K \RTIIQI 



119 



twenh -< -i^lit corresponding months ; and it to remark, liad not Seilor Troncoco been 



ah.se nt from Serena on the 26th May, 1S.V2, tin- ili.s|,n.].i,rti.n would d<nil.tl<a have been 

 greater. See.. ml : They prove that there are no peinian. -m . -. ntreH of disturbance, theapp.i 

 direction of the vihratimis varying at each occurrence. Third: A large proportion of these 

 tremors arc neither undulations nor vihrat i..ns, but rather rapid vertical displacements of the 

 crust of the earth ; almoHt, if not absolutely, siniultan< the whole disturbed district. Our 



sensations raused suspicion of the fact, the .shivering of our jiemluluin without oscillation gup- 

 ported the ! lief, the instrument of Sefior Troncoso afforded direct evidence, and the tele- 

 graph confirmed it on two occasions. The instrument alluded to consisted of an inverted pendu- 

 lum within a closed glass globe from which the air had been exhausted. The pendulum is a 

 spiral made of steel wire sensible to very slight disturbances, and he frequently remarks, "the 

 spring is opened as far as the top of the globe will permit, hut the pendulum has no lateral 

 motion." A very experienced English gentleman wrote to me on this subject from the mining 

 districts of Atacama: "Shocks are sometimes horizontal, sometimes vertical; but the former 

 appear to me the more dangerous. A few days ago, we had quite a strong horizontal shake 

 that did much damage, though a vertical shock two days after, which to our senses was of the 

 same force, caused very little injury. At the same time the latter was so strong as to throw 

 the water out of tumblers and jars." Fourth: So far as conclusions may be drawn from 

 observations during thirty-five consecutive months at one place, and twenty-eight months at 

 the other, the season of the year has influence. The numbers in each season, with the average 

 monthly number of shocks at each city, are embodied in the subjoined table : April at Santiago, 

 and November at Serena, embracing the extraordinary disturbances of 1849 and 1851. 



Earthquakes at Santiago and Serena. 



Humboldt thinks we have no right to reject belief in "the influence of particular seasons, 

 the vernal and autumnal equinox, the setting in of tropical rains after long-continued drought, 

 and the change of monsoons, solely because we do not at present understand the causal connec- 

 tion which may exist between meteorological and subterranean phenomena." Popular belief 

 even yet associates them with peculiar meteorological conditions: many assert that the baro- 

 meter is low, the thermometer high, the atmosphere calm and oppressive, and that the color of 

 the sky changes just before the shock. The tables bear directly on all these questions ; and 

 whilst instrumental data, with other recorded evidence extracted from our meteorological journal, 

 show that neither the pressure, the temperature, nor the hygrometric condition of the air have 



* Kosmos, Vol. I. 



