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Degrees Delisle (°De) Unit Definition
The Delisle scale is a temperature scale invented in 1732 by the French astronomer Joseph-Nicolas Delisle (1688–1768). The Delisle degree is -2/3 of a kelvin (K) (or a degree Celsius or Centigrade).
Overview
Delisle built a thermometer that used mercury as a working fluid. He chose his scale using the temperature of boiling water as the fixed zero point and measured the contraction of the mercury (with lower temperatures) in hundred-thousandths. The Celsius scale also originally ran from zero for boiling water down to 100 for freezing water. This was reversed to its modern order sometime after his death. Thus, the unit of this scale, the Delisle degree is -2/3 of a kelvin (or a degree Celsius or Centigrade) and absolute zero is at 559.725 °De.
History
In 1732, Delisle built a thermometer that used mercury as a fluid. Delisles scale used the temperature of boiling water as the fixed zero point and measured the contraction of the mercury (with lower temperatures) in hundred-thousandths. Delisle thermometers usually had 2400 or 2700 gradations, appropriate to the winter in St. Petersburg. Deslisle had been invited by Peter the Great to St. Petersburg to found an observatory in 1725.
In 1738, Josias Weitbrecht (1702–47) recalibrated the Delisle thermometer with two fixed points, keeping 0 degrees as the boiling point and adding 150 degrees as the freezing point of water. He sent this recalibrated thermometer to various scholars, including Anders Celsius. The Celsius scale, like the Delisle scale, originally had zero degrees for boiling water and 100 degrees for freezing water. The Celsius scale was reversed to its modern order after his death, in part at the instigation of Swedish botanist Carl Linnaeus and the manufacturer of Linnaeus thermometers, Daniel Ekström.
The Delisle thermometer remained in use for almost 100 years in Russia. One of its users was Mikhail Lomonosov, who reversed it, as Jean-Pierre Christin did with Celsius's scale. This made the freezing point of water 0 °De and the boiling point 150 °De.
Common Temperatures
Absolute zero (exactly): 559.725 °De
Boiling point of liquid nitrogen: 443.70 °De
Sublimation point of dry ice: 267 °De
Melting point of H2O (purified ice): 150 °De
Room temperature (NIST standard): 120 °De
Normal human body temperature (average): 94.50 °De
Waters boiling point at 1 atm (101.325 kPa) (approximate: see Boiling point): 0.02415 °De
Conversion Formulas
Here are the conversion formulas used to convert both from and to degrees delisle:
From Delisle |
To Delisle |
|
Celsius or Centigrade |
[°C] = ((100 - [°De]) × (2⁄3)) |
[°De] = ((100 - [°C]) × (3⁄2)) |
Fahrenheit |
[°F] = ((212 − [°De]) × (6⁄5)) |
[°De] = ((212 − [°F]) × (5⁄6)) |
Newton |
[°N] = (([°De] + 100) ÷ 4.5455) |
[°De] = (([°N] × 4.5455) - 100) |
Rankine |
[°Ra] = ((671.67 − [°De]) × (6⁄5)) |
[°De] = ((671.67 − [°Ra]) × (5⁄6)) |
Réaumur |
[°Re] = (([°De] + 100) ÷ 1.875) |
[°De] = (([°Re] × 1.875) - 100) |
Rømer |
[°Rø] = ((([°De] + 100) ÷ 2.8571) + 7.5) |
[°De] = ((([°Rø] - 7.5) × 2.8571) - 100) |
Kelvin |
[K] = ((373.15 − [°De]) × (2⁄3)) |
[°De] = ((373.15 − [K]) × (3⁄2)) |
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Sources
“Delisle Scale.” Wikipedia, Wikimedia Foundation, 19 Jan. 2020, en.wikipedia.org/wiki/Delisle_scale.