Volcanos and Earthquakes. 357 



the Andes. The later these elevations are supposed to have 

 taken place, the more probable will such a hypothesis be. 



If further proofs are still necessary to shew that the causes 

 of earthquakes are only to be sought in' the interior of the 

 earth, we certainly find them in the fact, that these phenomena 

 are totally independent of external circumstances. They take 

 place whether the sky be clouded or serene, in hot as well as 

 in cold weather,* before or after rain, sometimes with rain, 

 and sometimes without it. Even the strength and direction of 

 the wind seem to have no kind of connection with them.-f* Nor 

 do they seem to be confined to any particular season of the 

 year, although it is certainly remarkable, that of fifty-seven 

 earthquakes which were felt at Palermo during a period of 



* Many observers allude, indeed, to variations of temperature of the at- 

 mosphere before and after earthquakes ; but, the academicians of Tunn only 

 have actually made observations on the temperature in the county oiPignerd. 

 (Joum. de Phys. t. Ixvii. p. 202.) They found that their thermometer al- 

 ways descended as soon as shocks had been felt. Thus they felt a vehe- 

 ment shock in the morning at half-past ten on the 10th of April, and their 

 thermometer descended till noon from 26° to 22°. In fact it is to be desired, 

 that farther observations should be made on other occasions, in order to con- 

 firm or refute the assertion of so remarkable a phenomenon. 



t The late F. Hoffman in vain endeavoured to discover in the Meteoro- 

 logical Journal of the Observatory of Palermo (which included a series of 

 years from 1792 to 1832, and where particular attention had been paid to the 

 observation of earthquakes, of which no less than fifty-seven had there been 

 accurately observed) some peculiarity of weather, which might, with any 

 degree of plausibility, be supposed to have been connected with the earth- 

 quakes. The same result was obtained by Domenicq Scink in his memoir 

 on the numerous earthquakes, which, in the years 1818 and 1819, caused so 

 much apprehension in the neighbourhood of the Madontan hills. — Poggen- 

 dorff *s Ann. t. xxiv. p. 50 and 60. In contradiction to this are the traditions 

 current in many countries. See among others, Berghaus' Almanack, 1837, 

 p. 97, and following. There seems to be in fact some truth in the opinion, 

 that earthquakes are most frequent and vehement at the beginning of 

 rainy weather, and this phenomenon is even ascribed in Jamaica to a locking 

 up of the pores in the crust of the earth by water, which impedes the rising 

 of gases. On the other hand, cases have occui-red in which earthquakes 

 were preceded by a long-continued drought. — Barhara in the Philos. Trans, 

 t. XXX. p. 837, y. 1718, and t. xlix. p. 403 ; Relat. Ilist. t. ii. pp. 273, 281, and 

 t. v. p. 15 and 57 ; Ilaus Sloane's Letter with several accounts of the earth- 

 quake in Peru, Oct. 20. 1687, at Jamaica, 10th Feb. 1688, 7th June, 1692 ; 

 ibid. y. 1694, p. 78 ; Hist, des Trembl. de Terre, t. ii. p. 442 ; Collect of the 

 Massachusetts Ilist. Soc, t. v. p. 223. 



