the throat of the volcano, although the pit was full of whirling
vapours and the heat was so great that the protection of a mask was
necessary, it was possible to see something of what was going on at
the moment of an explosion.

The pipe of the volcano was full of white-hot lava. Even in a day of
sunshine, which was only partly obscured by the vapours which hung
about the opening, the heat of the lava made it very brilliant. This
mass of fluid rock was in continuous motion, swaying violently up and
down the tube. From four to six times a minute, at the moment of its
upswaying, it would burst as by the explosion of a gigantic bubble.
The upper portion of the mass was blown upward in fragments, the
discharge being like that of shot from a fowling piece; the fragments,
varying in size from small, shotlike bits to masses larger than a
man's head, were shot up sometimes to the height of fifteen hundred
feet above the point of ejection. The wind, blowing at the rate of
about forty miles an hour, drove the falling bits of rock to the
leeward, so that there was no considerable danger to be apprehended
from them. Some seconds after the explosion they could be heard
rattling down on the farther slope of the cone. Observations on the
interval between the discharge and the fall of the fragments made it
easy to compute the height to which they were thrown.

At the moment when the lava in the pipe opened for the passage of the
vapour which created the explosion the movement, though performed in
a fraction of a second, was clearly visible. At first the vapour was
colourless; a few score feet up it began to assume a faint, bluish
hue; yet higher, when it was more expanded, the tint changed to that
of steam, which soon became of the ordinary aspect, and gathered in
swift-revolving clouds. The watery nature of the vapour was perfectly