Hendrik Lorentz's thumb
[Painting of Hendrik Lorentz by Arnhemensis. Photo by Bob Tubbs. From Wikipedia]
I am not a native english speaker (well, duh?!), so it took me some years before I first came across the expression "rule of thumb".
As it happens, this occured in a physics lecture on electromagnetism, still in high-school, when our teacher drew on the blackboard the mnemonic for visualizing the direction of a magnetic field, as given by the Lorentz force law.
I thought it was cool! I imagined the important Dutch physician smiling at me, and giving me a "thumbs up!" for finally understanding his laws.
I think it's fair to say that I like rules of thumb!
And all that magnetism...
posted by Anonymous at
6:27 AM
3 Comments:
The great thing about not being a native speaker is exactly the fact that you take nothing for granted -- I never knew the source of this phrase. I never even wondered. It makes perfect sense though, that it's physic(al) in origin. A law of nature.
The illustration doesn't really help me grasp the theory at hand (ahem) but it does remind me of sth else that I learned in high school.
Actually I don't think that this is the source of the phrase, although it is one of the most well known rules of thumb.
According to Wikipedia, 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:
"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."
But sometimes it's not size, it's skill that matters :-)
Interesting folk etymology -- but unfortunately another phallacy (sic), like the one I committed, apparently. I'm afraid I have to concur "that the phrase rule of thumb uses the word rule in the sense of ruler, not regulation," and refers to the method of using the length of the first joint of the thumb (about an inch) as a unit of measure.
Physical, indeed.
And, since we're on the topic, who is it that says you should beat your wife three times a day? If you don't know why, she does. Now that's a rule of thumb.
Post a Comment
Subscribe to Post Comments [Atom]
<< Home