PHILOSOPHICAL 
TRANSACTIONS, 
OF THE 
ROYAL SOCIETY 
O F 
LONDON. 
FOR THE YEAR MDCCCXXI. 
PART II. 
LONDON, 
PRINTED BY W. BULMER AND W. NICOL, CLEVELAND ROW, ST. JAMEs’s; 
AND SOLD BY G. AND W. NICOL, PALL-MALL, BOOKSELLERS TO HIS MAJESTY, 
AND PRINTERS TO THE ROYAL SOCIETY. 
MDCCCXXI, 
