her," I observed, and entered the one on the
left.

Once started, we advanced with a rush. The passage was straight and
narrow, clear of obstruction, and we kept at a steady run.

"They may have an hour's start of us," came Harry's voice at my side.

"Or five minutes," I returned. "We have no way of knowing. But I'm
afraid we're on the wrong trail."

Still as I had said, one chance was as good as another, and we did not
slacken our pace. The passage went straight forward, without a bend.
The roof was low, just allowing us to pass without stooping, and the
walls were rough and rugged.

It was not long before we found that we had taken the wrong chance,
having covered, I think, some two or three miles when a wall loomed up
directly in our path.

"At last, a turn!" panted Harry.

But it was not a turn. It was the end of the passage. We had been
following a blind alley.

Harry let out a string of oaths, and I seconded him. Twenty minutes
wasted, and another twenty to return!

There was nothing else for it. We shouldered our spears and started to
retrace our steps.

"No use running now," I declared. "We can't keep it up forever, and we
may as well save our strength. We'll never catch up with 'em, but we
may find 'em."

Harry, striding ahead two or three paces in front, did not answer.

Finally we reached the cavern from which we had started.

"And now what?" asked Harry in a tone of the most utter dejection.

I pointed to the exit in the middle. "That! We should have taken it
in the first place. On the raft we probably descended altogether
something like five hundred feet from the level where we
started--possibly twice that distance. And this passage which slopes
upward will probably take us back."

"At least, it's as good as the other," Harry agreed; and we entered it.

We had not proceeded far before we found ourselves in difficulties.
The gentle slope became a steep incline. Great rocks loomed up in our
path.

In spots the passage was so narrow that two men could hardly have
walked abreast through it, and its walls were rough and irregular, with
sharp points projecting unexpectedly into our very faces.

Still we went forward and upward, scrambling over, under, round,
between. At one point, when Harry was a few yards in front of me, he
suddenly disappeared from sight as though swallowed by the mountain.

Rushing forward, I saw him scrambling to his feet at the bottom of a
chasm some