How many degree Delisle in 1 Reaumur? The answer is -1.2. We assume you are converting between degree Delisle and degree Réaumur. You can view more details on each measurement unit: degree Delisle or Reaumur The SI base unit for temperature is the kelvin. 1 kelvin is equal to -1.5 degree Delisle, or 1.25 Reaumur. Note that rounding errors may occur, so always check the results. Use this page to learn how to convert between degrees Delisle and degrees Réaumur. Type in your own numbers in the form to convert the units!
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The Delisle scale is a temperature scale invented in 1732 by the French astronomer Joseph-Nicolas Delisle (1688–1768). It is similar to that of Réaumur. Delisle was the author of Mémoires pour servir à l'histoire et aux progrès de l'Astronomie, de la Géographie et de la Physique (1738).
He had been invited to Russia by Peter the Great. In 1732 he built a thermometer that used mercury as a working fluid. Delisle 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 too originally ran from zero for boiling water down to 100 for freezing water. This was reversed to its modern order some time after his death, in part at the instigation of Daniel Ekström, the manufacturer of most of the thermometers used by Celsius.
The Delisle thermometers usually had 2400 graduations, appropriate to the winter in St. Petersburg. In 1738 Josias Weitbrecht (1702–1747) recalibrated the Delisle thermometer with 0 degrees as the boiling point and 150 degrees as the freezing point of water. The Delisle thermometer remained in use for almost 100 years in Russia.
Thus, the unit of this scale, the Delisle degree (sometimes spelled de Lisle), is -2/3 of a kelvin (or a degree Celsius) and absolute zero is at 559.725 Delisle degrees.
The Réaumur scale is a temperature scale named after René Antoine Ferchault de Réaumur, who first proposed it in 1731. The freezing point of water is 0 degrees Réaumur, the boiling point 80 degrees Réaumur. Hence, a Reaumur degree is 1.25 Celsius degrees or kelvins. The Réaumur temperature scale is also known as the octogesimal division (division octogesimale in French).
Réaumur's thermometer was constructed on the principle of taking the freezing point of water as 0°, and graduating the tube into degrees each of which was one-thousandth of the volume contained by the bulb and tube up to the zero mark. It was the dilatability of the particular quality of alcohol employed which made the boiling point of water 80°. Mercurial thermometers, the stems of which are graduated into eighty equal parts between the freezing and boiling points of water, are not Réaumur thermometers in anything but name. Réaumur may have chosen the octogesimal division because the number 80 could be halved 4 times and still be an integer (40, 20, 10, 5); the number 100, for instance, could only suffer this process 2 times (50, 25).
The Réaumur scale saw widespread use in Europe, particularly in France and Germany, but was eventually replaced by the Celsius scale. Today it is only of historical significance.
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