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    Contents of Maskelyne's Tables Requisite
    From: Ken Muldrew
    Date: 2003 Jun 5, 16:46 -0600

    I'm interested in learning about the navigational techniques used by
    land geographers in the late 18th and early 19th centuries;
    particularly those used by the fur traders exploring the Canadian
    West at that time (such as David Thompson, Peter Fidler, Philip
    Turnor, etc.).
    It appears that there is an active group of enthusiasts here who are
    trying their hand at finding longitudes by lunar distances. Through
    the excellent articles in the archives, as well as a remarkable paper
    by Jeff Gottfred in the Northwest Journal
    (http://www.northwestjournal.ca/dtnav.html) where a longitude
    calculation is fully worked, I have come to have an understanding of
    the technique. Though as Sophocles warned, "One must learn by
    doing the thing; for though you think you know it, you have no
    certainty until you try".
    I would really like to gain an appreciation of the mechanical aspects
    of the calculation, as it was done ca. 1800. I know that they used
    Merrifield's approximate method for clearing the lunar distance,
    using calculated altitudes of the moon and star (with a double
    altitude of the sun to establish latitude). But I don't know what their
    method of manual calculation was (although I have used log tables to
    perform mechanical calculations...long ago). I would like to know
    what tables were used by these navigators. Does anyone here know
    what tables were included in Maskelyne's Tables Requisite as it
    would have appeared in the late 1700's and what precision the
    numbers were given to?
       \----------------------------+---------------------------------+   o_,
     O_/ \    Ken Muldrew, PhD      | Voice: (403) 220-5976           |   <\__/7
     <\__  \  Dept. of Cell Biology | Fax:   (403) 270-0617           |     | /
      "\ L  | University of Calgary | kmuldrew@acs.ucalgary.ca        |   / /
       <    +-----------------------+---------------------------------+ / /
                   Morning coffee recapitulate phylogeny               L/

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