.

I laid a hand on his arm.

"Not yet. Others may be waiting for them in the passage. Wait till
they return."

In a few minutes they reappeared in the light of the flaming urns. I
waited till they had advanced half-way to the water's edge, some thirty
feet away. Then I whispered to Harry: "You for the left, me for the
right," and released my hold on his arm, and the next instant we were
bounding furiously across the ledge.

Taken by surprise, the Incas offered no resistance whatever. The
momentum of our assault carried them to the ground; their heads struck
the hard granite with fearful force and they lay stunned.

Harry, kneeling over them, looked up at me with a question in his eyes.

"The lake," said I, for it was no time for squeamishness.

Our friend the king thought us dead, and we wanted no witnesses that we
had returned to life. We laid hold of the unconscious bodies, dragged
them to the edge of the lake, and pushed them in. The shock of the
cold water brought one of them to life, and he started to swim, and
we--well, we did what had to be done.

We had our spears. I examined them curiously.

The head appeared to be of copper and the shaft was a long, thin rod of
the same material. But when I tried it against a stone and saw its
hardness I found that it was much less soft, and consequently more
effective, than copper would have been. That those underground savages
had succeeded in combining metals was incredible, but there was the
evidence; and, besides, it may have been a trick of nature herself.

The point was some six inches long and very sharp. It was set on the
shaft in a wedge, and bound with thin, tough strips of hide.
Altogether, a weapon not to be laughed at.

We carried the spears, the raft, and the oars behind a large boulder to
the left of the ledge with considerable difficulty. The two latter not
because we expected them to be of any service, but in order not to
leave any trace of our presence, for if any searchers came and found
nothing they could know nothing.

We expected them to arrive at any moment, and we waited for hours. We
had about given up watching from our vantage point behind the boulder
when two Incas appeared at the mouth of the passage. But they brought
only oil to fill the urns, and after performing this duty departed,
without a glance at the lake or any exhibition of surprise at the
absence of their fellows.

Every now and then there was a commotion i