Referee's report by Edward Neville da Costa Andrade, on a paper 'The mean free path of electrons in polar crystals' by Herbert Fröhlich and Nevill Francis Mott Sectional Committee: Physics Recommended for publication in the 'Proceedings of the Royal Society of London'. Does not consider himself an expert on the modern theory of electrical induction, but finds the paper worthy of publication. [Published in the 'Proceedings of the Royal Society of London'] Endorsed on recto as received 14 April 1939. [April 1939]