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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: How did Sumner navigate in 1837?
From: Jim Thompson
Date: 2003 May 19, 06:45 -0300
From: Jim Thompson
Date: 2003 May 19, 06:45 -0300
Herbert (and George and others), Thank you for your very useful insights. I have Bowditch 2002. Can you direct me more specifically to method "No. 3"? I'm not savvy enough yet to read between the lines and so find it in the book. To further demonstrate my ignorance, have I made the correct defintions for the variables? T = chronometer GMT D = declination (from almanac) L = latitude (from dead reckoning) H = altitude (from sextant) log (1-cos T) = log [cos(D-L) - sin H] + log sec L + log sec D I have been revising my draft as my ignorance diminishes: http://www.jimthompson.net/boating/CelestialNavigationNotes.htm#Sumner The other key point was my finally realizing that the southern entrance of St. George's Channel is between Ireland and Wales. I have not been able to find an online chart of those waters. Jim Thompson jimt@jimthompson.net www.jimthompson.net Outgoing mail scanned by Norton Antivirus ----------------------------------------- > -----Original Message----- > From: Navigation Mailing List > [mailto:NAVIGATION-L@LISTSERV.WEBKAHUNA.COM]On Behalf Of Herbert Prinz > Sent: Wednesday, May 14, 2003 8:37 AM > To: NAVIGATION-L@LISTSERV.WEBKAHUNA.COM > Subject: Re: How did Sumner navigate in 1837? > > Jim Thompson wrote: > > 3. Exactly how would he [Sumner] have determined his longitude in 1837? > > Herbert Printz wrote: > By chronometer and time sight, using one of the methods given in > a contemporary > Bowditch (preferring No.3 over No.1, passing over No.2).
