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Arthur,
Thank you for including the Gregory material on your site. Hope people find
it useful

Regards
Kieran Kelly

-----Original Message-----
From: Navigation Mailing List
[mailto:NAVIGATION-L@LISTSERV.WEBKAHUNA.COM]On Behalf Of Arthur Pearson
Sent: Friday, 26 September 2003 8:28 AM
To: NAVIGATION-L@LISTSERV.WEBKAHUNA.COM
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
http://members.verizon.net/~vze3nfrm/LunarsFiles/Thomson.pdf.

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
Problems)

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
http://users.bigpond.net.au/kjkelly/gregorylunar/A%20Lunar%20Distance%20Calc
ulation%20v1.pdf.
  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.

Regards,
Arthur


Arthur Pearson
arthurpearson@hotmail.com

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