the
cave fell in, they would not know it was anything but a lake when they
did see it. And as for letting off the water, nobody but the people who
knew about it could possibly do that, unless somebody was fool enough to
take the cold bath I was obliged to take, and even then it would have
been one chance in a hundred that he found the lever, and would know how
to turn it when he did find it. This whole thing is the work of the
ancient South Americans, and I imagine that this stone mound is the tomb
of one of their kings."

At this moment the captain heard something, and turned to listen. It
was a voice--the voice of a boy. It was Ralph calling to him. Instantly
the captain turned and hurried away, and as he went he extinguished his
lantern. When he reached his pail of water he picked it up, and was
very soon joined by Ralph, who was coming to meet him over the bottom
of the lake.

"I have been looking for you everywhere, captain," said he. "What have
you been after? More water? And you took a lantern to find it, eh? And
you have been ever so far into the cave. Why didn't you call me? Let me
have the lantern. I want to go to explore."

But the captain did not give him the lantern, nor did he allow him to go
to explore.

"No, sir," said he. "What we've got to do is to hurry outside and help
get supper. We must wait on ourselves to-night."

When supper was over, that evening, and the little party was sitting out
on the plateau, gazing over the ocean at the sunlit sky, Mrs. Cliff
declared that she wished they could bring their bedding and spread it on
the ground out there, and sleep.

"It is dry enough," she said, "and warm enough, and if there is really
nothing to fear from animals or men, I don't want ever to go inside of
those caves again. I had such horrible fears and ideas when I was
sitting trembling in those dismal vaults, expecting a horde of human
devils to burst in upon us at any moment, that the whole place is
horrible to me. Anyway, if I knew that I had to be killed, I would
rather be killed out here."

The captain smiled. "I don't think we will give up the caves just yet. I,
for one, most certainly want to go in there again." And then he told the
story of the stone mound which he had discovered.

"And you believe," cried Mrs. Cliff, leaning forward, "that it is really
the tomb of an ancient king?"

"If it isn't that, I don't know what it can be," said the captain.

"The grave of a king!" cried Ral