NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Sumner lines
From: Nigel Gardner
Date: 2001 Feb 19, 2:48 AM
From: Nigel Gardner
Date: 2001 Feb 19, 2:48 AM
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
