Sir 'William Hamilton’s De/cnptlon 
forms; but I have remarked, both in Sicily and at Naples, 
that fuch lava’s as have run into the fea, are either formed into 
regular bafaltes, or have a great tendency towards fuch a form. 
The lava’s of Mount Etna, which ran into the fea near Xacci, 
as appears in my account of them in the Campi Phlegraei, are 
perfed bafaltes ; and a lava that ran into the fea from Mount 
Vefuvius, near Torre del Greco, in 1631, has an evident ten- 
dency to the bafaltic forms. On Mount Vefuvius I never 
found any thing like columns of bafaltes, except the above- 
mentioned at Torre del Greco, and fome fragments of very 
complete ones, which I picked up near the crater, after 
the eruption of 1779, and which had been thrown out of the 
mouth of the volcano. 
The illand of Palmarole, which is about four miles from 
Ponza, is not much more than a mile in circumference, is 
compofed of the fame volcanic matter, and probably was once 
a part of Ponza ; and indeed it appears as if the illand of 
Zannone, which lies at about the fame diftance from the illand 
of Ponza, was once likewife a part of the fame illand of Ponza ; 
for many rocks of lava rife above water in a line between 
the two laft mentioned iflands, and the water is much fhal- 
lower there than in the other parts of the gulph of Terracina. 
The illand of Zannone is larger and much higher than Pal- 
marole, and the half of the illand neareft the Continent is 
compofed of a lime-ftone, exactly fimilar to that of the Apen- 
nines, on the Continent near it ; the other half is compofed of 
lava’s and tuffa’s, refembling in every refpe<ft the foil of the 
other iflands juft defcribed. Neither Palmarole nor Zannone 
are inhabited ; but the latter furnifhes brulhwood in abun- 
dance for the ufe of the inhabitants of Ponza, whole number, 
including the garrifon, amounts to near feventeen hundred. 
The 
