Professor Pippard with Foucault Pendulum mechanism, 1988.

UNITED KINGDOM - APRIL 11: Made in the workshops of the Cavendish Laboratory in Cambridge, Kent, this version of Foucault�s Pendulum has been demonstrating the Earth�s rotation at the Science Museum in London since 1988. Unlike its predecessor, this pendulum runs continually, so avoiding the need to re-swing the pendulum each hour. In this 1988 view, its designer Professor Brian Pippard is shown maintaining the moveable scale, which indicates time against the angle rotated. Gently raising and lowering the pendulum pivot, using a motor in conjunction with a sensor, keeps the pendulum in motion. Known as �parametric amplification�, it uses the same principle which keeps a child�s swing in motion. (Photo by SSPL/Getty Images)