PHYSICAL AND LITERARY. 3 



expedient to keep the end in view. Fads 

 and experiments are ufelefs lumber, if we 

 are not to reafon about them, nor draw 

 any confequences from them. In all our 

 operations, we may have an eye to theory : 

 Nay we mufl: have it ; for fuch is the con- 

 ftitution of our mind. Theory becomes 

 only a fource of error, when we indulge in 

 it too much, or attach ourfelves to it be- 

 yond what fads and experiments can ju- 

 itify. In fhort, theory is vain without ex- 

 periments, and experiments are beft un- 

 derftood by applying them to theory. 



Natural philofophy, it mufl be ac- 

 knowledged, is far from being ripe for firm 

 and lafling theory. But we have fads and 

 experiments in great abundance, to be a 

 foundation for theoretical fketches ; which 

 may be fafely indulged, provided they be 

 done in fo flight a manner, as to leave the 

 jnind free from any wrong bias. 1 ho' 

 we have not materials for a regular build- 

 ing, there is nothing to hinder us to ven- 

 ture upon a^model. 



Almost every author who treats of the 

 laws of motion, has thought it incumbent 



upon 



