Notice of Active and Extinct Volcano s. 73 



volcanos do also produce earthquakes. But, it will be asked 

 may not earthquakes be produced by other causes? To this 

 inquiry we must answer, that we know not of any other cau- 

 ses that are sufficient to produce earthquakes, except those 

 which modern science has assigned as the causes of volca- 

 nos, and, as these are, agreeably to the Newtonian rule, 

 " both true and sufficient" we are bound to admit them, at 

 least till other and more probable causes can be suggested. 



" When we observe two volcanic districts, both subject to earth- 

 quakes, which are ascertained to have a connection with the vol- 

 canic action going on, and find that an intermediate country, in 

 which there are no traces of the operation of fire, is agitated by 

 subterraneous convulsions, similar in kind, but stronger in degree 

 than those which occur in the more immediate vicinity of the 

 volcanos ; have we not reason to conclude, that the same action 

 extends throughout the whole of the above space, and that it is 

 this which produces in the intermediate country the effects allu- 

 ded to, which are only the more alarming from the absence of 

 any natural outlet, from which elastic vapours might escape ? 



"Now in proof of the former of these positions, it may be 

 scarcely necessary to do more than appeal to the case of Etna or 

 Vesuvius, which rarely return to a state of activity, after a long 

 interval of comparative quiescence, without some antecedent 

 earthquake, which ceases so soon as the mountain has established 

 for itself a vent.* Such was the case before the celebrated erup- 



* Humboldt gives us the following series of phcenomena, which presented 

 themselves on the American Hemisphere between the years 1796 and 97, as 

 well as between 1811 and 1812. 



1796. — September 27. Eruption in the West India Islands ; volcano of Guada- 

 loupe in activity. 



November The volcano of Pasto begins to emit smoke. 



December 14. Destruction of Cumana by earthquake. 



1797. — February 4. Destruction of Riobamba by earthquake. 



1811. — January 30. Appearance of Sabrina Island in the Azores. It increases 

 particularly on the 15th of June. 



May Beginning of the earthquakes in the Island of St. Vincent, 



which lasted till May, 1812. 



December 16. Beginning of the commotions in the valley of the Mis- 

 sissippi and Ohio, which lasted till 1813. 



December Earthquake at Caraccas. 



1812. — March 26. Destruction of Caraccas ; earthquakes which continued 

 till '1813. 



April 30. Eruption of the volcano in St. Vincent's ; and the same day 



subterranean noises at Caraccas, and on the banks of 

 the Apure. Pers. Narr. Vol. IV. 



See also Gemellarro on the Meteorological Phcenomena of Mount Etna, ex- 

 tracted in the Journal of Science, Vol, 14, 1813. 



Vol. XIV.— No. 1. 10 



