NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: sextant index error measurement
From: George Huxtable
Date: 2006 Nov 12, 13:48 -0000
From: George Huxtable
Date: 2006 Nov 12, 13:48 -0000
Thanks to Jim van Zandt for correcting my posting [NavList 1613], which was itself an attempt to correct my earlier posting [NavList 1588]. And I agree with him, that this time it is indeed right; that the offset between the two viewlines from a sextant, when it's set to 0 degrees, will be 2 d sin A, in which d is the distance between the parallel reflecting surfaces (allowing for the refractive index of any intervening glass) and A is the tilt of the horizon mirror, from being at right-angles to the axis of the telescope. Sorry about getting it wrong twice before. Funny, isn't it, how I had just written, in [NavList 1666]- "This list acts an an almost-instant peer review, for which I have been truly grateful when it has found flaws in my own arguments; a more frequent occurrence than I wish to recall." and then to have it exemplified so graphically! It's good to see how effective this list can be, at detecting rubbish. George. contact George Huxtable at george@huxtable.u-net.com or at +44 1865 820222 (from UK, 01865 820222) or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK. --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to NavList@fer3.com To , send email to NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---
