Riebecks Kasteel was one of the main stations used on both Lacaille's and Maclear's surveys to find the 'arc of the Meridian'. The artist William Mann was at this time second assistant under Thomas Maclear at the Royal Observatory, Cape of Good Hope (South Africa) and a major part of his work was to take part in this survey.

The purpose of first Lacaille's and then Maclear's surveys was to investigate the shape of the Earth and in particular, to find out if the shape south of the equator mirrored that of the northern hemisphere (since it was already known the Earth is not a perfect sphere but rather bulges at the equator). Maclear's survey was a continuation of the work of Everest who, in turn, had set out to rediscover as many of Lacaille's stations, including this one at Riebecks Kasteel as possible. Maclear's survey ran from 1840 to 1848.

Though the survey took place after the Herschel family had returned to England they still kept in touch with a number of people still there, and with Maclear in particular. Indeed these families would all become interconnected as Thomas Maclear's children married into both the Mann and the Herschel families.