( 3ot ) 



REFLECTIONS and COROLLARIES. 



THE fads explained in the prefent chap- 

 ter are highly inflrudive, from their teach- 

 ing us the nature of the different volcanic 

 rocks of the Euganean mountains ; but 

 they are flill much more fo from their ena- 

 bling us to form a comparifon between thefc 

 volcanos and others in Italy and its vicinity, 

 either extinguifhed or at prefent burning. 

 We are taught by obfervation and experi- 

 ence, that nothing exifts in nature detached 

 andfolitary; but that the whole is connected 

 with a variety of relations, and that we caa 

 acquire an accurate knowledge of no fmgle 

 part but by means of comparifon. In my 

 other v^'^orks on phyfical fubje£ts, I have 

 conftantly made it the primary objed: of 

 my ftudies and refearches to analyfe and 

 compare the facts I difcovered with each 

 other, and with fimilar fads difcovered by 



othey 



