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CATION AND See also:SIEGE-See also:CRAFT. Mountings of the See also:barbette type are much favoured in the See also:British service for guns of types (a) and (b); one of the most See also:modern is shown in fig. 84, where a 9.2" B.L. See also:gun, See also:Mark X., moantte is placed upon a Mark V. mounting, a See also:combination which logs. admits of over five aimed rounds in two minutes. The British 9.2" B.L. Gun.—F' mounting, fig, 85 a longitudin larger See also:scale. The gun, which i and recoils in the See also:cradle C, bei slide in See also:longitudinal grooves i attached the buffer See also:cylinder B gun, while the See also:piston See also:rod L i engaging with the buffer cyli See also:bronze casting containing two attached to the See also:rear of the cr E in the See also:lower See also:carriage. Thu are built up into a shallow See also:dome which See also:complete mountings as with a cap: the whole structure turns t traversed See also:round a central See also:pivot. The See also:chase of the through a See also:port which admits of the necessary See also:play A notable example of a See also:cupola was erected at Spez two See also:Ito-ton See also:Krupp guns, the structure complete weigh A Krupp cupola of chilled See also:cast-See also:iron for two 28-cm. in fig. 82. These are designed principally for See also:coast sites. The cupola, which is built up like a Gruson cu heavy iron masses. is revolved and the guns laid by by practice being occasionally to See also:mount two 11'' guns in the same cupola. The cast-iron cupola was introduced by Gruson of See also:Magdeburg, Cupolas. but See also:nickel See also:steel is now generally employed by Krupp. In Gruson's See also:design the gun and mounting are placed upon a turn-table upon which also See also:rest the bases of a See also:series of cast- iron plates; these are very massive, are See also:curvilinear in See also:section, and y covers the gether, being gun emerges of See also:elevation. is containing g 2050 tons. I ") is shown efence in See also:low ola of several raulic See also:power. hows a See also:general view of the n through the cradle on a less, carries a See also:cross-See also:head A rted by its guides D, which See also:die. To this cross-head is 85) which recoils with the to the front of the cradle: in the same axial See also:line is a ers F and G : the casting is h is supported by trunnions , the gun carries the buffer also connected with a See also:hydraulic See also:accumulator (not shown) which can be placed in any convenient position in the See also:work, and the power thus stored up be employed for raising the projectiles, for which purpose two lifts are provided. One of these (W) is in the See also:floor of the emplacement, the other (W') is attached to and moves with the mounting. Underneath and suspended from the circular gun plat- cylinder backwards with it, draws it off its piston rod L and forces it into the See also:air chamber F. The air in the See also:chambers F and G is at a high initial tension and, on recoil, the air in F is further compressed and forced through the See also:valve H into the chamber G. At the conclusion of recoil the air expands and forces the buffer cylinder to the front, which carries with it the gun into its loading position; but the valve H closes and the air has to make its way through a narrow hole before it can See also:act on the end of the buffer, thus preventing violent See also:action, which is further guarded against by the " See also:control See also:ram " M which is bolted into the rear end of the buffer. To prevent leakage of air between the air chamber and the buffer at the gland K the packing employed is a viscous liquid which is in communication by means of the See also:pipe J with the intensifier I. The latter consists of a cylinder containing a piston and rod See also:free to move: the front See also:face of this piston is subject to the pressure of the air in the air chamber, the rear face is in communication with the liquid in the gland. Now, as the piston head is held in position by the pressures on either See also:side of it, and as the effective See also:area of the front face is greater than that of the rear—on See also:account of the rod—the liquid pressure per square See also:inch of the fluid in the gland, &c., must be greater than that of the air in the air chamber, hence the latter cannot See also:escape through the former. The pressure in the chambers F and G is adjusted on preparing for action by an air See also:pump worked by See also:hand. The See also:energy of recoil is further utilized as follows: hydraulic cylinders called compressors are held in the cradle, and in them work rams connected with the cross-head A (see fig. 85) : they are See also:form RR, which forms a See also:shield, is an overhead railway QQ, on which run trollies, each taking a projectile. The projectiles are stored in the See also:recess shown in section at O. By means of a See also:shell See also:barrow any projectile can be placed on the lift W and raised to a trolley which can be run round over the lift W', which raises the projectile, as shown at S, to a point suitable for loading. The British 6" B.L. Gun.—A typical mounting for guns of type (b) is afforded by the British C.P. (central pivot), Mark II. mounting for the 6" B.L. Mark VII. gun, a combination which admits of six rounds a See also:minute aimed See also:fire. Fig. 86 shows a side elevation of the mounting with See also:half the shield removed; fig. 87 a longitudinal section of See also:part of the cradle through the See also:axis of the buffer. The
gun, which is trunnionless, recoils in the cradle A; the latter See also:con-
tains a buffer B and two cylindrical boxes containing springs S.
Attached to the See also:breech of the gun is a piston rod C with piston D,
the latter having an opening or ' port " E, through which the oil
passes on recoil, the pressure in the buffer, which would otherwise
vary with the velocity of the recoil, being kept See also:constant by the
variation in the area of See also:aperture afforded by E. This area is governed
by the action of the valve See also: As the gun elevates the tape is paid out, the slack being taken in and the pointer revolved by the action of a See also:clock spring.' The mounting carries an automatic sight (see See also:SIGHTS, Gun Sights). The British 12-pr. Q.F. Gun.—A typical mounting for guns of class (c) is the British pedestal mounting for the 12-pr. Q.F. gun. This mounting consists of a cradle, a pivot, a pedestal and holdfast. The cradle is a gunmetal casting, provided with trunnions that rest in See also:bearings on the pivot; the gun recoils in the upper portion of the cradle and the lower part of the latter is bored at the rear for an hydraulic buffer and at the front for a See also:running-out spring. The pivot is of steel, is See also:fork-shaped at the top end, where are the trunnion bearings for the cradle; its lower end is conical and fits into bushes in the pedestal, where it is free to revolve but is pre-vented from lifting by a holding-down See also:screw.' The pedestal is bolted down to the See also:platform. The gun has a See also:shoulder-piece and it can be trained and elevated by the layer. It has also an automatic sight. A typical Krupp mounting of this See also:kind is shown in fig. 88, Plate VI., which represents an 8.8-cm. (3.4") automatic gun firing, it is stated, 40 aimed rounds in the minute. The See also:United States See also:Mortar.—A typical mounting for pieces of class (d) is afforded by the United States mounting, See also:model of 1896, for the 12" B.L. mortar. The piece is mounted in a top carriage or See also:saddle consisting of two arms connected by a heavy See also:web. This saddle is hinged on a heavy See also:bolt 2nd is connected to the -front of the turntable (fig. 89). The saddle inclines to the rear and upwards at an angle of 45°, the upper ends forming trunnion bearings: it is supported at a point about one-third of its length from the bolt or fulcrum by five columns of See also:double springs arranged in a See also:row, side by side. The recoil is checked by two hydraulic cylinders, one on each side, the pistons of which are attached to the saddle near the trunnions of the piece. When the mortar is fired the saddle revolves about its fulcrum to the rear and downwards, carrying the mortar and compressing the spring columns until the action is stopped by the hydraulic buffers; the springs then assert themselves and return the piece to the firing position. The mortar must always be brought horizontal for loading. ' The elevation indicators are now read on a plate provided with a See also:spiral groove, which guides a See also:stud on the reader along the scale of graduations. 2 In a later mark there is no holding-down screw for pivot. The fighting See also:units of coast See also:artillery in the British service are the fire command, the See also:battery command and the See also:group. The limits of a fire command are governed by the possibility of efficient surveil-See also:lance and control that can be exercised by an individual, and these limits vary much from See also:time to time. Usually a number of forts or emplacements are included in a fire command. The fire command is broken up into battery commands, in every one of which it must be possible for its See also:commander actually to take See also:charge of the guns therein contained in all phases of action. The battery command is divided up into gun See also:groups, each consisting of one or more pieces of like calibre, nature and See also:shooting qualities. As a- See also:rule a fire commander is a See also: The " Majestic," " See also:Glory," " Ex-mouth," " See also:London " and " See also:Bulwark " classes differed from each other only in such details, all of them subordinate to the See also:main raison d'etre of the battleship, i.e. the number and nature of the guns which she carries. The strength and disposition of the armaments of the See also:ships of these classes were identical except in small details (see fig. 9o). In every See also:case the main armament consisted of a pair of 12-in. guns forward and a pair aft, each pair enclosed in a hooded barbette, which was more commonly designated a See also:turret. The turrets were on the midship line, and the guns in each commanded an arc of fire of 240°, i.e. from right ahead to 30° abaft the See also:beam on either side in the case of the fore turret, and from his funnels, destroy any navigational or sighting appliances which were exposed, set his woodwork on fire and render extinction of the fires impossible, and by piercing or bursting on astern to 3o° before either beam in the case of the after turret. capacity which were to kill and demoralize his personnel, See also:pierce The secondary armament, consisting of twelve 6-in. guns, was also symmetrically disposed. Two guns on either side (four in the " Majestic " class) were mounted with arcs of fire of from 6o° before to 6o° abaft the beam, while two guns each side forward 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 See also: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 See also:practical experience in the See also:rate and accuracy of fire of this gun that suggested its See also:adoption in battleships to replace the whole or a part of the 6-in. armament. During the See also:period in which the battleships referred to above were constructed, the See also:idea of the "Dreadnought" See also:Lord See also:Nelson" s" •'e" London 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 See also:cover him with a See also:hail of shells of large unarmoured portions of his side diminish his reserve of buoyancy and so impair his See also:sea-going qualities. These ideas were' gradually losing favour; it was realized that the damage done by an armour-piercing shot, whether or not it See also: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 See also: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 See also:attention should be directed. At the same time, while the rate of fire of the 6-in, guns, to which See also: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 See also:powers rendered possible more accurate firing at See also: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 85o lb, that of the 9.2-in. 38o lb, that of the 6-in. too 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 See also: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 See also:battle conditions, is in the approximate proportions of I : I.5 : 4, which would thus produce a shell effect (supposing the hits made by each type of gun to See also:bear a fixed proportion to the rounds fired), in the proportions of 72: 22: 4, for the 9•2-in. and 6-in. guns respectively. This See also:argument of course takes no account of the probably greater effect produced by the See also:dispersion of the larger number of hits of the smaller gun over the exposed area of the See also:target, nor, on the other hand, does it take account of the greater armour-piercing power of the I2-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 avail-able 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. 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 See also: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 See also: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-See also:ill., g• a-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 (luring 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 See also:train of argument led to the substitution of 9•2-in. guns in the 8 " See also: It can only be ascertained with certainty by a See also:process of " trial and See also: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 estimatewhich is termed " spotting," a See also:duty the performance of which calls for the exercise of the most accurate See also: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 See also: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 See also:change in range, due to the movements of our own ship and of the enemy, for the See also:interval between successive shots, in order to continue hitting. This change of range, which may be considerable (e.g. See also:I000 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 See also: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 each nature must be spotted for independently, and it is obvious that this adds considerably to the elaboration and complication of the fire control system. This constitutes one of the reasons for the adoption of the See also: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 avail-able for fire on either side of the ship (see fig. go). Thus in the " Dreadnought," eight of her ten I2-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 See also: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 85o lb with a charge of cordite of 26o 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 296o ft. per second. This gun appears to mark the See also:climax of development along the present lines, since the See also: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 Io-in. calibre is found in the battle-ships " See also: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 battle-ships, and the See also:principal armament of all armoured cruisers (excepting the " See also:County " class) antecedent to the " Invincibles." The latest gun of this calibre has See also:developed from earlier types in a similar manner to the that is to say, it has experienced a See also:gradual increase in length, weight, and weight of charge, with 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 13o lb gives to a projectile of 38o 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 " See also:Minotaur," " See also:Duke of See also:Edinburgh " and " See also:Devonshire " classes. The 6-in. gun, of which there are a very large number afloat in modern, though not the most See also: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. 8o-pounder B.L. gun, constructed at See also:Elswick, which was the first breech-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 Too-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 See also:foreign navy—notably that of the See also:Japanese, with their practical experience of modern See also:war at sea—its See also: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 See also:anti-See also:torpedo-See also:boat armament. The increase in See also:size of modern torpedo craft and the increased range of modern torpedoes has led to a reconsideration of the type of gun suitable for the protection of large ships against torpedo attack. The conditions under which the anti-torpedoboat armament comes into play are the most unfavourable possible for accurate gun-fire. The target is a comparatively small one; it comes into view suddenly and unexpectedly; it is moving rapidly, and the interval during which the boat must be stopped, i.e. that between her being first sighted and her arrival at the distance at which she can expect to fire her torpedo with success, is in all See also:probability a very short one. Moreover, in the great See also:majority of cases the attack will be made at See also:night, when the difficulties of rapid and correct adjustment of sights, and of range-finding and spotting, are intensified. Two requirements then are See also:paramount to be satisfied by the ideal anti-torpedo-boat gun: (T) it must have a low trajectory, so that 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 See also: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 See also:officers that the 6-in. guns will prove to be the most effective weapon against torpedo craft. The gun armament of destroyers being required to See also: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. 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 insufficient to withstand the stresses set up by the See also:discharge of a gun giving very high muzzle velocity, the 4-in. gun for use inlight 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 puffing boats and all See also:steam-boats are fitted with arrangements for mounting one or two guns, according to the size of the boat; the See also:object of the boat armaments being for use in See also:river operations, for covering a landing, or in guard-boats. Three descriptions of gun are used, the 12-pounder 8 cwt. and 3-pounder, See also:light Q.F. guns, and the See also:Maxim See also:rifle-calibre See also:machine gun. Gun-Mountings.—Gun mountings in the British navy may be divided broadly into two classes, power-worked and hand-worked 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 See also: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. Hydraulic power has been adopted almost universally in the British navy for power-worked mountings, although See also: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 See also: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 electric light and other machinery, whereas hydraulic power, when used, is generally installed for the purpose of working the guns only. The 12-in. guns in the " Majestic " class, following the practice with the earliest heavy B.L. guns, were loaded normally at extreme elevation of 13-1°, and the turret had to be trained to the fore and aft line and locked there for each occasion of loading. An alternative loading position was also provided, in which the guns could be loaded at 1° of elevation and with the turret trained in any direction. Loading in the alternative position could, however, only be continued until the limited See also:supply of projectiles which could be stowed in the turret was exhausted. Experience showed that a greater rapidity of fire could be obtained by the use of this " all round " loading position, as it was termed, and in the latest ships of the " Majestic " class, and in subsequent battleships, the fixed loading position has been abandoned. The details of recent 12-in. mountings vary considerably, a See also: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 of cases there is a " working chamber " revolving with the turret. A fixed See also:ammunition hoist brings the shell and cartridges from shell-See also:room and See also: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 See also:press placed underneath the slide, and the gun is run out again into the firing position by hydraulic power. Loading is carried out by means of a hydraulic 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 gun-layer 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. Elevating is by hydraulic power, and is effected by cylinders placed underneath the slide, the pistons working on an See also:arm projecting downwards. Turret turning engines are also hydraulic, and much attention has been given of See also:late years to the perfection of elevating and turning gear such as will enable the turret or gun to See also: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 See also:motion on the ship. The breech is opened and closed by hand or by hydraulic -, 1L= See also:ICi I;L: --•-tom From a drawing supplied by Messrs. Vickers, Sons & Maxim. A, See also:Roller ring. K, Elevating presses. RI, Transferring rammer . See also:pro- R4, Transferring chamber. B, Gun slide. L, See also:Guide See also:rail for loading cage. jectiles from See also:trunk cage to R4, Training rack. C, Recoil buffer. N, Trunk cage. gun-loading cage. R5, Training engine. Breech See also:block in D, Gun cradle. Rs, Transferring rammer for S, Rotating trunk. open position. Pa, Breech operating hand G, Rammer. See also:powder charges from trunk T, Turntable. H, Loading cage. See also:wheel. cage to gun-loading cage. W, Casing for chain rammer. power, and a douche of See also:water or blast of air, or a combination of both, removes any smouldering fragments of cordite or See also: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. 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 See also:tray in rear of the gun, but the breech is opened and closed, and the charge and projectile rammed See also: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 See also:thirty-two projectiles is stowed in a " shell See also: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 See also:hatch in rear of the gun, when the projectile is raised by a hydraulic press on to a swinging loading tray. It is intended that the shell carrier shall be replenished See also:direct from the shell-room during the pauses of an engagement. A new type of 9.2-in. mounting has been installed in the " Lord Nelson " and " Agamemnon," in which greater use is made of hydraulic power with a view to improving rapidity of fire. In this mounting, each projectile is brought up from the shell-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 arethe 4-in. and I2-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 See also:box. The gun and cradle are balanced for elevation about trunnions on the cradle, which See also:fit into trunnion bearings on the carriage. The latter carries the elevating and training gear, and the whole moving weight is See also:borne by a pivot See also:pin which rotates on a See also: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 a 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 See also:original position. The breech is opened by the . single motion of a hand See also:lever. A " See also:bare " charge is used in the 6-in. and 4-in. guns, with the de Bange type of obturation, while a See also:brass cartridge case has been retained with the l2-pounder, as with the earlier Q.F. guns. Firing is by electricity, percussion being available as an alternative if required, and the current is usually taken off the See also:dynamo mains of the ship. Sighting: The great advances recently made in accuracy of fire have been rendered possible, to a very great extent, by the use of telescopic sighting apparatus. Arrangements are made in all modern sights for the bars or disks which carry the range graduations to be of considerable length or See also:diameter respectively, in order that no difficulty may be found in adjusting the sights for every 25 or 5o 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 See also:parallelism of the axes of the two telescopes having )' From a drawing supplied by Messrs Vickers, Sons & Maxim. FIG. 92.—Diagram of a 9.2-i1R Gun and Mounting, " Hogue " type. A, Roller ring. G, Elevating press. P2, Breech operating hand- B, _Recoil buffer. H, Shell-lifting press. wheel. C, Gun cradle slide See also:frame. K, Fixed armoured trunk. RI, Training rack. D, Loading tray. L, Radial shell-lifting See also:crane. See also:R2, Training engine. E, Shell carrier. M, Axial powder hoist. T, Turntable. F, Pressure water pivot pipes. Pr, Breech block. U, Powder See also:door. been secured, the adjustments to one sight made by the sight-setter are simultaneously effected at the sight on the opposite of the gun. In practice with the 6-in. and 4-in. guns, one See also:man is responsible for the laying of the gun for direction, and has consequently only to think about the coincidence of the See also:vertical cross-See also:wire with the target, while another man, who also fires, keeps the gun laid for elevation, and is responsible only for the coincidence of the target with the horizontal cross-wire. The r 2-pounder has one sight only, one man being considered sufficient to keep the gun laid for elevation as well as for direction, and to fire. It is essential that the sights shall be unaffected by the recoil of the gun, so that they can be adjusted up to the moment of firing by the sight-setter, and that it shall not be necessary for the gun-layer to remove his See also:eye from the See also:telescope while the gun is being fired and reloaded. It is also essential that the sights shall move automatically in elevation and direction with the gun. These two requirements are easily met in the hand-worked mountings by the See also:attachment of the sights to the cradle, which does not move on recoil, and remains constantly parallel to the gun; but in turret mountings the case is more complicated and involves greater complexity of gearing. The older turret sighting arrangement consisted of two horizontal shafts, one for each gun, running across the turret, which were rotated by pinions gearing into racks underneath the gun-slides, the latter remaining of course always parallel to the guns. Pinions keyed to these shafts geared in their turn into racks formed on vertical sighting columns in the sighting positions, these columns, which carried the sighting telescopes, accordingly moving up and down with the guns. With this arrangement an appreciable amount of backlash was found to be inevitable, owing to the play between the See also:teeth of the several racks and pinions, and to the torsion of the ,hafts, and the arrangement was also open to the objection that the telescopes were much exposed to possible injury from an enemy's fire. These defects have been very largely obviated by the " rocking motion sights," which have been fitted in the turrets of the latest British battleships and cruisers. In these sights a sight-bracket is secured to and rotates with the trunnion of the mounting; the sight-carrier and telescope move along the top of the sight-bracket, on a curved arc of which the trunnion is not the centre. When the sight is at zero, the telescope is parallel to the axis of the gun, while to adjust the sight, the sight-carrier with telescope is moved along the curved arc by means of a rack and pinion a distance correspondingto the graduations shown on the range See also:dial, which is concentric with the pinion. Organization.— The organization of a large ship for action is necessarily highly elaborate. Among the officers, next to the captain, the most important duties are probably those of the fire control officer. He is in communication by See also:telephone or See also:voice See also:tube with each of the several units composing the ship's armament. This See also:office is usually filled by the gunnery See also:lieutenant. In the conning See also:tower with the captain is the navigating officer, who attends to the course and See also:speed of the ship, assisted by See also:petty officers to work the wheel and engine-room telegraphs. The torpedo lieutenant, or another officer at the torpedo director, is also in the conning tower, prepared to fire the torpedoes if opportunity offers. Other officers of the military See also:branch, and marine officers, are in charge of various sections of the " quarters." The rate of advance in naval gunnery has been much accelerated since 1902. The construction of the " Dreadnought," which em-bodied a new principle both in nature and disposition of armament, the rise of the United States and Japanese navies to the first See also:rank, and the practical experience of the Russo-Japanese war, were all factors which contributed to the increase of the normal rate of advance due to progress in metallurgy and See also:engineering See also:science. In the British as well as in other navies, notably those of See also:Germany, the United States and See also:Japan, ever-increased attention is being devoted to the attainment of a rapid and accurate shell-fire, and large sums are being expended upon fire control See also:instruments and elaborate aiming and sighting appliances. Size of armaments, power of guns, resistance of armour, efficiency of projectiles, and, above all, rapidity and accuracy of fire, all seem to be advancing with See also:giant strides. But there are two important ingredients of naval gunnery which are not subject to change: the human See also:factor, and the factor of the elements—wind, sea and See also:weather. The latter ensures at any rate one datum point to the student of the science, that is, that the extreme range in action is limited by the maximum distance at which the enemy can be clearly seen, which may be considered to be a distance of 8000 to Io,000 yds. The permanence of the human factor assures that, however great the advance in material, and, provided that no great discrepancies exist in this respect between opposing navies, success at sea will be the See also:lot of the nation whose officers are the coolest and most intelligent, whose men are the best disciplined and best trained, and whose navy is in all respects the most imbued with the habits and traditions of the sea. (S. Additional information and CommentsThere are no comments yet for this article.
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