The base of a Foucault pendulum at the China Science and Technology Museum in Beijing, China. This type of long suspension pendulum is named after French physicist Leon Foucault. A Foucault pendulum at the poles oscillates in the same plane in inertial space as the Earth rotates beneath it, so the plane of oscillation would appear to rotate relative to the Earth once every 24 hours. At lower latitudes, the plane precesses more slowly, which is why this scale is marked up to 37 hours.