ON THE YOLCANIC PHENOMENA OF VESUVIUS. 397 
Report of the Committee, consisting of Mr. H. Baverman, Mr. F. 
W. Ruprer, Mr. J. J. H. Teatt, and Dr. H. J. Jounston-Lavis, 
appointed for the investigation of the Volcanic Phenomena of 
Vesuvius and its neighbourhood. (Drawn up by Dr. H. J. 
Jounston-Lavis, F.G.S., Secretary.) 
State of Vesuvius.—The eruptive vent to the N.N.W. of the crater of 
May 1889 soon moved slightly eastwards, where, with slight variations, it 
remained. During September the activity rarely rose to the 2nd degree, 
and presented no phenomena of importance. In October much the same 
state was maintained as far as could be seen from Naples. The weather 
in the early part of the month was exceedingly cloudy, and although the 
Geologists’ Association’s excursion to the crater was one of the first 
objects on the programme for their trip to the volcanic regions of 
Southern Italy, it was not till the 12th that a suitable day was forth- 
coming. Neither was that at first very favourable for the purpose, there 
being much cloud and wind. Fortunately, at the moment of our arrival 
at the crater the clouds cleared off, and the party were able to examine 
the volcano to perfection. I have visited the crater over sixty times, and 
only on one other occasion was the eruptive mouth more susceptible of a 
close approach and examination. By making the circuit of the crater 
plain on the 8. side (fig. 1) the vent was approached from the E. until 
the party reached a spot about 10 or 12 m. from the vents, to do which 
they had to traverse the small mound and the remnants of another low 
crater ring covered up between October and the date when fig. 1 repre- 
sented the mountain summit. The crater rim f of the eruptive cone, as 
shown in the figure, was then very much lower, and enclosed a shallow 
basin-shaped crater, so that when standing at m we were not more than 
5 m. above the double vent, which was about 10 to 12 m. distant. The 
two vents were situated on a line N. and §.; the largest about 3 m., the 
smaller about 14 m. in diameter. Both were ejecting blasts of dry vapour, 
with fragments of pasty lava, which were fortunately very small, and 
carried to the W. by the wind. These vents strongly reminded one of 
two enormous Bessemer converters being rather roughly worked. So 
easy was the approach that I was able to go and return several times to 
conduct sections of our party to the inner crater edge, and amongst 
these were various ladies and a veteran geologist of fourscore years. 
Some 50 or 60 m. down the eastern slope of the great cone lava 
was oozing forth in a small stream, with about a sectional area of 
half a square metre, and at the rate of one metre in 20 seconds, which 
would give an outflow of about 2,160 cub. m. in 24 hours, or, subtracting 
something for viscous drag and retardation along the sides and bottom, 
let us call it 2,000 cub. m. The daily outflow rarely amounts to a smaller 
quantity than this, so that if we calculate this as the daily average from 
May 5 to December 25, the respective dates when the outflow commenced 
and finished—in all 234 days—we have the considerable quantity of 
468,000 cub. m., or nearly half a million cubic metres of lava represented 
by a cube whose sides are 78 m., or a steep side cone over 100 m. high. 
The major part guttered over and remained attached to the slopes of the 
cone. ‘The point of issue was about one quarter way down the great 
