NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Slocum's lunars / Chauvenet
From: Herbert Prinz
Date: 2003 Dec 19, 01:24 -0500
From: Herbert Prinz
Date: 2003 Dec 19, 01:24 -0500
CORRECTION. I wrote: > To my knowledge, [Chauvenet] is the only one to consider for a sea-method > the > oblateness of the earth, the effect of which can change the final result > for the distance by typically 6" or 0.1' of arc in mid-latitudes. Nonsense. Charles Borda had already given such a procedure, as well as a small auxiliary table of moon parallax corrections to be used with it, in his "Description et usage du cercle de reflection", 1787. (I even mentioned this briefly in a post to this list, a year ago.) His method was rigorous. Chauvenet may have been the only one to suggest it for an "approximative" method. Whether the accuracy of the ephemeris around 1800 actually warranted the extra effort that this step would cost the navigator, is another question. Borda certainly thought that the quality of his instrument justified it. Herbert Prinz
