Ch.VII. south AMERICA. S5 



matter was not totally exhausted, nor tlie cause of 

 the shocks absolutely remo\ed. 



The frequent earthquakes to wliich South Ame- 

 rica, particularly Lima, and all the country of 

 Vallo-, is subject, opens a field for enquiry not less 

 ample than that just mentioned, concernini^ their 

 cause. Many hypotheses have been formed by phi- 

 losophers; but the generality, and with the greatest 

 appearance of truth, agree in deducing them princi- 

 pally from the violent force of the air contained in 

 sulphureous substances and other minerals, and also 

 that confined in the pores oí' the earth; which being 

 compressed by the incumbent load, make a very vio- 

 lent resistauce. This is so far from implying any con- 

 tradiction, that besides being counteiaaced by reason 

 it is also confirmed by experience. But tlie appaifent 

 difficulty consists in explaining how the vents of the 

 earth become again filled with air, after one concus- 

 sion has happened; it being natiual to think, that the 

 quantity which struggled for vent, Vvas thereby dis- 

 charged, and that a long interval of time was neces- 

 sary before another could be produced. Also why 

 some countries are more subject to these terrible con 

 vuisions than others. Though this subject has been 

 treated of by several authors, 1 think it my duty here 

 to deliver the opinion which to me seems most pro- 

 bable. 



Experience has sufficiently shewed, especially in 

 this country by the many volcanoes in the Cordil- 

 leras which pass through it, that the bursting of a 

 new burning mountain causes a violent earthquake, 

 so as totally to destroy all the towns within its 

 reach ; as happened at the opening of the volcano in 

 the desert of Carguagoazo as mentioned in Vol. I. 

 This tremulous motion, which we may properly 

 call an earthquake, does not so usually happen in 

 case of a second, eruption, when an aperture has 

 been before made ; or at least, the motion it causes 



in 



