Foucault's gyroscope

The Foucault gyroscope was a gyroscope created by French physicist Léon Foucault in 1852, conceived as a follow-up experiment to his pendulum in order to further demonstrate the Earth's rotation.

Foucault felt that the results of his famous pendulum experiment had been misunderstood. He therefore endeavored to create an apparatus with a "body freely suspended by its center of gravity and rotating around one of its principal axes", allowing the study of a plane with "absolute directional stability". The mechanical precision of Foucault's gyroscope allowed this to be proven clearly to the scientific establishment, and the gyroscope became a widely popular instrument.