The only thing I've been able to imagine for this is that the ruler is
intended for a check of thread sizes. SAE threads of 18/in and 22/in are
decently common. This place probably just grabbed some oddball ruler
they had lying around. Hey, they sell unclaimed luggage contents!
Jim
On 2011-02-13 1652, James R. Frysinger wrote:
Here's how to convince me that the inch is easy to use... Just hand me a
ruler with two inch scales, one with 22 divisions per inch and one with
18 divisions per inch!
http://www.unclaimedbaggage.com/unpackthebag2.html
I've seen typesetters scales with points and picas as subdivisions for
the inch, but this one was new to me! The ruler is being used to measure
an emerald. Is this something that gemologists once used? Mostly what
I've seen gemologists use is the metric system.
The site is that of Unclaimed Baggage in Scottsboro AL. They buy up
baggage that has gone unclaimed after airlines have tried for 90 days to
find the owners. (The claim is that airlines are successful more than
99.9 % of the time.)
Jim
--
James R. Frysinger
632 Stony Point Mountain Road
Doyle, TN 38559-3030
(C) 931.212.0267
(H) 931.657.3107
(F) 931.657.3108
