510 
DRS. T. AXDERSOX AXD J. S. FLETT OX THE ERUPTIOXS OF THE 
start its rush down the slopes at once, but rolled and tumbled, squirted and seethed, 
for quite a perceptible time. Then it began to move with greater and greater speed 
down the hillside. Faster and faster it came till it struck the sea, when its velocity 
Ijegan to diminish, at first slowly, then more and more rapidly. It was like a 
toljop’p’an on a snow slide. It was not the blast of a o;un, it was the rush of an 
avalanche. Gravity did the work and supplied the energy. There was no 
explosion ; had there been any, we would certainly have seen it. The lightnings 
were visible only when the cloud came near. 
Like an avalanche, it drives the air before it and parts it on each side. In the 
statements of Captain Fueevan and Mr. Scott there is the clearest eGdence that the 
Idast struck the vessels and heeled them over before the hot dust began to fall* :— 
“ On a sudden he (Captain Freemax) heard a tremendous noise, as though the entire 
land had parted asunder. Simultaneous with the noise there was a great rush of 
wind, which immediately agitated the sea, and tossed the shipping to and fro. He 
rushed out of the chart-room, and, looking over the town and across the hills, he saw 
a sight he cannot describe. He remembers calling out to Mr. Campbell and saying, 
‘ Look I ’—-and then an avalanche of lava was upon them.” 
But these discharges are not mere avalanches; they are more, for they have 
properties unlike those of avalanches, and by means of which they approach more 
clo.sely to l^lasts. In an ordinary avalanche the gases are more or less accidentally 
involved, and form only a small part of the whole mass. They are compressed by 
the weight of the moving solid mass, and when that pressure is relieved they expand 
again. 
But here their presence is essential; they are an original part of the mass, and 
without them there would be no flow. They are expanding, surging of their own 
inherent energy, and lift the dust and sweep it along, while tlie dust in turn fetters 
them and compels them to keep to the surface of the ground. 
The dust avalanches, or blasts emitted by these two volcanoes during the recent 
eruptions, though essentially similar, show minor points of difference. The fii’st 
discharges have been in both cases those which contained most solid matter. In 
particular, the great avalanche which blocked the Wallibu and Babaka Valleys in 
St, Vincent on May 7th must have consisted to so great an extent of red-hot sand 
that it may best be pictured as rivers of dust and stones flowing down from the 
crater. But before the main avalanche, and on each side of it, a great black cloud 
swept over the country ; it consisted mostly of gases, though laden with hot dust, 
and resembled a hot blast far more than an avalanche. 
On Montague Pelee also the first ei'uption probably sent out more solid matter 
than an}^ of the others, and was consequently more like an avalanche than those 
which succeeded it. 
* Blue Book : “ Correspondence relating to the Volcanic Eruptions in St. Vincent and Martinique in 
May, 1902,” p. 45. 
