Joseph Henry's Yale Magnet, by Harrell, Alfred, 1974, Smithsonian Archives - History Div, Joseph Henry's Yale magnet, showing windings and conductors for connection to the battery. Shortly after completing an article on his electromagnet for Benjamin Silliman's American Journal of Science, Joseph Henry, who would later become the first Secretary of the Smithsonian Institution, began making a large electromagnet for Silliman to demonstrate to his students at Yale c. 1830s. The 82.5 -pound magnet proved capable of supporting more than 2,000 pounds..