The Works Of Messrs. Schneider And Co.

10-CENTIMETRE AND 12-CENTIMETRE GUNS. 181 head of which acts as a cani and prevents any accidentai opening of the breech-piece after the charge is inserted. The breech-bloek is carried by a bracket, that turns round a vertical bolt attachée! to the back of the gun. Obturation is insured by a plastic ring placed between the front end of the screw and the movable head. The gun is fired by means of a percussion bolt that inoves between two slides on opening the breech, thus immediately closing the vent. The percussion tube can only be inserted and the trigger worked, when the breech is completely closed. The central pivot mounting consists of three main parts —the bolster, the .slide, and the gun-carriage. The bolster is fixed to the deck, and is fitted with a roller path and central pivot ; the slide rests on the roller path, and so as to maintain a practically uniform pressure in the cylinder. Buffers regulate the travel of the gün-carriage during its automatic return. 12-Centinietre (4.724-In.) Gun. Type 1885 (Fig. 597). —Guns of this type have been supplied to the Haytian Government for armament of the despatch boat Toussaint Louverture. Weight of gun... „ mounting ... ,, projectile (armotir-pierc- ing shell) Weight of charge (black powder) ... Muzzle velocity Pressure Angles of elevation ... 2000 kg. 3500 kg. 4400 Ib. 7700 Ib. 21 kg. 8.4 kg. 565 in. 2400 kg. 28 deg. 46.2 Ib. 18.5 Ib. L853 ft. 15.24 tons per square inch 10 deg. Fig. 597. 12-Centimetre Gun and Mounting ; Model, 1885. consists of two cheeks provided with cross-stays ; it com- prises also a plate disc into which is fitted the bolster pivot ; the gun carriage is made movable in tlie inclined planes of the slide, and is fitted with the trunnion plate, the front stay carrying the pivots of the recoil piston-rod crosshead. For elevating, a hand-wheel is provided, which works a toothed sector fixed to the gun by means of a hélicoïdal screw and pinion. The gun is trained by means of a pinion gearing in the toothed ring that surrounds the bolster. The pinion itself is worked by a hélicoïdal wheel, upon which acts a plate chain set in motion by a crank. The recoil cylinder placed between the cheeks of the slide is fixed ; the piston is worked by the action of the recoil, and the liquid in the cylinder passes through lateral ports and an annulai- space between the edges of the piston and central rod. The sections of this rod are made to vary, The breech-block is cylindrical, with interrupted screw threads, and slides to-and-fïo in guides at the rear of the gun. The opening and closing mechanism is operated by a lever and cam, and a safety device prevents accidentai opening of the breech. A plastic obturator is placed between tlie front end of the breech-block and the movable head. The firing mechanism comprises a percussion boit, the striker of which can only act on the percussion tube when the breech is completely closed. The mounting of this gun consists of three main parts, the bolster, the slide, and the gun-carriage proper. On the bolster is attachée! tlie roller path and the central pivot, around which the slide turns, on conical rollers. The carriage is fitted with recoil cylinders and elevating gear and it rests on the inclined slides of the frame, guide-blocks beino’ introduced as inclicated in the illustration. A pinion gearing with the toothed sector fixed to the gun, régulâtes the elevating movement ; this pinion is