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 there are two related points projected onto the surface of the Earth. These points can be used to determine the corresponding surface velocity components that are in opposition and not acting in the same plane of the swing. The magnitude of the difference between these two points (for a given latitude of the center-point) is a relative measure of the time to observe one full rotation. The ratio of the velocity vector difference to the corresponding points at the North Pole with the same equidistance from the center of the swing and the same projection to the surface can then