NOME II. VESICULAR LAVA. 353 



He ascended Etna in 1727, and remarked 

 two craters, one larger than the other. The 

 latter he only mentions, but the former he de- 

 scribes at some length. Its circumference was 

 perhaps somewhat, more than four miles. From 

 it issued clouds of smoke and reddish flames. 

 These, however, did not prevent his approach- 

 ing to the edge of the gulf; though, to prevent 

 the danger of falling into it, he and his compa- 

 nions fastened themselves to a rope held by three 

 men. On looking into the crater, they were 

 unable to discern the bottom, on account of the 

 flames and smoke : they only observed that a 

 conical hill, formed of lava, rose in the middle of 

 the crater, the top of which they estimated to 

 be sixty feet below them ; and they were able to 

 see perhaps about sixty lower; where, as they 

 conjectured, the circuit of this hill might be 

 from six hundred to eight hundred feet*. 



" We have here a remarkable circumstance 

 relative to Etna, as it appeared in the time of 

 M. D'Orville, and not observed by any one of 

 the four travellers above cited, I mean the coni- 

 cal hill within the crater. Every observation, 

 therefore, tends to confirm the inconstancy of 

 the internal configuration and dimensions of this 



* Jacobi Philippi D'Orville Sicula, 

 VOL, II. 2 A 



