Referee's report by Sydney Chapman, on a paper 'Experimental determination of the thermal conductivities of gases' by H Gregory and C T Archer Sectional committee: Physics Reccommended of publication in Philosophical Transactions. It would be well placed in Proceedings, thanks to it's experimental nature but it is too long in length. It should be published in full,as it 'is an account of some very high class and difficult experiment'. [Published in Proceedings of the Royal Society A, 1926]. Endorsed on verso as received 2 October 1925. June 1925