What is the Delisle Temperature Scale?

The Delisle temperature scale is a historical temperature scale that was proposed by French astronomer Joseph-Nicolas Delisle in the 18th century. Unlike other temperature scales, the Delisle scale is based on the freezing point of water being at 0°, and it progresses in the opposite direction compared to Celsius or Fahrenheit. The scale is rarely used today but is an interesting part of temperature measurement history.

History of the Delisle Scale

The Delisle scale was introduced in 1732 by Delisle, who developed it for use in Russia, where it gained some popularity in the 18th and 19th centuries. The scale was based on the assumption that the freezing point of water is at 0 and that the boiling point of water is at 150°. However, its inverse relationship with temperature led to its eventual abandonment in favor of more commonly used scales like Celsius and Fahrenheit.

How the Delisle Scale Works

The Delisle scale is unique in that it starts at 0° at the freezing point of water and increases as the temperature decreases. The boiling point of water is set at 150°, and as the temperature goes lower, the Delisle value increases. This is opposite to the way other temperature scales such as Celsius or Fahrenheit behave.

The Delisle scale is often used in conjunction with temperature conversions, with the following formulas:

Delisle to Celsius Conversion

Celsius (°C) = 100 - (Delisle (°D) / 1.5)

Delisle to Fahrenheit Conversion

Fahrenheit (°F) = 212 - (Delisle (°D) * 2)

Applications of the Delisle Scale

While the Delisle temperature scale is no longer widely used, it had some applications in the past:

• Historical Use in Russia: The scale was used in Russia for scientific and meteorological purposes.
• Astronomy: Early astronomers employed the Delisle scale for recording temperature data in scientific observations.
• Scientific Curiosity: The Delisle scale remains a point of interest for historians and scientists studying historical temperature measurement systems.

Comparison of Delisle with Other Temperature Scales

The Delisle scale is quite different from more commonly used temperature scales like Celsius and Fahrenheit. While Celsius and Fahrenheit have a direct progression as temperatures rise or fall, the Delisle scale works in reverse, making it more challenging to use in modern applications. Here’s a quick comparison: