Henry

   , HENRY INDUCTANCE

   Joseph Henry (1797-1878) was an American physicist who made fundamental discoveries related to electromagnetism. His experiments played a large part in the development of the telegraph, telephone, radio, and dynamo.

   Henry was born at Albany, New York, and dropped out of school at age thirteen to become a watchmaker's apprentice. Fortunately for the scientific world, he resumed his education three years later, and began experimenting while teaching at Albany Academy. His first important work was the development of the electromagnet. In 1831 Henry demonstrated a telegraph. Samuel Morse used many of Henry's ideas in the telegraph, which he patented six years later. Henry also found a way to produce electric current by moving a magnet through a coil of wire. He arrived independently at this discovery of induced current, but did not publish his work until after Michael Faraday announced the same findings. Faraday received the credit for the discovery, but the unit of electric inductance is now called a henry. Henry taught at Princeton University from 1832 to 1846, at which time he became the first secretary, then a director, of the Smithsonian Institution.

   Through Henry's meteorological work, a weather-reporting system was created. Henry became the first weather forecaster to initiate scientific weather reporting, a practice that led to the creation of the U.S. Weather Bureau. He also was a primary organizer of the National Academy of Science and its second president.