e clambered.

This floor of lava, which seems likely to be a more or less permanent
feature, was, three or four years ago, upon a level with the top of the
high ridge, or ledge, whose base you skirt. The main part of the crater
was then a floor of lava vaster even than it now is. Suddenly one day, and
with a crash which persuaded one or two persons at the Volcano House that
the whole planet was flying to pieces, the greater part of this lava floor
sank down, or fell down, a depth of about five hundred feet, to the level
whereon we now walked. The wonderful tale was plain to us as we examined
the details on the spot. It was as though a top-heavy and dried-out
pie-crust had fallen in in the middle, leaving a part of the circumference
bent down, but clinging at the outside to the dish.

[Illustration: LAVA FIELD, HAWAII--FLOW OF 1868.]

After this great crash the lava seems from time to time to have boiled up
from beneath through cracks, and now lies in great rolls upon the surface,
or in the deeper cracks. It is related that later the lake or caldron at
the farther end of the crater boiled over, and sent down streams of lava
which meandered over the black plain; that, continuing to boil over at
intervals, this lake increased the height of its own banks, for the lava
cools very rapidly; and thus was built up a high hill, which we ascended
after crossing the lava plains, in order to look down, in fear and wonder,
upon the awful sight below. What we saw there on the 3d of March, 1873,
was two huge pits, caldrons, or lakes, filled with a red, molten, fiery,
sulphurous, raging, roaring, restless mass of matter, to watch whose
unceasing tumult was one of the most fascinating experiences of my life.

The two lakes were then separated by a narrow and low-lying ledge
or peninsula of lava, which I was told they frequently overflow, and
sometimes entirely melt down. Standing upon the northern bank we could see
both lakes, and we estimated their shortest diameter to be about 500 feet,
and the longest about one-eighth of a mile. Within this pit the surface of
the molten lava was about eighty feet below us. It has been known to sink
down 400 feet; last December it was overflowing the high banks and sending
streams of lava into the great plain by which we approached it; and since
I saw it, it has risen to within a few feet of the top of the bank,
and has forced a way out at one side, where, in September, 1873, it was
flowing out slowl