Léon Foucault Léon Foucault Jean Bernard Léon Foucault (; 18 September 1819 – 11 February 1868) was a French physicist best known for his demonstration of the Foucault pendulum, a device demonstrating the effect of the Earth's rotation. He also made an early measurement of the speed of light, discovered eddy currents, and is credited with naming the gyroscope. Foucault was the son of a publisher in Paris, where he was born on 18 September 1819. After an education received chiefly at home, he studied medicine, which he abandoned in favour of physics due to a blood phobia. He first directed his
Foucault pendulum vector diagrams The central axis of the pendulum aligns with the axis of rotation of the Earth. The central axis of the pendulum is always determined by the force of gravity directed towards the center of the Earth. A pendulum bob at rest at the North Pole still has spin on the bob. The Foucault pendulum connection is constructed such that the pendulum is free to swing in any direction. If the bob is displaced from the central axis of the pendulum in preparation for swinging and held in place, then the bob will revolve about the central axis of the pendulum