Letter from Fred T [Frederick Thomas] Trouton, Physical Department, University College, London, to [Joseph] Larmor He sends a paper by Dr. [Louis Napoleon George] Filon on stained glass ['Measurements of the absolute indices of refraction in stained glass'], the work of two years. It has interesting points about absorption lines in glass. He explains the difficulty in getting the glass made, as the Germans will not reveal the composition and no-one in Britain can undertake the work. He sends it for the [Philosophical] Transactions. In view of the length and number of discrepencies, he would like to speak to Larmor about it. He would not like to see Filon disappointed. 24 January 1907