September 21, 1883. 



SCIENCE. 



397 



a product of decomposition of this tufa, of submarine 

 origin, wliicli passes occasionally into a plastic argil- 

 lite well suited for tlie making of brick. Casamic- 

 ciola was built upon this disintegrated clayey soil; 

 while Lacco is partly upon trachyte, and partly upon 

 the tufa of Epomeo; and Forio, as also Fonlana, 

 Serrara, etc., are built exclusively upon the above- 

 mentioned tufa. 



To these formations constituting the inland must 

 be added the trachytic lava and scoriae of Arso, the 



are of three classes, — hot mineral springs, stufas or 

 jets of aqueous vapor, and fumaroles. These will be 

 easily seen on the accompanying chart. They could 

 not all be given with so small a scale, but I was 

 obliged to limit myself to the most important. 



The northern coast contains the chief evidences of 

 volcanic activity. Thus, traversifig the coast from 

 east to west, we find the thermal spring-t of Pontano, 

 Fornello, and Fontana, near Iscliia; the stufas and 

 thermal springs of Ctistiglione, near the point of that 



ISLAND OF 18C11IA, EAUTIIQCAKE OF JCLT 28. 18ft.3. 



O Hot mineral springs. 9 8tuf:i8 and jcls of sleam. Q Fumuri>lca. Ali, CD, suppostd B* 



sincf July 28. 



E, F, Laud-slides, happened 



last eruption of which occurred in the year 1301 ; 

 and, filially, the gravelly or clayey deposits, contain- 

 in;; numerous marine fossils of species now living, 

 indicating, that, in an epoch not very remote, a great 

 part of the island was submerged. 



For the description and analyses of the rocks form- 

 ing the soil of Ischia, we must refer to the very 

 important monograph of Fuchs previously cited : 

 what chiefly interests us now is to observe how they 

 are connected with the manifestations of innate 

 activity which are developed in the island. These 



name; the stufas of Cacciuto, on the trachytic lava 

 of Tabor; the rich and abund-ant thermal springs of 

 Gurgitello, near the mountain (il Monte) at Cas.amic- 

 ciola, besides others, less important, in that neighbor- 

 hood; the fumaroles of Monte Cito, to the west of 

 Casaraicciola, which on the day of my visit was act- 

 ively emitting steam and sulphuric acid from different 

 crevices in the tufa of Epomeo; and, finally, trending 

 slightly to the south-west, the thermal springs which 

 are so valuable at the Bagno Cotugno or Paolone of 

 Forio, and which flow from the side of Monte \uovo 



