NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Brad Morris
Date: 2013 Dec 14, 12:16 -0500
Hi Noell
In older texts, the nonius of the vernier is the zero of the vernier.
Brad
Good point. When I put the arm all the way to the left, with the 15" still over some marks, the zero on the vernier is at just over 118 degrees. For sure 1/6 of a circle times two is not the effective measuring range. I still don't think they should have busted it all the way back to octant. :<)
I looked up nonius and got to Petrus Nonius and his predecessor to the vernier scale but I don't find anything designating a point on the vernier - or does it refer to the whole vernier?
Henry was correct - the tangent screw mechanism has something worn or disconnected inside. It looks fine from outside and nothing obvious is missing. I spotted this before I bought it and decided, since it was hidden, it would not be too difficult to repair.
Regards, Noell
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