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    Re: AP terminology, WAS: 2-Body Fix -- take three
    From: Tom Sult
    Date: 2009 Nov 13, 14:38 -0600

    Well the summer calculated 3 points based on assumptions also. If you
    recall the story he calculated his position then made an sumption a
    few degrees one way then the other to get three point. So in a sence
    summer is a third redundancy of the St H method.
    
    Thomas A. Sult, MD
    Sent from iPhone
    
    On Nov 13, 2009, at 14:33, John Karl  wrote:
    
    >
    > No one has addressed my question of why the St Hilaire method
    > calculates an altitude at a location our ship is NOT at, when we've
    > just measured the altitude where our ship IS at.  (For politically
    > correct reasons, I'm not using the name of this location.)
    >
    > Now lets go back to Sumner's 1837 calculation, where he picked three
    > different longitudes and calculated three points on the circular LOP.
    > This calculation is exact, and the equation for each point is the same
    > as the one of the two necessary in the St Hilaire method (thus each
    > Sumner point is half the work of a St Hilaire reduction).  And he
    > could calculate as many exact points as he wished.
    >
    > So I'll put my question yet another way:  Why is the St Hilaire method
    > superior to Sumner's and consequently the only one used today??
    >
    > I claim that the answer to this question has been made confusing
    > because of the conventional name (names?) used for the location of the
    > St Hilaire altitude calculation.  As evidence of this confusion I note
    > that some authors write that we need to assume some point because the
    > distance between the GP and the LOP is too great to plot, that there's
    > insufficient information to plot the LOP, or that iterations are
    > required to get exact points on the LOP.  The Sumner calculation
    > demonstrates that none of this is correct.
    >
    > JK
    >
    >
    > >
    
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