180 Jounston-Lavis—The Eruption of Vesuvius in April, 1906. 
of Vesuvius, the Atrio del Cavallo, the Val d’ Inferno, and the Pedimentina. At 
the termination of the eruption at the end of April, the new Vesuvian crater was 
limited by an irregular edge, the western border only approaching horizontality, 
and giving the cone a symmetrical outline (Pl. III.), which, looked on at that 
side, was remarkable for a few days after the eruption. On the west, the maximum 
altitude in the September following was 1223 m. From this point the altitude of 
the edges steadily fall, so that almost opposite, on the same date, the lowest lip 
was a little north of east where the height was only 1103 m. Immediately after the 
eruption in the latter days of April, the lowest point was due north(PI. IV.). Rapid 
disintegration was, however, constantly proceeding in the north-east quadrant. 
Early in May the lowest point was to the north-east. During the summer of 
1906 there was a constant crumbling and slipping of the edges, considerably 
lowering them, and enlarging the diameter of the crater. This occurred mostly in 
the north-east quadrant, and also to the north-west. The parts that had prac- 
tically remained undisturbed when I examined the crater early in November were 
the south-south-west and north lips. This was due to the much larger amount of 
lavas entering into the structure of the cone at these places ; whereas the north- 
east side of the cone seemed almost entirely composed of relatively incoherent 
materials, that were constantly crumbling into the crater. 
During the months subsequent to the eruption, not only did the crater increase 
in the size of its upper opening, but this was continually changing. Still it has 
maintained up to November, 1906, a fairly circular outline. Signor Fiechter’s 
survey in September shows a maximum diameter N. N. E. to 8. S. W. of 720 m., 
and a minimum diameter in W.S. W. and E.S. E. of 620 m. To be quite 
correct, it is ovoid in plan, with the larger extremity to the N.N. E. 
Various estimates have been given of its depth, all of which are extremely 
problematical, as it is impossible to get a view of the crater-apex. Towards the 
end of April, when I was first able to reach the crater-edge, this sloped inward at 
an angle of 34° for a distance of from 10 to 30 m., and then plunged at an extremely 
high angle downwards. In consequence of the extreme danger of approaching 
the friable and unstable edge, and still more of venturing inside, no view was 
obtainable of the bottom even up to November (Pl. XVI.). Professor Loezy in my 
company made some trigonometrical observations early in May, and as far as could 
be reached by the eye, spots on the opposite wall could be fixed at 200 m. in 
depth. Knowing what I do of the slopes attained in Vesuvian craters, 1 have no 
hesitation in saying that at that date it was still quite 400 m. in depth. 
The dying efforts of the eruption at the end of April were represented by 
explosions from the crater-apex, which was situated considerably to the west; and 
this eccentricity persisted right on to November, as can be seen in fig. 6, Pl. VIII, 
and Pl. XVI,, where the issuing puffs of steam rose up the western wall of the 
