C 29 3 
fummer time, by the vapours from the ftagnated 
waters of the lake, which is adliially the cafe. 
You have, Sir, from thefe accounts, an inftance of 
a mountain, of a conhderable height and dimenfions, 
formed in a plain, by mere explofion, in the fpace of 
forty-eight hours. The earthquakes having been 
fenfibly felt at a great diftance from the fpot where 
the opening was made, proves clearly, that the fub- 
terraneous fire was at a great depth below the furface 
of the plain ; it is as clear that thofe earthquakes, 
and the explofion, proceeded from the fame caufe, 
the former having ceafed upon the appearance of the 
latter. Does not this circumftance evidently contra- 
dict the fyftem of M. Buffon, and of all the natural 
hifiorians, who have placed the feat of the fire of 
volcanos towards the center, or near the fummit of 
the mountains, which they fuppofe to furnifli the 
matter emitted ? Did the matter which proceeds from 
a volcano in an eruption come from fo inconfiderable 
a depth as they imagine, that part of the mountain 
fituated above their fuppofed feat of the fire muft 
necefiarily be deftroyed, or difiipated in a very (hort 
time: on the contrary, an eruption ufually adds to 
the height and bulk of a volcano, and who, that has 
had an opportunity of making obfervations on vol- 
canos does not know, that the matter they have 
emitted for many ages, in lavas, afhes, fmoke, &c. 
could it be collected together, would more than 
fufiice to form three fuch mountains as the fimple 
cone or mountain of the exifling volcano ? With re- 
fpeCl to Vefuvius, this could be plainly proved j and I 
refer to my letter upon the fubjeCt of Etna, to fhew 
the quantity of matter thrown up in one fingle erup- 
tion. 
