Referee's report by William Lawrence Bragg, on a paper 'On the purity and intensity of the radiation from an x-ray crystal monochromator' by G I Harper Sectional Committee: Physics Not recommended for publication in the 'Proceedings of the Royal Society of London'. The work is considerable but uninspired. The theory is not supported by the experiments. [Not published] Endorsed on verso as received 18 July 1933. [July 1933]