Resetting Foucault's Pendulum, 1988.
© Science Museum / Science & Society Picture Library
Made in the workshops of the Royal College of Science (now Imperial College London) in 1883, this Foucault Pendulum was used by the Science Museum until 1988 to demonstrate the rotation of the Earth. In this view, the pendulum is shown being reset by a member of staff. It is held at the end of its swing by a leather strap with cord attached to a hook. Once motionles, the pendulum is released by burning through the thread with a match. The French physicist Leon Foucault (1819-1868), who conceived the display, first demonstrated it at the Parisian Pantheon in 1851. Its replacement, the Pippard Pendulum, designed by Profesor Brian Pippard, runs continually therefore avoiding the need to re-swing the pendulum each hour.