Foucault Pendulum at National Museum of History and Technology

ID: SIA Acc. 11-009 [75-3965]

Creator: Harrell, Alfred

Form/Genre: Color negatives

Date: 1975

Citation: Smithsonian Institution Archives, Acc. 11-009, Image No. 75-3965

Summary

On exhibition January 1, 1964 - October 30, 1998.
Modeled after French physicist J. B. L. Foucault's 1851 pendulum, the museum's pendulum demonstrates the axial rotation of the earth. The 240-pound brass, hollow bob is suspended by a 54-ft. steel cable from the ceiling of the 4th floor. Although the pendulum's vertical plane seems to change, in fact it remains fixed. What is actually moving is the floor, which rotates under the pendulum because of the Earth's rotation. As the Earth moves, the red markers, arranged in a circle around an inlaid compass rose, move into the path of the pendulum, and the bob knocks them over one by one.

Smithsonian Institution Archives, Acc. 11-009, Image No. 75-3965

Smithsonian Institution Archives Capital Gallery, Suite 3000, MRC 507; 600 Maryland Avenue, SW; Washington, DC 20024-2520

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Color negatives

SIA Acc. 11-009 [75-3965]

4 x 5;