Robert M.W. Swan, British mining engineer and surveyor, was for many years a companion of the explorer and archaeologist J.T. Bent*. In 1891 the British South Africa Company, which had occupied Mashonaland (now part of Zimbabwe) the year before, sponsored the first detailed investigation of the ancient ruins at Great Zimbabwe (first described by Karl Mauch*) and other sites, with the support of the Royal Geographical Society and the British Association for the Advancement of Science. Bent was chosen to lead the investigation and was accompanied by his wife, who was a skilled photographer, and by Swan*. The latter made detailed surveys of the ruins, but also studied aspects of the geography of Mashonaland.
Swan reported his geographical findings in "Notes on the geography and meteorology of Mashonaland" (Proceedings of the Royal Geographical Society, 1892), which included a list of stations in Mashonaland at which he had made astronomical and other observations to determine their geographical position and altitude. Another paper dealt with "Rain with a high barometer" (Nature, 1892) and a third with "The geography and ethnology of Mashonaland" (Proceedings of the Glasgow Philosophical Society, 1893).
His surveys of the ruins were reported in "The orientation of the buildings at Zimbabwe" (Proceedings of the Royal Geographical Society, 1892). This paper, and his first one on the geography of the territory, were also included in Bent's book, The ruined cities of Mashonaland (London, 1892). Further papers included "Some features of the ruined temples of Mashonaland" (Scottish Geographical Magazine, 1892), "The ruins in Mashonaland" (Geographical Journal, 1893) and "Some notes on the ruined temples in Mashonaland" (Journal of the Royal Anthropological Institute, 1896). He concluded that the ruined structures had been laid out with careful planning and high precision, using a system of measurement based on a fixed unit of length (a cubit of 523 mm) and incorporating multiples of pi (the ratio of the circumference to the diameter of a circle). He also identified sighting lines towards the rising and setting sun in mid-winter and mid-summer, as well as towards certain bright stars. However, his assumptions with regard to the advanced mathematical and astronomical knowledge of the builders, and their ability to lay out the sites with great precision, were unconvincing. Later investigations by F.P. Mennell* and others indicated that his measurements were of doubtful validity, often representing the distance or direction between points that were selected somewhat arbitrarily. None the less he produced the first reasonably accurate plans of the Great Enclosure and Acropolis at Great Zimbabwe, including some features that were destroyed as a result of later reconstruction and vandalism, as well as of the Lundi and Matendere ruins. He discovered further minor ruins in Zimbabwe in 1894.