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Attached is a small gif file of the formulas I determined some years ago for the Royal
Astronomical
Society of Canada's Observer's Handbook annual based on the WGS84 ellipsoid. They give
distances on the ellipsoid accurate to the cm level.
-- Richard Langley

Quoting Andres Ruiz :

> 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
> 
>  
> 
> 
> > 
> 


===============================================================================
 Richard B. Langley                            E-mail: lang@unb.ca
 Geodetic Research Laboratory                  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics Engineering    Phone:    +1 506 453-5142
 University of New Brunswick                   Fax:      +1 506 453-4943
 Fredericton, N.B., Canada  E3B 5A3
     Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
===============================================================================


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