by Nikolai Shokhirev
In a qualitative manner, we can describe the temperature of an object as that which determines the sensation of warmth or coldness felt from contact with it (http://www.unidata.ucar.edu/staff/blynds/tmp.html).
During human history, people tried to make this notion more quantitative (see e.g. the above link). In 1724 (or in 1714, http://encarta.msn.com) Gabriel Fahrenheit, an instrument maker of Amsterdam constructed the first thermometer employing mercury instead of alcohol. According to unconfirmed information, his temperature scale was supposed to be "natural". Therefore, he took the lowest temperature in Amsterdam as zero and the temperature of human body as 100 degrees.
In this connection, we should make two remarks. First, the lowest possible temperature (so called Absolute Zero) is much lower and is -273.15 C or -459.67 F. Second, he used to measure his wife's temperature (unconfirmed) for the second reference point. Later it was discovered that the majority of humans are colder and the average value is close to 96 F. This is an example that the accuracy of an individual measurement is different from statistical reliability (see our Statistical page).
Commonly accepted Celsius scale was actually introduced by Carolus Linnaeus of Upsula, Sweden. In 1745 he described a scale in which the freezing point of water was zero, and the boiling point 100, making it a centigrade (one hundred steps) scale. Anders Celsius (1701-1744) used the reverse scale in which 100 represented the freezing point and zero the boiling point of water, still, of course, with 100 degrees between the two defining points.
The average temperature of the Universe is only 3 centigrade degrees above the Absolute Zero. However stars a very hot. Their temperature is estimated by their color: the coldest are red and the hottest are blue. It is interesting, that a human body displays the opposite tendency.
Picture by Max Shokhirev
There are several memory aids that can be used to help the novice understand the degree Celsius temperature scale.
One such mnemonic is: Or another one to remember: When it's zero it's freezing,
when it's 10 it's not,
when it's 20 it's warm,
when it's 30 it's hot!30's hot
20's nice
10's cold
zero's ice
The Fahrenheit - Celsius converting programs can be downloaded here.
©Nikolai Shokhirev, 2001-2003.
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