Joseph Henry is widely considered the foremost American scientist of the 19th century. Although Henry at an early age appeared to be headed for a career in the theater, a chance encounter with a book of lectures on scientific topics turned his interest to science. Henry's early investigations concerned electromagnetic phenomena, and his discovery of electromagnetic self-induction in 1831 established his reputation in America. Interestingly, Henry appears to have discovered the principle of electromagnetic induction independently of British scientist Michael Faraday, but because Faraday published his results before Henry, he is credited with the discovery.
In 1846 Henry was named first secretary of the newly established Smithsonian Institution, a position he held until his death. In 1868 he was elected president of the National Academy of Sciences; this position, too, he held until his death.