NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Lunars.
From: Herbert Prinz
Date: 2001 Jul 09, 11:54 AM
From: Herbert Prinz
Date: 2001 Jul 09, 11:54 AM
Dear Steven, I am excited to hear about your dissertation about LDs and Mayer and I am looking forward to the time when it will be available to the public. I am not aware of any exhaustive treatment of the subject of LDs since Cotter's excellent book, "A History of Nautical Astronomy", 1968. My best wishes to you. I am actually surprised to hear that Mayer contributed to lunar theory. I always assumed (without checking) that his merit was mainly to go to the labour of casting Euler's theory into the format of tables. Can you give us a lead to relevant literature? Did Mayer actually believe that his tables could be directly used at sea, without any further transformation? (Obviously, the fact that Maskelyne could use them did not prove their usefulness for just any odd navigator). My impression was they were just meant to prove the principal possibility of using LDs and to assist the Board in having suitable ephemeris or distance tables produced. The impracticability at sea was the reason why the Board originally denied him an award. Where the 14-plus 'equations' are concerned: In fact they were just for longitude. Add 11 more for latitude and then some for parallaxe. But I never suggested that iteration was a good method for manual evaluation. I did say 'for modern use'. I still think it's the only way to go. Best regards Herbert Prinz (from 1368950/-4603950/4182550 ECEF) Steven Wepster wrote: > I'm working on a Ph.D. thesis about Lunar Distances (LD) and Mayer's > lunar theory that made it all possible. and in an other message: > > [...] the procedure that Tobias Mayer proposed to use, when > he submitted his Lunar Tables to the Board of Longitude in 1754. Quite a > cumbersome method, because his tables were for _calculating_ the position > of the moon from epoch + mean motion + 14-plus 'equations' (perturbation > terms). Imagine that you have to _iterate_ ... It took Maskelyne up to 4 > hours to compute a Lunar when on the way to St. Helena in 1761.