Volcanos and Earthquakes, 359 



halations of steam and gases, may act as vents, and thus serve 

 as a protection against them.* 



Indeed, the ancients endeavoured 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 Pkhincha.X But this is by no means confirmed 

 by experience, 



FarOier reasons in support of the hypothesis which attributes volcanic 

 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 connexion of these two classes of phenomena refeis us to 

 one and the same cause. In proportion as satisfactory grounds 

 can be adduced in support of any hypothesis, which explains 

 one class of phenomena, so much the more probable does the 

 hypothesis appear 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 exa- 

 mine the phenomena of the former on the surface of the earth, 

 and every point of time selected by the observer for this pur- 

 pose proves equally favourable. ' 



'•' HoflPman is inclined to ascribe the rarity and weakness of the earth- 

 quakes at Sc'mcca to the numerous exhalations of aqueous vapours, and to the 

 gi-eat number of hot sulphureous springs, which occur in that neighbourhood, 

 compared with other parts of Sicily, that are so often and so terribly vi- 

 sited by these destructive phenomena. Poggefidorfs Annal. t. xxiv. p. 70. 



fLib. ii. c. 82 (ed. Par. 1723. t. i. p. 112.) 



J Von Humboldt, Reise, t. i. p. 491. In PerUy 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 neighbourhood 

 of the toAvn. Leonhard's Taschenbuch, 1822, p. 917. Von HofF quotes 

 many instances, in which several wells in llomcy Naples, and Capua, are said 

 to have diminished or totally paralyzed the effects of earthquakes. But, in 

 my opinion, an undue importance is ascribed to this eflfect of wells, for it 

 is hardly to be conceived, that the effects of a cause, existing so deep in the 

 J^ interior of the earth, should be modified in any considerable degree, by an 

 ^K< opening which penetrates the crust of the earth to so slight a depth. 



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