Re: [PipingDesign] rules of thumb

From: <Christopher>
Date: Thu Jul 21 2005 - 11:20:00 EDT

On Jul 21, 2005, at 9:27 AM, Conner, Randy wrote:

> I suspect there are many books in effect talking about "rules of thumb"
I can't let this sort of thing go. I sure wish I could
> Rule of thumb
> From Wikipedia, the free encyclopedia.
> <http://en.wikipedia.org/wiki/Rule_of_thumb>
> A rule of thumb is an easily learned and easily applied procedure for
> approximately calculating or recalling some value, or for making some
> determination. Compare this to heuristic, a similar concept used in
> mathematical discourse, or in computer science, particularly in
> algorithm design. See also mnemonic.
> The term "rule of thumb" or similar exists in many languages and
> cultures. Its likely origin is that the thumb is often used for rough
> measurement by carpenters, seamstresses, and many others. In fact, the
> measurement of an inch is believed to have been derived from the
> distance between the tip of the thumb and the first joint. Rules of
> thumb such as the right hand rule in electromagnetics are also used as
> mnemonic devices. This usage, of course, is of more recent vintage.
>

> Myths about origins of term
>
> It is often claimed that the term originally referred to the maximum
> size of a stick with which it was permissible for a man to beat his
> wife. This claim has been debunked, for instance by Christina Hoff
> Sommers in her book Who Stole Feminism? (1994 ISBN 0684801566). In
> particular Sommers notes that there is no mention of this in the legal
> commentaries of William Blackstone.
> The popular etymology of the expression or its urban legend may have
> received a boost in the following quote from Del Martin of the
> National Organization for Women:
> "In America, early settlers held European attitudes towards women. Our
> law, based upon the old English common-law doctrines, explicitly
> permitted wife-beating for correctional purposes. However, certain
> restrictions did exist and the general trend in the young states was
> toward declaring wife-beating illegal. For instance, the common-law
> doctrine had been modified to allow the husband 'the right to whip his
> wife provided that he used a switch no bigger than his thumb' -- a
> rule of thumb, so to speak"
> —Del Martin, Battered Wives Volcano Press, 1976, page 31.
> Regardless of whether Martin's analysis of old English common-law
> doctrines and possibly even her facts, are accurate, there is no
> evidence that she suggested this usage was the origin of the
> expression under consideration. However the legend persists. For
> example:
> "Until the 19th Century, there was a charming little rule of thumb
> that applied to family life. A man was allowed to beat his wife as
> long as the stick he used was no wider than a thumb."
> —Ellen Goodman, Washington Post, April 19, 1983.
> "In state courts across the country, wife beating was legal until
> 1890. There was a rule of thumb, by which courts had stated a man
> might beat his wife with a switch no thicker than his thumb."
> —Chicago Tribune, March 18, 1990.

In engineering, no rule of thumb is universally valid. If you don't know your job, you can do yourself a lot of damage by misunderstanding the applicability. That also holds true with beating up people. If you misjudge the situation, you could end up learning the hard way that your can pick up a stick and use it just as easily as you can. Maybe easier.
Christopher Wright P.E. |"They couldn't hit an elephant at chrisw@skypoint.com | this distance" (last words of Gen.

.......................................| John Sedgwick, Spotsylvania
1864)
http://www.skypoint.com/~chrisw/ Received on Thu Jul 21 11:20:00 2005

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