ut of the
blackness surrounding me came the words, in Harry's voice, much lower,
but distinct:

"Paul! Paul, where are you?"

"Thank Heaven!" I breathed; and I answered:

"Here, Harry boy, here."

"But where?"

"I don't know. On a ledge of rock at the edge of the water. Where are
you?"

"Same place. Which side are you on?"

"The right side," I answered with heartfelt emphasis. "That is to say,
the outside. If it weren't for this infernal darkness--Listen! How
far away does my voice sound?"

But the innumerable echoes of the cavern walls made it impossible to
judge of distance by sound. We tried it over and over; sometimes it
seemed that we were only a few feet apart, sometimes a mile or more.

Then Harry spoke in a whisper, and his voice appeared to be directly in
my ear. Never have I seen a night so completely black as that cavern;
we had had several hours, presumably, for our eyes to adjust themselves
to the phenomenon; but when I held my hand but six inches in front of
my face I could not get even the faintest suggestion of its outline.

"This is useless," I declared finally. "We must experiment. Harry!"

"Yes."

"Turn to your left and proceed carefully along the edge. I'll turn to
my right. Go easy, lad; feel your way."

I crawled on my hands and knees, no faster than a snail, feeling every
inch of the ground. The surface was wet and slippery, and in places
sloped at an angle that made me hang on for dear life to keep from
shooting off into space.

Meantime I kept calling to Harry and he to me; but, on account of our
painfully slow progress, it was half an hour or more before we
discovered that the distance between us was being increased instead of
lessened.

He let fly an oath at this, and his tone was dangerous; no wonder if
the lad was half crazed! I steadied him as well as I could with word
of encouragement, and instructed him to turn about and proceed to the
right of his original position. I, also, turned to the left.

Our hope of meeting lay in the probability that the ledge surrounded a
circular body of water and was continuous. At some point, of course,
was the entrance of the stream which had carried us, and at some other
point there was almost certainly an outlet; but we trusted to luck to
avoid these. Our chances were less than one in a thousand; but,
failing that, some other means must be invented.

The simplest way would have been for me to take to the water and