Cape datum
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The Cape Datum is based on the Clarke 1880 ellipsoid and has its origin point at Buffelsfontein near Port Elizabeth, South Africa. The Cape Datum is based on the work of HM Astronomers Sir Thomas Maclear, between 1833 and 1870, and Sir David Gill, between 1879 and 1907, whose initial objectives were to verify the size and shape of the Earth in the Southern Hemisphere and later to provide geodetic control for topographic maps and navigation charts. From these beginnings, this initial network was extended to eventually cover the entire country and now comprises approximately 29,000 highly visible trigonometrical beacons on mountains, high buildings and water towers as well as approximately 20,000 easily accessible town survey marks.
External Links:
WGS-84 and the Cape Datum (http://www.gpswaypoints.co.za/FAQ_world_geodetic_system_1984.htm)