FAHRENHEIT

From Agepedia

FAHRENHEIT, Gabriel Daniel, bom a< Dantzic about the end of the 17th century, known for his arrangement of the thermometer and barometer, was originally designed for the commercial profession. His inclination for natural philosophy in o duced him to quit that business, and, having travelled through Germany and Eng land to enlarge his knowledge, he settled in Holland, where the most celebrated men in this branch of sciences'Gravesande and otherswere his teachers and friends. In 1720, he first conceived the idea of using quicksilver instead of spirits of wine in thermometersa discovery by which the accuracy of the instrument was veiy much improved. He took, as the limit of the greatest cold, that which he had observed at Dantzic in the winter of 1709, and which he could always produce by mixing equal quantities of snow and salammoniac. The space between the point to which the quicksilver fell at this temperature, and that to which it rose in boiling water, he divided into 212 parts ; and this distinguishes his thermometrical scale from Reaumur's. (See Thermometer.) He gives an account of it in the Philosophical Transactions for 1724. Nine degrees of Fahrenheit are equal to four of Reaumur, and five of the centigrade scale. Fahrenheit also employed himself, during his residence in Holland (where he died, 1740), in the construction of a machine for draining the parts of the country exposed to inundations, for which he received a patent, but was prevented from completing it by death. The changes which s'Gravesande, whom he had requested to finish the machine for the benefit of his heirs, made in it, rendered it so useless in the first trial, that no attempt was afterwards made to complete it. A detailed account of Fahrenheit's theory of the thermometer may be found in Biot's Physique Experiinentale, vol. 1st.