PHILOSOPHICAL TRANSACTIONS 
OF THE 
ROYAL SOCIETY OF LONDON. 
Series A, Vol. 217. TITLE, &c. 
TITLE, CONTENTS, INDEX, 
A, VOL. 217. 
Printed and Published for the EOYAL SOCIETY by 
HARRISON AND SONS, 44-47, ST. MARTINS LANE, LONDON, W.C. 
Printer* tn ©rirtnarg to ^tajcrip. 
1918. 
«fec. 
A 560. 
Price Sixpence. 
31.12.18 
