far in beyond them, for the sound went muttering by,
and seemed to die away as if far down a long passage.

"Not yet, but I think I can hear 'em," replied Ramsden.

"You can hear a self-satisfied fool talking," said the boatswain,
ill-humouredly.

"So can Mr Jones," muttered the man. "Hear you. That's what I can
hear."

"What are you muttering about?"

"I think I can hear 'em, sir. Now then, you two, give up. It'll be the
worse for you if you don't."

Don's hand tightened on his companion's wrist, and they stood fast, for
Ramsden was stopping in a bent attitude, listening.

There was nothing to be heard but the whisperings and gurglings, and
then they saw him draw his cutlass and come on.

Jem's muscles gave another jerk, but he suffered himself to be drawn
farther and farther into the cave, till they must have been quite two
hundred yards from the mouth; and now, for the first time, the almost
straight line which it had formed, changed, and they lost sight of the
entrance, but could see the shadow of their enemy cast upon the
glistening wall of the place, down which the water seemed to drip,
giving it the look of glass.

All at once Don, as he crept back, felt his left foot, instead of
encountering the smooth rock floor, go down, and as he quickly withdrew
it and felt nearer to him, it was to touch the edge of what seemed a
great crack crossing the floor diagonally.

As he paused, he felt that it might be a "fault" of a few inches in
width or depth, or a vast chasm going right down into the bowels of the
mountain!

"There's a hole here," he whispered to Jem. "Hold my hand."

Jem gripped him firmly, and he reached out with one leg, and felt over
the side outward and downward; and, just as he was coming to the
conclusion that the place was terribly deep, and a shudder at the danger
was running through him, he found that he could touch bottom.

He was in the act of recovering himself, so as to try how wide the crack
or fault might be, when a peculiar strangling sensation attacked him,
and he felt that he was falling.

The next thing he felt was Jem's lips to his ear, and feeling his
whisper,--

"Hold on, lad. What's the matter?"

He panted and drew his breath in a catching way for a few minutes before
whispering back,--

"Nothing. Only a sudden giddiness."

Jem made no comment, but gripped his hand tightly, and they stood
listening, for the shadow cast faintly on the walls was motionless, an