233 



top of the Piton. I have endeavoured to render 

 these researches interesting, by comparing the 

 phenomena of the volcano of TenerifFe with those 

 that are observed in other regions, the soil of 

 which is equally undermined by subterranean 

 fires. This mode of viewing Nature in the uni- 

 versality of her relations is no doubt prejudicial 

 to the rapidity suitable to an itinerary; but I 

 thought, that, in a narrative, the principal end 

 of which is the progress of physical knowledge, 

 every other consideration ought to be subservi- 

 ent to those of instruction and utility. It is by 

 isolating facts, that travellers on every other ac- 

 count respectable, have given birth to so many 

 false ideas of the pretended contrasts, which Na- 

 ture offers in Africa, in New Holland, and on the 

 ridge of the Cordilleras. The great geological 

 phenomena are subject to the same laws, as well 

 as the forms of plants and animals. The ties 

 which unite these phenomena, the relations 

 which exist between such varied forms of organ- 

 ized beings, are discovered only when we have 

 acquired the habit of viewing the Globe as a 

 great whole ; aod when we consider in the same 

 point of view the composition of rocks, the 

 forces which alter them, and the productions of 

 the soil, in the most distant regions. 



After having treated of the volcanic substances 

 of the isle of TenerifFe, we have to solve a ques- 

 tion intimately connected with the preceding in- 



