[ ■'•93 ] 



NATURAL HISTORY. 



Earthquakes and their 



Causes. 



[From A. de Humboldt's personal 

 Narrative of Travels, translated 

 by Helen Maria Williams.] 



TT is a very old and commonly 

 received opinion at Cumana, 

 Acapulco, and Lima, that a per- 

 ceptible connection exists between 

 earthquakes, and the state of the 

 atmosphere that precedes these 

 ))hsenomena. On the coast of New 

 Andalusia, the inhabitants are 

 alarmed, when, in excessively hot 

 weather, and after long droughts, 

 the breeze suddenly ceases to blow, 

 and the sky, clear, and without 

 clouds at the zenith, exhibits, near 

 the horizon, at six or eight degrees 

 elevation, the appearance of a red- 

 dish vapour. These prognostics 

 are, however, very uncertain ; and 

 when the whole of the meteorolo- 

 gical variations, at the times when 

 the Globe has been the most agi- 

 tated, Hvecalled to mind, it is found, 

 that violent shocks take place 

 equally in dry and in wet weather ; 

 when the coolest winds blow, or 

 duringadead and suffocating calm. 

 From the great number of earth- 

 quakes, which I have witnessed to 



the north and south of the equator ; 

 on the continent, and in the basin 

 of the seas ; on the coasts, and at 

 2,500 toises height ; it appears to 

 me, that the oscillations are gene- 

 rally very independent of the pre- 

 vious state of the atmosphere. This 

 opinion is embraced by a number 

 of enlightened persons, who inha- 

 bit the Spanish colonies; and whose 

 experience extends, if not over a 

 greater space of tl.e globe, at least 

 to a greater number of years than 

 mine. On the contrary, in parts 

 of Europe where earthquakes are 

 rare compared to America, natu- 

 ral philosophers are inclined to ad- 

 mit an intimate connection between 

 the undulations of the ground, and 

 certain meteors, which accidentally 

 take place at the same epocha. 

 In Italy, for instance, the sirocco 

 and earthquakes are suspected to 

 have some connection ; and at 

 London, the frequency of falling 

 stars, and those southern lights, 

 which have since been often ob- 

 served by Mr. Dalton, were consi- 

 dered as the forerunners of those 

 shocks, which were felt from 1748 

 to 1756. 



On the days when the earth is 

 shaken by violent shocks, the re- 

 gularity of the horary variations of 

 the barometer is not disturbed 



