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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: � � � Re: David Thompson's Navigational Technique
From: Ken Muldrew
Date: 2004 May 31, 14:11 -0600
From: Ken Muldrew
Date: 2004 May 31, 14:11 -0600
On 31 May 2004 at 15:03, Bruce Stark wrote: > The point is, 1800 was not a leap year. It isn't divisible by 400. > Wasn't this the cause a big foofaraw, and a humiliation for Moore? For > Oct. 11th the d eclination is given as 7? 24' south. For Oct. 12th, 7? > 47' south. Is that correct? Thompson only writes down the sun's declination when he actually uses the sun for a lunar (when he uses a star he only writes down the sun's right ascension). In this case, I think the lunar is done on the 11th, but entered into his journal on the 12th, although you can see from the scans that it's tough to tell for sure. I read the declination as 7? 29' S from this entry. The lunar is taken at 20:47 local time on the 11th. Since their time starts at noon, this would be 8:47 AM on the 12th by our present reckoning. The longitude by account gives a time of about 7 hours 39 minutes so Greenwich time would be about 4:26 on the 12th. The online Nautical Almanac gives a sun declination of 7? 29' S for this time and date, exactly in accord with what Thompson writes. Ken Muldrew.
