[ 6 5 8 ] 
plofions, Fermentations, and Fires from inflammable 
Minerals, that caufe thefe Convulfions of the Sur- 
face. 
I {hall nor pretend to deny, that there may be 
fuch Vapours, Fermentations, Rarefactions, and in- 
flammable Subflances, and actual Fires, in the Bowels 
of the Earth, and that there may be fome Caverns 
under-ground, as well as we find lome few above- 
ground, Tool's Hole , Okey Hole , and the like, in 
mountainous Countries. \Ve know there arc hot 
Springs running continually, and Vnlcano’s fre- 
quently belching out Flames and Smoke; and to 
thefe, moft probably, fome fmaller Earthquakes are 
owing. 
But thefe Matters are very rare, much rarer than 
Earthquakes, both as to Time and Place. Vefwmus 
in Italy , and in that Part of it abounding with 
Mines of Sulphur; z^/Etna in Sicily ; fome on the 
great Andes Mountains in America , and the like. 
The Scarcity of them, in my Opinion, is fo far 
from being a Proof of the general cavernous State 
of the Earth, that it ftrongly proves the contrary. 
How many thoufand Acres of Coal-Mines, Stone- 
Pits, and the like, do they daily work in England, 
and have done for Ages ? I have been myfelf ioo 
Yards deep in a Salt-Rock. I have walked half a 
Mile lengthwife, direCtly into the Earth, and un- 
der the Bed of the Ocean : But we never hear, from 
the many Hundreds of Thoufands of Workmen in 
this kind, of the cavernous State of the Earth. 
On the contrary, by their hard Labour they con- 
fefs it far otherwife. Nor have we any Rcafon, in 
England, to believe there are great Mines of Sulphur, 
and 
