e most imposing crater in the world is probably that of Kilauea, at a
height of about 4000 feet on the side of Mouna Loa, in the Island of
Hawaii. It has a diameter of 2 miles, and is elliptic in outline, with a
longer axis of about 3, and a circumference of about 7 miles. The
interior is a great lake of lava, the level of which is constantly
changing. Generally, it stands about 800 feet below the edge, and the
depth is about 1400 feet. The heat is intense, and, especially at night,
when the clouds are coloured scarlet by the reflection from the molten
lava, the effect is said to be magnificent. Gradually the lava mounts in
the crater until it either bursts through the side or runs over the
edge, after which the crater remains empty, sometimes for years.

A lava stream flows down the slope of the mountain like a burning river,
at first rapidly, but as it cools, scoriae gradually form, and at length
the molten matter covers itself completely (Fig. 22), both above and at
the sides, with a solid crust, within which, as in a tunnel, it
continues to flow slowly as long as it is supplied from the source, here
and there breaking through the crust which, as continually, re-forms in
front. Thus the terrible, inexorable river of fire slowly descends,
destroying everything in its course.

[Illustration: Fig. 22.--Lava Stream.]

The stream of lava which burst from Mouna Loa in 1885 had a length of 70
miles; that of Skaptar-Jokul in Iceland in 1783 had a length of 50
miles, and a maximum depth of nearly 500 feet. It has been calculated
that the mass of lava equalled that of Mont Blanc.

The stones, ashes, and mud ejected during eruptions are even more
destructive than the rivers of lava. In 1851 Tomboro, a volcano on the
Island of Sumbava, cost more lives than fell in the battle of Waterloo.
The earthquake of Lisbon in 1755 destroyed 60,000 persons. During the
earthquake of Riobamba and the mud eruption of Tunguragua, and again in
that of Krakatoa, it is estimated that the number who perished was
between 30,000 and 40,000. At the earthquake of Antioch in 526 no less
than 200,000 persons are said to have lost their lives.

Perhaps the most destructive eruption of modern times has been that on
Cosequina. For 25 miles it covered the ground with muddy water 16 feet
in depth. The dust and ashes formed a dense cloud, extending over many
miles, some of it being carried 20 degrees to the west. The total mass
ejected has been estimated a