Foucault pendulum with a 67-m-long wire from the dome of the Panthéon, Paris. The plane of the pendulum's swing rotated clockwise approximately 11.3° per hour, making a full circle in approximately 31.8 hours. The original bob used in 1851 at the Panthéon was moved in 1855 to the Conservatoire des Arts et Métiers in Paris. A second temporary installation was made for the 50th anniversary in 1902. During museum reconstruction in the 1990s, the original pendulum was temporarily displayed at the Panthéon (1995), but was later returned to the Musée des Arts et Métiers before it reopened in 2000. On April 6,
Foucault pendulum vector diagrams The central axis of the pendulum aligns with the axis of rotation of the Earth. The central axis of the pendulum is always determined by the force of gravity directed towards the center of the Earth. A pendulum bob at rest at the North Pole still has spin on the bob. The Foucault pendulum connection is constructed such that the pendulum is free to swing in any direction. If the bob is displaced from the central axis of the pendulum in preparation for swinging and held in place, then the bob will revolve about the central axis of the pendulum