68 DISSERTATION SECOND. [part i. 



Negative instances, or (hose where the given form is 

 wanting, are also to be collected. 



That glass, when pounded, is not transparent, is a nega- 

 tive fact, and of considerable importance when the form of 

 transparency is inquired into; also, that collections of va- 

 pour, such as clouds and fogs, have not transparency, are 

 negative facts of the same kind. The facts thus collected, 

 both affirmative and negative, may, for the sake of refe- 

 rence, be reduced into tables. 



Bacon exemplifies his method on the subject of Heat; 

 and, though his collection of facts be imperfect, his method 

 of treating them is extremely judicious, and the whole 

 disquisition highly interesting. ' He here proposes, as an 

 experiment, to try the reflection of the heat of opaque 

 bodies. 2 He mentions also the vitrum calendared or ther- 

 mometer, which was just then coming into use. His re- 

 flections, after finishing his enumeration of facts, show 

 how sensible he was of the imperfect state of his own 

 knowledge. 3 



After a great number of exclusions have left but a few 

 principles, common to every case, one of these is to be 

 assumed as the cause ; and, by reasoning from it synthe- 

 tically, we are to try if it will account for the phenomena. 



So necessary did this exclusive process appear to Ba- 

 con, that he says, " It may perhaps be competent to angels, 

 or superiour intelligences, 1o determine the form or essence 

 directly, by affirmations from the first consideration of the 

 subject ; but it is certainly beyond the power of man, to 

 whom it is only given to proceed at first by negatives, and, 

 in the last place, to end in an affirmative, after the exclu- 

 sion of every thing else." 4 



1 Nov, Org. Lib. ii. Aph. IS, 20, &c. 2 Ibid. Aph. 11 

 3 Ibid. Aph. 14. " Ibid. Aph. 15. 



