Copy letter from Robert William Frederick Harrison, to the Editor, the Engineering Record, 114 Liberty Street, New York, USA 'Dear Sir, The paper by Messrs Hill & Greenwood was published in the "Proceedings [of the Royal Society]" No. B 519, and may be obtained of Messrs Harrison & Sons, 45 St Martin's Lane, London, W.C. We have no separate issue for disposal, I am sorry to say, but you might apply to the author, Dr Leonard Hill. I am, faithfully yours, Robt [Robert] Harrison Assistant Secretary R.S. [Royal Society]'. 15 May 1906