Foucault's Pendulum

Adapted to show the earth's rotation. In Feb. 1851 Foucault pointed out that the plane of vibration of a simple pendulum suspended above either pole of the earth would change through an angle 2n once in every 24 hours. This phenomenon is only apparent, since in fact the plane of oscillation is fixed while the earth rotates beneath the pendulum. If the pendulum be suspended in any latitude A, Foucault arrived at the general result that the plane of oscillation will make one complete revolution in 24csc.A hours. This ingenious experiment attracted great attention at the time, since it afforded direct and independent proof of the rotation of the earth.