Referee's report by Harold Jeffreys, on a paper 'Primary and secondary vortices in oscillating fluids: their connection with skin friction' by (the late) H Ayrton Sectional committee: Mathematics Recommended for publication in Proceedings, although the referee is unsure what to make of the paper. The experimental part of the paper is 'certainly good and worth publishing' but the theoretical part is 'very thin'. [Published in Proceedings of the Royal Society A, 1926]. Endorsed on verso as received 31 March 1926. March 1926