Nikola Tesla U.S. Patent 511,916 - Electric Generator Patent Wrapper Page 22

T T T T casing F in which a laminat ed core G' secured to the piston rod H is caused to vibrate. Surrounding the plunger are two exciting coils C¹ C¹, and one or more induced coils D' D'. The coils C' C' are connected with a generator of continuous currents E' and are wound to produce consequent poles in the core G'. Any movement of the latter will therefore shift the lines of force through coils D' D' and produce currents therein. In the circuit of coils D' is shown a condenser H¹. It need only be said that by the use of a proper conden-. ser the self induction of this circuit may be neutralized. Such a circuit will have a certain natural period of vibration, that is to say that when the electricity the rein is disturbed in any way an electrical or electro-magnetic vibration of a certain period takes place, and as this depends upon the capacity and self induction, such period may be veried to approximately accord with the period of the engine. 4 In case the power of the engine be comparatively small, as when the pressure is applied through a very small fraction of the total stroke, the electrical vibration will tend to control the period, and it is clear that if the charact er of such vibration be not very widely different from the average period of vibration of the engine -1329