Letter from John Walter Ryde, on a paper 'Application of the image force model to the theory of contact rectification and of rectifier breakdown' by E Billing, to D C Martin, Assistant Secretary of the Royal Society Paper reference code: A173 Ryde has read Billing's revised paper and remarks 'the author has now largely met the points I raised in my first report [RR/73/228]. Recommended for publication in the Proceedings. Written from Research Laboratories, The General Electrical Company Ltd, Wembley [England]. [Published in Proceedings A, 1951]. Endorsed on recto as received 26 January 1951. 25 January 1951