Adrian Tuddenham wrote:

I believe some variation of this method was the standard way of
determining the gauge of wires many years ago. It had the advantage
that the reading was averaged over a number of wires (some of which may
not have been exactly circular in cross-section) and, once established,
could be used by anyone with a ruler to give a fairly good degree of
accuracy.


I saw a prototype optical measuring system about 30 years ago that
was being refined to measure copper wire on the production line. It was
already accurate to under 1/1000 inch, at production speeds.

--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.