%0 Journal Article
%A
%T A new determination of the free-space velocity of electromagnetic waves
%D 1958
%R 10.1098/rspa.1958.0172
%J Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences
%P 109-122
%V 247
%N 1248
%X The paper describes the determination of the free-space phase velocity of electromagnetic waves in vacuo by means of a millimetre-wave interferometer capable of high precision. As already provisionally announced (Froome 1958) the result is: co =299792.50±0.10 km/s, where the variation represents the standard deviation of a single determination in statistical combination with estimated systematic errors.%U http://rspa.royalsocietypublishing.org/content/royprsa/247/1248/109.full.pdf