27th the lava stream, bearing down upon Resina, having covered a few
cultivated fields, stopped; the lava descending from the summit of the
mountain towards the Camaldoli also stopped; and the great lava torrent,
which passed the shoulders of the Observatory through the Fossa della
Vetrana, lowered the level of its surface below those of its two sides,
which appeared like two parallel ramparts above it.

If these streams had continued on the 27th, flowing in the same manner
as they did on the night of the 26th, they would have reached the sea,
bringing destruction to the very walls of Naples.

But before leaving the subject of these lavas I must narrate an
important fact to which I was witness, and which was thrice repeated,
near the banks of the great river of fire that ran close to the
Observatory. At three several points, and at different times, I observed
great balls of black smoke issue from the lava, driven up with continued
violence, as if from a crater; through the smoke I frequently observed
numerous projectiles thrown up into the air, but I could not say whether
with noise or in silence, for the noise of the central crater was
deafening. Each of these little eruptions, which I may call _external
eruptions_, lasted from fifteen to twenty minutes. The first took place
at the most elevated point of the Fossa della Vetrana, on the right bank
of the torrent; the second, under the hill of Apicella, where the lava
divided into the two branches, before described; and the third near to
the Observatory on the left bank of the lava stream. These singular
explosions terminated without leaving little cones or craters, the lava
in its impetuosity carrying every trace away. These eruptions were seen
from Naples, and the Observatory was justly believed to be in danger.
One has been clearly photographed, the one which was the best seen from
Naples, being the nearest and the least darkened by the smoke of the
lava. (Plate 4.) Is this the first time that the phenomenon has been
remarked? I believe that it is at least the first time it has been
authenticated. The authority of Julius Schmidt, quoted by Scrope, has no
weight with me, for I was also a witness of what happened at Vesuvius in
1855; and, although these cones were in the midst of the lava in the
Atria del Cavallo, they originated, according to the opinion of
everyone, from the fissure from which the other and much larger cones
proceeded. The same phenomenon was observe