TRANSACTIONS OF THE SECTIONS. 
593 
themselves into the neighbouring sea, of which the bed, bris¬ 
tled with sharp points and edges, affords only a dangerous an¬ 
chorage. 
In the centre of the island rises the mountain called 11 Bosco, 
with conical sides, truncated summit, and elliptical contour, whose 
longer axis runs N.E. and S.W. It is from this mountain, ac¬ 
cording to the Duke of Buckingham’s observations, that the 
earliest lavas appear to have flowed ; they contain ci^stals or 
felspar, but neither pyroxene nor mica ; are superficially scori¬ 
fied ; tinted with oxide of iron; and split into large rectangular 
prisms. Three fumaroli appear in the ascent toward the sum¬ 
mit of Monte del Bosco, at a place called Favaro, from whence 
constantly issues vapour, at the temperature of 60° R. — 135°F.; 
but no sublimation of any kind was noticed, nor were the pumice 
and scoriae in the bank above the fumaroli at all changed by 
the vapours, which, when condensed, yielded only pure water. 
Aqueous vapour is the only product of another fumarole, which 
opens at a place called II Bagno Secco, on the S.W. side of the 
mountain, from beneath a trachytic current, containing large 
crystals of felspar, thickly studded with microscopic crystals of 
oxide of iron. The current appears to have flowed down di¬ 
rect from the summit of the mountain. This natural vapour- 
bath is much used in rheumatic cases. 
At the S.E. extremity of the island, a conical eminence, called 
Codia di Scaviri Supra, rising with a truncated summit to the 
height of 500 feet above the sea, is especially recommended to 
the attention of geologists. The currents of lava which have 
O O 
flowed from it, and which have all directed their course towards 
the interior, are composed of semivitreous matter, filled with 
small crystals of felspar and laminae of mica,—mixed with pu¬ 
mice, and containing geodes lined with delicate acicular crystals. 
Fumaroli have at different periods opened in several points in 
the interior of this crater ; but none are now in action. Litho- 
marge, hyalite, cacholong, and chalcedony of various colours 
appear in the volcanic products. The chaJcedonic formation is 
found equally at the summit of the cone and at the seaward 
base of the mountains. Chalcedony was observed in similar 
lava currents on the sea-shore on the S.W. by W. point of the 
island, near a spring of boiling water, by the vapour of which it 
appeared in some places to have been decomposed. 
In the western part of the island is a large crater, well de¬ 
fined, elliptical in figure, the larger diameter from N. to S. being 
about ^rd of a mile ; its depth, 300 feet; the interior nearly 
filled with fallen prismatic blocks of lava. Some of the trachytic 
currents which have flowed from this crater contain geodes of 
2 p 
