PHILOSOPHICAL 
TRANSACTIONS 
OF THE 
EOYAL SOCIETY 
OP 
LONDON. 
(A.) 
FOR THE YEAR MDCCCXC. 
VOL. 181. 
PRINTED EY HARRISON AND SONS, ST. MARTIN’s LANE, W.C., 
printtrs iit Orbinarj) to Pajtstg. 
MDCCCXCI. 
