In 1851, the French physicist Léon Foucault provided an experimental proof of the Earth’s rotation using a pendulum. Although Foucault is best known for this ingenious experiment, he also made several important contributions to physics including the discovery of eddy currents as well as measuring the speed of light. Foucault is one of the 72 scientists whose names are engraved on the sides of the Eiffel tower.
At the Arts et Métiers museum in Paris, visitors can witness Foucault's pendulum experiment in action twice daily. The setup features a 17-meter metal cable suspended from the ceiling, with a brass-encased lead sphere attached to its lower end. As the pendulum swings, it gradually knocks over wooden pegs arranged on a circular table below, demonstrating the Earth's rotation.
