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Joseph Henry

Joseph Henry (December 17 1797 May 13 1878) was an American scientist. While building electromagnets, he discovered the electromagnetic phenomenon of self-inductance. He also discovered mutual inductance, independently of Faraday, but Faraday was the first to publish his results. His work on the electromagnetic relay was the basis of the electrical telegraph, jointly invented by Morse and Wheatstone.

The SI unit of inductance, the henry, is named after him.