PHILOSOPHICAL 
i E A N S A C T I O N S 
OF THE 
KOYAL SOCIETY 
OF 
LONDON. 
(A.) 
FOR THE YEAR MDCCCXC. 
VOL. 181. 
LONDON: 
PRINTED BY HARRISON AND SONS, ST. MARTIN’s LANE, AV.C , 
printers hr ©rbiirarg to |^fr IJtajisti). 
MDCCCXCI. 
