Referee's report by Edward Victor Appleton, on a paper 'Supersonic dispersion in gases II. Air containing water vapour' by M Mokhtar and E G Richardson Sectional Committee: Physics Recommended for publication in the 'Proceedings of the Royal Society of London', but not during wartime. The propagation of ultrasonic waves could be involved in defence problems, and as such the publication should be withheld. [Published in the 'Proceedings of the Royal Society of London'] Endorsed on verso as received 22 January 1940. [January 1940]