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    Re: DR by any other name....
    From: Brendan Kinch
    Date: 2010 Dec 31, 13:18 -0800


    Peter wrote;
    "I am curious now, what was the original term St. Hilaire himself used in the original French: "point rapproche"?"

    Continuing on this subject with some information for Peter: again referring to the book ‘Line of Position Navigation’ by Michael Vanvaerenbergh and Peter Ifland, The authors quote from Marcq Saint-Hilaire’s 1873 book, translated as follows....."in summary to calculate an observation, make the calculation of the altitude and the azimuth of the star from the DR position"...... They then add their own note.....'The only difference is that we use an Assumed Position rather than a DR in order to simplify the calculation.'
    I guess I never got round to simplifying the calculation, but then again I never used Sight Reduction Tables.
    They also give a list of terms and definitions translated from the French, one of which is; ‘point approché’ which is noted as “An approximate position based on a DR if current and wind are not known; on an EP if the DR position is corrected for wind and current.
    (I suppose I really could have answered my own initial question ...... as happens so often! The AP would be a well known term for those working the more convenient sight reduction tables. You may be surprised though, that there are still some people around that never did.....maybe I am as old as my wife thinks I am!)

    Kinch.

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