A steam-drier, for drying wet gun-cotton for use as primers, consists of a sheet-iron box containing two removable galvanized-iron wire baskets in which the blocks to be dried are supported, strung on rods. The blocks are separated from each other by small iron washers, ¼ inch thick, also strung on the rods, to permit free circulation of the air. A door in the front of the box permits entering and withdrawing the baskets. In the bottom of the box is a flat of steam-pipe the two ends of which, projecting from the side, are screw-threaded for ready connection with steam-heating apparatus, or with any other convenient source of low-pressure steam. A wire-gauze bottom, below the flat of steam-pipe, permits the entrance of air and serves to keep out dust and to prevent undue radiation of heat toward the outside. In the top of the box is a ventilating opening, with a rotary damper, protected by a hood, and also a hole for the introduction of a thermometer. CHEMICAL BOX. This box is marked on top “Chemical Box.” For contents see Box 16, “List of Articles in Outfit supplied from Torpedo Station.” For use of contents see “Inspection of Gun-Cotton.” The outfit includes a number of spare washers, spherical packings, diaphragms, etc., to supply necessary waste. In addition to the articles already mentioned, every vessel having a “Ship‘s and Boat‘s” spar-torpedo outfit is supplied from the Torpedo Station with the following articles, to be placed on board at the navy yards, as permanent fittings; viz.: Double-conductor insulated copper wire, incased in lead, in such quantity as may be required for permanent wires; 2 electric switches; 13 terminal binding-screws. PERMANENT WIRES. =Plate IX.= In order to do away with the inconvenience of leading out lengths of wire from place to place, and to avoid injury to the wire, permanent wires are put in place when the ship is fitted out. These wires are led from terminals conveniently placed for battery connections via the electric switches or firing apparatus to the terminals, abreast the heels of the torpedo-spars. Permanent wires should be protected from hostile fire, from chafe, wear, and the sun; should never be taut; should never be led around sharp angles; metal staples should never be used to hold the wires in position, even temporarily; no part of the copper wire should be exposed to the action of salt water; splices should be soldered and carefully insulated; and the wires should be boxed in throughout their lengths. ELECTRIC SWITCHES. =Plate X.= In connection with permanent wires electric switches are used, and are permanently placed in a suitable position before a ship leaves the navy-yard.