te and we saw the arch directly ahead of us, round a bend
in the stream. The strength of the current carried us toward the off
bank, but we plied our oars desperately and well, and managed to keep
fairly well in to the end of the curve.

We missed the wall of the tunnel--black, grim rock that would have
dashed out our brains--by about ten feet, and were swept forward under
the arch, on our way--so we thought--to the land of sunshine.

Chapter XX.

AN INCA SPEAR.

Here I might most appropriately insert a paragraph on the vanity of
human wishes and endeavor. But events, they say, speak for themselves;
and still, for my own part, I prefer the philosopher to the historian.
Mental digestion is a wearisome task; you are welcome to it.

To the story. As I have said, we missed the wall of the tunnel by a
scant ten feet, and we kept on missing it. Once under the arch, our
raft developed a most stubborn inclination to bump up against the rocky
banks instead of staying properly in the middle of the current, as it
should.

First to one side, then to the other, it swung, while Harry and I kept
it off with our oars, often missing a collision by inches. But at
least the banks were smooth and level, and as long as the stream itself
remained clear of obstruction there was but little real danger.

The current was not nearly so swift as I had expected it would be. In
the semidarkness it was difficult to calculate our rate of speed, but I
judged that we were moving at about six or seven miles an hour.

We had gone perhaps three miles when we came to a sharp bend in the
stream, to the left, almost at a right angle. Harry, at the bow, was
supposed to be on the lookout, but he failed to see it until we were
already caught in its whirl.

Then he gave a cry of alarm, and together we swung the raft to the
left, avoiding the right bank of the curve by less than a foot. Once
safely past, I sent Harry to the stern and took the bow myself, which
brought down upon him a deal of keen banter from Desiree.

There the tunnel widened, and the raft began to glide easily onward,
without any of its sudden dashes to right or left. I rested on my oar,
gazing intently ahead; at the best I could make out the walls a hundred
yards ahead, and but dimly. All was silence, save the gentle swish of
the water against the sides of the raft and the patter of Harry's oar
dipping idly on one side or the other.

Suddenly Desiree's voice came throu