16,351. Hardingham, G. G. M., [Electric Boat Co.]. Aug. 14. Submarine vessels.-In order to make a submarine vessel more lively in diving and in rising to the surface, the weights are concentrated towards the centre as far as possible. As shown in Fig. 3, the ballast tank is of horse-shoe form, and its upper ends are reduced and fitted with air-discharge valves. The vessel is prevented from diving to too great a depth by the automatic discharge of water ballast. The extra pressure of the external water on a diaphragm opens a valve to admit air to a ballast tank. Its contents are thus discharged through an outwardly-opening valve in the bottom. This valve can be opened by hand to fill the tank. The water-ballast tank is divided into three parts ; only the bottom compartment is filled when the water is fresh. In salt water, the wing compartments also are filled. There is also a small safety-compartment from which the water is discharged as referred to above. The vessel dives under the control of horizontal rudders, by which it is caused to move down in a convex path, until it has nearly attained the required depth. The rudders are then, automatically, moved to cause the vessel to move in a concave path until the required depth is attained, whereupon the rudders are placed amidships. Fig. 6 shows the apparatus used. When the vessel is to dive, the hand-gear 48 in the conning-tower is operated to throw over the piston valve 36 of an oil or other engine, so that fluid under pressure enters the right-hand end of the cylinder, and drives the piston to the left to move the rudders downwards into the diving position. The band-gear is then returned to the original position. As the boat descends, the increasing water pressure on the diaphragm 52 slowly overcomes the spring 56, and, through the link 49 and lever 42, moves the valve 36 to the right. Fluid is thus admitted to the left-hand end of the cylinder, to bring the rudders to the midship position. When the vessel has nearly reached the desired depth, the pressure on the diaphragm 57 throws the cylindrical valve 67 to the left to increase the fluid supply to the lefthand end of the cylinder, and place the rudders in an upward position. The vessel then moves in a concave curve to the required depth. The further movement of the diaphragm 57, as the boat descends, through the toggle-link 63 moves the valve 67 to the right, so that the rudders are left under the control of the diaphragm 52. Fig. 8 shows means for automatically adjusting the amount of water ballest to suit the density of the water in which the vessel floats. A tank 81 contains water of the density of that outside. It is filled through a pipe 83 up to the level of the discharge pipe 84. It contains a float which rises and falls as the density of the water varies, and moves an electric circuit-maker 91 between two terminals 94, 95. When the vessel runs into fresh water, the float falls and makes contact between 91 and 95. The circuit 93 is thus closed, and a valve 19 is opened to admit compressed air to blow water out of the tank 70. Should the water become denser, the circuit 93<a> is closed, and the valve 72 opened to admit water to the tank 70. A float 85 regulates the positions of the terminals 94, 95, and an indicator 98 shows the density of the water. Fig. 9 shows a depth and trim indicator. A plate 100, cut to resemble the outline of the vessel, is carried by a rod 103, moved up and down by a diaphragm 107, to show the depth on a graduated card 104. The card is hung on a pendulum, so that the inclination of the boat is shown. Fig. 12 shows the means of compensating for the torpedoes discharged. A tank 111 contains water, which is passed into the firing- tube 110 before the torpedo contained in it is discharged. After the torpedo is discharged, the outer cap is closed. The tank 111 is then filled from the tube 110, and the remainder of its contents passed into the tank 113. Another torpedo 19 is then moved towards the tube 110, and, at the same time, the contents of the tank 113 are passed into the tank 20. Means are provided for preventing the firing-device from being used until the cap or the discharge tube has been removed.