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Requirements for Class A and Class B sextants
From: Noell Wilson
Date: 2022 Mar 26, 09:18 -0700
From: Noell Wilson
Date: 2022 Mar 26, 09:18 -0700
Today on eBay there’s a vernier sextant tested in 1913 and given a Class B designation. It has a 6x inverting scope, a 3x star scope, 4 index shades, 3 horizon shades, vernier to 10”, an adjustable rising piece, and no correction errors listed. I can’t read the tarnished silver arc but the inspection certificate includes a reading at 120 degrees.
I didn’t understand the reason for the Class B designation.
I found
https://journals.lib.unb.ca/index.php/ihr/article/download/28301/1882521056on the Class A and B requirements from some time after 1928. Bottom line is that it looks like they wanted a third scope.
It seems to me that the required fields of view are listed incorrectly as 25 degrees for the 6x and 9x scopes and 15 degrees for the 3x.
I looked up some scopes from reputable sources and found:
7 x 35 6.5 degrees
4 x 40 7 degrees
6 x 18 3.5 degrees.
Regards, Noell
Sent from my iPad
