http://www.excludedmiddle.com/earthquake.htm "...He constructed a simple device consisting of a piston suspended in a cylinder, which bypassed the necessity of a camshaft driven by a rotating power source, such as a gasoline or steam engine. In this way, he hoped to overcome loss of power through friction produced by the old system. This small device also enabled Tesla to try out his experiments in resonance. Every substance has a resonant frequency which is demonstrated by the principle of sympathetic vibration&endash;the most obvious example is the wine glass shattered by an opera singer (or a tape recording for you couch potatoes.) If this frequency is matched and amplified, any material may be literally shaken to pieces.