The Earthquake Machine - Nikola Tesla

Nikola Tesla: "Tesla himself described an incident of experimenting with one such device in 1887, when he tuned to the building's frequency and a cracking sound was heard. As he changed the frequency the sound became more intense until everything in his laboratory started 'flying around' and people nearby were terrified. When he realized what was happening, and that the police was on the way, he destroyed the device with a hammer."