1727-1817

Swiss chemist, meteorologist, and geologist who made several firsts in scientific discovery. He first used the term "geologie" (1778), and interpreted the six days of Mosaic creation as epochs of geological time. He was first to provide correct measurement of the heights of mountains by the effects of heat and pressure on a thermometer and to publish the correct rules for equivalent heights to barometric pressure. Along with other meteorological instrument ideas, he invented a hygrometer using gut as the medium for measuring the humidity of the air and became involved with French scientist Horace de Saussure (1740-1799) in arguments over evaporative theory. He noted the independence of vapor pressure to atmospheric air pressure before John Dalton (1766-1844); described the chemical and electrical effects of the electric pile; and shared with Joseph Black (1728-1799) the discovery of latent heat.