ee 
Sie eee 
Natural History of Volcanos and Earthquakes. 271 
flames, was only the ferilli in the smoke.* Lightning, caused by 
the electricity excited by the rapid evaporation, was observed 
there, as it is during the eruptions of Vesuvius and other igneous 
mountains. At the end of December, 1830, this island, which 
was 2100 feet in circumference, and the highest point of which 
tose 210 feet above the sea, shared the fate of Sabrina, and dis- 
appeared. E'rom the bottom of the sea it had risen between 700 
and 900 feet ; and from what depth below, may be conjectured 
from the calculations previously given. : 
Thus, then, the rising of islands out of the sea, is a well au- 
thenticated fact, and if we should for a moment be left in doubt 
concerning the cause of this phenomenon, by the appearance of 
steam in the presence of the sea-water, yet the evolution of 
aqueous vapor from volcanic islands, enclosed on all sides by 
solid rock, seems to dispel such doubts. : 
Examples of elevations on land in historical times are much 
More rare. Of these we are only acquainted with the elevation 
of Monte Nuovo, near Puzzuoli, in 1528, which rose 400 feet in 
about three days; that of Monte Rosso, near Catania, in Sicily, 
n 1669, which rose to a height of 820 feet in about four weeks, 
and that of Jorullo, which rose to a height of 1480 feet above 
the plain, in one day, on the 29th September, 1759. 
These are also formed, like the volcanic islands, in two differ- 
‘it ways. The Monte Nuovo was formed by the accumulation 
of the loose masses ejected from the volcano, whilst mountains 
* basalt, trachyte, phonolite, &c. which are so abundantly scat- 
tered Over the surface of the earth, have been formed by the up- 
‘alsing of solid rocks.t : 
esuvius, or rather its cone, seems also to present an example 
of an elevation in the historic area. Its formation perhaps does 
Not go farther back than the period of the famous eruption of 79 
* &t the Christian era, in which Herculanewm and Pompeii were 
destroyed ; for ancient writers never speak of the mountain as 
#* WP: : i ; 
: Without exactly wishing to generalize, this circumstance is yet sufficient to 
ender us distrustful in judging of descriptions of similar phenomena in which 
a 
' °s are so often mentioned. F q 
ae Humboldt, Nouv. Espagne. v. ii. p. 290. See Burkart loco cit. vol. i, p. 
z The late investigations of Buch, Dufrenoy, and Elie Beaumont, show that the 
of | € Nuovo is a crater of elevation, therefore not entirely or chiefly composed 
O8e masses of ejected rocks.—Ed, New. Phil. Journ. 
