Main Page | See live article | Alphabetical index 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. Career 1826 - Professor of Mathematics and Natural Philosophy at Albany Academy, New York. 1832 - Professor at Princeton. 1846 - First secretary of the Smithsonian Institution. Second president of National Academy of Sciences. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.