



PHILOSOPHICAL 



TRANSACTIONS 



OF THE 



KOYAL SOCIETY OF LONDON 



SERIES A. 



CONTAINING PAPEKS OF A MATHEMATICAL 01! PHYSICAL CHAKACTER. 



VOL. 209. 



i^>r 



LONDON: ^ \ 



PRINTED BY HARRISON AND SONS, ST. MARTIN'S LANE, W.C., 



|)rmltrs in rbinarg ID is Pajtslg. 



OCTOBEB, 1909. 



