Oct. 1, 1868.1 



HARDWICKE'S SCIENCE-GOSSIP. 



217 



PHENOMENA OF EABTHQUAKES. 



By BARON VON HUMBOLDT. 



F it be the duty 

 of the men of 

 science who visit 

 the Alps of Swit- 

 zerland, or the 

 coasts of Lap- 

 land, to extend 

 our knowledge 

 respecting the glaciers and 

 the aurora borealis, it may 

 be expected that a traveller 

 who has journeyed through 

 Spanish America should 

 have chiefly fixed his atten- 

 tion on volcanoes and earth- 

 quakes. Each part of the 

 globe is an object of parti- 

 cular study ; and when we 

 cannot hope to penetrate the 

 causes of natural phenomena, 

 we ought at least to endea- 

 vour to discover their laws, and distinguish, by 

 the comparison of numerous facts, that which is 

 permanent and uniform from that which is variable 

 and accidental. 



The great earthquakes, which interrupt the long 

 series of slight shocks, appear to have no regular 

 periods at Cumana. They have taken place at 

 intervals of eighty, a hundred, and sometimes less 

 than thirty years ; while on the coast of Peru, for 

 instance at Lima, a certain regularity has marked 

 the periods of the total destruction of the city. 

 The belief of the inhabitants in the existence of 

 this uniformity has a happy influence on public 

 tranquillity, and the encouragement of industry. It 

 is generally admitted that it requires a sufficiently 

 long space of time for the same causes to act with 

 the same energy; but this reasoning is just only 

 inasmuch as the shocks are considered as a local 

 phenomenon ; and a particular focus, under each 

 point of the globe exposed to those great cata- 

 No. 46. 



strophes, is admitted. Whenever new edifices are 

 raised on the ruins of the old, we hear from those 

 who refused to build that the destruction of 

 Lisbon on the first day of November, 1755, was 

 soon followed by a second, and not less fatal con- 

 vulsion, on the 31st of March, 1761. 



It is a very ancient opinion, and one that is com- 

 monly received at Cumana, Acapulco, and Lima, 

 that a perceptible connection exists between earth- 

 quakes and the state of the atmosphere that pre- 

 cedes those phenomena. But from the great number 

 of earthquakes which I have witnessed to the north 

 and south of the equator, on the continent and on 

 the seas, on the coasts and at 2,500 toises height, 

 it appears to me that the oscillations are generally 

 very independent of the previous state of the atmo- 

 sphere. This opinion is entertained by a number of 

 intelligent residents of the Spanish colonies, whose 

 experience extends, if not over a greater space of 

 the globe, at least over a greater number of years, 

 than mine. On the contrary, in parts of Europe 

 where earthquakes are rare compared to America, 

 scientific observers are inclined to admit an intimate 

 connection between the undulations of the ground 

 and certain meteors, which appear simultaneously 

 with- them. In Italy, for instance, the sirocco and 

 earthquakes are suspected to have some connection, 

 and in London, the frequency of falling stars, and 

 those southern lights which have since been often 

 observed by Mr. Dalton, were considered as the 

 forerunners of those shocks which were felt from 

 1748 to 1756. 



On days when the earth is shaken by violent 

 shocks the regularity of the horary variations of 

 the barometer is not disturbed within the tropics. 

 I had opportunities of verifying this observation at 

 Cumana, at Lima, and at Puobamba ; and it is the 

 more worthy of attention, as at St. Domingo (in 

 the town of Cape Francois) it is asserted that 

 a water-barometer sank two inches and a half 

 immediately before the earthquake of 1770. It is 



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