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Subject: Re: Sumner lines
From: nigel_gardner (Nigel_Gardner@XXX.XXX)
Date: Mon Feb 19 2001 - 04:47:47 EST
In reply to George Huxtable's comment, he is absolutely right of course and
perhaps I was being a bit too generalistic, there is the possibilty of
course of a star/planet twilight shot.
The main point I was making was that it is along track and across track
information that is usually required, a fix will give this but not
exclusively, and that single p/l's used intelligently will give a fix by
run or can be used in conjunction with DR to give the navigation
information required.
In reply to Gordon Talge's comment, Capt. Sumner's book was published in
1843. Norie's Epitome was rewritten by Rosser in 1889.
A number of authors (Lecky included) refer rather loosely to any Sun p/l
taken off the meridian as a 'Sumner line'.
I have the second edition of a book by Cross on the Marc St Hilaire method
called appropriately enough 'The New Navigation' undated but the worked
examples are for 1913. In his introduction he bemoans the fact the although
the Royal Navy used the method, few merchant navigators did.
NG
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