Nikola Tesla U.S. Patent 517,900 - Steam Engine Patent Wrapper Page 9

J T B is connected in any manner so as to be reciprocated by the piston rod of a small engine of constant period, constructed substantially as follows:- a is the cylinder, in which works the piston b. An inlet pipe c passes through the side of the cylinder at the middle portion of the same. The cylinder exhausts through ports d d into a chamber d' provided with an opening d". The piston b is provided with two circumferential grooves e, f which communicate through openings in the same with the cylinder chembers on opposite sides of the piston. The special construction of this device may be varied considerably, but it is desirable that all ports, and more particularly, the exhaust por ts be made. larger than is usually done, so that no force due to the action of the steam or compressed air in the chambers will tend to retard or accelerate the movement of the piston in either direction. the The piston b is secured to a rod h which extends through the cylinder heads, the lower end carrying the slide valve above described and the upper end having secured to it a plunger i in a cylinder i fixed to the cylinder a and in line with it. The cylinder i is without ports of any kind and is air-tight except that leakage may occur around the piston -481