VESUVIUS. 173 



among the number of nearly extinguished craters. At 

 a later epoch, ^Elian asserted that the mountain itself 

 was sinking, so that seamen lost sight of the summit at 

 a less distance across the seas than of old. Yet within 

 the last two hundred years there have been eruptions 

 from Etna rivalling, if not surpassing, in intensity the 

 convulsions recorded by ancient historians. 



We shall not here attempt to show that Vesuvius 

 and Etna belong to the same volcanic system, though 

 there is reason not only for supposing this to be the 

 case, but for the belief that all the subterranean regions 

 whose effects have been shown from time to time over 

 the district extending from the Canaries and Azores, 

 across the whole of the Mediterranean, and into Syria 

 itself, belong to but one great centre of internal action. 

 But it is quite certain that Ischia and Vesuvius are 

 outlets from a single source. 



While Vesuvius was dormant, resigning for awhile 

 its pretensions to be the principal vent of the great 

 Neapolitan volcanic system, Ischia, we have seen, was 

 rent by frequent convulsions. But the time was ap- 

 proaching when Vesuvius was to resume its natural 

 functions, and with all the more energy that they had 

 been for awhile suspended. 



In the year 63 (after Christ) there occurred a 

 violent convulsion of the earth around Vesuvius, 

 during which much injury was done to neighbouring 

 cities, and many lives were lost. From this period 

 shocks of earthquake were felt from time to time for 

 sixteen years. These grew gradually more and more 



