Referee's report by William Hume-Rothery, on two papers 'Imperfections in the structure of cobalt. I. Experimental work and proposed structure' by Olive S Edwards and Henry Solomon Lipson, and 'Imperfections in the structure of cobalt II. Mathematical treatment of proposed structure' by Arthur James Cochran Wilson Sectional Committee: Physics Recommended for publication in the 'Proceedings of the Royal Society of London' once amended. The theory is interesting, but presented in an unsatisfactory way. Suggests re-arrangement of the papers into a single paper. If the papers are to be published as they are, suggests an amendment to the title. Suggests standardising the use of the term 'fault' over 'mistake'. The word 'fault' is used in Geology for a phenomenon not unlike that which the authors have described'. Contains extra question - 'Is there any information contained in the paper which likely to be of value to the enemy?' Referee replies no. [Published in the 'Proceedings of the Royal Society of London'] Endorsed on verso as received 5 September 1941. [September 1941]