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On Wed, 22 Jul 1998 09:24:32 EDT, Maurice Millard  said:
>...
> I want to call the attention, to those interested in these affairs, to an
> article in "Navigation",  Winter 1997-1998, Volume 44, #4 by  Arne Molander,
> titled "The Celestial Navigation of Christopher Columbus." (Yes, its some time
> ago, but it takes a while for the library circulation to work its way through
> the subscribers in the company.)
>
> The author suggests that Columbus could have used the Lunar Distance technique
> to establish his Longitude. Interesting!

Columbus is known to have had Johann Mueller's almanac, which predicted
the lunar eclipses for 1474-1504. With this and the tools available he
could have fixed his time to within 15 minutes, and thus his longitude
to within 3-4 degrees.

The paper that I got that information from ("The Navigational Mysteries
and Fraudulent Longitudes of Christopher Columbus", by Keith A. Pickering,
1997, Society for the History of Discoveries and the Haklyut Society)
contains this tantlizing footnote:

    A recent alternative suggestion [Molander, Arne B. (1992) Columbus
    and the Method of Lunar Distance, _Terrae Incognitae_ 24, 77-103]
    has been shown to be flawed [Pickering, Keith A. (1996) Columbus's
    Method of Determining Longitude: An Analytical View, _The Journal
    of Navigation_ 49:1, 99-113. See also ensuing discussion in _The
    Journal of Navigation_ 49:3, 444 and 50:1, 144-147.]

Does anybody have access to either of these journals? I, too, doubt that
accurate tables of lunar distance existed in Columbus's time, but I could
almost believe that _a posteriori_ calculations could have been performed
to determine his time and longitude.
--
Peter Smith -- psmith@wellspring.us.dg.com
Data General Corp., Westboro, Massachusetts  (for whom I do not speak)
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