374 Sir William Hamilton’s Defcrlption 
brick or rather tile buildings, as may be feen in the drawing 
(fee Tab. XI fig. i.) taken on the fpot. One rock, as appears 
in the drawing (fee Tab* XII. fig. 4.) is compofed of large 
fpherical bafaltes ; and In many parts of the ifland I found the 
lava had inclined to take the like fpherical form, though on a 
qauch fmalier fcale, fome of the firft mentioned round bafaltes 
being near two feet in diameter. All thefe rocks have certainly 
been detached by the adlion of the fea from the ifland, which 
is intirely compofed of volcanic matter, lava’s, and tuffa’s, of 
various qualities and tints, green, yellow, black, and white. 
Some of the tuffa’s, as well as the lava’s, are of a texture 
more compact than others ; and in fome parts of the ifland 
great trails feem to have undergone the fame operation as is 
mentioned in one of my former communications to be in full 
force at a fpot called the Pifciarelli, on the outfide of the Sol- 
faterra, near Puzzole, and where a hot fulphureous vitriolic 
acid vapour converts all which it penetrates, whether lava’s, 
tuffa’s, volcanic afhes, or pumice ftones, into a pure clay, 
moftly white, or with a light tint of red, blue, green, or 
yellow. The appearance of a trail of volcanic country, which 
has undergone this operation, is well expreffed in the view of 
the infide of the harbour of Ponza (Tab. XI. fig. 2.). But I 
was fo ftruck with the beautiful and uncommon appearance of 
one of thefe high volcanic grounds converted to a pure light- 
coloured clay (Tab. XII. fig. 1 ) in contrail with a neighbour- 
ing dark bafaltic rock, that I caufed the drawing, which 
accompanies this letter (fee Tab. XII.) to be made on the fpot. 
You, Sir, who have feen fuch a variety of countries, will Hill 
think this view lingular and beautiful. I can allure you, it is 
very exa£l, except the rock of round bafaltes (fig. 4.) which, 
in nature, is at a dillance from this fpot, and only placed here 
to 
