While at the Cape, Lacaille determined the radius of the earth in the southern hemisphere. He set out a baseline in the Swartland plain north of present-day Darling. Using triangulation he then measured a 137 km arc of meridian between Cape Town and Aurora, determining the latitudes of the end points by means of astronomical-geodetic observations. There is a memorial to his work at a location near Aurora, pictured here. His result suggested that the earth was more flattened towards the south pole than towards the north. George Everest, of the Indian Survey, while recuperating from an illness at the Cape nearly seventy years later, suggested that Lacaille's latitude observations had been affected by the gravitational attraction of Table Mountain at the southern end and by the Piketberg Mountain at the northern. In 1838, Thomas Maclear, who was Astronomer Royal at the Cape, repeated the measurements over a longer baseline and ultimately confirmed Everest's conjecture. Maclear's Beacon was erected on the Table Mountain in Cape Town to help with the verification.