New Determinations of the Velocity of Light

Abstract

IN 1953 the Ordnance Survey was asked by the U.S. Armyr Map Service to test its Bergstrand AGA geodimeter. This was done by using it to re-measure the two bases of the recently completed primary re-triangulation of the United Kingdom¹. From these measurements it was possible to deduce a new value for the velocity of light in vacuo. Recently, the Ordnance Survey has received the account of a fresh determination by R. Schöldström² on the Öland base line in Sweden which gives a value which agrees very closely with that deduced from our results. The comparison between the generally accepted value determined by Bergstrand in 1950³ and the three recent determinations is as follows : Bergstrand, Öland base 1950 (5,402 metres): 299,793.1 ± 0.2 km./s. Ordnance Survey, Ridge Way base 1953 (11,261 metres): 299,792.4 ± 0.11 km./s. Ordnance Survey, Caithness base 1953 (24,829 metres): 299,792.2 ± 0.13 km./s. Schöldström, Öland base 1955 (5,402 metres): 299,792.4 ± 0.4 km./s.