of five centuries, as if it had cooled down yesterday. A few
scantlings of wild thyme, and two or three other dwarfish plants, alone
appear in the interstices of the scoriae, while the Vesuvian lava of 1767
is already covered with a luxuriant vegetation. Pontanus, whose
country-house was burnt and overwhelmed, describes the dreadful scene as
having lasted two months.[500] Many houses were swallowed up, and a
partial emigration of the inhabitants followed. This eruption produced
no cone, but only a slight depression, hardly deserving the name of a
crater, where heaps of black and red scoriae lie scattered around. Until
this eruption, Ischia is generally believed to have enjoyed an interval
of rest for about seventeen centuries; but Julius Obsequens,[501] who
flourished A. D. 214, refers to some volcanic convulsions in the year
662 after the building of Rome (91 B. C.) As Pliny, who lived a century
before Obsequens, does not enumerate this among other volcanic
eruptions, the statement of the latter author is supposed to have been
erroneous; but it would be more consistent, for reasons before stated,
to disregard the silence of Pliny, and to conclude, that some kind of
subterranean commotion, probably of no great violence, happened at the
period alluded to.

_History of Vesuvius after_ 1138.--To return to Vesuvius:--the next
eruption occurred in 1306; between which era and 1631 there was only one
other (in 1500), and that a slight one. It has been remarked, that
throughout this period Etna was in a state of such unusual activity, as
to lend countenance to the idea that the great Sicilian volcano may
sometimes serve as a channel of discharge to elastic fluids and lava
that would otherwise rise to the vents in Campania.

_Formation of Monte Nuovo_, 1538.--The great pause was also marked by a
memorable event in the Phlegraean Fields--the sudden formation of a new
mountain in 1538, of which we have received authentic accounts from
contemporary writers.

[Illustration: Fig. 42.

Monte Nuovo, formed in the Bay of Baiae, Sept. 29th, 1538.

1. Cone of Monte Nuovo.
2. Brim of crater of ditto.
3. Thermal spring, called Baths of Nero, or Stufe di Tritoli.

]

The height of this mountain, called ever since Monte Nuovo, has been
determined by the Italian mineralogist Pini, to be 440 English feet
above the level of the bay; its base is about eight thousand feet, or
more than a mile and a half in circumference. Acc