(Twelve are issued, two of which are empty, for use from ships or boats). This torpedo, 12½ inches long and 3¹/₁₆ inches square, inside measurement, is made of tin and is closed at the lower end. It is coated inside and out with shellac. To the upper end is soldered a brass flange having a loop on one side and a throw-back hinge on the opposite side. The cover consists of a square brass plate with two loops one of which rests over the loop on the flange, the other receiving the lug of the throw-back hinge. A thumb-screw, fitted to the end of the lug, secures one side of the cover and a transportation thumb-screw, fitted to the loops, secures the other side. The cover bears a stuffing-box for the entrance of the spar leading-wires. A rubber washer between the cover and flange makes the case water-tight. A loop is fitted to one side of the case to receive the lower end of the spindle. The weight of this torpedo, empty but complete, except the spindle, is 3¼ lbs. and its charge is equivalent to about 4 lbs. of dry gun-cotton. When issued, all the exercise torpedo-cases, except two, are completely filled with wet gun-cotton, the cover is closed tight and the hole in the stuffing-box is closed tight by screwing down the water-cap over the spherical rubber packing placed sideways in its seat. STUFFING-BOXES. =Plates I. and II.= Stuffing-boxes provide a water-tight entrance for the spar leading-wires through the covers of the torpedo-cases. In the center of each cover, around the hole for the entrance of the leading-wires, is a brass rim fitted with a screw-thread outside, and bored out, inside, with a slightly conical taper, providing a seat for the packing. The packing is of partly vulcanized rubber, 1 inch in diameter, spherical in shape, with two parallel holes, each ¼ inch in diameter, for reeving the leading-wires. The water-cap screws on the brass rim and compresses the packing in its seat, a friction-ring in the top of the cap preventing twisting of the packing when screwing down. A hole, ⅝ inch in diameter, through the top of the water-cap, permits reeving the spar leading-wires. When rubber packing is to be left seated for a long time the seat for the packing should be coated with shellac and the packing brushed with black lead to prevent adhesion. CIRCUIT-CLOSER.—CONTACT TORPEDO. =Pattern B.—Plate III.= (Four are issued, to convert Service Torpedoes into Contact Torpedoes, for use from boats.)