# Way off subject - metrics again [was Re: Vulgar fractions]

From: Mark Davis (markdavis@ispchannel.com)
Date: Fri Feb 11 2000 - 11:05:44 EST

Unfortunately, in the US you really only get the metric system in school (which for me was over a gigasecond ago). Even now, megaseconds go by without my ever seeing any metric measurements in common use. And, sadly, people are the most resistant to using metric *time* measurements, despite the fact that time is -- by far -- the value measured by the most people the most often. After all, metric time only takes a few hektoseconds to learn, and are far more logical than the arcane and irregular combinations of older English units: years, months, weeks, days, hours, minutes, seconds. Compared to this, inches, feet and miles are child's play. One despairs of Americans ever being as enlightened and progressive as Europeans.

Mark

P.S. For Americans interested in filling this chasm in their education, there is a quick chart at http://www.macchiato.com/mark/Time/MetricTimeUnits.html (with vulgar fractions, as an extra bonus). It does not cover the use of the binary prefixes, which can be found at http://physics.nist.gov/cuu/Units/binary.html. The binary pronunciations are also practical in many other situations, as in "The 49ers mebisecond overall, but they had a good season."

Markus Kuhn wrote:

> Michael Everson wrote on 2000-02-11 12:50 UTC:
> > >But these countries manage to trick us into using their units, world-
> > >wide. E. g., everybody seems to dubb 90-mm floppies as "3½-inch
> > >floppies" (though their diameter is endeed 90 mm, exactly).
> >
> > The box here next to me says 3.5"
>
> Just for the record: ANSI X3.171-1989 here next to me says that the
> outer dimensions of the familiar cartridge are 90.0 x 94.0 x 3.3 mm and
> that the magnetic disk material itself has a diameter of 85.80 mm.
> Indeed, nowhere in the drawings appears a measure of 3.5 inches.
>
> Peter Westlake <peter@harlequin.co.uk> wrote:
> >Why are fractions only usable with Imperial units? Do ISO standards
> >forbid metric units to be written as fractions?
>
> ISO 31-0 strongly suggests that SI units should be used only with
> decimal fractions, because this significantly increases user convenience
> and safety. It is obviously much easier for humans to compare 0.2734375
> and 0.28125 than 35/128 and 9/32. Use of fractions in technical
> drawings, product documentation, etc. is today widely considered to be a
> gross violation of good engineering and documentation practice. Infinite
> decimal fractions such as 1/3 are trivially avoided in real life by
> making design dimensions multiples of a module size (such as 300 mm in
> building construction) with a sufficient number of prime factors, as any
> well-trained technical designer will be happy to tell you. Vulgar
> fractions are as antiquated, inappropriate and useless in the 21st
> century as are the inch-pound Flintstone units. It is amazing, how one
> locale manages to need over a century longer to grasp this than all
> others.
>
> Good official style guides for using units of measurement are available
> on:
>
> http://physics.nist.gov/cuu/Units/
>
> Those i18n gurus of you advising technical authors on internationally
> appropriate writing conventions might especially find the following
> brief text useful:
>
> http://physics.nist.gov/cuu/Units/checklist.html
>
> Markus
>
> --
> Markus G. Kuhn, Computer Laboratory, University of Cambridge, UK
> Email: mkuhn at acm.org, WWW: <http://www.cl.cam.ac.uk/~mgk25/>

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