VESUVIUS. 189 



rent from Pithecusa in the course of a tremendous 

 upheaval, .though Pliny derives the name Prochyta 

 (or "poured forth") from the supposed fact of this 

 island having been poured forth by an eruption from 

 Ischia. Far more probably, Prochyta was formed 

 independently by submarine eruptions, as the volcanic 

 islands near Santorin have been produced in more 

 recent times. 



So fierce were the eruptions from Pithecusa, that 

 several Greek colonies which attempted to settle on 

 this island were compelled to leave it. About 380 

 years before the Christian era, colonists under King 

 Iliero of Syracuse, who had built a fortress on 

 Pithecusa, were driven away by an eruption. Nor 

 were eruptions the sole cause of danger. Poisonous 

 vapors, such as are emitted by volcanic craters after 

 eruption, appear to have exhaled, at times, from exten- 

 sive tracts on Pithecusa, and thus to have rendered 

 the island uninhabitable. 



Still nearer to Vesuvius lay the celebrated Lake 

 Avernus. The name Avernus is said to be a corrup- 

 tion of the Greek word Aornos, signifying " without 

 birds," the poisonous exhalations from the waters of the 

 lake destroying all birds which attempted to fly over 

 its surface. Doubt has been thrown on the destructive 

 properties assigned by the ancients to the vapors 

 ascending from Avernus. The lake is now a healthy 

 and agreeable neighborhood, frequented, says Hum- 



