The Foucault pendulum, or Foucault's pendulum, named…

The Foucault pendulum, or Foucault's pendulum, named after the French physicist Léon Foucault, conceived as an experiment to demonstrate the rotation of the Earth, is is a tall pendulum free to oscillate in any vertical plane.

The direction along which the pendulum swings rotates with time because of Earth's daily rotation.

The first public exhibition of a Foucault pendulum takes place in February 1851 in the Meridian Room of the Paris Observatory.

A few weeks later, Foucault makes his most famous pendulum when he suspends a twenty-eight kilogram bob with a sixty-seven-meter wire from the dome of the Panthéon in Paris.