Gabriel Daniel Fahrenheit, a German physicist and mechanician, born in Dantzic about 1690. died in Amsterdam, Sept, 16, 1736. His predilection for the natural sciences led him to abandon mercantile life and travel in pursuit of knowledge. After visiting various parts of Germany, France, and England, he settled at Amsterdam as a maker of philosophical instruments. Here some of the most eminent natural philosophers of the day became his friends and instructors. Fahrenheit improved the areometer, and made some* progress with the design of a hydraulic machine for the draining of marshes, which he left unfinished; but he is chiefly distinguished for the changes which he made in the thermometer, which were first carried out in 1720, and have added much to the accuracy and value of that instrument. (See Thermometer.) His thermometer since its first introduction has been in general use in Holland, Great Britain, and the United States. Its constructor was elected a member of the royal society of London in 1724, in whose "Philosophical Transactions" for that year are papers by him.