112 Volcanos. 



occsional paroxysms. Vesuvius was in this condition from 

 the beginning of the present century to October 1 822, when 

 there was a violent eruption. A similar state of things existed 

 from 1767 to 1779, when a violent eruption gave vent to the 

 force, and the volcano became inactive till 1 803 a period of 

 twenty-four years. 



./Etna was eruptive with intermediate agitations in 1 805-9 

 -11-12 and 19, but both these volcanos have had periods of 

 long repose, even for centuries. 



Popocatepetl, in Mexico, has been active ever since the 

 conquest of Mexico, and that of Sangay in Quito, has been in 

 incessant activity for about one hundred years. 



Mr. Scrope mentions as instances of remarkable volcanic 

 paroxysms, those of Vesuvius A. D. 79, 203, 472, 512, 685, 

 993, 1036, 1139, 1306, 1631, 1760, 1794, and 1822. 



^Etna, in 1169, 1329, 1535, this latter eruption lasted 

 two years " with terrific violence," and occurred after a qui- 

 escence of nearly one hundred years. 



Teneriffe,in 1704, 1797-8. 



San Georgio, one of the Azores, in 1808. 



Palma, one of the Canaries, in 1558, 1646, and 1677. 



Lancerote, one of the Jame group, in 1730. 



Kattlagia Jokul, in Iceland, in 1755, which lasted a year, 



Skaptar Jokuhl, in 1783. 



Violent eruptions are generally succeeded by periods of 

 long repose, sometimes extending even to centuries. Decom- 

 posed lava forms a soil even in the crater, and vegetation 

 springs up. 



"All appearances of igneous action are effaced; forests 

 grow up and decay, and cultivation is carried on upon a sur- 

 face, destined, perhaps, to be blown to atoms, and scattered 

 to the winds, when the crisis arrives for the renewal of the 

 volcanic phenomena. Thus during the quiescent interval, 

 between the eruptions of 1139 and 1306, the whole surface 

 of Vesuvius was in cultivation, and pools of water and chesnut 

 groves occupied the sides and bottom of the crater ; as is at 

 present the case with so many of the craters of iEtna, Au- 

 vergne, the Vivarais, &c. 



" Terrific eruptions occasionally break out from mountains 

 not previously suspected to be of a volcanic nature, or in 

 which the accounts, of former catastrophes of this sort, ex- 

 isted but as vague traditionary fables. 



