Copy letter from Robert William Frederick Harrison to H F Parshall, Salisbury House, London Wall, EC 'Dear Sir, We are unable to forward you copies of Mr Duffield's two papers, as requested in your letter of the 13th. We can supply you with a copy of his first paper on Arc Spectra under Pressure (Iron) if you will send a postal order for 3/6. The second paper (Copper) is not yet published, but will be out in a week or two.' 16 November 1908