Natural History of Volcanos a7id Earthquakes. 47 



have at different periods ravaged Smyrna* Messina,-f Kings- 

 town in Jamaica 1792, the county of Pignerol 1808, J Cala- 

 hria^W Talcahuano in Chili,§ &c., have always had a greater 

 effect on diluvium and alluvium, than on rocks. Houses, for in- 

 stance, built on sandy ground, were demolished, while those 

 which stood on rocks were but little damaged. The shocks 

 therefore act less violently and destructively on solid and rocky 

 ground than on loose soil, which is unable to resist, and propa- 

 gates the shock irregularly. In Calabria, where the loose soil 

 occurred lying on granite on the declivity of the hills, the latter 

 threw off the former, which glided down. Lastly, there are also 

 instances of shocks extending irregularly in rocks.H 



Many instances present themselves of earthquakes, which in 

 extending longitudinally, follow the direction of the rocks. This 

 is the case, according to Palassou,**" in the Pyrenees. Remarka- 

 ble instances are presented in the phenomena of the 28th Dec. 

 1779 ; the 10th July 1784 ; the 8th July 1791 ; the 22d May 

 1814, &c. The regions situated more to the south, are, how- 

 ever, more affected than the chain itselfff Earthquakes in 

 South America seem also to follow the direction of the mountains. 

 Thus, that at Caraccas (1812) followed the direction of the lit- 

 toral Cordilleras from E. N. E. to W. S. W.H That of Cumana 

 1797, presented an instance of the same fact. The predominant 

 direction of the frequent earthquakes on the coasts of Chili and 

 Peru, is also that of the large chain of the Andes, which is par- 

 allel to the coast. II II All the older reports likewise state, that in 

 these countries their direction is from S. to N., or vice versa ; and 

 Mrs. Graham remarked, that she felt, during the violent earth- 

 quake in Chili 1822, as if the whole ground from north to south 



tranquillity was restored, a whirlpool was observed in the sea, as if the waters 

 were being swallowed up in an immense gulf. The temperature of the sea in the 

 bay was raised, and bubbles of gas were seen rising all over the surface. 



* Hist, de I'Acad. des Sciences, an. 1688. Buffon, Hist. Nat. t. i,p. 515. 



t Spallanzani, Voyage, t. iv, p. 138. X Journ. de Phys. t. Ixvii, p. 238. 



II Oryktologische Bemerkungen Uber Calabrien &c., 1784. 



§ Nautical Magazine, Nos. 49 and 51, March and June 1836. 



IT Berghaus' Almanack fiir das Jahr 1837, p. 72. 



** Mem. pour servir k I'Hist. Nat. des Pyren., p. 260. 



ft Ibid p. 916. XX Von Humboldt, Rel. Hist. t. v. 



III! That at Cumana followed the direction from N. to S., vvhich is extremely sin- 

 gular, 1. cit. t. iv, p. 16. 



