eculation, and I was compelled to repudiate the report of
it through the public papers.

The evolutions of carbonic acid (_mofette_), which usually appear at the
end of great Vesuvian eruptions at low-situated spots or hollows, with
very rare exceptions, were observed on this occasion a few days after
the eruption had completely ceased. They appeared in the direction of
Resina. I found the most elevated at Tironi, and the most numerous
between La Favorita and the Bosco Reale di Portici.

The water in wells was on this occasion neither deficient nor scarce
previous to the eruption, but was very acid after the appearance of the
carbonic acid evolutions in those neighbourhoods in which they
abounded. Having stated that the disastrous conflagration of the 26th
April ought, in my opinion, to be regarded as the last phase of a long
period of eruption, which commenced at the beginning of 1871, I consider
it right to discuss the question at somewhat greater length.

Not only from twenty years' personal observations, but from the
attentive study of accounts of previous eruptions, I have found that
when the central crater awakens with small eruptions after a certain
time of previous repose, these almost always have a long duration, and,
after various phases of increase and decrease, terminate in a great
eccentric eruption, that is to say, with the production of an aperture
from which a copious lava stream issues. The eruptions of 1858, 1861,
1868 and 1872, furnish the most recent examples of what I affirm. I
might cite many others of earlier date, but I shall content myself with
recording the greatest conflagration of this century, that of October,
1822.

Before the erection of the Vesuvian Observatory, it was impossible to
obtain a consecutive account of all the phases which the Volcano
presented; but we generally obtained the description of the more
splendid phases of the eruption which arrested the attention of
everyone. Hence, notices of the small phenomena which preceded a great
eruption are frequently wanting. We cannot always ascertain whether the
fumaroles of the craters became active and at what periods, what was
their temperature and what the diverse nature of their emanations, etc.:
whether and when any change in the crater with slight eruptive
manifestations occurred; discharges which sometimes commenced in the
bottom of a crater becoming active, and so are invisible at Naples.

But it may be asked whether the in