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Origins of the Temperature Scales

What is Celsius?

Celsius is the most widely used temperature scale in the world today. It was developed by Swedish astronomer and physicist Anders Celsius in the 18th century.

Celsius proposed a temperature scale with 0 degrees as the freezing point of water and 100 degrees as the boiling point of water. Its simplicity with reference points based on the properties of water made it widely adopted and essential for scientific and everyday temperature measurements.

The Celsius scale is also known as the centigrade scale.

What is Fahrenheit?

The Fahrenheit temperature scale was developed by Polish-German physicist and engineer Daniel Gabriel Fahrenheit. In 1724 Fahrenheit created the mercury-in-glass thermometer which had a standardized temperature scale and greater accuracy than existing thermometers.

Fahrenheit used a specific mixture of ice and salt to define zero degrees on the Fahrenheit scale. He used the average human body temperature to define 100 degrees on the scale.

What is Kelvin?

The Kelvin scale is also called the absolute temperature scale. William Thomson, known as Lord Kelvin, proposed the idea of an absolute temperature scale based on absolute zero, where molecular motion stops.

Lord Kelvin collaborated with other physicists, including James Joule, to refine the Kelvin temperature scale. It has become an invaluable tool in scientific research and engineering because it provides a universal reference point for measuring temperature that is independent of the properties of any specific material.

What is Rankine?

The Rankine scale was developed in the 19th century by Scottish physicist and engineer William John Macquorn Rankine. Rankine's scale is related to the Kelvin scale, where the Kelvin degree is the same size as the Rankine degree. Rankine begins at absolute zero, so 0 °R is the same as -459.67°F.

The Rankine scale is still used in some engineering calculations involving thermodynamic processes, especially in fields related to heat transfer, fluid dynamics, and energy systems.

What is Réaumur

The Réaumur temperature scale is named for René-Antoine Ferchault de Réaumur. It is a historical temperature measurement system that divides the temperature range between the freezing and boiling points of water into 80 equal parts. So the freezing point of water is 0 degrees Réaumur, and the boiling point is 80 degrees Réaumur.

The Réaumur scale was widely used in parts of Europe, particularly in France and Germany, for scientific and industrial applications during its time. Modern use of the Réaumur scale occurs in some European cheese factories, and in the Netherlands when cooking sugar syrup.