Chap. 47-1 [ 3 '9 1 



CHAP. XLVIL 



VOLCANOES. 



ances, 

 noes in 



General Gtyr-vatiOfis on Volcanoes, Their Connexion with the 

 Immatje Force of fultcrrane out Fires exemplified in various Inft 

 Theory cf Volcanoes. Great Depth. Traces of Volcan 

 different Parts of the World. De/criptidn of JStna. Eruption of 



fifkvitat, in 1794. 



TTOLCANOESare peculiar to no climate, and 

 V have no neceffary or regular connection with 

 any other mountains, but feem to have fome with the 

 fea, for they are generally in its neighbourhood. Ic 

 has been remarked by thole who have obferved them, 

 that volcanoes often throw out matters which belong 

 to the fea, as the relics of fifh, fea-weed, and often 

 immenfe quantities of lea-water itfelf. Sir William 

 Hamilton obferves, in the Philofophical T ran factions 

 for the year 1776, u that the operatipns of Vefuvius 

 are very capricious and uncertain, except that the 

 finoke increales confiderably and conftantly when 

 the fea is agitated, and the wind blows from that 

 quarter." 



There are ancient extJnguilhed volcanoes, it is true, 

 which are inland ; but this is only one of many proofs 

 that the fea covered thofe countries at fome remote 

 period. Volcanic mountains are of all heights ; fome 

 fo low as four hundred and fifty feet, as that of Tanna j 

 Vefuvius is three thoufand fix hundred feet high, and 

 ^Etna eleven thoufand. They in general form lofty 

 fpires, and the volcano itfelf is internally (haped like 

 an inverted cone, placed on a broader bafis. This 

 cone is called the crate/, or bow), and through it the 



lava 



