ON THE VOLCANIC PHENOMENA OF VESUVIUS. 399 
Tn the early part of January the activity was rarely above the 1st de- 
gree ; the crater edge was tumbling in, so that on the 9th it was observable 
that slight truncation of the eruptive cone was visible. The low lava 
level, and consequently the 1st degree of activity as well as the crumbling 
in of the inner slopes of eruptive cone, I am inclined to attribute to 
an extension of the S.H. dyke, as the fissures marked i; in fig. 1, 
lying above it, were increased in size and number about this time. 
For the next four weeks the volcano was very quiet, showing usually 
abont the Ist degree of activity. On February 9 the new small crater 
cavity of a month before was yet little altered, the walls still crumbling 
in and the eruptive vent situated under the eastern edge in the direction 
of the rift in the side of the great cone from which the last lava had 
issued, ‘Till the end of the month little could be seen from Naples. 
During March more reflection at the crater was visible from Naples, 
which indicated the repair of the eruptive cone, and the rise of lava 
level within the chimney. Unfortunately during February, March, and 
April several attacks of illness and the resulting weakness prevented me 
from making observations with that regularity that I should have wished. 
During May a further marked increase of activity was visible, so that 
the eruptive cone grew rapidly in height. On the 11th, when I visited 
the crater, the eruptive cone had already considerably surpassed the 
height of the crater edge of May 1889. The general arrangement of the 
eruptive apparatus and summit of the great cone can be seen from the 
semi-diagrammatic plan, fig. 1. 
As the cone of eruption rose in height, so also did the level of the 
Java, so that cakes of lava were ejected very abundantly. The activity 
therefore often equalled the 2nd to 3rd degree. 
The month of June showed little or no variation in the state of the 
mountain. During this month I quitted Naples on a trip to Iceland, and 
my friend and pupil Mr. L. Sambon kindly undertook to continue the 
observations on Vesuvius, and therefore for the following information I 
am gratefully indebted to him, knowing as I do his precise method of 
observation. 
The quiet state of the voleano continued through July till August 5, 
the activity rarely rising above the lst degree, but on that and the 6th 
and 7th of the month the 8rd and 4th degrees prevailed. On August 
7, at noon, following small local earthquakes and boati, the summit of 
the mountain was split open along the 8.H. fissures in the crater-plain, 
which now was prolonged right through the side of the eruptive cone. 
Lava issued from this new rift at the foot of the cone of eruption; the 
first gush, however, soon stopped and cooled, but later in the same day 
the lava burst out afresh about 50 m. lower down (and therefore on the 
slopes of the great cone) and continued to flow. On the 9th a distinct 
reflection was visible on Vesuvius from the flowing lava. My friend 
visited the scene of the outburst on July 12, and found the cone of 
eruption with its edges undermined so as to be overhanging, due no 
doubt to the sousing about of the lava at a lower level in the chimney. 
The ejections were, as usually the case after a lateral outburst, what is 
commonly called ashy, that is, no longer composed of soft hot lava 
cakes, but the broken-up sides of the chimney and eruptive cone projectes: 
as dust, sand, lapilli, and breccia by the escaping vapour which whiffed 
out continually. 
The cone of eruption lost little in height, though the undermining 
