^ Natural History of Volcanos and Earthquakes. 



steam and gases, may act as vents, and thus serve as a protection 

 against them.* 



Indeed, the ancients endeavored to diminish the violence of 

 subterranean explosions by means of wells and excavations. 

 What Pliny,f 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 i?i support of the hypothesis ivhich 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. 



* HofFmaii is inclined to ascribe the rarity and weakness of the earthquakes at 

 Sciacca to the numerous exhalations of aqueous vapors, and to the great number 

 of hot sulphurous springs, which occur in that neighborhood, compared with 

 other parts of Sicily, that are so often and so terribly visited by these destructive 

 phenomena. Poggendorfs Jlnnal. t. xxiv, p. 70. 



t Lib. ii, c. 82 (ed Par.'l723 t. i, p. 112 ) 



X Von Humboldt, Reise, t. i, p. 491. In Peru, the earthquakes are less frequent 

 than in Latacunga, which 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 quotes many instances, in which sev- 

 eral wells in Rome, J\'apl£s, and Capua, are said to have diminished 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 bo conceived, that the effects 

 of a cause, cxisting.so deep in the interior of the earth, should be modified in any 

 considerable degree, by an opening which penetrates the crust of the earth to so 

 slight a depth. 



