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The Foucault Pendulum was installed at the United Nations Headquarters in New York City, NY in 1955. The gold-plated structure weighs 200 lbs. It is suspended 75 feet above the floor of the lobby, over a raised metal ring, some six feet in diameter, and containing an electromagnet in the center. The Foucault Pendulum was a gift to the U.N. form the Netherlands. It provides visual proof of the rotation of the earth. The sphere, 12 inches in diameter, is held by a stainless steel wire which allows the weighted ball to swing freely in any plane. It swings directly over the raised metal ring, its plane shifting slowly in a clockwise direction. A complete cycle will take approximately 36 hours and 45 minutes. The pendulum utilizes the principle first demonstrated by the noted French physicist, Jean Bernard Leon Foucault, in Paris in 1851, when he suspended a heavy sphere from the dome of the Pantheon by a 220 foot wire. (KEYSTONE/SCIENCE SOURCE/Science Source)