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    Re: Latitude by Spica
    From: Bruce Stark
    Date: 2004 Jan 13, 12:47 EST

    Kieran,
    I've never sailed on a square rigger, but suspected that "full and by" meant
    something like a close reach, and steering by the wind rather than the
    compass. That the course is given as "full and by," without stating which tack, gave
    me the idea they must be wearing around to the other tack at regular
    intervals, and I wonder if this was a standard procedure on the whaling grounds. Those
    ships probably were not very weatherly, even when clean bottomed. Full and by
    may have kept them fairly near a back-and-forth track, moving gradually to
    windward.
    
    You and I approached the AM-PM problem from different directions, but came to
    the same conclusion. I figured that since it was spring, the sun's right
    ascension had to be between zero and six hours. Spica was on the meridian, and her
    RA is about thirteen and a half hours. So the sun was between thirteen and a
    half and seven and a half hours past the meridian. That bracketed the time
    between seven-thirty PM and one-thirty AM, no matter what the longitude.
    
    That the latitude is logged for 12 PM, rather than noon, is another clue
    suggesting an AM-PM mix up.
    
    Bruce
    
    
    

       
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