' rii E ME D 1 T ElUt ANEAE A ATI. PAL! AJ 
50 
and that even with several precautions, so that the 
At the summit of the great cone the crumbling 
in. of the edges was constantly going on but the 
upper extremity of the lateral rift at the foot of 
the cone of eruption and at the summit of the j 
great Vesuvian cone had nearly ceased t< give j 
forth vapour. Along the line of rent on the i 
mountain side no fumaroles or other sigus of 
activity were visible except quite at the foot where 
those commence of which I have spoken. 
Up till June 26th. there was a struggle to clear 
the upper part of the volcanic chimney of the 
impeding materials which were constantly being 
added to by the slips from the craters edge; but on 
that evening a dull red glow was visible in the 
crater bottom showing that a fairly clear passage 
had been temporarily made So. the continuous 
escape of vapour, and also that the lava was at no 
very great depth from the summit of the volcano. 
This, of course, indicates that the lateral opening 
was insufficient to drain off much of the lava 
which occupies the chimney above the level of the 
lateral outlet. Had such evacuation really taken 
place the eruption would have assumed enormous 
proportions from the actual amount of lava above 
the tap, but more from frothing up of that below 
that level, in consequence of the relief of pressure 
that would then occur. Of course during all these 
days, the ejection of dust often took place giving 
the smoke a peculiar dark grey color. Further 
destruction of the crater edge again occurred so as 
to partly block the outlet, and it was not till our 
next visit that it again cleared. 
On June 30th. I again paid, a visit to the crater- 
in company with my friend Mi A. Green. All the 
summit of the great cone was covered by a thick 
coating of dust and sand upon the surface of 
which were the usual white and yellowish green 
chloride crusts seen in such occasions so rich in 
copper as to plate with that metal the iron nails 
of our boots. The crater had considerably 
enlarged, the edges were in an extremely unstable 
state with often considerable strips marked off by 
cracks parallel to the free edge, so that with a 
slight push with a stick, it was possible to detach 
large masses of the loose fragmentary materials 
which form the sides of the crater in the recent 
cone of eruption. So dangerous were the edges 
that it was but in two places that my experience 
indicated as being. safe to approach and look over, 
accident to Senor Silva Jardina who accidentally 
lost his life is not to be wondered at. 
On looking down some 45 to 50 m. beneath us, 
we could see the glow from a month some 2 or 3 
metres in diameter. The walls of the crater were 
concave so that although overhanging at the top yet 
a plumb line let fall from the edge would strike 
the bottom of the cliff. The crater bottom was 
roughly plane, due to the combination of a talus 
all round, and an attempt at a cone around the 
main vent. It will be thus seen that the crater 
cavity was of the form of a convex sided cylinder 
j or simph barrel-shaped with its upper end some 
45 to 50 m. in its maximum diameter at the top. 
With much difficulty we made our way around 
to the north side of the cone of eruption which 
had now lost its usual loose scoria surface which 
was buried beneath a thick coat of sand and dust 
with a thin saline crust on its surface. The up- 
per limit of the radial rift, which we were pre- 
vented from examining three weeks before on 
account of its giving out so much vapour as to 
constitute the temporary escape aperture of the 
volcano, had now become quiescent so that we 
I could fully examine it. It only gave out a cur- 
rent of hot air, but 1 was able to collect some fine 
masses of crystallized Molysite and Kremersite 
from its edges. Its average breadth was about 
o‘ 50 m. where it traversed compact lava, but had 
disappeared as soon as the looser fragmentary 
materials were reached. The real azimuth of its 
orientation, which we could now determine with 
greater accuracy than when we were walking over 
hot rock and enveloped in hot irritating vapours, 
proves to be, as it radiates away from the axis of 
Vesuvius, about 15° AY. of N. It curves then a 
little to the north, and near the foot of the great 
cone it again assumes nearly the same azimuth as 
at starting, an arrangement which is quite evi- 
dent when the Vesuvian cone is regarded from 
the Punta del Nasoue. From that, the highest 
point of Somma, the lower extremity of the 
rift lies a little to the right or W, and faces that 
part of the Somma ridge which corresponds to the 
extremity of the Yallone Cancherone. 
As one stands on the Punta del Nasone and 
embraces that magnificent view of Vesuvius and 
the Atrio del Cavallo one sees at their feet the 
