ON ITS EXTERIOR. EARTHQUAKES. 1/7 



gave especial occasion to the formation of hypotheses 

 respecting causal connection in volcanic activities. It 

 was then that Aristotle originated the singular theory of 

 the power of winds entangled in the bowels of the earth. 

 (Met. II. p. 368.) The frequency of earthquakes in 

 Greece and Lower Italy, by destroying the monuments 

 of the most nourishing period of Art, has exercised a 

 most unfavourable influence on the study of the Greek 

 and Roman cultivation at different periods. Egyptian 

 monuments also (for example a colossal statue of Mem- 

 non, 27 B. c.) have suffered from earthquake shocks, 

 which, as Letronne has shown, were not so rare in the 

 Valley of the Nile as has been supposed. (Les Statues 

 Vocales de Memnon, 1833, p. 23-27, and 255.) 



The considerations on which we have been dwelling 

 will make it appear still more remarkable, that so many 

 warm sanatory springs should have retained their com- 

 position and their temperature unaltered for centuries ; 

 and must therefore flow from fissures which have appa- 

 rently undergone no changes either at their bottom or 

 sides. Channels of communication opened with higher 

 strata would have diminished, and with lower strata 

 would have increased, the temperature of the spring. 



At the great outburst of the volcano of Conseguina in 

 the State of Nicaragua, on the 23rd of January 1835, 

 the subterranean noise ( 249 ) (los ruidos subterraneos) 

 was heard simultaneously in the island of Jamaica and 

 on the highlands of Bogota (nearly 9000 feet above the 

 sea) ; a distance greater than that between Algiers and 

 London. I have already remarked elsewhere that at 

 the eruption of the volcano in the Island of St. Vincent, 

 on the 30th of April 1812, at two in the morning, a 

 VOL. iv. N 



