PHILOSOPHICAL 
RANSACTION 
OF THE 
ROYAL SOCIETY 
OF 
LONDON. 
FOR THE YEAR MDCCCLXXX1. 
VOL. 172.—PART II. 
LONDON: 
PRINTED BY HARRISON AND SONS, ST. MARTIN’S LANE, W.C., 
printers in Orbinarg to fjer pnjestrr. 
MDCCCLXXXI. 
