Joseph Henry was an American physicist, noted for his early experiments in electromagnetic induction. Much of Henry's work was devoted to the field of electromagnetism and he was generally regarded as an excellent experimenter. By the 1830s he was making powerful electromagnets using iron cores and many turns of insulated wire. He independently discovered electrical induction (although Faraday published his findings first) and constructed the first practical electric motor. Later he went on to develop the relay (1835) which became extremely important in the field of electric telegraphy. His meteorological studies at the Smithsonian Institution led to the formation of the US Weather Bureau. The SI unit of inductance was named after him in 1893.
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