rYia<-foi 1 



ON VOLCANOES AND EARTHGLUAKES. 359 



matter is produced, appearing in vivid and frequent 

 flashes of lightning, and adding much to the splen- 

 dour of the scene. At the same time, sulphureous 

 gas is generated hy the combustion of sulphur ; and, 

 in some eruptions, white smoke, apparently the 

 steam of water, is produced in considerable quan- 

 tities. 



The appearances now described are drawn chiefly 

 from the eruptions of Vesuvius, of which more than 

 thirty have been recorded since the reign of Titus. 

 By these, Pompeii and Herculaneum were over- 

 whelmed, preserving invaluable records of Roman 

 times and manners ; and, by one of them, Monte Nuo- 

 vo, three miles in circumference, was thrown up in 

 forty-eight hours. To convey a further notion of the 

 quantity of matter ejected, Herculaneum is now seventy 

 feet below the surface, and Pompeii ten or twelve. 



Breislak has been at the trouble of computing the 

 quantity of lava ejected by some remarkable eruptions 

 in different places. That which flowed from Vesuvius 

 in 1794 was estimated at nearly 3,000,000 of cubic 

 fathoms. In 1796, the mass of ejected matters in 

 Bourbon was computed at upwards of 9,000,000, in 

 1787, at nearly 12,000,000, and in 1791, at 8,000,000. 

 One current of lava from JEtna is stated by Recupero 

 to be forty miles in length ; and that which flowed in 

 1669 measured fifteen miles by seven in breadth, while 

 it filled all the intermediate valleys. One of the erup- 

 tions in Iceland is said to have covered a space of 

 ninety-four miles by fifty, or four thousand seven 

 hundred square miles. These facts will convey a 

 notion of the immense masses of matter that are thus 

 brought up from the subterranean regions which are 

 the seat of the volcanic fire. 



In many cases, as in those of .flStna and Teneriffe, 



