Fahrenheit, Gabriel Daniel

, the celebrated improver of the thermometer, was horn at Dantzic, May 14, 1686. He was originally intended for commerce, but having a decided turn for philosophical studies, employed himself in the construction of barometers and thermometers, which art he carried to great perfection. About 1720 he introduced an essential improvement in the thermometer, by substituting meccury for spirit of wine. He also made a new scale for the instrument, fixing the extremities of it at the point of severe cold observed by himself in Iceland in 1709, which he conceived to be the greatest degree of cold, and at the point where mercury boils, dividing the intermediate space into 600 degrees. His point of extreme | cold, which is the same that is produced by surrounding the bulb of the thermometer with a mixture of snow, sal ammoniac, and sea salt, he marked 0, and carried his degrees upwards; though few thermometers have been practically formed which carry their degrees much above 212, the point at which water boils. Forty degrees below the [zero] of Fahrenheit, have since been observed at Petersburg, and elsewhere; and as this is the point at which mercury freezes, it would make a better limit to the scale, which would thus be confined between the utmost extremities of heat and cold that can be examined by means of that fluid. Our English philosophers have in general adopted the scale of Fahrenheit; those of France have preferred Reaumur’s. Fahrenheit published a dissertation on thermometers in 1724. He travelled to Holland, and in various parts of the continent, in pursuit of knowledge, and died Sept. 16, 1736. 1