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'vius in 1737 (in which account many of the.phs- 
nomena of the volcano are recorded and very well 
accounted for) fays, that at the convent of Dominican 
Fryars, called the Madona del Arco, fome years ago, 
in linking a well, at a hundred feet depth, a lava was 
difcovered, and foon after another, fo that in lefs than 
three hundred feet depth, the lavas of four eruptions 
were found. From the- lituation of this convent it 
is clear beyond a doubt, that thefe lavas proceeded 
from the mountain called Somma^ as they are quite 
out of the reach of the exiding volcano. ^ 
From thefe circumftances, and from repeated ob- 
fervations I have made in the neighbourhood of Ve- 
fuvius, I am fure that no virgin foil is to be found there, 
and that all is compofed of different Ifrata of erupted 
raatter>even to a great depth below the level of the fea. 
Infliortjl have not any doubt in my own mind, but that 
this volcano took its rife from the bottom of the fea ; 
and as the whole plain between Vefuvius and the 
mountains behind Caferta, which is the bed part of 
the Campagna Felice, is (under its good foil) compofed 
of burnt matter, I imagine the fea to have waflied 
the feet of thofe mountains, until the fubterraneous 
fires began to operate, at a period certainly of a mod 
remote antiquity. 
The foil of the Campagna Felice is very fertile;,. 
I faw the earth opened in many places laft year in 
the midft of that plain, when they were feeking for 
materials to mend the road from Naples to Caferta. 
The flratum of good foil was in general four or five 
feet thick ; under which was a deep flratum of cin- 
ders, pumice, fragments of lava and fuch burnt 
matter as abounds near Vefuvius and all volcanos.. 
The 
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