Copy letter from Robert William Frederick Harrison, to Thomas Howell Laby, Emmanuel College, Cambridge Harrison sends four sets of proofs of the sheets containing Laby's paper and Kleeman's paper, and also sends the old slip proofs. He asks that Laby correct one set and return it to him as soon as possible so it may be sent to press. The three remiaining spare proof copies of each paper are at his disposal. 2 May 1907