Date: Wed, 22 Apr 1998 13:04:21 -0700 From: Rick Walker <walker@cutter.hpl.hp.com> To: cp@opus.hpl.hp.com Message-Id: <aabcdefg1347$foo@default> Subject: Fahrenheit and Celsius - history
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I hope you can stand just a little more on the Fahrenheit/Celsius
thread, but not converting between the scales but on the history of the
two scales.
On Tue, 21 Apr 1998, Fernando Rivadavia, in the second paragraph below,
commented on the previous comment, as given in the first paragraph
below.
> >Unfortunately, for some strange reason, in the Fahrenheit scale,
> >water boils at 212degrees but at 100degrees Celsius and freezes at
> >32degrees F and 0degrees C so there is effectively a 32degree
> >'offset' on the Fahrenheit scale.
>
>
> As far as I know, the difference mentioned above exists only
> because
> the Celsius scale was based on FRESH water while the Farenheit on SALT
> water. The latter freezes at lower temperatures and boils at higher
> temperatures because of all the dissolved salts it contains. Now why
> would anyone choose salt water instead of fresh water is the mystery
> for me........
Both Fahrenheit and Celsius attempted to set up temperature scales that
could be reproduced for reference purposes by anyone almost anywhere.
As we know the Celsius scale is the more recent and uses the reference
points of 0 degrees as the freezing point, and 100 degrees as the
boiling point of pure water.
Fahrenheit, many years before Celsius, also used the 100 degree range
for his temperature scale. For 100 degree reference, he selected the
temperature of the human body, obtained by placing the thermometer under
the arm. For the 0 degree reference point, he selected the temperature
obtained by making a saturated solution of sodium chloride, NaCl -
common table salt, in water. Both of these conditions could be met in
any laboratory. Unfortunately, Fahrenheit must have been ill when he
set his reference for 100 degrees, as we now use 98.6 F as the
temperature of the human body.
I hope you find this interesting.
John
-- Dr. John J. Rupp Department of Chemistry St. Lawrence University Canton, NY 13617 Phone: 315-229-5856 FAX: 315-229-7421 email: ch03@music.stlawu.edu--------- end of forwarded message ------------
N.B: (by Rick Walker)...
I've always found it interesting that 98.6 F is *exactly* 37 C. That makes me think that Human body mean temp is "defined" as 37C for convenience, and that the 98.6F is a translation thereof.
If the real human mean was *actually* 37.4C, then it might be rounded to 37 for pedantic text-book purposes, which gives an equivalent of 99.3F, which is pretty close to 100F. I think there is more variation than this between oral, rectal, and under-the-arm temperatures.
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