f 
52 Natural History of Volcanos and Earthquakes. 
against them.* 
Indeed, the ancients endeavored to diminish the violence of 
subterranean explosions by means of wells and excavations. 
What Pliny, the great Roman naturalist says of the efficacy 
of these expedients, is repeated by the ignorant inhabitants of 
Quito, when they point out to the traveller the Guaicos, or clefts 
of the Pichincha.{ But this is by no means confirmed by ex- 
‘perience. 
Farther reasons in support of the hypothesis which attributed vol- 
canic phenomena to increased temperature of the interior. 
However distinct natural philosophers may consider the causes 
of volcanic action, and those of hot springs, yet the close connec- 
tion of these two classes of phenomena refers us to one and the 
same cause. In proportion as satisfactory grounds can be ad- 
duced in support of any hypothesis, which explains one class of 
phenomena, so much the more probable does the hypothesis ap- 
pear when applied to the other class. Though the seat of hot 
springs be concealed deep in the interior of the earth, and be 
as little accessible to immediate observation and investigation 
as volcanic action is; yet we may pursue and examine the phe- 
nomena of the former on the surface of the earth, and every point — 
of time selected by the observer for this purpose proves equally 
favorable. 
* Hoffman is inclined to ascribe the rarity and weakness of the earthquakes at 
Sciacca to the numerous exhalations of aqueous vapors, and to the eet number 
of hot sulphurous springs, which occur in that neighborhood, compar d with 
other parts of Sicily, that are so often and so terribly visited by these cate 
en 
{ Von Humboldt, Reise, t. i, p. 491.. In Peru, the earthquakes are less frequent 
than in Latacunga, w bah 3 is ascribed to the great number of deep hollows which 
intersect the ground in all directions in the neighborhood of the town. Leon- 
hard’s Taschenbuch, 1822, p. 917. Von Hoff ales many Soe sree which sev- 
eral wells in Rome, Naples, and Capua, are said to h or totally parali- 
zed the effects of earthquakes. But, in my opinion, an undue importance is 
ascribed to this effect of wells, for it is hardly to be conceived, that the effects 
a cause, existing so deep in the interior of the earth, should ~~ modified in any 
considerable degree, by an opening which penetrates the crust of the earth to 8? 
slight a depth. 
steam and gases, may act as vents, and thus serve as a protection 
