Referee's report by Charles Herbert Lees, on a paper 'On the velocity of sound in gases and vapours, and the ratio of the specific heats' by Harold Baily Dixon and Gilbert Greenwood Sectional Committee: Physics Recommended for publication in the Proceedings of the Royal Society of London, if reduced in length. The experimental descriptions are trustworthy, but the molecular calcualtions use an approximate equation of doubtful accuracy. [Published in the 'Proceedings of the Royal Society of London' A, 1924] Endorsed on verso as received 18 December 1923. [December 1923]