External firing gear for guns using loose ammunition. The primer is inserted in the firing gear when the breech mechanism is open, but is held at an angle to the lighting vent until the final locking motion of the breech block, making it impossible to light the gun’s charge before the breech mechanism is safely closed, even if the primer should be prematurely exploded. The primer case is automatically ejected by the opening of the breech mechanism. FUSES. (See page 405.) The fuses shown from left to right are: minor caliber percussion fuse, minor caliber magazine percussion fuse, major caliber percussion fuse, major caliber magazine percussion fuse, triple, double and single train time fuses. The time fuses all contain a percussion element to insure their exploding on impact if not previously exploded. No special tool is required for setting these fuses. They are made up to 27 seconds burning time for guns of 2,600-foot seconds muzzle velocity, and up to 36 seconds for mortars and guns of 1400-foot seconds muzzle velocity. * * * * * What is a Deep-Sea Diver’s Dress Like? There are now two general types of deep-sea diving equipment: an India rubber dress, covering the entire body, except the head, which is covered by a helmet, and another apparatus which is constructed entirely of metal. The India rubber dress has a neck-piece or breast-plate, fitted with a segmental screw bayonet joint, to which the head-piece or helmet, the neck of which has a corresponding screw, can be attached or removed. The helmet has usually three eye-holes, covered with strong glass, and protected by guards. Air is supplied by means of a flexible tube which enters the helmet and communicates with an air pump above. To allow of the escape of the used air there is sometimes another flexible tube, which is led from the back part of the helmet to the surface of the water. But in the more improved forms of the dress, the breathed air escapes by a valve so constructed as to prevent water from getting in, though it lets the air out. Leaden weights are attached to the diver, and his shoes are weighted, that he may be able to descend a ladder, walk about below, etc. [Illustration: DIVING-DRESS AND DIVING-HELMET, BY SIEBE, GORMAN & CO. A. Pipe by which air is supplied. B. Valve by which it escapes.] Communication can be carried on with those above by means of a cord running between the diver and the attendants; or he may converse with them through a speaking tube or a telephonic apparatus. One form of diving-dress makes the diver independent of any connection with persons above the water. It is elastic and hermetically closed. A reservoir containing highly compressed air is fixed on the diver’s back, which supplies him with air by a self-regulating apparatus at a pressure corresponding to his depth. When he wishes to ascend he simply inflates his dress from the reservoir.