50 Natural History of Volcanos and Earthquakes. 
of the Andes is said to be one of the latest, this cooling and 
contraction may continue even at the present time in that part 
which is within the earth. It is therefore possible to conceive 
that these effects are the cause of the frequent earthquakes in the 
Andes. 
Besides, there is nothing opposed to the hypothesis, that the 
powers, whatever they may be, which produced so remarkable a 
phenomenon as these elevations, may not even now operate ina 
less degree, and occasion the earthquakes so frequent in 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 show 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.t Nor do they seem to be 
* Many observers allude, indeed, to or of temperature of the atmos+ 
phere before and after aitthvihinn: but tk of Turin only have actu- . 
ally made observations on the temperature in the county of Pignerol. (Journ 
Phys. t. Ixvii, p. 292.) They found that their thermometer always descended as 
soon as shocks had been felt. Thus they felt a vehement shock in the morn- 
ing at sired ma ten, on the 10th of April, and their thermometer descended till 
noon from 26° to 22°. In fact itis to be desired, that farther observations should 
be made on wehas occasions, in order to confirm or refute the assertion of so re- 
+ The late F. Hoffman in vain endeavored to discover in the Meteorological 
Journal of the Observatory of P alermo, (which ineluded a series of years fro 
supposed to have been connected with the ele: SO The same result was ob- 
tained by Domenico Scina in his memoir on the numerous earthquakes, which, 10 
the years 1818 and 1819, caused so much apprehension i in the neighborhood of the 
Madonian hills —Poggendorff’s Ann. t. xxiv, p. 50 and 60. ‘tn contradiction t0 
this are the traditions current in many countries. See among others, Berghau u's 
Almanack, 1837, p. 97, and following. There seems to be in fact, some truth im 
the opinion, that eurihiquated 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 erust of the earth by water, which impedes the rising of gases 
On the other hand, cases have occurred in which earthquakes, were preceded by 
a long continued drought.—Barham in the Philos. Trans. t. xxx, p. 837, y. 1718 
and t. xlix, p. 403; Relat. Hist. t. ii, pp. 273, 281, and t. v, p: 15, and 57; Hans 
