Copy letter from Herbert Rix, to Sir George Gabriel Stokes, Fellow of the Royal Society 'Dear Sir Gabriel, Capt Abney [Captain William de Wiveleslie Abney] whose paper is in your hands, writes that he desires to borrow some diagrams that he may photograph them for lantern use when his paper comes on. Could you, as soon as convenient, return the diagrams to me, and they shall be sent back to you as soon as the photographing is finished. Yours truly Herbert Rix Asst Sec [Assistant Secretary]'. 25 January 1892