To the Honourable 
Sir ROBERT SOVTHWELLJ&x. 
PRESIDENT,- 
And to the 
Council ana 
OF THE 
Royal Society 
LONDON, 
FOR THE 
Advancement of. Natural Knowledge, 
This Eighteenth Volume 
OF THE 
Philosophical Transactions 
Is humbly Dedicated 
By Richard Waller, S.R.Seci% 
