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    Re: Update of www.LunarDistance.com
    From: Kieran Kelly
    Date: 2003 Sep 26, 15:14 +1000

    Thank you for including the Gregory material on your site. Hope people find
    it useful
    Kieran Kelly
    -----Original Message-----
    From: Navigation Mailing List
    [mailto:NAVIGATION-L{at}LISTSERV.WEBKAHUNA.COM]On Behalf Of Arthur Pearson
    Sent: Friday, 26 September 2003 8:28 AM
    Subject: Update of www.LD-DEADLINK-com
    Ladies and Gentlemen:
    After a long season of distractions, I have been able to update
    www.LD-DEADLINK-com with several items that have been posted to our
    discussion group or forwarded to me over the summer.  I apologize for
    falling behind in keeping the site current. I hope those of you who may have
    been similarly distracted can catch up with some very interesting new
    material. Simply visit the site and go to the Site Map for a guide to the
    following new articles and links.
    David Thomson's 1824 tables for clearing the Lunar Distance. Jan Kalivoda
    continues with his historical perspective on the development of methods for
    clearing the distance.  Jan presents an introduction to David Thomson and
    his highly regarded set of tables.  He then presents with commentary a
    rigorous piece by George Huxtable on the math and theory behind them. The
    article is available at
    Bruce Stark's Tables in historical perspective.
    Jan Kalivoda applies his historical perspective on the methods used to clear
    the lunar distance to Bruce's 1997 tables.  Jan concludes that "They don't
    repeat old solutions mechanically, but are significantly better than
    renowned works of the past, although they don't misuse the modern technical
    possibilities and go the fully traditional way of tabular and paper
    solution. It had to be an intellectual adventure to compose them and it is a
    delight to study them."  Visit
    http://www.i-DEADLINK-com/lists/navigation/0307/0122.html and you may agree with
    Jan "that with these Tables, the history of Lunar Distances is consummated
    now and the long line of rigorous methods for clearing them ends
    successfully - only in our days."
    Contents of Maskelyne's 1766 Tables Requisite
    In 1766, Nevil Maskelyne produced the first publications that made it
    practical for mariners to apply the lunar distance method for finding
    longitude at sea.  First was his Nautical Almanac and Astronomical Ephemeris
    which among other data included pre-calculated lunar distances to five well
    selected bodies for every three hour interval of Greenwich time.  The
    companion piece to the Almanac was Maskelyne's Tables Requisite to be Used
    with the Nautical Ephemeris for Finding the Latitude and Longitude at Sea.
    This volume contained 30 tables needed for correction of observations and
    calculation of latitude and longitude.  In addition, it contained an
    explanation of the tables and 13 problems that illustrated the solution to
    various navigational situations.
    Bruce Stark has a copy of the Tables Requisite and kindly posted a full
    listing of all the tables and problems listed in its table of contents.  The
    listing offers a wonderful insight into the systematic and thorough approach
    taken by Maskelyne in his historic breakthrough in the quest for accurate
    longitude at sea.  The contents are posted in two parts at:
    http://www.i-DEADLINK-com/lists/navigation/0306/0012.html (Tables)
    http://www.i-DEADLINK-com/lists/navigation/0306/0013.html (Explanation and
    A Lunar Distance Calculation, Sir Augustus Charles Gregory, North Australian
    Expedition, 1855-56 by Kieran Kelly.  A detailed analysis of the
    extraordinary work of A. C. Gregory during his surveys of Australia.  This
    63 page article is a testament to the skill and professionalism of a
    remarkable explorer.  The analysis of Gregory's lunars demonstrates the
    amazing precision attained by true masters of the technique during the
    period of it's greatest relevance to geographical exploration.  The article
    is available at
      The author also has posted a website with descriptions of his recent visit
    to Gregory National Park with photos and sketch maps of an area explored by
    Gregory in 1856.  Anyone who wants a glimpse of the stark landscape surveyed
    by this pioneer should visit http://users.bigpond.net.au/kjkelly/.
    Best wishes to all, I continue to enjoy the discussions this community of
    navigators and hope to contribute more regularly in the future.
    Arthur Pearson
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