Jounston-Lavis—The Eruption of Vesuvius in April, 1906. 181 
crater. This eccentricity not improbably marks the actual axis of the volcanic 
chimney, and has an important bearing upon the oblique truncation of the crater, 
and the direction of the fragmentary ejecta to the north-east. 
The great paroxysm that commenced late on the evening of April 7th, and 
lasted for twenty-four hours, was characterized by the ejection of a vast amount 
of fragmentary materials, which, as we have seen, collected on the slopes of the 
cone, and spread away to the north-east quadrant of the mountain. ‘The sections 
in Pl. XX. show the chief fall on the road that encircles the north and east of 
Monte-Somma and joins up the towns there at its base, as being limited by the 
Lagno del Purgatorio to Terzigno. ‘The cloud of lapilli and dust spread out, 
extending in a fan-shape over the Campanian Plain, the Apennines, away over the 
Puglian plains, and the Adriatic coast. Its northern limit passed near Campobasso, 
and its southern limits would be represented by a line drawn from Vesuvius to 
Baia. Along the Nola-Bajano railway-line the thickness of fine lapilli reached 
from 8 to 12 cm. 
During the days following the great outburst of fragmentary ejecta, some of 
the dust even crossed the Adriatic; and later the fall of dust, supposed to be of 
Vesuvian origin, is reported from Spain, Paris, Berlin, and other places.* 
The amount of dust spread around the immediate neighbourhood of Vesuvius 
was very considerable, and depended on the caprice of the winds. Naples was 
reduced to a filthy state, though the actual depth of dust was not very great. It 
has been variously estimated at from $ to 5 centimetres. No doubt, different 
parts of the town received more or less, as they were sheltered from the wind that 
was blowing. The amount was, however, sufficient to collect on the roof of the 
market-house of Montoliveto, and cause it to collapse, killing several people 
beneath its ruins. This accident, however, is more attributable to the disgrace- 
fully neglected condition of the building than to the weight it had to support. 
Professor Fergola estimated 153 tons of dust per hectare, which equal 15 kg. per 
square metre. Sabatinit quotes Professor O. Fava as finding on his terrace at the 
Salita Stella in the centre of Naples material that weighed 12 kg. per square 
metre. As this spot is not far from Montoliveto, we have some idea of the slight 
weight necessary to crush in the market roof. Professor O. Fava estimated the 
thickness at 5mm. It must be remembered that Capodimonte is nearer the north- 
easterly quadrant, and therefore probably received more and heavier material. 
Several explanations have been offered of the distribution of the fragmentary 
ejecta, almost exclusively limited to the country in the north-east quadrant from 
* Dr. Lenand, at Neustadt, after heavy rain and wind that blew on the 14th and 15th from the south, 
collected, on his verandah, a yellow powder. Prof. Braum, of Kiel, who examined the specimen, found 
the material very pure, with all the mineral components of the rocks of Vesuvius. 
} Eruzione Versuviana dell’ Aprile, 1906. 2a edizione. Roma, 1907. 
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