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
Paraconical pendulum about its vertical axis as well as swinging in two perpendicular directions. Therefore a paraconical pendulum has three degrees of freedom. When the rotation of the Earth is taken into account, the formal equations in classical mechanics of the behavior of this dynamical system are rather complex. The rolling friction of the ball upon the flat is extremely low, so that a paraconical pendulum has a high Q factor, principally determined by air resistance. Typically a paraconical pendulum is built as a solid body with a stiff rod, rather than with a flexible wire or cord, and its length is