Nikola Tesla U.S. Patent 511,916 - Electric Generator Patent Wrapper Page 19

26 site side of the plunger J and tends to drive it forward. The compressions of the air in the cylinder I and the consequent loss of energy due mainly to the imperfect. elasticity of the air, give rise to a very considerable amount of heat. This heat I ut ilize by conducting the steam or compressed air to the engine cylinder through the chamber formed by the jacket surrounding the airspring cylinder, the heat thus taken up and used to raise the temperature of the steam or air acting upon the pist on is availed of to increase the efficiency of the engine. In any given engine of this kind the normal pressure will produce a stroke of det ermined length, and this will be increased or diminished according to the increase of pressure above or the reduction of pressure below the normal. In constructing the apparatus proper allowance is made for a variation in the length of stroke by giving to the confining cylinder I of the air spring properly determined dimensions. The greater the pressure upon the piston, the higher will be the degree of compression of the air-spring, and the consequent counteracting force upon the plunger. The rate or period of reciprocation of the piston however, is mainly determined as described above by the rigidity of the air spring and the inertia of the moving system, and any period of oscillation within very wide -10