Copy letter from Robert William Frederick Harrison to F P Burt 'Dear Sir, In reply to your letter of yesterday to Sir Joseph Larmor, I enclose a copy of notes with reference to the paper by yourself and Mr Usher communicated for the Philosophical Transactions [of the Royal Society]. I am also sending you, on loan, the MS of the paper; I enclose a note on the subject of MSS lent to authors.' [no enclosure] 20 July 1910