Notice of Active and Extinct Volcano s. 26 9 



The Grotto del Cane or Dog's grotto is mentioned by every 

 traveller ; it is in the same situation as in the days of Pliny. 

 It is on the borders of the lake Aquano, an ancient crater ; it 

 has a stratum of carbonic acid gas on the floor which flows 

 over the lip of the cavern like water, and suffocates a dog 

 whose nose is immersed in this deadly atmosphere, while a 

 man walks in security. Phosphorus would burn at two feet 

 from the floor but the heat of the steel spark was not sufficient 

 to explode gunpowder in a pistol pan. 



The Lake of Avernus is supposed to have been the cra- 

 ter of a volcano ; birds now resort to it with impunity. 



The Monte Barbara, the most lofty ancient extinct volcano 

 near Naples, has a solitary farm house in its now verdant cra- 

 ter, and the crater of Astroni, nearly a mile in diameter, is so 

 perfect an inclosure that the king of Naples uses it " as a pre- 

 serve for his wild boar and other animals destined for the 

 chase. Its walls are a congeries of scoriae, pumice and other 

 ejected materials. 1 ' 



The region around Naples and Vesuvius still retains its 

 ancient name — The Phlegrean Fields, and the appearances 

 which it now presents, justify the belief that it was anciently a 

 region of extensive and furious volcanic action. 



"Even if we limit the craters that existed in the Phlegrean 

 fields to those of which present appearances leave no doubt, 

 their number will be sufficient to give us a frightful picture of 

 the condition of the country at an early period of history, and 

 serve to account for the fables of the Poets, who imagined the 

 entrance to the Infernal Shades to lie among these recesses. 



" It was not then, as at present, a single mountain which sent 

 forth flames and melted matters at certain intervals, and secured 

 a comparative immunity to the rest of the district ; but there was 

 a constant exhalation of noxious vapours from a variety of orifi- 

 ces, attended with earthquakes, and other phenomena, which 

 bespeak the operation of volcanic agency over a widely exten- 

 ded surface. 



" If then the early settlers, in Sicily were so alarmed at the 

 eruptions of Mount Etna, as to fly to some other part of the isl- 

 and, and if in modern times, among the Canaries, the inhabi- 

 tants of Lanzerote were compelled to migrate on account of the 

 ravages made upon their possessions during a succession of years 

 by subterranean fire, it is not unnatural that the picture which 

 Homer had received of the Phlegrean fields should have been s© 



