ar to keep us off from the
walls if it should prove necessary. But we entered exactly in the
center and were swept forward with a rush.

The ceiling of the tunnel was so low that we could not stand upright on
the raft, and the stream was not more than forty feet wide. That was
anything but promising; if the stream really ran through to the western
slope, its volume of water should have been increasing instead of
diminishing. I said nothing of that to Harry or Desiree.

We had sailed along thus without incident for upward of half an hour,
when my carelessness, or the darkness, nearly brought us to grief.
Suddenly, without warning, there was a violent jar and the raft
rebounded with a force that all but threw us into the water. Coming to
a bend in the stream, the current had dashed us against the other bank.

But, owing to the flexibility of its sides, the raft escaped damage. I
had my oar against the wall instantly, shoving off, and we swung round
and caught the current again round the curve.

But that bend was to the left, as the other had been, which meant that
we were now going in exactly the opposite direction of that in which we
had started! Which, in turn, meant the death of hope; we were merely
winding in and out in a circle and getting nowhere. Harry and Desiree
had apparently not noticed the fact, and I said nothing of it. Time
enough when they should find out for themselves; and besides, there was
still a chance, though a slim one.

Soon the bed of the stream became nearly level, for we barely moved.
The roof of the tunnel was very low--but a scant foot above our heads
as we sat or crouched on the raft. It was necessary to keep a sharp
lookout ahead; a rock projecting from above would have swept us into
the water.

The air, too, was close and foul; our breath became labored and
difficult; and Desiree, half stifled and drowsy, passed into a fitful
and broken sleep, stirring restlessly and panting for air. Harry had
taken the bow and I lay across the stern. Suddenly his voice came,
announcing that we had left the tunnel.

I sat up quickly and looked round. The walls were no longer to be
seen; we had evidently entered a cavern similar to the one in which we
had embarked.

"Shall we lay off?" I asked, stepping across to Harry's side.

He assented, and I took the oar and worked the raft over to the left.
There was but little current and she went well in. In a few minutes we
were in shallow wa