Copy letter from Robert William Frederick Harrison, to The Librarian, Royal Institution, Albemarle Street, W. In 1908 Lord Rayleigh borrowed from the Library a quarto volume of Tracts 52. There is no trace of it having been returned, although Rayleigh states that it was. It is possible it is still at the Royal Institution, and Harrison would be obliged if they could make an enquiry into it. 22 December 1909