Tesla's oscillator

Steam would be forced into the oscillator, and exit through a series of ports, pushing a piston up and down that was attached to an armature, causing it to vibrate up and down at high speed, producing electricity.

[3] In 1935, at his annual birthday party/press meeting, 79-year-old Tesla related a story where he claimed a version of his mechanical oscillator caused extreme vibrations in structures and even an earthquake in downtown New York City.

[4] Reporter John J. O'Neill's biography of Nikola Tesla includes a version of this story (date of the telling not given).

As the speed grew, he said that the machine oscillated at the resonance frequency of his own building and, belatedly realizing the danger, he was forced to use a sledgehammer to terminate the experiment, just as the police arrived.

[5] Other versions have Tesla smashing the device before the police arrive and have multi-ton equipment in the basement moving around.