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    Maskelyne and lunar distance
    From: Ducruy Jacques
    Date: 2020 Jul 30, 08:58 -0700

    Hello,

    In the "british mariner's guide" (1763), Maskelyne give a method for compute the longitude by lunar distance, but this method is not the methode given in the Nautical almanach 1767.

    Method 1763 : from the true lunar distance, Maskelyne compute the difference of celestial longitude between the moon and the sun (or a star) ; he compute the longitude of the moon, search the longitude of the moon given by Mayer's tables for the estimed time of Greenwich, and find the longitude of the ship : it seems to me that the principle is the same that the methode of Chabert (1751) and Pingré (1756).

    Method 1767 : the methode is similar to the methode of Lacaille, but with more precision : we compare here a observed distance et a cumputed distance. 

    But it seems that, during his travel to St Helena, he had used the two methods !

    Have you some ideas on this question ?

    Regards

    Jacques

       
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