That false duality of "degrees Celsius" and "Celsius degrees" was
someone's 'bright idea'. Someone NOT in a position to define SI units.
I saw this in a couple of textbooks during my latter teaching days and I
suspect that this "someone" was a textbook author.
I have a theory. Textbook authors paraphrase each other so much instead
of reading the authoritative materials themselves that they start to
feel stifled by their own lack of creativity. So occasionally they have
a "bright moment" and stick the resulting errors in their own textbooks.
Then other textbook authors take what they read as gospel and paraphrase
those errors into their textbooks!
No kidding. I've talked to some of these people. I also field a (metric)
ton of comments on IEEE standards from similar people.* Folks seem to
think that the SI is up for popular vote. Most folks don't realize that
the SI is promulgated by a standard which is developed by a recognized
and solemnic process. Many of those folks don't even know what a
standard is!
Who among you has had a technical course in college where the professor
discussed standards, other than 'author guides'? Perhaps a few of you
have studied the IUPAC naming conventions, which comes from a standard.
Others, though, probably have never had standards explained to you in
schools. I know that (except for that IUPAC bit) I did not.
Among the few who do know what a standard is a misconception often
arises that standards must reflect "what is commonly seen in use". As it
turns out, very few standards are "descriptive"; most are "prescriptive".
Wouldn't it be swell if every college student were forced to read the SI
Brochure in their first math or science course or the like?
Jim
* I am reviewing comments just now that were garnered from the balloting
of a draft revision to IEEE/ASTM SI 10. I'm amazed at the number of new
SI units or practices that people seem to think we can just "vote into
effect" here. Betcha they couldn't even spell BIPM.
JF
On 2010-09-01 1439, John M. Steele wrote:
I vaguely remember an old convention of degrees Celsius for temperatures
and Celsius degrees for temperature differences; however, it is not
documented anywhere (anymore?). Resolution 3 of 13th CGPM seems to
clearly say the kelvin is used for BOTH temperature and temperature
difference, there is no degree Kelvin. The degree Celsius is also used
for both temperature and temperature differences.
There is a fuzzy reference to some prior decisions being abrogated (Res
7, 9th CPGM, Res 12, 11th CGPM, and 1962 CIPM, but usages resulting from
those decions being "temprorarily OK." The abrogated decisions are not
in the SI Brochure, so they may be this obsolete practice.
(Without access to the former decisions, it is quite unclear.)
------------------------------------------------------------------------
*From:* "[email protected]" <[email protected]>
*To:* U.S. Metric Association <[email protected]>
*Sent:* Wed, September 1, 2010 3:16:57 PM
*Subject:* [USMA:48448] Re: kelvin
For temperature differences, "kelvin degree(s)" and "Celsius degree(s)"
are equally acceptable in contrast with *positions* on a temperature
scale with respect to conventional points of reference. e.g. absolute
zero, freezing point of water, triple point of water, boiling point of
water (at a specified pressure).
---- Original message ----
>Date: Wed, 1 Sep 2010 11:42:29 -0700 (PDT)
>From: "John M. Steele" <[email protected]
<mailto:[email protected]>>
>Subject: [USMA:48443] Re: kelvin
>To: "U.S. Metric Association" <[email protected]
<mailto:[email protected]>>
>...
> The one thing we should consider is in a compound
> unit such as themal resistance, that depend on
> temperature difference, only kelvins be used, or
> for increments, 30°C is 5 K warmer than 25 °C.
--
James R. Frysinger
632 Stony Point Mountain Road
Doyle, TN 38559-3030
(C) 931.212.0267
(H) 931.657.3107
(F) 931.657.3108
