PHILOSOPHIC A L 
transaction s, 
OF THE 
\ 
ROYAL SOCIETY 
O F 
L O N D O N. 
VOL. LXX. For the Year 1780. ^ 
PART I. 
SOLD BY LOCKYER DAVIS, AND PETER ELMSLY, 
PRINTERS TO THE ROYAL SOCIETY. 
MDCCLXXX 
