Volcanos and Earthquakes. 35B 



England is from S.S.W. to N.N.E. &c. Sometimes the earth- 

 quakes originate from a common centre in a radiating direction 

 on all sides. That of Lisbo7i (1755), that in Calabria (1783), 

 and that at Lima (1746), &c. offer instances of this kind. 



With regard to the earthquakes in South America, it ha8 

 been observed that they occur principally in the mountainous 

 countries. The cause which produces them, seems, as Bous- 

 singault* believes, to be so constantly in operation, that,' if all 

 the earthquakes, which are felt in the inhabited countries of 

 America, could be noted, the earth would be found to quake 

 nearly without intermission. These frequent movements of the 

 ground of the Andes, and the slight coincidence between these 

 convulsions and the volcanic eruptions, induce us to adopt the 

 opinion of Boussingault, that the former are, for the most 

 part, independent of the latter. He ascribes the greatest num- 

 ber of the earthquakes in the Andes to the sinking of rocks in 

 the interior, which is a consequence of the former elevations of 

 these chains of mountains. In favour of these suppositions, he 

 affirms that these gigantic rocks have been thrown up, not in a 

 doughy, but in a solid and fragmentary state, but that the 

 consolidation of these fragments bf crystalline rocks might not 

 at first have been so firm, as not to admit of some sinking after 

 the elevation. He refers to the Indian tradition which pre- 

 serves the memory of the sinking of the celebrated mountain 

 of Capac-Urcu, near Riobamba, the name of which signifies 

 the chief, i.e. the highest, of all the mountains near the Equator. 

 It is said that the top of this mountain has sunk in consequence 

 of a subterranean shock which took place before the discovery 

 oi America. At the present time Capac-Urcu h lower than 

 Chimborazo. Boussingault alludes to many instances, in which 

 it is asserted, that the Cordilleras have sunk. Without taking 

 into consideration the inferences drawn from barometrical 

 measurements, made by Boussingault and his predecessors, 

 which seem indeed to confirm that supposition, we will only 



I mention the following circumstances. The French academi- 

 cians, who, a century ago, were sent to Quito for the purpose 

 of determining the form of the globe, were very much embar- 



* AiinaL de Chim. et de Phys., t. Iviii. p. 83. 



