UNCLE IN ENGLAND. 51 



any volcano ; and what renders this remark- 

 able is, that Jorullo appears to be in the exact 

 line of continuation of a chain of distant vol- 

 canoes, as if there were a subterranean com- 

 munication. Though the fire is now much 

 less violent, and though the plain and even the 

 great volcano begin to be covered with vegetation, 

 yet Humboldt found the air dreadfully heated 

 by the small ovens, and the thermometer rose to 

 202 on being plunged into the aqueous vapour 

 emitted by every fissure in the ground. 



<( It is said, that two rivers fall into the burning 

 chasm, and that at some miles distance they 

 emerge from the ground in a heated state. You 

 may recollect Colonel Travers told you that he 

 had seen the thermometer at 200 in a subterra- 

 neous spring called Nero's baths, at Solfaterra, 

 near Naples; and that he had eaten an egg 

 which it had completely boiled in a few minutes. 

 <f It is computed that there are at present 

 nearly a thousand volcanoes known to exist, and 

 yet there is no doubt that, in a former state of the 

 globe, they must have been more numerous, and 

 far more active and extensive in their operations. 

 Remains of extinct volcanoes of great size are 

 scattered in almost every country, and geologists 

 are every day discovering large tracts of rocks 

 and earths, which there is every reason to ascribe 

 to volcanic agency. 



te Several have been found in Europe, which 



F 2 



