n, pl  henrys  or  henries  :  the practical mks unit of inductance equal to the self-inductance of a circuit or the mutual inductance of two circuits in which the variation of one ampere per second results in an induced electromotive force of one volt
 
Henry, Joseph (1797-1878), American physicist. Henry was a professor of mathematics and natural philosophy at schools in Albany, New York, and later Princeton, New Jersey. In his spare time he conducted a series of investigations into electric phenomena, particularly those related to magnetism. His first major achievement was building a powerful electromagnet, for which he developed insulated wire in order to make a closely wound coil of several layers. He is also credited with constructing primitive versions of the telegraph and the electric motor. In 1832, after reading about Michael Faraday's announcement of the discovery of the self-inductance of current in a coil, he resumed his own investigations of this phenomenon and established that he had independently observed it, possibly as early as 1830. In recognition of his work, his name was given to the henry, the unit of electrical inductance, by international agreement in 1893.
 
 
 
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