_The Method of Sinking and Raising a Lay Torpedo Boat._--The apparatus by which this is effected is shown at Fig. 131, which is a longitudinal section of a portion of a torpedo boat. The hull _A_ of the torpedo boat is provided with a water chamber _l_, which has holes or apertures _l_^{1} in the bottom of the same, and is also provided with an air cock at _l_^{2}. In connection with this chamber is arranged a small cylinder _m_, provided with a piston _m_^{1}, whose rod _m_^{2} is attached to the lever of the said cock. A spiral spring _m_^{3} is provided to resist the inward movement of the said piston. The said small cylinder _m_ is connected by a pipe _m_^{4} with a valve chest, in which is arranged a slide valve _m_^{5}. The said slide valve is connected by a rod or rods to the lever or levers _m_^{6}, whose fulcrum is at _m_*, and the said levers are connected by the links or rods _m_^{7} with the armatures of electro magnets _n_, which are included in the circuit of the cable, whereby the boat is controlled from the keyboard at the station; _o_ is a pipe extending from the said valve chest to the aforesaid water chamber _l_; _p_ is a feed pipe by which gas is conducted from the reservoir or generator to the valve chamber. When it is desired to sink the torpedo boat an electric current is sent in one direction through the said magnets, and thereby operates the slide valve to admit gas to the cylinder _m_ in front of the piston _m_^{1}, which is thus forced inward and opens the air cock _l_^{2}. The opening of this cock permits the escape of the air from the water chamber _l_, and consequently the entrance of water through the apertures _l_^{1}, and the boat then immediately sinks. When it is desired to raise the boat a current is sent in the opposite direction through the said electro magnets, thereby operating the said valve and piston in such a manner as to close the cock _l_^{2} and open the port _o_^{1} and the pipe _o_, thereby allowing the gas to pass from the valve chamber into the compartment _l_; this gas by its pressure expels the water from the said compartment, and the boat then having its normal buoyancy restored immediately rises to the surface.