VOL. LXXVI.] PHILOSOPHICAL TRANSACTIONS. 133 



it always boiled up in the same manner, winter and summer ; and that it was 

 of great use to them in bending their planks for ship-building ; and that the 

 fishermen also frequently made use of this natural cauldron to boil their fish. 

 In his description of the island of Ischia mention is made of several spots where, 

 near the shore, he had found, when bathing in the sea, the sand under his feet so 

 hot as to oblige him to retire hastily. Sir W. visited most of the small islands in 

 the group near the city of Naples: as Ischia, Ventotiene, Stefano, Ponza, Palma- 

 roU, 2^nnone, &c. in which the chief curiosities are the stupendous rocks anti 

 other volcanic remains, especially the perfect basaltes which are found in several 

 of them, and which he ascribes to the cooling of lava. To confirm this idea he 

 says, when I was last in England, I inquired of many of the manufacturers of 

 glass, whether it had ever happened, that the glass cooling in their furnaces had 

 taken any distinct forms like prisms or crystallizations ; but I got no satisfactory 

 answer till I applied to the ingenious Mr. Parker, of Fleet-street, who not only 

 informed me, that some years ago, a quantity of his flint glass had been ren - 

 dered unserviceable by taking such a form in cooling ; but also gave me several 

 curious specimens of the glass itself: some of them are in laminae, which may 

 be easily separated ; and others resemble basaltic columns in miniature, having 

 regular faces. I was much pleased with this discovery, proving beyond a doubt 

 the volcanic origin of most basaltes. Many of the rocks of lava of the island 

 of Ponza are, with respect to their configurations, strikingly like the specimens 

 of Mr. Parker's above-mentioned glass, none being very regularly formed basaltes, 

 but all having a tendency towards it. Mr. Parker could not account for the 

 accident that occasioned his glass to take the basaltic forms ; but I have re- 

 marked, both in Sicily and at Naples, that such lavas as have run into the sea, 

 are either formed into regular basaltes, or have a great tendency towards such a 

 form. The lavas of Mount Etna, which ran into the sea near lacci, are perfect 

 basaltes ; and a lava that ran into the sea from Mount Vesuvius, near Torre del 

 Greco, in l631, has an evident tendency to the basaltic forms. 



It is probable, that all these islands and rocks may in time be levelled by the 

 action of the sea. Ponza, in its present state, is the mere skeleton of a volcanic 

 island, as little more than its harder vitrified parts remain, and they seem to be 

 slowly and gradually mouldering away. Other new volcanic islands may likewise 

 be produced in these parts. The gulphs of G^eta and Terracina may, in the 

 course of time, become another Campo Felice ; for, as has been mentioned in 

 one of my former communications on this subject, the rich and fertile plain so 

 called, which extends from the bay of Naples to the Appennines, behind Caserta 

 and Capua, has evidently been entirely formed by a succession of such volcanic 

 eruptions. Vesuvius, the Solfaterra, and the high volcanic ground, on wliich 

 great part of this city is built, were once probably islands ; and we may conceive 



