was steadily
rising up on their legs. It was chilling them, yet they dared not move
much for fear of toppling off the narrow ledge.

Frank did not answer. He was busy trying to think of some way of
escape. Yet, rack his brain as he did, no way out of the cave seemed
possible. Were they doomed to die there?

"Can we climb any higher?" asked Andy, after another period of silence.
"If we could, we might get out of reach of the water, even when the
tide is full. Let's turn on both our lights and look at the wall back
of us."

They had been saving the fast-waning current in the electric lamps
against the time of need. They might have but little further use for
it, so both Andy and his brother pressed the springs that turned on the
gleaming lights.

In the glow they could see the black and gurgling water at their knees.
It was swirling around from the force of the tide outside that was
rushing into the cave. Though the stone thrown down by the man at the
entrance prevented our heroes from escaping, the bowlder did not fit so
tightly but what water could come in.

"Now to see what's back of us," spoke Frank, turning around as well as
he could on the small shelf, and flashing his light on the wall behind
him.

"Say!" suddenly exclaimed Andy, "doesn't it strike you that the water
isn't coming in so fast is it was?"

Frank held his light lower, and looked at the rising tide.

"There doesn't seem to be quite so much force to it," admitted the
elder Racer lad, "but I'm afraid that's only because it's higher, and
because it has to wind in and out of so many passages, and force itself
under and around the rock which that scoundrel threw down. I wish we
had him here!"

"I guess he's far enough off by this time," remarked Andy. "But let's
see if there's a way to get higher up."

Together they examined the wall of the cave against which they had been
leaning. Frank uttered a cry of joy.

"It's mostly dirt, not stone!" he exclaimed. "We can cut steps in it,
and climb up. Maybe we can get high enough so that the tide won't
reach us, or at least we can keep our heads above water until it goes
down. Come on, where's your knife?"

Working by turns, with the only knife available between them, the boys
began frantically cutting niches or steps in the dirt wall.
Fortunately it was packed hard enough so that it did not crumble. They
took turns at the desperate labor, one holding the torch, and the other
wielding t