born Dec. 17, 1797, Albany, N.Y., U.S.
died May 13, 1878, Washington, D.C.
U.S. physicist.
He aided Samuel F.B. Morse in developing the telegraph. He discovered several important principles of electricity, including self-induction. He observed electromagnetic induction a year before Michael Faraday announced its discovery. He made improvements to electromagnets, discovered the laws on which the transformer is based, investigated electric discharge, and demonstrated that sunspots radiate less heat than the general solar surface. In 1846 he became the first secretary and director of the Smithsonian Institution, where he organized a corps of volunteer weather observers that led to creation of the U.S. Weather Bureau. He was a chief technical adviser to Abraham Lincoln during the Civil War and a primary organizer of the National Academy of Science. In 1893 the standard unit of electrical inductance , the henry, was named in his honour.