178 Jounston-Lavis—The Eruption of Vesuvius in April, 1906. 
tend to raise it. In addition to these influences, the hot air and gases escaping 
from the mountain side all tended to prevent materials adhering to it. I found 
at the end of April, 200° C. in the material of the south-west lip of the crater, 
that part in fact the most exposed to rapid loss of heat. 
Naturally the greatest thickness of these breccias is in the quadrant between 
the north and east of the mountain, where in a few hours ravines have been 
cut out that impress one as having required centuries to be eroded. In the 
photograph (PI. VI.) the lower terminations of two of these are shown. The 
maximum depth must exceed 30 m.; and if the new map (Pl. XXIII.) is compared 
with the old in some places, the addition must attain 50 m., where the much more 
acute angle between the base of the old cone and the Atrio existed. There were 
several spots where I was able to measure the height of the sides at over 20 m., 
and where there must have been quite another 10 m. below the barranco floor at 
the same spot. 
On the north-west and west (PI. III.), and also on the north-east and east sides 
of the mountain, there are still thick mantles of ejecta covering the cone; but on 
the north and south sides much of the loose materials have slipped down. Even on 
the south-west side, near the site of the old funicular railway, most of the materials 
have slid down. It was due to this that the major part of the railway was wiped, 
as it were, from off the mountain-side. 
The avalanche at this part was terrific in its destructive effects. It stripped 
off the upper two-thirds of the railway, cleared away the great water reservoirs, 
the restaurant, the station, boiler and machine-house, and stables, not leaving a 
trace of any of these. The last zigzag part of the electric tram-line was swept 
away down the mountain; the rails, hanging together by the fish-plates, formed 
long strips of twisted iron, stretching radially to the mountain, instead of in their 
original position tangentially to it. The remains of the cable, rolled up like a 
tangled ball of string, lay about a kilometre away on the Pedimentina; the two 
boilers, also several hundreds of metres below the site of the old boiler-house 
(figs. 4 and 5, Pl. VIII.). Scattered about were twisted and contorted rails, 
trolley-poles, wires, and other debris, projecting here and there from the chaotic 
jumble of rubble. 
All the higher bocche that emitted the lavas are entirely covered by great 
avalanches of debris, some of which had power enough almost to reach in places 
the edge of the Pedimentina. The extreme rending of the cone by the different 
radial dykes on the south side brought about a great deal of slipping of the older 
materials on that aspect of the cone, and there one may see some irregular couloirs, 
differing from the others in being branched. The quaquaversal structure of the 
cone has favoured the peeling off and slipping of a very considerable thickness. 
The process continued for months after the eruption, and was still in progress 
