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A WEEKLY ILLUSTRATED JOURNAL OF SCIENCE 
"© To the solid ground 
Of Nature trusts the mind which builds for aye.” —WoRDSWORTH 
THURSDAY, NOVEMBER 7, 1872 
THE LAST ERUPTION OF VESUVIUS 
HE scientific results of the late eruption of Vesuvius 
promise to be as important to science as the phe- 
nomena were grand and awe-inspiring to the spectator. 
Not only has Prof. Palmieri published an account of the 
observations from his dangerous standpoint, in Italian and 
German, which will shortly make its appearance here in 
the English translation by Mr. Mallet, but M. Henri 
‘Saussure has also published in the Geneva Bibliothégue 
Universelle an account of an excursion made by him to 
Vesuvius about the middle of last May, shortly after the 
violent eruption of April. This account, given by such a 
competent observer, is so interesting and valuable, from 
all points of view, that it must be regarded as a most 
valuable addition to the literature of one of the most 
popularly-known volcanoes on our planet. For the better 
understanding of the geographical features we may refer 
our readers to the article in NATURE, vol. vi. p. 2. 
Vesuvius, as Prof. Phillips has taught us, was formerly a 
mountain forming a vast circle, whose central part, occupied 
partly by a crater—which, without doubt, has been often 
displaced within the limits of the circumference—was not 
less than three kilometres in diameter, and the projecting 
part of which, occupied at present by the cone, formed then 
only a kind of plateau. The famous eruption of A.D. 79, 
which happened unexpectedly after a very long period of 
repose, entirely changed the form of the mountain. Very 
little lava seems to have been given forth during that 
eruption, which was characterised by tremendous showers 
of stones and ashes, and by rivers of mud. This it was 
that buried Pompeii and Herculaneum, the former being 
covered by fifteen feet, the latter by thirty or forty feet 
of débris, and which, at the same time, appears to have 
formed, by accumulation, the presentmountain of Vesuvius, 
- placed in the centre of the ancient circle, the work having 
been completed by innumerable successive eruptions. 
The Vesuvius group, then, is at present composed of 
No. 158—vo., vit. 
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two distinct mountains—namely, the cone of Vesuvius, 
and the rest of the ancient circle which form, to the north 
and west, a vast amphitheatre, named Za Somma, Between 
the two mountains is an elevated horse-shoe shaped valley, 
the middle part of which bears the name of Aério del Ca- 
vaillo, and the upper extremity, towards the east, that of 
Canale del Inferno. This elevated valley is depressed 
and widened towards the west, where it takes the name of 
Gli Atri, and ends by being lost upon the slopes of the 
Piano which form the buttresses of the two mountains, 
and which emerge by various ravines into the plains 
which stretch from San Sebastiano to Torre del Greco. 
This description would be incomplete if we did not 
mention a knoll or hillock, apparently insignificant, but 
in reality of great importance from the part it plays in 
giving direction tothe lava. This little eminence, named 
Monte de Canteroni, has the form of an elongated saddle- 
back ; it runs east and west, parallel with the western ex- 
tremity of the crest of La Somma, rising towards Vesuvius. 
It divides, as it were, in the direction of its length, the 
outlet of the elevated valley, and as it does not reach the 
foot of the cone of Vesuvius, it forms only an incomplete 
partition which divides the currents of lava flowing out of 
Atrio del Cavallo. At the lower or western extremity of 
this saddleback is situated the Observatory. 
The greatest overflows are always those which make 
their way across the mass of the mountain; for when a 
volcano has acquired a certain height, the weight of the 
liquid column which issues from the vent becomes so 
considerable that the incandescent matter must rush from 
the fissures at a lowerlevel. But, for a certain number of 
years, the centre of eruption of lava seems to have shifted 
towards Atrio del Cavallo, in the elevated valley situated 
between the two mountains, 
In 1855 and the following years, eruptions made their 
way or had been thrown upon this point, and have trans- 
formed the elevated ‘valley into a sort of sea of lava, 
which at present may be about 1,000 metres in breadth, 
The burning torrent makes its way to the west, but on 
leaving the valley of Atrio, it very soon encounters Mente 
de Canteroni, which divides the current into two unequal 
parts, giving to each a different direction, throwing back 
B 
