198 
ON THE SOLFATARA AND FUMAROLES IN THE 
NEIGHBOURHOOD OF NAPLES. 
BY PROFESSOR D. T. ANSTED, M.A., F.RS. 
A BOUT a mile and a half west of tlie ridge of volcanic 
tufa., pierced by the celebrated gr.otto of Posilipo, a 
ridge which is certainly part of a very old and much 
broken volcanic crater of large dimensions, we come to the 
small and picturesque Lake of Agnano, familiar enough to 
tourists and all visitors to the environs of Naples as the 
place where the Grotto del Cane is exhibited. Rather more 
than a mile further west is the Solfatara, almost equally 
familiar to the Naples sight-seer. Less than another mile, 
in the same direction, is the site of the Temple of Jupiter 
Serapis, dear to geologists, and where may still be seen, 
in use, old Roman baths of hot mineral waters. Another 
two miles beyond we come to the cone of Monte Nuovo ; 
and half a mile further the classical Avernus, over which, 
in former times, no bird could safely fly. On the coast 
adjacent are the hot mineral springs of Baia and the hot 
vapour-baths of Nero. Just at the extremity of the ridge 
forming the headland of Posilipo there rises the small but 
picturesque island of Nisita., a simple crater long since ex- 
tinct; and the coast abounds with hot springs and fissures 
or crevices, whence issue hot air and steam, quite to the 
extremity of Ischia. 
Along this extended and familiar line of country, whose 
classical interest is so great as frequently to absorb every 
other feeling, there is everywhere abundant proof of some 
powerful forces still at work, unable to shake and split the 
earth, but quite sufficient to produce marked results by 
means of slow chemical action, of the same general nature 
as that which is recognized after systematic eruptions from 
or near the principal craters. This district, and the country 
to the north, is that of the celebrated “ Campi Phlegrsei,” 
or Phlegrsean fields. Above ground, the district terminates 
to the west in the island of Ischia, celebrated for its hot 
mineral springs, but it is not unlikely that subterranean 
