Charles F. Marvin, a meteorologist who spent his career with the Army Signal Corps and its successor, the U.S. Weather Bureau, introduced this type of hygrometer in 1908. Unlike the original described by Horace Benedict de Saussure, of Geneva, in 1783, the Marvin instrument had two bundles of hair. The inscription on this example reads “PERCENTAGE OF SATURATION / (RELATIVE HUMIDITY) / HAIR HYGROMETER / No. 19 / U.S. WEATHER BUREAU / HENRY J. GREEN / B’KLYN, N.Y.”
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