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Fahrenheit, Gabriel Daniel (1685-1736)
Polish-born Dutch physicist who invented the first accurate thermometer in 1724 and devised the Fahrenheit temperature scale.

Using his thermometer, Fahrenheit was able to determine the boiling points of liquids and found that they vary with atmospheric pressure.

His first thermometers contained a column of alcohol which expanded and contracted directly, as originally devised in 1701 by the Danish astronomer Ole Römer (1644-1710).

Fahrenheit substituted mercury for alcohol because its rate of expansion, although less than that of alcohol, is more constant and could be used over a much wider temperature range.

To reflect the greater sensitivity of his thermometer, Fahrenheit expanded Römer's scale so that blood heat was 90° and an ice-salt mixture was 0°; on this scale the freezing point was 30°.

Fahrenheit later adjusted the scale to ignore body temperature as a fixed point so that the boiling point of water came to 212° and the freezing point was 32°. This is the Fahrenheit scale that is still in use today.

For more details, see Centigrade as well as this Thermometer and Temperature Scale page.

This entry is located in the following unit: Science and Technology (page 1)
(historical perspectives of thermoscopes to thermometers: Daniel Fahrenheit, Galileo Galilei, Anders Celsius, and Lord Kelvin; among others, were major contributors to temperature calculations as we know them today)