[sdiy] HP 202C Low Frequency Oscillator

[Magnus Danielson]

From: "john mahoney" <jmahoney at gate.net>
Subject: Re: [sdiy] HP 202C Low Frequency Oscillator
Date: Fri, 2 Jul 2004 12:08:23 -0400
Message-ID: <008b01c4604e$cf296a50$6500a8c0 at BABYUTEST>

> ----- Original Message ----- 
> From: "Magnus Danielson" <cfmd at bredband.net>
> >
> > Oh, and if you use Inch, be sure to use the *right* Inch definition. Even
> that
> > isn't correct in the US (sigh!).
> 
> Yeah, people *say* that these new digital inches are the same as the old
> analog inches, but we're old enough to remember when an inch was an inch.
> ;-)

No, that's not it... but I agree it was funny! ;O)

The real story is that the US metric law from 1866 defines a meter to be
3937 / 100 inches long. However, if you trace it from the SI meter definition
that would result in the US inch being 100 / 3937 meters long which is about
25.4000508001 mm. Now, when CE Johansson made his measurement set of lengths,
such an ratio was too much of an inconvenience, so he simply defined it as
exactly 25.4 mm. This definition was then taken by Ford and General Motors as
they introduced his measurement system into the production floors. By the time
they became aware of the deviation it was too late, and nobody felt it was a
good move to change everything. So, the US metric law has been abandoned by the
industry but not by the legislators. This makes the whole situation a bit
peculiar to say the least.

For other parts of the measuring world, the US metric law makes life even
messier, since the U.S survey foot is based on the US metric law (which makes
sense in its own logic) but the U.S. survey foot is slightly longer than an
international foot, so longer distances measured with the different foot
definitions end up in quite noticeable distance deviations. Now we really
created a mess.

So, which definition do you use?

> ----- Original Message ----- 
> From: "Don Tillman" <don at till.com>
> >
> > I'll claim that the US will never go metric for a very good reason --
> > metric units just do not work in poetry or song lyrics.
> 
> Let me try a conversion:
>     Imperial: "Give 'em an inch and they'll take a mile."
>     Metric: "Give 'em a centimeter and they'll take a kilometer."
> I think you're right, Don, metric has bad meter! ;-)

Actually, if you take a centimeter and gets a kilometer you get a better deal
than when you take an inch and only get ONE mile!

Cheers,
Magnus - 6'4"