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Luis Mederos asked-

>Hello,
>I am new to this list and this is may first message. I have been looking
>for information on the old "lunnar distances"
>method. I am interested in the mathematics behind the method. Could any
>one give references on this topic (web site,
>book, etc)?.
>Thanks a lot,
>Luis Mederos

George Huxtable responds-

Welcome to Nav-L, Luis.

Presumably you have a copy of my series of postings "About lunars",  parts
1 to 4 having appeared on Nav-L since New Year. Part 5 is still being
assembled and is somewhat overdue, I'm sorry to admit. If you don't have
these 4, just ask me for copies, or else consult the Nav-L archive.

The best book I know about the mathematical background is Charles H Cotter,
History of Nautical Astronomy, Hollis and Carter, London, 1968. It is of
course long out of print and is hard to find second-hand. The proof-reading
wasn't perfect and I am aware of several errors (any interested owner is
welcome to contact me for a listing of them).

There's a really good account of lunars in "The Mathematics of the
Longitude" by Wong Lee Nah, a dissertation for a degree at the National
University of Singapore, which can be found in full on the web. I was led
to this by a recommendation on Nav-L but am sorry to say I seem to have
lost the web address. Perhaps another list member can help to retrieve it,
or perhaps a search engine. I remember that the word aslaksen (= name of
supervisor) was part of the web address. This publication has good
illustrations and the formulae are expressed in very clear typescript.
There's an unfortunate error in his calculation of an example using Borda's
method, where he switches from 5-figure logs to 4-figures at the wrong
place, and is led to some incorrect conclusions. But otherwise, it's pretty
reliable.

There are some very relevant papers about lunars in "The Quest for
Longitude", ed. Andrewes (Harvard, 1996). Mainly about the chronometer
solution to longitude, it's beautifully produced and full of interesting
stuff. But rather expensive.

Good reading...

George Huxtable.

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george@huxtable.u-net.com
George Huxtable, 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
Tel. 01865 820222 or (int.) +44 1865 820222.
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