PHILOSOPH IC A L 
TRANSACTI ON S, 
OF THE 
ROYAL SOCIETY 
O F 
L O N D O N . 
V O L. ,LXXr. For the Year 1781, 
P A R T IL 
L O N D O N, 
SOLD BY LOCKYER DAVIS, AND PETER ELMSLY, 
PRINTERS TO THE ROYAL SOCIETY. 
MDCCLXXXII 
