Nikola Tesla U.S. Patent 514,169 - Reciprocating Engine Patent Wrapper Page 18

JUJEJOLCULL LODDD ( no mal. In construct ing the apparatus I allow for a variation in the length of stroke by giving to the con fining 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 reciprocat ion of the pist an however is no more dependent upon the pressure applied to drive it, than would be the period of oscillation of a pendulum permanently main ta in ed in vibration, upon the force which periodically impels it, the effect of variations in such force being merely to produce corresponding variations in the length of stroke or amplitude of vibration respectively. The period is mainly determined by the rigidity of the air spring and the inertia of the mo ving system, and I may therefore secure any period of oscillation within very wide limits by properly port ioning these factors, as by varying the dimensions of the air chamber which is equivalent to varying the rigidity of the spring, or by adjusting the weight of the moving parts. These conditions are all readily determinable, and described may be made to an engine constructed as here in follow the principle of operat ion above stated and maintain a perfectly uniform period through very much wider limits of pressure than in ordinary use, it is ever like ly -863