eruption. The old central valley which existed before the eruption of
79, and continued to be distinct for long after that time, has been
filled up by a smaller cone, bearing a relatively tiny crater of vent,
the original wall being visible only on the eastern and northern parts
of its circuit, and here only with much diminished height. On the
western face the slope from the base of the mountain to the summit of
the new cone is almost continuous, though the trained eye can trace
the outline of Monte Somma--its position in a kind of bench, which is
traceable on that side of the long slope leading from the summit of
the new cone to the sea. The fact that the lavas of Vesuvius have
broken out on the southwestern side, while the old wall of the cone
has remained unbroken on the eastern versant, has a curious
explanation. The prevailing wind of Naples is from the southwest,
being the strong counter trades which belong in that latitude. In the
old days when the Monte Somma cone was constructed these winds caused
the larger part of the ashes to fall on the leeward side of the cone,
thus forming a thicker and higher wall around that part of the crater.

From the nature of the recent eruptions of Vesuvius it appears likely
that the mountain is about to enter on a second period of inaction.
The pipes leading through the new cone are small, and the mass of this
elevation constitutes a great plug, closing the old crater mouth. To
give vent to a large discharge of steam, the whole of this great mass,
having a depth of nearly two thousand feet, would have to be blown
away. It seems most likely that when the occasion for such a discharge
comes, the vapours of the eruption will seek a vent through some other
of the many volcanic openings which lie to the westward of this great
cone. The history of these lesser volcanoes points to the conclusion
that when the path by way of Vesuvius is obstructed they may give
relief to the steam which is forcing its course to the surface. Two or