To the Right Honourable 
fOHN Lord SOMMERS, 
Lord High Chancellor of England^ 
Prefidenc of the Royal Society : 
And to the 
Council and Fellows 
Of the faid 
ROYAL SOCIETY 
I 0 ND 0 N, 
F O R T H E 
Advancement of Natural Knowledge. 
This Twentieth Volume 
O F T H E 
Philosophical Transactions 
Is humbly Dedicated 
By Hans Sloane, S. R. Secr. 
