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Northland Age, Volume V, Issue 7, 5 October 1908, Page 7

An instrument has just been installed in the Weather Bureau office in St. Louis (U.S.A.). It is for automatically measuring and recording the amount of humidity in the atmosphere for a given period. The instrument —called a hygrometer—is composed ol' twenty human hairs, suspended from a fixed arm, and attached at the lower ends to a lever, which works an automatic pen over a paper-covered cylinder revolved by clockwork. The hairs are 12 inches lolig and perfectly parallel. They are specially treated with chemicals to remove all oil or other natural coating that would prevent oi moisture before being nlacei in the instrument, and in their present condition are very sensitive to the action of moisture. The Lairs become longer or shorter, according to the amount of moisture in the atmosphere, and in varying send the recording needle forward or backward over the sheet of paper on the revolving cylinder.