# Daniel Fahrenheit

In science, Daniel Fahrenheit (1686-1736) was a Polish-born German physicist noted for his circa 1720 invention of the mercury thermometer. In prior alcohol thermometers, the variability in alcohol’s purity made it difficult to obtain reproducible results; the use of mercury by Fahrenheit solved this issue. [1]

The Fahrenheit scale (˚F), along with the improved Celsius scale (˚C), made by Anders Celsius in 1742, and eventual universal thermodynamics-based Kelvin scale (˚K), made by William Thomson in 1848, is one of the main indicators with which to measure temperature.

In a letter to his associate Herman Boerhaave, eponym of Boerhaave’s law, Fahrenheit acknowledged that he got his idea for his thermometer from Danish astronomer Ole Romer (who had invented his own thermometer in 1701), albeit using a renumbered scale, in which he used the fixed points of 96 (instead of 22.5 or 90), the temperature of his wife's armpit, 32 the temperature of ice melting in water), and 0 the temperature of a bath of ice melting in a solution of common salt; a scale that he says he began using in 1717. [2] In the letter, Fahrenheit is said to have commented: “as this graduation is inconvenient and awkward because of the fractions, I decided to alter the scale, and to use 96 instead of 22½ or 90; this I have always used since then.” [3]

Education
Fahrenheit was orphaned in 1701, at the age of 16, when both his parents died of mushroom poisoning. He then was sent by his new guardians to Holland to apprentice at a bookkeeping firm, which he eventually ran away from. He then travelled about from city to city, studying under the likes of Gottfried Leibniz and Hermann Boerhaave, among others.

Photo | Note
No extant photos of Fahrenheit exist; the one shown is a 2012 computer-generated image (Ѻ) based on images of his relatives.

References
1. Blumberg, Mark S. (2002). Body Heat: Temperature and Life on Earth (pgs. 18-17). Harvard University Press.
2. Romer scale – Wikipedia.
3. (a) Ernst Cohen discovered in a Leningrad archive a letter in Dutch from Fahrenheit to Herman Boerhaave.
(b) Cohen, Ernst and Cohen-De Meester, W.A.T. (1936). “article”, Chemisch Weekblad, Vol. 33: 374-93.
(c) Middleton, W.E. Knowles. (1966). A History of the Thermometer and its Use in Meteorology (pg. 71). Johns Hopkins Press.

● Fahrenheit, D.G. (1724). “Experimenta et Observationes de Congelatione aquae in vacuo factae a D. G. Fahrenheit”, Philosophical Transactions, London, Vol. 33, pg. 78.
● Bolton, Henry Carrington (1900). Evolution of the Thermometer, 1592-1743 (section: "Fahrenheit and the First Reliable Thermometers", pgs. 61-79). The Chemical Publishing Company.

Daniel Fahrenheit – Wikipedia.