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    Cross Staff in use, 1574 image
    From: Brad Morris
    Date: 2009 Oct 16, 13:13 -0700

    Attached, please find an image from Cosmographia, Petri Apiani, of the cross staff in use.
    
    This image is consistent with the direction given in Bourne's A Regiment for 
    the Sea, in that the user is directed to align the cross staff to the center 
    of the sun's body.  How in the world was the cross staff operator to know 
    when he was aligned to the center??  
    
    Thus the resultant latitude would always be an estimate, say plus or minus 8 
    arc minutes, based upon the judgement of the operator.  Perhaps in 1574, that 
    was plenty good enough.  
    
    There is plenty of discussion on our list of just what is good enough and how 
    far we should take it.  Clearly, this is not a new topic whatsoever!
    
    Best Regards
    Brad
    
    
    
    
    
    
    File:
    COSMOGRAPHIA-PETRI-APIANI-1574.doc
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