Nikola Tesla U.S. Patent 514,169 - Reciprocating Engine Patent Wrapper Page 14

JUJILIJULIU 133 LJUJEJLIG3133300 3 tenance of iso chronous vibration, and also to better utilize the heat generated by the compression, to employ an independent plunger connected with the main piston, and a chamber or cylinder therefor, containing air which is normally, at the same pressure as the external atmosphere, thus a spring of practica. can st an rigidity is obtained, but the air or gas within the cylinder may be maintain ed at any pressure. IC In order to describe the best manner of which I am aware in which the invention is or may be carried in to effect, I refer now to the accompanying drawing which represents in central cross-section an engine embodying my improvements. A is the main cylinder in which works a piston E. Inlet ports C C pass through the sides of the cylinder, opening at the middle portion thereof and on opposite sides. Exhaust ports D D extend through the walls of the cylinder and are formed with branches that open into the interior of the cylinder on each side of the inlet ports and on opposite sides of the cylinder. The piston B is formed with two circumferential grooves E F, which communicate through openings G in the piston with the cylinder on opposite sides of said piston 59