came up so fast it scared me, and I
slipped right into it."

"We saw you," said Bud, sitting down on the rock to get his wind, so he
might be at his best in helping Nort on the return journey.

"It was--awful!" spoke Dick simply, and then he made no further
reference to his mental agony.

"Well, are you ready to go back?" asked Bud, after a pause, in which
interim they had called to those across the pool that the lost lad was
all right.

"I'm ready, yes," was Nort's answer. "But I'd sort of like to see what
this hard lever-like object is."

"Oh, yes," spoke Dick. "You said you had something hard to hold to.
Let's have a look--if we only had a light," he added, for it was quite
dark on the great rock in the midst of the black pool. The light of
the lanterns did not brightly penetrate that far.

"I have some matches, in a waterproof case, if I didn't lose it out of
my pocket," said Nort, feeling in his soaking trousers. "Here they
are," he went on a moment later. And as his hands were drier than
those of Bud or Dick, Nort opened the box and managed, after one or two
failures, to strike a light.

As the little taper flared up the three boys on the rock saw, standing
upright about in the centre of the large boulder a great handle, or
lever, of copper. The metal gleamed dully red in the flickering light.

"What is it?" asked Bud, as Nort struck another light.

"I don't know," was the answer from Nort. "I discovered it when I was
crawling about and feeling around. I thought, if worst came to worst,
I could hold to this if the waters rose."

"They seem to be as high as they're going to get," said Bud. "But this
sure is queer! Hold your match closer, Nort."

Another of the tapers was lighted, and across the pool came the voice
of Snake Purdee, asking what was going on.

"There's some sort of a handle, or lever, here," answered Bud, as he
examined it more closely. "It moves, too," he added as he laid his
hands on it and pulled it toward him.

"Look out!" cautioned Dick, but it was too late.

Bud had pulled the copper lever toward him, and, in spite of its size
and weight, it moved easily in what appeared to be a slot in the rock.
It clicked slightly, as though connected with hidden mechanism.

Then, with a suddenness that was startling, a low but ever-increasing
roar seemed to fill the cavern in which was the black pool. The roar
grew louder and louder, and the very rock beneath their feet seemed to