Referee's report by George Paget Thomson, on a paper 'An optical examination of thin films. I.—The optical constants of mercury' by Leif Tronstad and C G P Feachem Sectional Committee: Physics Recommended for publication in the 'Proceedings of the Royal Society of London'. Suggests expanding the description of the apparatus and clearly defining the mathematical symbols. [Published in the 'Proceedings of the Royal Society of London' A, 1934] Endorsed on verso as received 24 January 1934. [January 1934]