100-lb
projectile with a muzzle velocity of 2900 ft. per second. It has
only now passed out of favour on account of its inferior hitting
power at long range as compared with that of guns of larger
calibre, and as a secondary armament of 6-in. guns is still being
included in the latest battleship designs of more than one foreign
navy-notably that of the Japanese, with their practical experi- |
ence of modern war at sea-its abandonment in the British Navy
can scarcely be considered final. The 4-in. Q.F. gun is mounted in
the third-class cruisers of the "P" class as their main armament,
and an improved gun of this calibre, with muzzle velocity of
about 2800 ft. per second, is mounted in the later "Dread-
noughts," as their anti-torpedo-boat armament.

Hydraulic power has been adopted almost universally in the British navy for power-worked mountings, although electricity has been experimented with, and has been largely applied in some foreign navies. The principal advantages of hydraulic, as compared with electric, power are its comparative noiselessness and reliability, and the ease with which defects can be diagnosed and rectified. On the other hand, electric power is more easily transmitted, and is already installed in all ships for working The increase in size of modern torpedo craft and the increased electric light and other machinery, whereas hydraulic power, range of modern torpedoes has led to a reconsideration of the when used, is generally installed for the purpose of working the type of gun suitable for the protection of large ships against guns only. The 12-in. guns in the "Majestic " class, following torpedo attack. The conditions under which the anti-torpedo- the practice with the earliest heavy B.L. guns, were loaded boat armament comes into play are the most unfavourable normally at extreme elevation of 131°, and the turret had to be possible for accurate gun-fire. The target is a comparatively trained to the fore and aft line and locked there for each occasion small one; it comes into view suddenly and unexpectedly; it of loading. An alternative loading position was also provided, is moving rapidly, and the interval during which the boat must in which the guns could be loaded at 1° of elevation and with be stopped, ie. that between her being first sighted and her the turret trained in any direction. Loading in the alternative arrival at the distance at which she can expect to fire her torpedo position could, however, only be continued until the limited with success, is in all probability a very short one. Moreover, supply of projectiles which could be stowed in the turret was in the great majority of cases the attack will be made at night, exhausted. Experience showed that a greater rapidity of fire when the difficulties of rapid and correct adjustment of sights, could be obtained by the use of this "all round "loading position, and of range-finding and spotting, are intensified. Two require- as it was termed, and in the latest ships of the "Majestic ments then are paramount to be satisfied by the ideal anti-class, and in subsequent battleships, the fixed loading position torpedo-boat gun: (1) it must have a low trajectory, so that has been abandoned. its shooting will not be seriously affected by a small error in the range on the sights; (2) one hit from it must suffice to stop a hostile destroyer.

For many years it was considered that these requirements would be met by the 12-pounder, which was the anti-torpedo-boat gun for battleships from the "Majestics "to the " Dreadnought," the 12-pounders mounted in the "King Edwards" and the "Dreadnought" being of a longer and heavier type, giving a higher muzzle velocity. The introduction of a larger gun has, however, been considered desirable, and a 4-in. gun of new type is mounted in the later "Dreadnoughts," while in the older battleships and large cruisers with secondary armaments it is considered by many officers that the 6-in. guns will prove to be the most effective weapon against torpedo craft. armament of destroyers being required to answer much the same purpose as the anti-torpedo-boat armament of large ships, namely, to disable hostile torpedo craft, the type of gun used has followed a similar line of development.

The gun

Starting with 6-pounders in the first destroyers built, the majority of the new destroyers have a fixed armament consisting of one 12-pounder forward, and four 6-pounders. This armament has been changed in the larger destroyers to one of 12-pounders only, while the latest ocean-going destroyers have two 4-in. guns. Owing, however, to the strength of the decks of such craft being insuficient to withstand the stresses set up by the discharge of a gun giving very high muzzle velocity, the 4-in. gun for use in

The details of recent 12-in. mountings vary considerably, a drawing of one of the most recent being shown in fig. 91, for which thanks are due to Messrs Vickers, Sons & Maxim, but in the majority A fixed ammunition hoist brings the shell and cartridges from shellof cases there is a "working chamber" revolving with the turret. room and magazine respectively into the working chamber, where they are transferred to a cage which takes them up, by hydraulic power, to the rear of the gun. The gun is strapped by steel bands to a cradle (see fig. 91) which moves in and out along a slide on recoil, the gun always remaining parallel to the slide. Gun, slide and cradle are pivoted for elevation on trunnions carried in trunnion bearings fixed to the structure of the turret, and the whole moving weight is balanced with the gun in the "run out" position. The recoil of the gun on firing is taken up by a hydraulic press placed underneath hydraulic power. Loading is carried out by means of a hydraulic the slide, and the gun is run out again into the firing position by rammer, with the gun in the " run out position, and at an angle of elevation which varies with different mountings. In the most recent mountings loading can be carried out with the gun at any elevation, thus affording considerably greater facility to the gunlayer for keeping his sights on the target during the process of loading, and so increasing the rate of fire by enabling the gun to be discharged immediately the loading operations are completed. underneath the slide, the pistons working on an arm projecting Elevating is by hydraulic power, and is effected by cylinders placed downwards. Turret turning engines are also hydraulic, and much attention has been given of late years to the perfection of elevating and turning gear such as will enable the turret or gun to respond instantly to the wish of the gun-layer, and to move either with considerable rapidity, or very slowly and steadily as would be the case when following a target at long range and with but little motion on the ship. The breech is opened and closed by hand or by hydraulic

power, and a douche of water or blast of air, or a combination of both, removes any smouldering fragments of cordite or cartridge material before a fresh round is loaded.

Although there is little difference in principle between the arrangements of the mountings in the later Majestics" and those in the "Dreadnought," improvements in detail have enabled the interval between successive rounds to be reduced from about 55 seconds in the former case to 25 or 30 seconds in the latter.

In the turrets containing 9-2-in. and 7.5-in, guns, which exist in most British armoured and first-class protected cruisers, the moving weights are, of course, not so large, and, as might be expected, the assistance of hydraulic machinery is not necessary in so many operations. A drawing of a typical 9-2-in. gun and mounting is shown in fig. 92.

R1, Transferring rammer pro

jectiles from trunk cage to
gun-loading cage.

Rs, Transferring

rammer for powder charges from trunk cage to gun-loading cage.

Rs, Transferring chamber.
R, Training rack.

Rs, Training engine.
S, Rotating trunk.
T, Turntable.

W, Casing for chain rammer.

the 4-in. and 12-pounder, which are mounted in small cruisers and destroyers.

The principles of the 6-in., 4-in. and 12-pounder mountings are similar. The rear part of the gun is partially enclosed in a metal cradle, which carries the recoil cylinder and running out spring box. The gun and cradle are balanced for elevation about trunnions on the cradle, which fit into trunnion bearings on the carriage. The latter carries the elevating and training gear, and the whole moving weight is borne by a pivot pin which rotates on a ball bearing. The gun recoils in the line of fire, and the energy of recoil is absorbed by means of the recoil piston, whose rod is secured to the gun, passing over a valve key secured to the cradle, in such a way as to produce channel of varying sectional area through which the liquid in the recoil cylinder must pass from one side of the piston to the other. Springs run the gun out again after firing into its original position. The breech is opened by the single motion of a hand lever. A "bare" charge is used in the 6-in. and 4-in. guns, with the de Bange type of obturation, while a brass cartridge case has been retained with the 12-pounder, as with the earlier Q.F. guns.

a

Firing is by electricity, percussion being available as an alternative if required, and the current is usually taken off the dynamo mains of the ship.

Training the turret and elevating the guns are, however, in all cases performed by hydraulic power, as is the raising of the projectiles to their place on the loading tray in rear of the gun, but the breech is opened and closed, and the charge and projectile rammed home, by hand power only, while the gun, after recoil, is forced out again to its firing position by means of springs. A ready supply of thirty-two projectiles is stowed in a "shell carrier," which is a circular trough running on rollers round the turret, but independently of it. When a projectile is required to be loaded into the gun, the shell carrier is rotated until the required projectile is under a hatch Sighting.-The great advances recently made in accuracy in rear of the gun, when the projectile is raised by a hydraulic press of fire have been rendered possible, to a very great extent, by on to a swinging loading tray. It is intended that the shell carrier shall be replenished direct from the shell-room during the pauses of the use of telescopic sighting apparatus. Arrangements are an engagement. A new type of 9-2-in. mounting has been installed made in all modern sights for the bars or disks which carry in the Lord Nelson" and "Agamemnon," in which greater use is the range graduations to be of considerable length or diameter made of hydraulic power with a view to improving rapidity of fire. In this mounting, each projectile is brought up from the shell-respectively, in order that no difficulty may be found in room as it is required, and the loading operations are performed by hydraulic power instead of by hand.

The "King Edward VII." class of battleships and "Duke of Edinburgh" class of cruisers are the last ships in which any 6-in. guns have been mounted, and with the exception of the 7.5-in. guns in the "Triumph" and "Swiftsure," these are the largest guns which are worked entirely by hand. Other hand-worked guns are

adjusting the sights for every 25 or 50 yds. of range. In the larger hand-worked mountings, where the laying of the gun for elevation and for direction is effected by two men on opposite sides of the gun, the sights used by them are "cross-connected," i.e. connected by rods and gearing to one another in such a way that, initial parallelism of the axes of the two telescopes having

been secured, the adjustments to one sight made by the sight- | to the graduations shown on the range dial, which is concentric setter are simultaneously effected at the sight on the opposite