( 10. ) 



This lava, which forms the large cavern, 

 defcends ahnoft perpendicularly into the 

 fea, and there affumes the form of prifms, 

 but larger than thofe before defcribed. It 

 is worthy of remark, that thefe prifms, 

 though in their lower part they fmk deep 

 into the water, do not rife above it, in their 

 upper, more than eight or nine feet. 



But in what manner are w^e to explain 

 the origin of this cavern ? How great muft 

 have been the violence of the waves of the 

 fea, to form by flow corrofion fo vaft an 

 excavation within this mafs of lava ! To 

 this caufe I cannot confent to afcribe it; 

 principally for this reafon, among others 

 that might be adduced, but which I omit 

 for brevity, that no fooner has the water 

 entered the mouth of the cavern but it lofes 

 all its force ; befides that the hardnefs of 

 this lava is fuch, that it does not eafily yield 

 to the ftroke of the waves. I incline rather 

 to think it the effed of the adion of the 

 gafes in the lava at the time it was in a ftate 

 of fluidity ; as we have examples at Etna of 

 H 3 caverns 



