Copy letter from James Hopwood Jeans, Secretary of the Royal Society; to Professor [Frederick] Soddy, FRS Informs Professor [Frederick] Soddy that Dr. [Francis William] Aston has also agreed to speak. Notes that Sir Joseph [John] Thomson will speak about the positive ray method and the chief physical implications of the theory of Isotopes. Asks if Professor Soddy would be happy to talk about the chemical bearing of the theory. 20 January 1921