The Works Of Messrs. Schneider And Co.

12-INOH COAST-DEFENCE GUN. 259 supporting bracket. The fuse is threaded, and is fired by friction or by electricity. The mounting is on the Schneider-Canet system, with inclined slide, central pivoting, and with hydraulic recoil cylinder. The gun, when loaded, being perfectly balancée! on its trunnions, one man alone can give it the required elevation. It can also be trained by one man, owing to the care taken in the arrangement of the conical bearing rollers ; indeed, for elevating and training, the only eßbrt required is that to compensate friction. No shock is caused in the recoil cylinder when the gun is fired ; the rods are protected from the eflects of grape shot, and the cylinders being of constant volume, air cannot enter, so they remain perfectly tight. The mounting body is of cast iron ; it is made with a large base ; the recoil cylinders are placed as near the trunnions as possible, thus reducing to a very large extent the reversing moment. The loading platform is placed about 1 metre below the gun ; a wide opening is cut out of it for allowing a free passage to the breech end of the gun during recoil under the greatest angles. When the gun is run out, this opening is covered by the movable flooring joined to the mounting; it is uncovered automatically during recoil. This does away with the trouble that attends the use, at the rear of the gun, of a portable flooring for loading, and which has to be removed previous to firing, Upon the cast-iron body is the cast-iron inclined slide, with two cheeks stayed togetlier in front ; a cast-iron transom is fitted to the slide ; there is a cast-iron bolster on which the transom turns through the medium of a set of twenty-four coned rollers. The mechanism for elevating the gun consists of a horizontal skaft with two cranks in the front of the slide, combined with two pairs of bevelled pinions on a vertical axle ; a shaft, circular in front and square in the rear, and inclined at the same angle as the roller-path of the slide ; a conical pinion made to slide on the square part of the shaft ; a vertical shaft on which are fitted a conical pinion and an endless screw ; a horizontal shaft fitted with a hélicoïdal wheel and a pinion ; a sector fitted to the gun, the hélicoïdal wheel being made to slide on the shaft. The required pressure for insuring the necessary compression of the system is given by screwed nuts and two Belleville springs, this arrangement deadening all shocks on the mechanism. Index plates show the direction for turning the cranks. One gunner, in 25 seconds, can elevate the gun from — 8 deg. to + 25 deg. When the gun recoils, the mounting draws along with it all the parts contained in the elevating mechanism, and the bevelléd pinion slides on the square shaft. The gun can, therefore, oscillate whatever be the position of the mounting on the slide. The gunners can maintain their hold on the cranks during firing. The mechanism for lateral training consists of a transverse shaft with two cranks ; two eylindrical wheels ; a transverse shaft on the transom, on which is keyed an endless screw ; a vertical shaft provided with a hélicoïdal wheel and a pinion ; a toothed ring fixed to the bolster ; the helicoidal wheel is made to slide on its shaft ; the pressure required for insuring the necessary contact is given by screwed nuts with two Belleville springs, this arrangement deadening all shocks on the teeth of the mechanism ; index plates are provided for showing the direction in which the cranks have to be turned. One gunner suffices for training the gun through a small angle ; for turning it completely round it takes two men five minutes. The gunners need not release the cranks while the gun is fired. There is also a mechanism for running in the gun, but it is only resorted to for maintenance and repair. The device for checking recoil consists of two forged- steel cylinders cased in the lower part of the mounting, and provided in the middle of their length with a lug for fixing them ; they are closed at both ends by covers. The two plunger-rods are fixed to the front stay ; the piungers are made with two round holes, through which pass rods of varying sections. (Figs. 861 to 863, Plate CXLVIIL). When the gun is fired, the mounting recoils and draws back the cylinders. The liquid in the front of the pistons flows to the rear through the openings made between the rods of varying sections and the holes in the piston. The sections of the rods are so calculated that résistance is constant during the time recoil lasts. When the gun runs out again, the liquid flows back through the same openings, the travel of the gun is moderated by the friction of the various parts, and the shock on the front buffers is very slight. The constant résistance recoil cylinders do not cause any strain on the mounting, and give practically equal recoil speeds whatever be the firing angles. The firing platform is in two parts, one fixed and the other movable. I2-In. Coast Defence Gun and Mounting (Figs. 864 and 865, and Figs. 866 and 867, Plate CXLIX.). — This mounting is fitted on an elevator, and disappears in a pit for loading the gun. The disappearing action can only take place when the gun is run in, and a special device has been designed to maintain it in that position after firing, and to lun it out again after it has been loaded and raised. The mounting is central pivoting, with inclined slides and hydraulic recoil cylinder, the return taking place by gravity. The carriage is of cast steel, and is made to carry the gun on its trunnions ; it is fitted with forged-steel rollers, which run on the slide. The latter is of cast steel, and consists of two cheeks stayed in front and strongly bolted on the cast-steel bedplate ; in its centre is the pivot-housing, and under- neath is a circular roller path. The transom is also of cast steel, provided with a pivot lined with gun metal, and is made with a circular racer ; the transom is bolted on the elevator platform. A set of 24 forged-steel rollers joined together by two rings is placed between the bed- plate and the platform. The two recoil cylinders and the cylinder for running in the gun are cast in one piece with. the mounting ; they are lined with gun metal. The recoil piston-rods are fixed to shoulders in the rear