28 THE POPULAR SCIENCE MONTHLY. 



Epomeo became tranquil after Vesuvius resumed its eruptions ; 

 and for long series of years the island of Ischia had no other outlets 

 for the escape of the gases generated in its depths than its thirty or 

 forty thermal springs, which have contributed, together with the pure 

 air and the beauty of the situation, to increase every year the crowd 

 of visitors. 



Every indication tends to support the belief that Ischia, a rival to 

 Vesuvius in the height of its volcano, is an ancient cone composed of 

 the matter thrown up by extremely violent submarine eruptions which 

 took place before the present epoch. As the mountain increased in 

 height through the successive accumulations of the trachytic projec- 

 tions from the central crater, the weaker parts of its flanks, yielding 

 to the height of the liquid column in the vent, were cleft in every di- 

 rection ; the injection of lavas into all the fissures thus formed giving 

 rise to the flows we have just mentioned, melted in with and consoli- 

 dated the structure, which is thus the result of a protracted alternation 

 of projected debris and flows of compact lavas. "We can in this man- 

 ner account for the disposition of the grand ravines which, descending 

 from Epomeo, plow the flanks of the mountain to a great depth. 



Fia. 2. — Coast or Ischia, been tboh the West, Fonrx Cohacchia. 



The island has, therefore, been progressively raised above the 

 waters, and has grown laterally during the historic period, as is testi- 

 fied by the flows of lava still visible on the Arso and on Monte Tabor, 

 which are prolonged to the sea, and by the numerous secondary cones 

 scattered over its plateaus. It definitely acquired its present relief 

 toward the beginning of this century. Since that time, Mount Epomeo 

 has not given any other signs of its volcanic character than those which 

 the scientific observer might deduce from the analogy of its form with 

 the forms of other volcanoes. Its arid, slashed summit, looking up to 

 the sky, served as the end of the promenade for the numerous visitors 

 who every summer frequented the thermal stations at Casamicciola,' 

 Castiglione, and San Lorenzo. Its springs, highly endowed with ther- 

 mal qualities, and the exceptional fertility of its volcanic soil, on which 

 small shrubs became arborescent, would have sufficed to give to the 

 fortunate, healthful, and gay island great wealth, had not its earth- 

 quakes always caused apprehensions. 



These disturbances of the earth, the relations of which with the 

 volcanic structure are most evident have repeatedly brought frightful 

 disasters upon Ischia. Hardly a trace of the splendid Roman struc- 

 tures once built upon it now remains ; without mentioning specifically 



