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    Re: Interpolation of Meridional Part Table
    From: Andrés Ruiz
    Date: 2009 Mar 26, 09:22 +0100

    In [NavList 7769] all values for a, are in nautical miles.

    a: Semi-major axis = equatorial radius. Is the radius of curvature in a meridian plane at the equator.

    Using the formula arc = angle(rad)* a, we have a =  360*60/(2π) [nm]

    But also a =  360*60/(2π) [geodetic miles]

    The radius is 21600 sexagesimal arcminutes, and geodetic minutes.

     

    Average minute of geodetic latitude is:

     

     

    I have attached the meridional parts table that appears in the “Tratado de Navegación - Mendoza Rios Tomo II” in 1787

    I have compared its values, and conclude that uses the spherical model of the Earth.

    The update from the spherical model to al ellipsoidal one must be done using a model like WGS84, WGS72, NAD83 or EUROPE1950. If this would have be done by Bowdith, no error of interpretation or concept will arise.

     

    Andrés Ruiz

    Navigational Algorithms

    http://www.geocities.com/andresruizgonzalez

     


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