PHILOSOPHICAL 
TRANSACTIONS 
OF THE 
ROYAL SOCIETY OE LONDON. 
Series A, 
CONTAINING PAPERS OF A MATHEMATICAL OE PHYSICAL CHARACTER. 
VOL. 212. 
LONDON: 
FEINTED BY HAERISON AND SONS, ST. MARTIN’s LANE, W.C., 
^rinRrs in (irbtitarg to fis Pajestg. 
March, 1913. 
