Jounston-Lavis—The Eruption of Vesuvius in April, 1906. 145 
in of the sides of the eruptive cone made great progress, as was indicated by the 
projection of the accessory lapilli, sand, and dust, which, with the increased 
discharge of vapour, rose as a fine pine-shaped cloud, bending to the south-west, 
and later, more westerly, so that in the late evening a greyish-black sand fell over 
Naples. Curiously, the lava that had been flowing from the north-west mouth for 
the last ten months was still doing so, so that after dark a red line was quite 
visible that night. This lava, which was rapidly covered by non-conducting 
fragmentary materials, was still hot, and exhibited blowing fumaroles in November, 
1906, more than six months after the last outpour. It was represented by a strip 
of lighter-coloured dry dust, extending radially from the north-west base of the 
great cone towards the strait between the escarpment of Somma and the Colle 
Umberto. It is evident, therefore, that the lava-top was still above the level of 
these two openings or radial fissures, almost at right angles to each other. ‘The 
new south stream tended to stop towards the evening. 
April 5th.—At about midnight, the same new radial fissure, by extending, 
reached the surface of the cone, at a much lower level, about 800 m. only, at a 
spot marked on the above-mentioned map called Cisterna di Casa Fiorenza, or 
Pedicino. As is usually the case, this outflow was more abundant, coming from 
a lower issue. It crossed the Pedimentina and followed down the slopes, till it 
nearly reached the Casa Bianca. With a fall of nearly 500 m. in a distance of 
2500 m. in thirty hours, it finally came to a standstill on the morning of April 6th. 
Simultaneously the old W.N.W. outflow stopped, and no doubt is now represented 
by a hollow dyke. During the night there was a state of relative quietness. 
April 6th.—At about 8 to 8.30 a.m. a new rent appeared at an altitude of only 
600 m. in the locality known as the Bosco Cognoli, that is nearly a kilometre to 
the east of the second opening. Professor Bassani and Dr. Galdieri* say they 
think this an extension of the same fissure. With this I cannot agree, unless the 
fissure meandered about in a circumferential rather than a radial manner. Care- 
fully going over the locality, not only do I think this was a separate fissure, but 
I am rather inclined to fancy there was even another between the two and three 
mouths from which part of the extensive sheets of lava in this region flowed.t 
Professor Mercallit speaks of new mouths in the plural, but does not indicate 
whether these were radially arranged or side by side. rom these issued a flood 
* “¢ Notizie sull’ attuale Eruzione del Vesuvio.”—Rend. R. Accad. Sc. Fis. e Mat. d. Napoli Fasc. 4° 
1906, p. 3. 
} Far more likely to my mind this row of mouths arranged circumferentially, and not radially, was 
due to a sill-like dyke, such as can be met with at Somma, and to that shown in fig. B, p. 185, sectionized 
in the new crater. 
t ‘‘Grande Eruzione,” etc.—Mem. d. Pontif. Accad. Rom, d. Nuovi Lincei, vol. xxiv., p. 7, 
