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    Re: The Plane Scale and Stereographic Projection in Early Navigation
    From: Robin Stuart
    Date: 2024 May 30, 06:42 -0700


    Thank you for your kind words. You mention a number of modern concepts, "ex-meridian corrections, time longitude, Sumner lines...". In 2010 https://navlist.net/Graphical-Solution-Double-Altitude-Sight-using-Stereographic-Stuart-jun-2010-g13200 I pointed out that stereographic projection could be used to solve the classic double altitude problem graphically and asked whether anyone knew of this being done in practice. It has taken until now to find out that a far richer suite of stereographic methods was available to the ancient mariners. The limitation of these methods is, of course, the accuracy with which things can be plotted but in the 17th and 18th century this may have been adequate and there were presumably a limited alternatives.

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