606 C. Darwin, Esq., on Volcanic 



denly subsided into their quiescent state*." The vents in Central Chile, nearer the chief focus of 

 disturbance, were not at the time of that earthquake affected: but according to the information 

 received by Dr. Gillies -f- in 1836, from a miner who had resided many years in sight of the vol- 

 cano of Maypu, its eruptions were very frequent during the four years immediately subsequent to 

 it. Many other instances are on record of earthquakes having passed over certain districts, in the 

 same manner as we see the eruptive force acted with respect to Villarica. Humboldt J remarks, 

 that the inhabitants of the Andes, speaking of an intermediary ground, which is not affected by 

 the general motion, say with simplicity, " that it forms a bridge " {que hace puente) ; and he adds, 

 " as if they meant to indicate by this expression, that the undulations were propagated at an im- 

 mense depth under an inert rock §." 



On the identity of the force which elevates Continents with that which causes 

 volcanic outbursts. 



It has frequently happened, that during the same convulsion large areas of 

 the globe have been agitated, and strange noises propagated to countries 

 many hundred miles apart |1 ; but in these cases, it is not possible to form any 

 conjecture over how wide an extent, any actual change has taken place in 

 the subterranean regions. It is different, when we hear from Humboldt, that 

 at the moment when the volcano of Pasto ceased to eject a column of smoke, 

 the city of Riobamba, sixty leagues to the southward, was overwhelmed by 

 an earthquake ; for the effect here produced certainly cannot be explained by 

 the mere transmission of a vibrationl. During the Concepcion earthquake, 



* Journal of Science, Vol. xvii. 



t The Edinburgh Journal of Natural and Geographical Science, August 1830, p. 317. 



\ Humboldt's Personal Narrative, Vol. iv. p. 21. English Translation. 



§ Another instance of earthquakes, violently affecting distant regions and passing over the in- 

 termediate country, is mentioned in the " True relation of the Earthquake of Lima, 1746." It is 

 there said (p. 192) that the shock was most violent at Lima and Callao, becoming gradually less 

 along the coast, but that at Guancavelica excessive shocks were felt and noises heard. The editor 

 believes, there is no other place called Guancavelica except the famous quicksilver mines of that 

 name, situated 155 miles to the S.E. of Lima. MacClelland {Report on the Coal Mines of India, 

 p. 43,) mentions some cases of intermediate places being little shaken during great earthquakes. 



II As examples of the first case, may be adduced the trembling of the ground on the coast 

 of Chile along a space of more than one thousand miles ; and during the Lisbon earthquake in 

 1755, countries about 3000 miles apart were affected (see Michell on Earthquakes : Phil. Trans. 

 1760.). With respect to the second case, Humboldt states, that during the eruption at St. Vin- 

 cent's, subterranean noises were heard on the banks of the Apure, a distance of two hundred and 

 ten leagues. (Person. Narr. Vol. iv. p. 27.) During the eruption of Coseguina in 1835, it is 

 said, that noises were heard at Jamaica, 660 miles distant. 



^ As other instances of the same kind, I may mention the outburst in 1 822, of the volcanos near 

 Valdiviaat the same moment that Valparaiso, nearly 400 miles distant, was levelled to the ground. 

 Again, in 1746, when I/ima was overthrown, three volcanos near Patas and one near Lucanas, the 

 two places being 480 miles apart from each other, burst forth during the same night. (Ulloa's 



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