Nikola Tesla U.S. Patent 517,900 - Steam Engine Patent Wrapper Page 15

) J The combination with a cylinder, a reciprocating pist on and valve mechanism for controlling the admission and exhaust of the steam or gas under pressure, of a cylinder, a piston connected with and operating said valve mechanism, and an air spring vibrated by the piston, the spring and piston being related in substantially the manner described to produce a reciprocating movement of constant period. S 5. Witnesses: Arthway Smith Ernest HopRenson Nikola Tesle 87