Let the semi-minor radius of the earth, (the polar radius), be b. Let the semi-major
radius, (the equatorial radius), be a. Then the eccentricity e is defined by :-
According to Col. A. Clarke's measurements of 1880, (the slightly inaccurate measurements on which the South African survey system is based), a = 6378249.145326 meters. b = 6356514.966721. e2 = 0.006803481018843. These figures are taken from [Schreiber 1943].