Degree Delisle (°De)
An inverted scale devised by Joseph-Nicolas Delisle in 1732 and later fixed with water boiling at 0° and freezing at 150°, so temperatures rise as it gets colder. Used in Russia for roughly a century.
0 degrees Delisle = 373.15 kelvins (exactly).
About the degree Delisle
Temperatures on the Delisle scale rise as things get colder, a reversal found in very few thermometer systems. Joseph-Nicolas Delisle, a French astronomer, built a mercury thermometer in 1732 with zero at the boiling point of water and measured the contraction of the mercury in hundred-thousandths. Peter the Great had invited him to Russia in 1725 to found an observatory in St. Petersburg, and his instruments were usually graduated to 2,400 or 2,700 divisions, a range suited to the severe local winters.
In 1738 Josias Weitbrecht, a colleague in St. Petersburg, recalibrated the instrument between two fixed points, 0 for boiling water and 150 for freezing. He sent such thermometers to scholars, among them Anders Celsius, whose own first scale was also inverted, running from 0 at boiling to 100 at freezing, before it was flipped after his death. Wikipedia says the Delisle thermometer stayed in use in Russia for almost a century, though that claim lacks a citation.
One degree Delisle is two thirds of a kelvin or Celsius degree. To convert, subtract two thirds of the Delisle reading from 100 to get Celsius, or from 373.15 to get kelvin. Boiling water is therefore 0 and freezing water is 150, so an ordinary winter day reads well above 100.
Sources: Wikipedia: Delisle scale
Degree Delisle conversion chart
100 degrees Delisle expressed in every other temperature unit:
| Unit | 100 degrees Delisle |
|---|---|
| Kelvin | 306.4833333 |
| Celsius | 33.33333333 |
| Fahrenheit | 92 |
| Rankine | 551.67 |
| Réaumur | 26.66666667 |
| Newton | 11 |
| Rømer | 25 |
More French (Ancien Régime) units
- degree Réaumur (temperature)
- ligne (length)
- pouce (length)
- pied du roi (length)
- toise (length)
- lieue (Paris league) (length)
- arpent (North American) (area)
- poncelet (power)
- pièze (pressure)
- sthène (force)
All French (Ancien Régime) units
Browse all temperature units.