Referee's report by Charles Galton Darwin, on a paper 'Optical and equivalent paths in a stratified medium, treated from a wave standpoint' by Douglas Raynar Hartree Sectional committee: Physics Recommended for publication in Proceedings, in full. There is a 'good deal of reference to Appleton's work'. It isn't easy to follow but the references should adequately solve this problem. The work may be better published by the Cambridge Philosophical Society. [Published in Proceedings of the Royal Society A, 1931]. Endorsed on verso as received 9 February 1931. February 1931