Re: MHO to Siemens

["Prof. John P. Ertel (wizard)" <jpe@nadn.navy.mil>]

I can in no way guarantee that the following is absolutely historically
correct as to the origin of the change to the unit Siemens, but here is
the explanation that was given in a very large session on standards at the
ASEE Conference in Reno, NV (~1987).

It was stated that we (the engineering community) felt that they had
positioned themselves for ridicule for a long time by using such a "cute
and frivolous" name for the unit of reciprocal resistance (1/OHM = MHO).
Further, the use of the inverted upper case omega to symbolically
represent the unit just exacerbated the problem.  From what was said, it
was clear the William Siemens was held almost in reverence as one of the
"greatest pioneering engineers" of all time, and that his name was the
only logical choice for the unit.  A number of folks from the floor made
comments that they understood that Siemens had been heavily involved in
measuring CONDUCTANCE and that they understood this to be the real reason
for the choice.  Those on the dais indicated that they had heard of this
explanation but that it was not historically substantiated, Siemens having
done more research in so many other areas.


Editorial comments:

I always thought that "flipping up-side-down" the upper case omega had
both a certain symmetry and was almost visually demanded given that the
unit is the reciprocal of the upper case omega.  When I made this comment
in the session, I was chided by the moderator that people like Physicists
could think that all they wanted, but engineers had to be more serious and
present a more serious image!  I should point out that this elicited a
significant round of chuckling.

These people that think the unit name MHO has caused a lot of funny
comments, have obviously never experienced the joking that goes on in a
class room with students (some possibly only slightly post pubescent) when
we first mention the unit Siemens.  It seems that at a certain age, the
unit Siemens sounds too much like a certain bodily fluid with which they
are all too interested.

With all due respect to our colleagues in Electrical and other Engineering
areas as well as to William Siemens, I find no good reason to switch from
the unit MHO in my class room.  In fact, from a pedagogical point of view,
I find it almost staying with the MHO almost required.  There is that
annoying problem of being at variance with internationally accepted
standards, but I'll live with it.  I note with some interest that the
engineers have retained the inverted upped case omega as the symbol for
conductance.

ERTEL SENDS.         _____________________
                    / Prof. John P. Ertel \
                   /   jpe@nadn.navy.mil   \
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On Thu, 27 Feb 1997, ABBY KALAM 303 556-3815 wrote:

> From:	MASH::CD_ABUL      "ABBY KALAM 303 556-3815" 25-FEB-1997 15:08:25.33
> To:	IN%"phys-l@mailer.uwf.edu"
> CC:	CD_ABUL
> Subj:	MHO to Siemens
>
> 	I wondered if someone could give me a historical insight on why the
> unit of conductance changed from Mho to Siemens ( S) after William Siemens
> (1823-83) [ besides the mere fact that it is impolite to distort people's names
>  - from Ohm to Mho. That seems an unlikely reason ]. Why Siemens, for example.
> 	Thanking you in advance.
>
> Abby
> COMMUNITY COLLEGE OF DENVER