NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: UNK
Date: 2012 Feb 20, 09:56 -0800
Hello All,
I see reproduction box sextants with all types of nonsense inscriptions but, in museum box sextants I often see a table of tangent values multiplied times 100. Why were these values included?
They list small angles, 0.1, 5, and 10 degrees but you can't use those to get larger tangent values - (Tan 20 + Tan 5 ) x 100 = 45.15 while Tan 25x 100 = 46.6.
They list most of the larger angles by 1 degree steps and also list the angle and Tan values for even numbered values - Tan 84.17 x 100 = 1000. (actually 979) This hints at a real application starting both with the angle AND working backwards from the values.
I've been look at all the sight reduction formulas I can find and none of them seem to be based on Tangent functions.
It's possible to derive other trig functions from Tan but it would be easier to start with a list of Sine values.
I'm hoping that the museum Box Sextants are real and the list of Tangents is not something that was included to sell a reproduction.
When I consider that the user of an original Box Sextant would probably be working the sights with a pencil and paper, I just can't think that tangents would be much help.
How were these values used in practice?
Regards, Noell
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