d in the Atria del Cavallo in
1858, when I caused two of the little cones to be brought to the
Observatory; but these also might belong to the fissure along which the
other cones were arranged. The same may be said of the little craters
observed, after they had been exhausted, by Professor Scacchi in 1850.
But the discharging mouths now observed in the Fossa della Vetrana,
which existed for twenty minutes and then disappeared, and which were
not at all in a continuous line, and could not be supposed to correspond
with any fissure beneath, constitute a circumstance which, if not new,
is evident for the first time, and cause the recognition of a power in
the lava itself to form eruptive fumaroles.[2]

The igneous period of the eruption having terminated on the evening of
the 27th, the ashes, lapilli, and projectiles became a little more
abundant, whilst the roaring noises of the craters apparently became
greater. The pine-tree cloud was of a darker colour, and was furrowed by
continual lightning, visible by daylight from the Observatory. Many
writers on the subject of Vesuvius affirm that the flashes which appear
through the smoke cloud were lightning unaccompanied with thunder, but
they studied the phenomena from Naples, or some place more or less
distant from the crater, where the report of the thunder was inaudible,
or could not be distinguished from the bellowing and detonation of the
mountain. The fact is that these flashes were constantly followed by
thunder, after an interval of about seven seconds.[D] When the flash was
very short, a simple noise like the report of a gun was heard, but if it
were long, a protracted sound like that from torn paper ensued.

On the 28th the ashes and lapilli, continuing to fall abundantly,
darkened the air, yet without diminishing the terrible noise; at Resina,
Portici, St. Giorgio a Cremano, Naples, etc., terror was universal.

On the 29th, with a strong wind blowing from the east, scoriae of such a
size fell at the Observatory, that the glass of the windows unprotected
by external blinds was broken. The noise from the crater continued, but
the projectiles rose to a less height, indicating a diminution in the
dynamic power of the eruption. Towards midnight the noise of the craters
was no longer continuous, and recurred with less force and for shorter
intervals. Almost at the same hour a tempest burst over the Campania
with loud thunder and a little rain. The grass, the seeds, the v