350 DOMAIN XII. VOLCANIC. 



the crater must have undergone great changes 

 in its structure; since if the stones that were 

 thrown into it gave no indications to the ear 

 that they struck against any solid body, it is 

 manifest that there must then have been an 

 abyss as well as a funnel; and as the funnel 

 terminated in a point when it was observed by 

 Sir William Hamilton, it is evident that the flat 

 bottom I have described, and which was about 

 two thirds of a mile in circuit, did not then 

 exist. 



" The internal sides of the crater, Sir William 

 tells us, were covered with a crust of salt and 

 sulphur ; but he does not specify the nature of 

 the former; and though the presence of the lat- 

 ter is not improbable, he might have been led 

 into a mistake by the yellow colour, and have 

 taken the muriate of ammoniac (sal arnmoniac) 

 for sulphur, as I did before I examined it. Sir 

 William has not told us that he made any 

 examination at all ; and it is probable that he 

 judged only from the appearance it presented to 

 his eye. 



" He observes, lastly, that the crater was two 

 miles and a half in circumference ; an estimate 

 which may be made to agree with mine by ne- 

 glecting the partition which separates the greater 

 crater from the less, and considering them both 



