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    Re: Portuguese shipwreck question
    From: George Huxtable
    Date: 2009 Nov 1, 20:55 -0000

    John Huth "Apache Runner" wrote-
    | Attached is an Exel spreadsheet with the names, latitudes and longitudes
    | from the article on the Marseilles tables.   Note that longitude is
    | referenced to the westernmost point of land in that time (13th century),
    | which I guess is the Canary Islands.
    Yes. The origin of longitude from the time of Ptolemy, and maybe from long
    before him, was from the Canaries, or "fortunate isles". They were the
    westernmost place that anyone could conceive of, and longitude was measured
    eastwards from there.
    I'm interested in the 1920s book that these place-names are found in. More
    details, please, John.
    I understand that the Toledan tables, mainly for predicting astronomical
    positions, were translated from Arabic into Latin in the 12th century, and
    the earliest copy which survives was that made by Raymond of Marseille
    around 1140; the document that John refers to. That was not quite the
    original tables based on Toledo, but had been recalculated to apply to
    Marseilles, by Raymond.
    The original Arabic document was a development of Ptolemy, with Islamic
    additions, as they had preserved and built-on the knowledge of the Greeks,
    the long dark-age period in which science had been extinguished by religion
    in Christendom.
    I haven't seen, before, that list of place-names from Toledo, so John's
    spreadsheet is of great interest. I will guess, but it's no more than a
    guess, than many of those places originated from the enormous list in
    Ptolemy's Geographia, but with many Islamic additions. However, none of this
    stuff is from a period in which I am familiar.
    I see that the spreadsheet shows three lots of position-plots, of which the
    first two are similar, but the third differs greatly. What are they based
    on? It would be interesting to see such plots superimposed on an outline
    Mercator map of Europe and Asia (which would call for translating the
    latitudes into meridional parts).
    contact George Huxtable, at  george@hux.me.uk
    or at +44 1865 820222 (from UK, 01865 820222)
    or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
    NavList message boards: www.fer3.com/arc
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