The Radcliffe Observatory in South Africa

Abstract

THE ‘turn-over’ article in The Times of August 7 by Mr. H. E. Wood, the Union Astronomer, deals with astronomy in South Africa in general, and refers in particular to the forthcoming re-establishment of the Radcliffe Observatory at Pretoria. The history of astronomy in South Africa begins,, in 1685, when Father Tachard called at the Cape on his way to Siam and determined the longitude by observations of Jupiter's satellites. During the next century, two expeditions visited the Cape, and 1820 saw the foundation of the Royal Observatory, which has made such notable contributions to our knowledge of the southern stars. In 1834 Sir John Herschel landed there and made his famous catalogues of nebulae and double stars. There are now four other observatories in South Africa: the Union Observatory and the southern station of Yale University Observatory at Johannesburg, and those of Harvard and Michigan at Bloemfontein. The Radcliffe Observatory, for more than a hundred and sixty years at Oxford, will, it is hoped, have started its new life at Pretoria within the next two years. Good progress is being made with the construction of its 74-inch reflector by Sir Howard Grubb, Parsons and Co. This will differ in several respects from its sister telescope at Toronto, as it will have, in addition to facilities for observation at the Newtonian and Cassegrain focuses, an arrangement for sending the beam of light down the polar axis to a fixed spectrograph, and it will be driven by a synchronous motor, the frequency of the alternating current being controlled by a tuning fork. The disk of Pyrex glass for the large mirror has been cast by the Corning Glass Co. and is now being annealed. The five secondary mirrors will be of fused silica, and the disks for these are being made by the Thermal Syndicate, Ltd.