On Volcanos and Earthquakes. ae 
must penetrate, under ground at four miles and seven-eighths 
below the surface of the earth, through the crevices o' 
rocks, and in all the subterranean vacurties which communi- 
cate with each other, or with the general reservoir of air. 
And if it meets there, or rather, when it meets there com- 
bustible substances, as bitumen, sulphur, coal, &c. a confla- 
gration must ensue, which is constantly supplied with a new 
quantity of blowing air, forced by the pressure of the sea, as 
if by a permanent forge bellows. The air, after ve sup- 
ported combustion, rarefied by the heat, vole way, and 
anic mountains, 
which we have called craters, as it does in common chim- 
nies at the top of the flues. Such is our conception of these 
subterranean fires called volcanoes, considered in their quiet 
and peaceful operation. 
It would be difficult to conceive how combustion should 
be constantly nn under ground without a constant 
supply of air; and we do not perceive how that air would 
brought into those a aanee cavities, except by the 
means just suggested; we see no hole or opening which 
might be considered as a draught for the pose of air; on 
the contrary, ~* the reel gen observed emit gases that may 
t of the conflagration of combusti- 
ble bodies, aid dec: angaiiot of water by fire. We see 
smoke ascending fot the top of volcanic mountains, and 
all these phenomena seem to speak in favour of our our hypoth- 
esis. 
We do not think it necessary to enlarge on the various 
products of these subterranean fires ; a great deal has been 
said and published on this subject ; the formation of carbo- 
nic acid; its emission in its natural gaseous state ; its combi- 
nation with lime, magnesia, metallic oxides, &e.; its abun- 
dance in mineral waters; the flowing of hot water springs, 
either sainiple or su Iphurous ; the rushing out of hydrogen 
gas, sulphuretted or carburetted : these results are the natu- 
—" fet of these permanent fires, considered in their 
