Joseph Bento wrote:
> It's interesting to read the historical context of what a meter,
> kilogram, etc is.  I wonder if such exacting scientific definitions
> exist for foot, pound, etc., other than the length from one's nose to
> the tip of the outstretched finger.  :-)

Remember that the foot and yard came about much earlier than the meter.  The
metric system was in part a response to the mess of units, with each little
region of Europe often having its own.  The yard and foot were standardized
somewhat long before the meter by using the king as the standard.  I'm not
sure how they then dissemminated that standard measurement.  But the point
is, people were thinking about these things and coming up with at least some
solutions long before the metric system.

Today the imperial units are defined in terms of metric ones, which are
defined against evolving standards as we discover ways to measure something
more accurately.  For example, the inch is 25.4mm exactly, by definition.
That makes the foot exactly 304.8mm, whatever a mm really is.  It used to be
1/1000 the distance between two scratches on a metal bar in Paris.  I think
it's now a certain number of wavelengths of the red emissions of Krypton 86,
but that may have changed again and I may be a bit off about it in the first
place.


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