r ^5 ] 
You have now, Sir, before you the nature of the 
foil, from Caprea to Naples. The foil on which this 
great metropolis hands has been evidently produced 
by explolions, fome of which feem to have been upon 
the very fpot on which this city is built ; all the high 
grounds round Naples, Paufilipo, Puzzole, Baia, 
Mifenum, the illands of Procita and Ifchia, all ap- 
pear to have been raifed by explofion. You can trace 
hill in many of thefe heights the conical flaape that 
was naturally given them atfirfi, and even the craters 
out of which the matter iffued, though to be fure 
others of thefe heights have fuffered fuch changes 
by the hand of time, that you can only conjedure 
that they, were raifed in the like manner, by their 
compoiition being exadly the fame as that of thofe 
mountains, which dill retain their conical form and 
craters entire. A tufa, exadly refembling the fpeci- 
inen I took from the inlide of the theatre of Her- 
culaneum, layers of pumice intermixed with layers 
of good foil, juft like thofe over Pompeii, and lavas 
like thofe. of Vefuvius, compofe the whole foil of the. 
country that remains to be defcribed. 
The famous grotto anciently cut through the; 
mountain of Paufilipo, to make a road from Naples 
to Puzzole, gives you an opportunity of feeing that 
the whole of that mountain is tufa. The firft evi- 
dent crater you meet with, after you have paffed the 
grotto of Pauftlipo, is now the lake of Agnano ; a 
fmall remain of the fubterraneous fire (which muft. 
probably have made the bafon for the lake, and raifed 
the high grounds which form a fort of amphitheatre 
round it) ferves to heat rooms, which the Neapoli- 
tans make great ufe of in fummer, for carrying off 
diverfe* 
