bed.

The French 10-7" Howitzer.-As a typical piece the 10-7 howitzer | hydraulic buffer is attached to the front of the slide and also to the may be taken, which the French transported by special horse draught, as it was found too heavy for the type of siege railway made use of at the mock siege of Langres in 1907. Its total equipment weighs 22 tons and it is transported in four components, namely, the piece, the carriage, the slide and the platform. A battery of six pieces would thus require, exclusive of ammunition

transport, 24 vehicles that would weigh 130 tons. The howitzer was designed originally for coast defence; it weighs about 5 tons and its bed weighed 6 tons: to this equipment was added a slide and a platform, consisting of a thick plate of iron upon which the slide moves. The platform is provided with a pivot upon which the front part of the slide fits. The latter consists of an iron framework, having lateral movement around the aforesaid pivot; its rear portion is provided with rollers to facilitate its movement on the platform. Its upper portion consists of two inclined rails along which the bed or carriage of the howitzer slides. To check recoil a

The fighting units of siege artillery in the British service are companies and brigades; each company would be armed with from 4 to 6 light siege pieces or from 2 to 4 heavy pieces. A company is usually a major's command. Three such companies would form a siege brigade under a lieutenant-colonel. If a siege train of

any magnitude were organized it might

be necessary to combine two or more brigades into a division under a colonel or brigadier. In the French service each siege train consists of three divisions. A division is divided into groups and comprises some 50 pieces of ordnance, heavy and light. (J. R. J. J.)

IV. GARRISON MOUNTINGS

The armament of modern coast fronts consists of (a) heavy B.L. guns, 9" and upwards; (b) medium guns, 4" and upwards, and (c) light Q.F. guns; all these being for direct fire; and (d) guns, howitzers or mortars of various calibres for high angle fire. Typical guns of type (a) are the Krupp 12" gun and the British 9.2 B.L. gun. The Krupp 12" gun is built up of crucible cast nickel steel, not wire wound. It is 45 calibres long and has the Krupp wedge-shaped breechclosing apparatus. It is fitted with a repeating trip lock. The cartridge is a metallic case containing a charge of 290 lb of tubular powder. The projectiles are of two weights, 770 lb and 980 lb, and the respective muzzle velocities are 3025 f.s. and 2700 f.s. The British 9.2 B.L. gun is of wire-wound construction and is over 48 calibres long. It has the asbestos pad and Welin screw system of obturation, and its charge of 103 lb of cordite, contained in a cartridge of silk cloth, fires a 380 lb projectile with a muzzle velocity of 2643 f.s. A typical gun of class (b) is the British 6" mark VII. It is similar in construction and breech mechanism to the lastnamed and fires a 100 lb projectile with a charge of 23 lb cordite, giving a muzzle velocity of 2493 f.s. A typical gun of class (c) is the British 12 pr. Q.F.; its weight is 12 cwt., it is made of steel, is 10-3 calibres long, and with a cordite charge of 1 lb 15 oz. it fires a projectile 12 lb in weight with a muzzle velocity of 2197 f.s. and a possible rate of 15 aimed rounds a minute. A typical piece of class (d) is the 11" Krupp howitzer. It is 12 calibres long, has a charge of 28 lb smokeless powder and fires steel shell weighing 470 lb or 760 lb. It is provided with a shrapnel shell of the former weight which contains 1880 bullets.

The methods of mounting of coast ordnance are many; space only permits of referring to certain typical arrangements.

Disappearing · mount. ings.

1. The Moncrieff Principle.-The disappearing carriage originated, at all events in England, with Colonel Sir A. Moncrieff, who, about 1864, proposed to utilize the energy of recoil to bring a gun into a protected position and at the same time to store up sufficient energy to raise it to a firing position when loading was completed. To effect this a heavy counterweight was so adjusted that its tendency was to raise the gun; when the latter was fired, it raised the counterweight and a ratchet and pawl followed the action up: when the pawl was released the counterweight brought the gun back to the firing position; this application of the principle had many drawbacks, and never had any success with guns over 7 tons in weight. It was not until Moncrieff invented the hydropneumatic appliances that any real progress was made. In 1888 was introduced into the British service the first of a large group of disappearing mountings for guns of types (a) and (b), where the energy of recoil was absorbed chiefly by forcing a large volume of liquid through a narrow opening or recoil valve and also by further compressing a large volume of already highly compressed air; when recoil was completed the recoil valve closed and the air was retained at very high pressure: the energy thus stored up returned the gun to the firing position. The action will be understood from the following example.

The British 6 B.L. Gun on H.P. Mounting, Mark IV-Fig. 78 shows. a general view of the mounting; fig. 79 is a vertical and

FIG. 78.-British 6" B.L. Gun on H.P. Mounting, Mark IV.

fig. 80 a transverse section through the recoil cylinder. The gun trunnions (fig. 78) are supported by the two arms of the elevator A, which is pivoted to the front of the lower carriage at B. The breech is supported by the two elevating bars C whose lower ends are attached to the elevating arcs D. These arcs are worked by the elevating gear actuated by the hand-wheel E. The arcs are struck with the bars C as radii, their centres being points at the upper end of the bars when the gun is in the loading position. Elevation can thus be given to the gun whilst it is being loaded. The lower carriage rests on a ring of live rollers G, which are free to traverse round on a circular racer H, motion being given by traversing gear actuated by the hand-wheel I. Supported by vertical stanchions attached to the lower carriage is a horizontal circular shield J through which the gun rises to the firing position. The manganese bronze ram F which is attached to the elevators A by the cross-head L is forced on recoil into the central chamber of the recoil cylinder (see fig. 79), which is supported by trunnions M resting in the brackets of the lower carriage. There are ten chambers N (figs. 79 and 80), all of which are connected at the bottom with the recoil valve chamber O, and consequently with each other. Nine of these contain liquid in their lower portions and highly compressed air above, and are connected at the top by a channel P to equalize the pressure in each chamber. The tenth chamber N', which is situated lowest in the cylinder, contains liquid alone and has at its upper end the raising valve Q. On recoil the liquid in the central chamber is forced by the ram through the recoil valve R into the outer chambers N, thus further compressing the air. As R is a non-return valve the air is maintained in this highly compressed state during loading. The gun is raised by pushing the lever S (fig. 78) to the front which actuates the rack T (fig. 79), thus opening Q, which allows the air in the nine chambers to force liquid from the tenth chamber N into the centre ram chamber, lifting the ram. U is a pump (fig. 79) by which the gun can be pumped down at drill. The liquid employed in the buffer is a mixture of methylated spirits, mineral oil, distilled water and carbonate of soda, and its aeration, due to the churning it receives on recoil, is a serious drawback to this class of mounting. From a 6 B.L. gun mounted in this fashion somewhat more than one aimed round a minute can be obtained; from a 9.2" B.L. about four such rounds in five minutes.

The foregoing description is now, however, principally interesting as showing an ingenious application of mechanical principles for military purposes. Mountings of this type are being gradually withdrawn from the British service.

The Buffington-Crozier Principle.-In the United States a type of disappearing carriage known as the Buffington-Crozier (fig. 81) is used. Here, as in the earlier types of Moncrieff carriage, a counterweight is employed, but the energy of recoil is partly absorbed by a buffer, and the counterweight, which is constrained by guides to move vertically up and down, is just able to raise the gun to the

firing position. A satisfactory rate of fire is claimed for this mounting. which has recently been improved.

Balanced Pillar.-Another type of disappearing mounting for guns of type (b) or (c), known as the balanced pillar. is found on the continent of Europe and in the United States, where it is used for 5" guns and under. A long steel cylinder, which supports the gun and its carriage, has a vertical movement of about 3 ft. in an outer cylinder. The inner cylinder and all that it carries is balanced by a counterweight. After the gun is fired it can be brought with its length parallel to the parapet. Then by the action of the mechanism the inner cylinder can be made to sink

in the outer cylinder and the gun is brought down to the loading position; the release of the counterweight will cause it to rise again. The gun has the usual motion of traverse round the common axis of the two cylinders.

The heavy gun cupola is found on the continent of Europe in the | A heavy chilled cast-iron collar protects the under side of the armaments of various Powers for guns of type (a), the German armoured structure and the working mechanism of the guns. Fig. 83,

Plate VI., represents a Krupp mounting for an 11-2" howitzer, with a cupola-like shield. This is worked both electrically and by hand. Vertical fire from a weapon of this type is sufficiently powerful to penetrate the protective deck of a vessel. Light and medium guns, types (b) and (c), are sometimes mounted in cupolas, especially on land fronts (see below), and disappearing cupolas have also been proposed for them: in the latter the whole structure is made to sink by the action of mechanism till the top of the cupola is level with the ground. Types and further de tails will be found in the article FORTIFICATION AND SIEGECRAFT. practice being occasionally to mount two 11" guns in the same cupola. Mountings of the barbette type are much favoured in the British The cast-iron cupola was introduced by Gruson of Magdeburg, service for guns of types (a) and (b); one of the most Cupolas. but nickel steel is now generally employed by Krupp. modern is shown in fig. 84, where a 9.2" B.L. gun, Mark X., mous!. In Gruson's design the gun and mounting are placed is placed upon a Mark V. mounting, a combination which Ings upon a turn-table upon which also rest the bases of a series of cast- admits of over five aimed rounds in two minutes. iron plates; these are very massive, are curvilinear in section, and The British 9.2" B.L. Gun.-Fig. 84 shows a general view of the are built up into a shallow dome which completely covers the mounting, fig, 85 a longitudinal section through the cradle on a mountings as with a cap: the whole structure turns together, being larger scale. The gun, which is trunnionless, carries a cross-head A traversed round a central pivot. The chase of the gun emerges and recoils in the cradle C, being supported by its guides D, which through a port which admits of the necessary play of elevation. slide in longitudinal grooves in the cradle. To this cross-head is A notable example of a cupola was erected at Spezzia containing attached the buffer cylinder B (see fig. 85) which recoils with the two 120-ton Krupp guns, the structure complete weighing 2050 tons. gun, while the piston rod L is attached to the front of the cradle: A Krupp cupola of chilled cast-iron for two 28-cm. (11) is shown engaging with the buffer cylinder and in the same axial line is a in fig. 82. These are designed principally for coast defence in low bronze casting containing two air chambers F and G: the casting is sites. The cupola, which is built up like a Gruson cupola of several attached to the rear of the cradle, which is supported by trunnions heavy iron masses, is revolved and the guns laid by hydraulic power. E in the lower carriage. Thus on firing, the gun carries the buffer

FIG. 81.-Buffington-Crozier Disappearing Carriage for 10" B.L. Gun, U.S.A.

Barbette

form RR, which forms a shield, is an overhead railway QQ, on which run trollies, each taking a projectile. The projectiles are stored in the recess shown in section at O. By means of a shell 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.

FIG. 84.-British 9.2" B.L. Gun, Mark X., on Barbette Mounting. cylinder backwards with it, draws it off its piston rod L and forces | it into the air chamber F. The air in the chambers F and G is at a bigh initial tension and, on recoil, the air in F is further compressed and forced through the 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 act on the end of the buffer, thus preventing violent action, which is further guarded against by the "control 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 pipe J with the intensifier I. The latter consists of a cylinder containing a piston and rod free to move: the front 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 side of it, and as the effective area of the front face is greater than that of the rear on account of the rod-the liquid pressure per square inch of the fluid in the gland, &c., must be greater than that of the air in the air chamber, hence the latter cannot escape through the former. The pressure in the chambers F and G is adjusted on preparing for action by an air pump worked by hand. The 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

The

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 minute aimed fire. Fig. 86 shows a side elevation of the mounting with half the shield removed; fig. 87 a longitudinal section of part of the cradle through the axis of the buffer. gun, which is trunnionless, recoils in the cradle A; the latter contains a buffer B and two cylindrical boxes containing springs S. Attached to the breech of the gun is a piston rod C with piston D, the latter having an opening cr 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 constant by the variation in the area of aperture afforded by E. This area is governed by the action of the valve key strip F of varying section, which is inserted in the buffer in such a way that as the gun recoils the port E is constrained to pass over it. On recoil the rods J, which are attached to the gun in rear and screwed into the flanged cylinder H in front, force back the front of the springs S, whose rear ends butt up against the rear of the spring boxes. After recoil the springs return the gun to the firing position. To check the violence of this

also connected with a hydraulic accumulator (not shown) which can be placed in any convenient position in the 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 floor of the emplacement, the other (W') is attached to and moves with the mounting. Underneath and suspended from the circular gun plat

action a control ram G is made use of: the piston rod has a cylindrical hole in front which, as the gun recoils, becomes filled with oil, and before the piston can come up against the front of the buffer this oil has to be displaced by the thrust of the ram G which checks the forward movement of the gun. The cradle A rests on its trunnions in seatings in the lower carriage and is elevated or depressed by the gear K'. The last-named drives the elevating arc L, which is attached to the cradle at M, the axis of the gun moving parallel to the axis of the cradle. In fig. 86 the lower carriage is almost entirely hidden by the gears carried on it, namely, the elevating gear K, the traversing gear N, which works a spur pinion, gearing into the rack O attached to the pedestal P: the elevation indicators Q and R for recording the angle of elevation of the gun and the bracket S' which support the 6 armour plate T. The weight of the lower carriage, cradle and gun is taken by a horizontal ring of hard steel balls resting on the top of a massive forged steel "pivot U, the lower portion of which is shown supported in the cast-iron pedestal. The elevation indicator consists of a sector Q bolted to the cradle trunnions; to its edge is attached a metal tape, the

"

FIG. 86.-British Mark II. Barbette Mounting for 6" B.L. Gun. FIG. 87.-Longitudinal Section of Part of Cradle of Gun shown in fig. 13, through Axis of Buffer. other end of which is fixed to the spindle supporting a pointer, reading angles of elevation on the drum R. As the gun elevates the tape is paid out, the slack being taken in and the pointer revolved by the action of a clock spring. The mounting carries an automatic sight (see 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 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 running-out spring. The pivot is of steel, is 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 prevented from lifting by a holding-down screw. The pedestal is bolted down to the platform. The gun has a shoulder-piece and it can be trained and elevated by the layer. It has also an automatic sight.

A typical Krupp mounting of this 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 United States 12" Mortar.-A typical mounting for picces of class (d) is afforded by the United States mounting, model of 1896, for the 12 B.L. mortar. The piece is mounted in a top carriage or saddle consisting of two arms connected by a heavy web. This saddle is hinged on a heavy bolt and 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 double springs arranged in a 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.

1 The elevation indicators are now read on a plate provided with a spiral groove, which guides a stud on the reader along the scale of graduations.

2 In a later mark there is no holding-down screw for pivot.

The fighting units of coast artillery in the British service are the fire command, the battery command and the group. The limits of a fire command are governed by the possibility of efficient surveil lance and control that can be exercised by an individual, and these limits vary much from 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 commander actually to take charge of the guns therein contained in all phases of action. The battery command is divided up into gun groups, each consisting of one or more pieces of like calibre, nature and shooting qualities. As a rule a fire commander is a field officer, a battery commander a major or a captain, a gun group commander a subaltern or senior N.C. officer. In connexion with coast artillery range-finders (q.v.) and electric lights (see COAST DEFENCE) are installed and electric communications established for the chain of command. UJ. R. J. J.)

V. NAVAL GUNS AND GUNNERY

British navy as the basis. At the close of the 19th and at the In dealing with naval guns and gunnery, we shall take the beginning of the 20th century it appeared that a type of British

battleship (see SHIP) had been evolved which was stable as regards disposition of armament, and that further advance would consist merely in greater efficiency of individual guns, in improvements of armour rendering possible the protection of greater areas, and in changes of engine and boiler design resulting in higher speeds. The "Majestic," "Glory," "Exmouth," "London" and "Bulwark" classes differed from each other only in such details, all of them subordinate to the main raison d'être of the battleship, i.e. the number and nature of the guns which she carries.

The strength and disposition of the armaments of the ships of these classes were identical except in small details (see fig. 90). In every 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 turret. The turrets were on the midship line, and the guns in each com manded an arc of fire of 240°, i.e. from right ahead to 30° abaft the beam on either side in the case of the fore turret, and from