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these problems in the numerous works hitherto 

 published on Etna and Vesuvius, the greater is 

 the desire of the traveller, to see with his own 

 eyes. He hopes to be more fortunate than those 

 who have preceded him ; he wishes to form a 

 precise idea of the geological relations, the vol- 

 cano and the neighbouring mountains bear to 

 each other ; but how often is he disappointed ? 

 when, on the limits of the primitive soil, enor- 

 mous banks of tufa and puzzolana render every 

 observation on the position and stratification im- 

 possible ! We reach the inside of the crater with 

 less difficulty than we at first expected ; we ex- 

 amine the cone from it's summit to it's basis ; 

 we are struck with the difference in the produce 

 of each eruption, and with the analogy which 

 still exists between the lavas of the same vol- 

 cano : but, notwithstanding the care with which 

 we interrogate nature, and the number of par- 

 tial observations which are presented at every 

 step, we return from the summit of a burning 

 volcano less satisfied, than when we were pre- 

 paring to go thither. It is after we have studied 

 them on the spot, that the volcanic phenomena 

 appear still more isolated, more variable, more 

 obscure,, than we figure them when consulting 

 the narratives of travellers. 



These reflections occurred to me on returning 

 from the summit of the Peak of Teneriffe, the 

 first unextinct volcano I had yet visited. They 



