Copy letter from Robert William Frederick Harrison, to Joseph Ernest Petavel, Fellow of the Royal Society, University, Manchester 'Dear Sir, The back volumes of Proceedings [of the Royal Society] from the beginning of the enlarged series are sold, bound in blue cloth, at 15/- for Series A., and 20/- for Series B. Volume 76 was the commencing one in each series of the enlarged character. You would be able to purchase the volumes of Messrs Harrison & Sons, 45 St Martin's Lane, W.C. I am, faithfully yours, Robt [Robert] Harrison Assistant Secretary R.S. [Royal Society]'. 17 June 1907