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    Re: How did Sumner navigate in 1837?
    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{at}jimthompson.net
    www.jimthompson.net
    Outgoing mail scanned by Norton Antivirus
    -----------------------------------------
    
    > -----Original Message-----
    > From: Navigation Mailing List
    > [mailto:NAVIGATION-L{at}LISTSERV.WEBKAHUNA.COM]On Behalf Of Herbert Prinz
    > Sent: Wednesday, May 14, 2003 8:37 AM
    > To: NAVIGATION-L{at}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).
    
    
    

       
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