Sir Frank Dyson, K.B.E., F.R.S

Abstract

SIR FRANK DYSON, Astronomer Royal, will terminate his official connexion with the Royal Observatory, Greenwich, on February 28. He went to Greenwich in 1894, when he was appointed a chief assistant. After retaining this position for ten years, he was appointed Astronomer Royal for Scotland. He returned to Greenwich after six years absence, being appointed as the successor of Sir William Christie. Throughout his career, Sir Frank has taken a keen interest in all the departments of the Observatory; it may perhaps be said that his greatest interest has lain in the determination of the proper motions of the fainter stars. In company with Mr. W. G. Thackeray, he made a careful re-reduction of the catalogue of faint stars observed by Groombridge at Blackheath a century earlier; these were compared with recent Greenwich observations, providing proper motions of several thousands of faint stars. The later Greenwich catalogues have all been planned with the view of the determination of proper motions for successive zones of the sky. Sir Frank has been a keen observer of solar eclipses, obtaining successful results in 1900 (Portugal), 1901 (Sumatra), 1905 (Tunis), 1927 (England); he wrote a paper in the Phil. Trans. for 1906, which is still regarded as providing the standard determination of coronal wavelengths. It was also under his auspices that the expedition went to Brazil in 1919 to test the Einstein shift of starlight. Both the magnetic department and the time-service have been revolutionised in recent years; the former was moved to Abinger, as the electric railways in London were a disturbing factor. For the latter, a series of Shortt clocks in air-tight cases give very precise results; also daily comparisons with other observatories are made by wireless signals. Sir Frank has considered his successor in obtaining the provision of a new reversible transit-circle, which is nearing completion. The present circle is eighty years old, and its shutters are too narrow, not permitting free circulation of air.