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From: msb@sq.com (Mark Brader)
Subject: Re: degrees Celsius
Message-ID: <1997Jan15.015353.29436@sq.com>
Organization: SoftQuad Inc., Toronto, Canada
References: <32C7046E.24F0@cs.purdue.edu> <32D94C56.7AB8@ix.netcom.com> <32D9580B.919@hal-pc.org> <32DB10A6.5751@cs.purdue.edu>
Date: Wed, 15 Jan 1997 01:53:53 GMT
Lines: 38
Xref: glinda.oz.cs.cmu.edu comp.std.internat:6556 sci.lang:68109

Markus Kuhn:
> The name "Centrigrade" implies just that some temperature difference
> between two reference temperatures has beed divided into 100
> grades. But this is how BOTH the Fahrenheit and Celsius scales have
> been defined!!! ...

> The respective reference temperatures were:
> 
>      0 C           freezing point of pure water
>    100 C           boiling point of pure water
>                     (at 101.3 kPa standard sea-level airpressure)
> 
>      0 F           lowest temperature that Mr. Fahrenheit reached
>                     with some ice/salt mix
>    100 F           Mr. Fahrenheit's body temperature at some hot day
>                     (he obviously had with 37.8 C a mild feaver,
>                     normal body temperature is 37.0 C)

For Celsius, this is backwards; the original definition was later inverted
to give the scale used today.  For Fahrenheit, it is disputed; there are
several mutually incompatible versions of the origin of that temperature
scale, and the above is the only one based on the strange and inconvenient
division into 100ths.

(Why disputed?  Because in Fahrenheit's time the matter of how he got his
thermometers to agree with each other so well was a *trade secret*, which
he had not reason to give out.  Why inconvenient?  Because he had to
construct the scale between the fixed points, and it's easier to divide
a given distance into halves or thirds.)

Of course, today even the Celsius definition has been superseded by a more
precise one, and the fixed points of that scale are now -273.15 and 0.01C.
-- 
Mark Brader             "Thus the metric system did not really catch on in the
msb@sq.com                States, unless you count the increasing popularity
SoftQuad Inc., Toronto     of the 9 mm bullet."         -- Dave Barry

My text in this article is in the public domain.
