Subject:
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Re: Conversion between LDU, inches and millimeters
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Newsgroups:
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lugnet.off-topic.geek
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Date:
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Tue, 24 Aug 1999 23:48:32 GMT
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Viewed:
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4028 times
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In lugnet.faq, Jeremy Sproat writes:
> Robert Munafo wrote:
> > The inch to millimeter conversion is (by international standard) exactly • 25.4
> > millimeters to an inch. That is also an exact figure (by international
> > agreement).
>
> This surprises me. *Exactly* 25.4 mm / inch? I thought that the conversion
> rate was kind of one of those irrational numbers (1) that had digits
> trailing off into infinity or, failing that, Imelda Marcos' shoe closet.
Yes. Here is a table provided by Lycos:
http://infoplease.lycos.com/ipa/A0001729.html
scroll down and notice that the value for inch->millimeter is given as
"25.4000"
The story I heard is that, at some point around 100 years ago it was decided to
redefine the English weights and measures in terms of the SI (international
system or "metric") and when they looked at the units of length they discovered
that the inch was so close to being 25.4 millimeters that the error term in the
measurement of the inch (which had hitherto been defined by the length of a
rod) was greater than the difference they would impose by choosing a value of
exactly 2.54. So, the value of exactly 2.54 was chosen, much to the convenience
of scientists and schoolchildren everywhere.
Since then the meter has been redefined (twice, I believe) and the inch got
redefined right along with it.
- Robert Munafo http://www.mrob.com/
LEGO: TC+++(8480) SW++ #+ S-- LS++ Hsp M+ A@ LM++ YB64m IC13
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Message is in Reply To:
 | | Re: Conversion between LDU, inches and millimeters
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| (...) This surprises me. *Exactly* 25.4 mm / inch? I thought that the conversion rate was kind of one of those irrational numbers (1) that had digits trailing off into infinity or, failing that, Imelda Marcos' shoe closet. :-, (...) *This* is cool. (...) (25 years ago, 24-Aug-99, to lugnet.faq)
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