 Tesla's Egg of Columbus

Tesla's Egg of Columbus was a device exhibited in the Westinghouse Electric display at the 1893 Chicago World's Columbian Exposition to explain the rotating magnetic field that drove the new alternating current induction motors designed by inventor Nikola Tesla by using that magnetic field to spin a copper egg on end.At the 1893 World's Columbian Exposition Westinghouse Electric (who had a large space in the "Electricity Building" devoted to their electrical exhibits) asked Tesla to participate and gave his devices their own exhibit space.