Copy letter from Robert William Frederick Harrison, to Dugald Clerk, 18 Southampton Buildings, Chancery Lane, W.C. In reply to Clerk's letter of the 5 October, Messrs Bairstow and Alexander's full paper has not yet been printed but an extended abstract appears in 'Proceedings [of the Royal Society]' A 511, volume 76, which can be obtained from the Society's printers Messrs Harrison & Sons, St Martin's lane, at two shillings and six. The only way to obtain separate off-prints is from the authors, who might have some left. Provides their address at the National Physical Laboratory. 8 October 1905