Letter from the Assistant Editor, to Cambridge University Press, regarding a paper 'Supersonic dispersion in gases II. Air containing water vapour' by M Mokhtar and E G Richardson Sectional Committee: Physics Encloses proof for Proceedings C. Any prints, from the enclosed list, should be marked confidential. Once prints have been issued, the paper should be retained in stereotype. [Published in the 'Proceedings of the Royal Society of London'] No sent date. 9 April 1940