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    Re: Cotter - copy located
    From: George Huxtable
    Date: 2004 Sep 12, 12:19 +0100

    Frank Reed wrote, about Cotter's "A history of nautical astronomy"-
    >As far as the book's contents, it's a good history but not great. Overall, I
    >would grade it a solid B. The choice of topics is a little haphazard, and it's
    >focused on mathematical theory rather than real practice at sea. For example,
    >there's a nice chapter on altitude corrections with several equations
    >derived, but, if I remember correctly, there's nothing on the 12/20 rule
    >(which Henry
    >H mentioned in another recent message on the list) that was so popular in the
    >early 19th century.
    Response from George-
    Well, as far as altitude corrections are concerned, it's rather worse than
    that! In many (interesting) pages about how the refraction corrections were
    refined, nowhere is it clearly stated whether refraction should be added
    to, or subtracted from, the measured altitude (it should be subtracted, of
    But the point that I think Frank is missing about Cotter's book is its
    uniqueness. Even though it has many deficiencies, nobody else (that I know
    of) has put together a volume like it, where so many different navigational
    procedures have been searched out, noted down in detail, and analysed in
    terms of how they work.
    Gordon Talge has told us he likes to consult the original manuals, but few
    of us have easy access to that sort of library. And faced with the sort of
    recipe supplied (by authors of lunar-distance clearing methods, for
    example) it's not easy for people like me, with weak trig. ability, to
    unravel such wording into a mathematical explanation, in modern notation.
    I'm a fellow who likes to understand what's going on under the bonnet
    ("under the hood", I think, in American), a trait I seem to share with many
    Nav-l subscribers.
    Recently, there's been discussion about Mendoza's approximate method, and
    Henry Halboth has raised Arnold's rather similar procedure. Although Cotter
    discusses neither of these, by referring to his detailed explanation of
    Merrifield's method (pages 227 to 231) it was possible to fathom just what
    Mendoza and Arnold were up to. Without that analysis, I wouldn't have known
    where to start, from their own explanations.
    So in spite of its many defects, Cotter is the book that's taken down from
    my library shelves for consultation, perhaps more than any other. It's also
    liberally coated with my pencilled comments: something I dislike doing to a
    book, which will infuriate its next owner when I'm dead-and-gone. That
    reflects those aspects of the navigator's business that particularly
    interest me, of course. You may have different priorities.
    contact George Huxtable by email at george@huxtable.u-net.com, by phone at
    01865 820222 (from outside UK, +44 1865 820222), or by mail at 1 Sandy
    Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.

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