Referee's report by Alfred Fowler, on a paper 'The hyperfine structure of the resonance lines of potassium' by Derek Ainslie Jackson and H Kuhn Sectional Committee: Physics Recommended for publication in the 'Proceedings of the Royal Society of London'. Agrees with the opinion of the first referee in that this is a good piece of experimental work. Suggests some modifications to the text to remove repetition. [Published in the 'Proceedings of the Royal Society of London'] Endorsed on verso as received 20 October 1934. 1 October 1934