Henry, JOSEPH

LL.D., 1797-1878. Prof. Princeton 1832; Sec. Smithsonian Institution from 1846; founder of its system of voluntary meteorological observers. He established 1855 the first daily weather map by telegraphic reports and weather predictions, was author of investigations and lectures on Climatology, Thunderstorms and Magnetism, and principal promoter of meteorology in the U. S. His first important paper was On some Modifications of the Electro - Magnetic Apparatus. He was the first to show the difference between a "quantity" magnet and an "intensity" magnet with a long fine wire of many turns. He point pointed out that the latter form only was suitable for telegraphic purposes. Early in 1832 he discovered the induction of a current on itself in a long coil of wire, greatly increasing the discharge. He was many times president of the National Academy of Sciences. His publications appeared chiefly in Silliman's Am. Journal of Science; Trans. Am. Phil. Soc.; Smithsonian Reports.