the glistening crisp bridge some yards
wide where he started, but as he went on, it grew narrower and narrower,
while the farther side of the gulf which had appeared so short a
distance away when he was high up and looking down, now looked far-off
to his swimming eyes.

The giddy feeling increased as he neared the middle, and then he stopped
short, and dropped upon his knees. For suddenly, with the profound gulf
on either side, there came a loud resonant crack, and a piece of the
lava split away and fell.

Lane knew that he ought to have rushed onward now, literally bounding
across, but the horror of his position, as he felt that the frail bridge
was giving way beneath his feet unnerved him, and he could not stir, but
knelt there seeing the rock before him seem to rise and fall while he
listened for what seemed as if it would never come, the echoing roar
when the mass which had fallen struck below. Even if the lava on which
he knelt had followed, he would not have stirred, only knelt there
gazing at the remainder of the bridge in front as it undulated, rising
and falling slowly, while the fume which arose from the chasm added to
the giddy swimming in his head.

At last! A deafening, reverberating roar, and Lane clutched at a piece
of the rock, and closed his eyes, feeling that all was over, but opened
them again directly to see that the bridge before him was not
undulating, and he knew that it was an optical illusion due to the heat
and the giddiness from which he was suffering.

Nerving himself once more, he rose cautiously, and holding his gun
across him with both hands, as if it were a balancing pole, he stepped
cautiously forward a dozen steps or so, feeling the brittle, glassy rock
quiver beneath his weight; and then with the lower side, and safety, not
a dozen yards away, he was unable to contain himself, and springing
forward he nearly ran, ending by making one great bound and landing
safely as the whole mass over which he had passed gave one crashing
sound and fell.

Oliver Lane dropped on his knees a few yards from the edge he had left
behind, and gazed wildly at the broad opening till a terrific roar arose
from the depths below.

For some moments his senses must have left him, and he was hardly
himself when he rose to his feet and reeled and staggered downward. But
this passed away; his consciousness fully returned, and no longer acting
upon the blind instinct which urged him to escape, he began to