The Howell general profile of the Howell torpedo, Fig. 5, is that of a spindle of revolution, the after body being a true spindle, the middle body a cylinder. and the fore body an approach to an ogive, 1 here are four detachable sections. The first (a) is the nose, carrying the firing pin and its mechanism. The latter is permanently fixed in a hollow bronze casting, attached to the front end by a bayonet catch for ready handling. The outer end of the firing pin is provided with fan-shaped corrugated horns, to prevent glancing or sliding along the object struck. The condition of the firing pin is at all times plainly visible, its length beyond the nose showing whether it is cocked or not. The dummy and the fighting heads are both made of sheet brass, the former being the lighter, so as to give about 13 lbs. buoyancy. In the fighting head the main part is filled with wet gun cotton (b), a small water-tight chamber being reserved for the dry guncotton primer (c). Two small holes are drilled through the cap of the primer compartment, and are filled with a substance that is soluble after long contact with water. This is to insure drowning the dry gun.cotton primer, and so preventing accidents.
The main section contains the fly-wheel, with its frame, the propeller gears (g), for ward sections of shafting, and the thrust bearings. The fly-wheel is gun steel, has a heavy rim and solid web connection with the hub, and is provided with frictionless bearings, no matter what be the plane of the axle when rotating. The connection between the tly-wheel and the steam motor that rotates it is made through the starboard side of the torpedo by means of clutch couplings to the end of the axle. The balance of the torpedo is preserved by means of a lead disk (k), which is regulated by inserting a key through a hole tapped through the shell. The flywheel is geared up to the propeller shafts, which are carried straight to the rear to the right and left-handed screws. The stern section is divided into two compartments, the forward of which contains the diving mechanism. and is open to free access of water ; while the after one is water-tight, and practically empty. The rudder is a steel rectangular plate completely filling the space between the outer ends of the screw shaft tubes. The steering tillers are directly connected, the one to a hydrostatic piston and the other to a spring. Should the immersion be less than that determined upon, there will be less pressure on the piston, and the spring will hold the rudder partially down and so steer the torpedo down to its proper depth, and vke versa.
A pendulum (p) has been introduced and suspended so as to swing in a fore-and-aft direction and insure the torpedo remaining in a horizontal position. It is connected with the tiller rod, and by it to the rudder. Two brass air tubes (1/ H) are connected with the main launching tube, Fig. 0. similar to the Whitehead, and connected at their forward ends by a cross tube (I). The right-hand tube, called the tiring tube, carries a little block (K K), in which is fitted a hammer, sear and mainspring. ln this tube is placed an ordinary metallic cartridge carrying less than half a pound of sufficient, however, to give the 500-lb. torpedo a discharge speed of over 35 knots. The rear end of the left-hand pipe, called the compression pipe, connects by an elbow with the main tube. The explosion of the cartridge compresses the air in this tube, which, when it enters behind the torpedo, ejects it with sufficient force to keep it from taking the water until it is 30 ft. from the ship. The entire time from pulling the firing lanyard until the torpedo leaves its tube is but little over one second, most of which is taken up by the torpedo itself gathering movement.
The Hall Torpedo has three compartments, the forward containing the magazine and the firing apparatus the middle, the air flask and engine ; the after, the diving and righting valves. The motive power is compressed air in a flask 8 ft. long, the engine case forming the after end of the flask. There is a single direct-acting engine for each screw. The pro peller shafts are geared to the crank shafts in the proportion of 3 to 1. The after section— the depth-regulating compartment—has in its top an adjustable telescopic tube and in the bottom an aperture ; by'both of these the compartment is accessible to water, which rises above the bottom of the telescope until the water and imprisoned air are iu equilibrium. There is a righting valve, worked by an arm connected with a float resting on the water in the after compartment, which gives outlet to the air so as to bring the torpedo to a proper immersion. The magazine is pivoted at its after end, suspended by hangers at its forward end, and centered by springs. permitting lateral movement which actuates pectoral fins. When the torpedo rolls, the lower fin is pressed out and the upper one pulled in, thereby preventing a deflection of the torpedo from its course due to rolling.