Copy letter from Robert William Frederick Harrison, to Dr L A Bauer, Carnegie Institution of Washington Following on from their letter of 22 February to Sir Joseph Larmor, Harrison is now sending photographs of the portions of a letter of Halley's which are preserved in a collection of such memorials. He will observe that there is a good autograph signature, and at Larmor's suggestion a passage of the letter has been photographed which may interest them. 15 March 1911