Bohnenberger's Apparatus
   The  gyroscope is the form we know it today was invented in 1852 by Leon Foucault. However, it had an ancestor in the device developed by Johann von Bohnenberger in 1817.

   Its construction and operation are discussed in the 1856 first volume of Benjamin Pike, Jr.'s Illustrated Descriptive Catalogue of Optical, Mathematical and Philosophical Instruments: "Bohnenberger's Machine. -- This apparatus consists of three movable rings, ..., mounted on a stout base. The two inner rings are mounted on pivots; those on the smallest ring at right angles to the middle one; in the smallest ring is supported a metal ball, having a roller on one of its pivots; around the roller a string may be wound, and when pulled off a rapid rotary motion may be given to the ball. This motion may be given with the axis in any position required, and when communicated, the ring supporting the ball will resist considerable effort to alter its position, and whatever way the instrument may be turned, its axis will continue to maintain the position it had when set in motion, illustrating the inertia, or that property of matter which resists any change of state, whether of rest or motion."

   This example is at the collection at the National Museum of American History at the Smithsonian Institution.

   These examples of Bohnenberger's apparatus have lost their rotating spheres. 

   The device at the left is from Colby College in Waterville, Maine. On the right is one from Transylvania University in Lexington, Kentucky.

   This Bohnenberger's apparatus at the United States Military Academy at West Point, New York, and probably dates from the early part of the twentieth century.
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