PHILOSOPHICAL 
TRANSACTIONS, 
OF THE 
ROYAL SOCIETY 
O F 
LONDON, 
FOR THE YEAR MDCCCXXL 
PART I. 
LONDON, 
FEINTED BY W. BULKER AND W. NICOL, CLEVELAND ROW, ST. JAMEs’s ; 
AND SOLD BY G. AND W. NICOL, TALL-MALL, BOOKSELLERS TO HIS MAJESTY, 
AND PRINTERS TO THE ROYAL SOCIETY. 
MDCCCXXI. 
