Magnet Revolving Around a Current-Carrying Wire
   In 1821 Michael Faraday demonstrated two related phenomena: (1) a current-carrying wire will rotate around a magnetic pole and (2) a magnetic pole will rotate around a current-carrying wire. This apparatus illustrates the later phenomenon.

   The permanent magnet has a double-bend in the middle. The electric current passes from the connection at the base, up the brass frame, and down the wire as far as the middle of the magnet. It then travels, by way of a short, curved wire, into the mercury contained in the ivory annulus, and then to the other connection. This apparatus is shown on pg 85 of the 1842 Manual of Magnetism.

   This apparatus is in the Collection of Historical Scientific Instruments at Harvard University.

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