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    Re: Lunars.
    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.
    

       
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