Tesla's oscillator or "Earthquake machine" is a mechanical oscillator that was invented by Nikola Tesla in the year of 1898. the original oscillator that Tesla designed and tested was small, almost seven inches long, and it weighed about one or two pounds. This small device was designed to be powered by steam pressure, only five pounds of air pressure against a special pneumatic piston device was used to operate it.

The concept of Tesla oscillator is purely mechanical, basically it works by applying forced steam into the oscillator, as the steam exists through a series of ports it caused high speed vibrates in the oscillators armature within the casing. As the casing was very strong it was able to handle more than 200 degrees pressure heating in the upper chamber and more than 400psi of pressure. Other versions of Tesla's oscillator were designed and built to be used as an electrical power generator which was able to generate both direct and alternating currents.

In 1898 Tesla had a lab on Huston Street in New York. It was claimed that while Tesla was experimenting his mechanical oscillator he generated a resonance of several buildings near his house causing complaints to the police, as the oscillator speed increased he hit the resonance frequency of his own house. belatedly Tesla realized that he was in danger and has was forced to use a sledge hammer to breakdown the oscillator and stop the experiment, just as the shocked police arrived.

To examine Tesla's claims, the Discovery channel's Myth Busters show tested Tesla's oscillator in their 60th episode. They was aiming to test the mechanical resonance physical phenomenon, to they took the device to a bridge that was built to withstand such forces in today's standards. the test resulted in deflecting a single I-beam of steal several feet in each direction, and they reportedly felt that the bridges was shaking for many yards away, but they did not have the "earth shattering" effect that Tesla described. However the buildings in Tesla's time where not designed to with stance such resonance and traffic bridges have a different and stronger structure than the houses do.

Source: http://ezinearticles.com/?Teslas-Oscillator-Or-Earthquake-Machine&id=2118695