HISTORY. The invention of the thermometer must be attributed to Galileo, who in about the year 1593 made an open-air thermoscope, con sisting of a bulb with a long tube attached, which was provided with a scale and dipped below the surface of a liquid—water or wine: some of the air was expelled from the bulb, and so the liquid rose in the tube. This thermometer was used by Galileo for various purposes, such as studying freezing mixtures and recording at mospheric temperatures. It was later used (1611) by Sanetorius in the diagnosis of fevers. The word `thermoseope' was used by Bianeoni in 1617, and 'thermometer' in 1624 by Leurechon. The first scaled thermometers were those of Ferdinand IL, Grand Duke of Tuscany (1641) ; these contained alcohol. In 1661 Fabri made a scale, using as the 'fixed' temperatures those of snow and of midsummer heat. Robert Hooke in 1664 proposed the freezing point of water as one of the fixed temperatures; and in 1694 Renal (Ifni proposed this as one, and the boiling point of water as the other, in 1709 Fahrenheit in troduced his alcohol thermometers, and 1714 his mercury ones. About 1731 Reaumur devised
his scale, which until recently was in extensive use on the Continent of Europe. In 1742 Celsius proposed a Centigrade scale, with the tempera tures of melting ice 100° and boiling water 0°. Christin. working independently of Celsius. pro posed a Centigrade scale in 1743 which is the Celsius scale inverted, and is the one used now. A complete history of the ordinary thermometer is given in Bolton. Evolution of the Thermometer (Easton, Pa.. 1900) ; in Abbe, .1IeleorologicalAp paratcs and Methods (Washington, 1887): and Gerland and Traumiiller, Geschichte der physika lischen Experimentticrkunst (Leipzig, 1899). See