Referee's report by Alfred Fowler, on a paper 'The spectrum of ionised potassium' by John Cunningham McLennan Sectional Committee: Physics Recommended for publication in the 'Proceedings of the Royal Society of London'. Suggests a change to the title to make the contents of the paper clearer. [Published in the 'Proceedings of the Royal Society of London' A, 1921] Endorsed on verso as received 12 July 1921. 11 July 1921