rhe P R E FAC E. XV 
far indulged Conjedure, in the In- 
ferences I have drawn from the 
Events of fome Experiments; they 
ought to confider that it is from 
thefe kind of Conjedures that frefli 
Pifcoverics firft take their Rife; for 
tho’ fome of them may prove falfe, 
yet they often lead to further and 
new Difcoveries. It is by the like 
Conjedures that I have been led on. 
Step by Step, thro’ this long and la- 
borious Series of Experiments; in 
any of which I did not certainly, 
know what the Event would be, 
till I had made the Trial, which 
Trial often led on to more Conjedures 
and farther Experiments. 
In which Method we may be 
continually making farther and far- 
ther Advances in the Knowledge of 
Nature, in proportion to the Num- 
ber of Obfervations which we have: 
But 
