The plug is inserted in a copper band; dry pulvurulent gun-cotton is loosely packed about the bridge and on top of the fulminate of mercury and the band is screwed on the upper end of the detonator-case, thus closing it. Detonators are painted red. They are supplied for use with gun-cotton torpedoes. DETONATOR BLOCKS. =Plate VIII.= Wooden cylinders, with a cover that has a small circular motion. Each block holds 8 detonators placed in holes around the circumference, the cover locking them in. Each block is placed in a covered tin cylinder painted red and marked “Dangerous.” These blocks will be placed in different parts of the ship, never below the water-line. (See Ord. Inst.) DUMMY DETONATORS. These are empty detonator-cases, with a hole bored in the bottom, for use in making connections in practice. The detonator-legs are not bridged but are cast in the plug on the bight. Dummy detonators are painted white and the legs are insulated with white cotton thread. IGNITERS. Igniters are cylindrical brass cases, closed at the lower end, containing a charge of rifle gunpowder. The upper end is closed by inserting a plug precisely similar to that used in detonators, except that the igniter-legs are insulated with white cotton thread instead of red. The bridge is primed by twining about it a wisp of long-staple, dry gun-cotton. Igniters are coated with white shellac. They are supplied for use with improvised gunpowder torpedoes. GUN-POWDER FUZES. These are stout, cylindrical, paper cases, closed at the lower end and charged with rifle gunpowder. In the center of the charge is placed an igniter the legs of which project on either side of a wooden plug which is seized in the upper end of the case to close it. Igniters are coated with orange shellac. A rubber insulator, for preventing short-circuit between the splices when the fuze is attached to leading-wires, is seized around the upper end of the case. Fuzes are supplied for use with improvised gunpowder torpedoes. BOX CONTAINING GUN-POWDER FUZES AND IGNITERS. This is marked with a list of contents. It is packed in Box 7, from which it is to be removed, when received aboard ship, and stowed in the magazine or ammunition room. GLASS JARS FOR DRY PRIMERS. =Pattern B.= Glass cylindrical jars, fitted with cork covers, each having a capacity for 6 two-inch, or 24 one-half inch blocks of gun-cotton. These blocks of dry gun-cotton are tied together with boiled tape and have litmus-paper between them. They are never to be stowed below, but must be placed in different parts of the ship above the water-line. Being glass, the jar, without being opened, renders the litmus-paper readily discernible. Each jar is placed in a wooden case fitted with a sliding cover, painted white, and is stencilled with contents, and with precautions. The dry primers, as used, are replaced by drying the wet blocks removed from the torpedoes in priming them. GUN-COTTON DRYING APPARATUS. =Plate XVIII.=