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    Re: "no plotting sheet required" - an interesting find in an old book
    From: Mike Freeman
    Date: 2019 Dec 22, 00:10 -0800

    Hello Tony,

    Seasons greetings to you also.

    It seems there are sufficient methods of creating a plotting sheet to be able to use a different method on each day of the year if you wish.

    I happen to have thousands of pieces of A4 paper clean on one side. I do not have a printer to print plotting sheets off the internet, in fact I have never seen a plotting sheet. I am just learning Celestial Navigation (at home) and it suits me to construct a plotting sheet using what I have to hand, although I would like to think the method is bona fide.

    The method of drawing a diagonal at the degrees of latitude, creating a right triangle then measuring the hypotenuse does seem to provide the correct Lat/Long ratio.

    I realise with the Mary Blewitt method it is irrelevant whether the latitude scale, longitude scale or in fact the diagonal is marked first as long as a line is scribed with a set of dividers from the diagonal to the latitude scale and a vertical line dropped from the diagonal to the longitude scale. Either this provides the correct ratio between lat and long or it does not. 1 on the lat scale = 1 on the long scale whether degrees or minutes.  The Mary Blewitt method relies on it and so does yours.

    There is one thing about your method I am having difficulty with (penny has not dropped).Movement of the observer. Perhaps you could provide additional explanation.



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