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,
Panthéon cross of the dome, which was retained in compromise, is again visible during the current major restoration project. In 1851, physicist Léon Foucault demonstrated the rotation of the Earth by constructing a Foucault pendulum beneath the central dome. The original sphere from the pendulum was temporarily displayed at the Panthéon in the 1990s (starting in 1995) during renovations at the Musée des Arts et Métiers. The original pendulum was later returned to the Musée des Arts et Métiers, and a copy is now displayed at the Panthéon. It has been listed since 1920 as a "monument historique" by the French