Little Bits of History

What’s the Temperature?

Posted in History by patriciahysell on May 19, 2014
Jean-Pierre Christin

Jean-Pierre Christin

May 19, 1743: A paper discussing temperature is published by Jean-Pierre Christin. He was a French physicist, mathematician, astronomer, and musician. Since he was born in Lyon, his newly designed thermometer was called the Thermometer of Lyon. While he was the designer, it was actually constructed by Pierre Casati and used a new scale where 0 was the temperature at which water froze and 100 was the temperature at which water boiled. In 1742, Swedish astronomer Anders Celsius created a temperature scale in which 0 represented the boiling point of water and 100 was the freezing point. He also discussed the effects of atmospheric pressure of the melting point of ice – none. Christin was working independently of Celsius.

The scale is either called centigrade because there are 100 units or steps and centum is Latin for 100, or it is called Celsius in honor of the Swedish astronomer. A degree Celsius or ⁰C is not only a specific temperature but can also be a temperature interval or the difference between two temperatures. Between 1743 and 1954 0 ⁰C was defined as the freezing point of water at a pressure of one standard atmosphere or the pressure of the atmosphere at sea level. Today, the scale is defined by two different temperatures, one of them absolute zero (the lower limit of the thermodynamic temperature scale). Absolute zero is the state at which matter theoretically reaches minimum entropy. This number is given as 0 in both the Kelvin and Rankine scales. It is -273.15 ⁰C and -459.67 ⁰F.

The SI base unit or Système International d’Unités (International System of Units) has kept the capital letter in Celsius, the only system to retain the upper case. The SI base unit for temperature is the kelvin (lower case). The plural for Celsius is degrees Celsius. SI is also concerned with other precise measurements and defines meter for length, kilogram for mass, second for time, ampere for electric current, candela for luminous intensity, and mole for the amount of substance. And of course, kelvin for temperature.

Kelvin is a scale and does not use the degree name or symbol. Thus 0 K is absolute zero and not a degreed measurement. Uniquely, -40 ⁰ is the same temperature in both Celsius and Fahrenheit but it is 233.15 K. The melting point of purified ice is -0.0001 ⁰C and 31.9998 ⁰F and it is 273.1499 K. Normal body temperature is 37.0 ⁰C and 98.6 ⁰F and over those numbers one is considered to be febrile. The kelvin equivalent is 310.1 K and would make the most placid person a bit squeamish. The boiling point of water which scientists qualify by pressure as well is 373.133 K, 99.9838 ⁰C, and 211.971 ⁰F. Most of the world uses the Celsius scale today but the US has stuck with the Fahrenheit and some scientists working with low temperatures use the Kelvin.

It doesn’t matter what temperature the room is, it’s always room temperature. – Steven Wright

The Harvard Law states: Under controlled conditions of light, temperature, humidity, and nutrition, the organism will do as it damn well pleases. – Larry Wall

When you can measure what you are speaking about, and express it in numbers, you know something about it, when you cannot express it in numbers, your knowledge is of a meager and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely, in your thoughts advanced to the stage of science. – William Thomson, 1st Baron Kelvin

Science is bound, by the everlasting vow of honour, to face fearlessly every problem which can be fairly presented to it. – William Thomson, 1st Baron Kelvin

Also on this day: Duty Calls – In 1780 the Dark Day arrives, bringing fear to many.
Fingerprints – In 1911, the first US conviction was brought on the basis of fingerprint evidence.
Longest Tunnel – In 1906, Simplon Tunnel began service.
Wilde About Douglas – In 1897, Oscar Wilde was released from jail.


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