Copy letter from Francis Alexander Towle, Assistant Secretary of the Royal Society; to the Editor, 'The Encyclopedia Britannica', 80 Regent Street, W1 Informs the Editor of 'The Encyclopedia Britannica' to expect permission to reproduce figure 5 from the paper ['Bakerian Lecture.— A new mass-spectrograph and the whole number rule' ] by Dr. [Francis William] Aston in Proceedings A.115. 9 June 1928