Foucault pendulum

Foucault pendulum, relatively large mass suspended from a long line mounted so that its perpendicular plane of swing is not confined to a particular direction and, in fact, rotates in relation to the Earth’s surface. In 1851 the French physicist Jean-Bernard-Léon Foucault assembled in Paris the first pendulums of this type, one of which consisted of a 28-kg (62-pound) iron ball suspended from inside the dome of the Panthéon by a steel wire 67 metres...