"My life," wrote Joseph Henry in defense of his reputation as a scientist and man of honor, "has been principally devoted to science. . . . I have sought . . . no patent for invention and solicited no remuneration for my labors, but have freely given the results to the world. . . . The only reward I ever expected was the consciousness of advancing science, the pleasure of discovering new truths, and the scientific reputation to which these labors would entitle me."
These sentences sum up the goals and achievements of one of the most important American scientists of the mid-nineteenth century. Joseph Henry was an experimental physicist, "a rare bird," historian Nathan Reingold calls him, "for his time and place." His investigations of electricity and magnetism led him to the discovery of the law of electromagnetic induction--a basic principle of electrical science-- and also to the practical invention of an electromagnet of great weight- lifting power and the consequent discovery of its use in a successful electric telegraph system. His realization of the oscillatory nature of electrical current advanced electrical theory and stimulated the invention of the transformer, while it also encouraged him to construct a reciprocating machine driven by direct electric current--what he called his "philosophical toy." In all of these researches, Henry anticipated modern developments in the science of electricity and advanced both theoretical and applied science. He himself, however, never took out patents on his inventions or discoveries in the belief that it was "unbecoming the dignity of true science to curtail the use of discovery to personal and selfish uses." Henry believed it was the obligation of the scientist to show what was possible, and to leave to the inventor the application of discovery to practical uses.
Joseph Henry was born in Albany, New York, of poor parents of Scottish descent. While attending the district school in Galway, New York, he clerked in a village store and read novels and plays vora-