shaking that presaged another earthquake. The shack rocked, and
threatened to come down about their heads.

"We must be doomed!" cried Mr. Parker. "The island is about to sink!
Make for the raft!"

"Wait and see how bad it is," counseled Mr. Hosbrook. "It may be
only a slight shock."

Indeed, as he spoke, the trembling of the island ceased, and there
was silence. The two ladies, who had retired to their own private
shack, ran out screaming, and Mr. Anderson and Mr. Nestor hastened
over to be with their wives.

"I guess it's passed over," spoke Mr. Fenwick.

An instant later there came another tremor, but it was not like that
of an earthquake shock. It was more like the rumble and vibration of
an approaching train.

"Look!" cried Tom, pointing to the left. Their gaze went in that
direction, and, under the light of a full moon they saw, sliding
into the sea, a great portion of one of the rocky hills.

"A landslide!" cried Captain Mentor. "The island is slowly breaking
up."

"It confirms my theory!" said Mr. Parker, almost in triumph.

"Forget your theory for a while, Parker, please," begged Mr.
Hosbrook. "We're lucky to have left a place on which to stand! Oh,
when will we be rescued?" he asked hopelessly.

The worst seemed to be over at least for the present, and, learning
that the two ladies were quieted, Tom started up the hill to his
wireless station. Mr. Damon and Mr. Fenwick went with him, to aid in
starting the motor and dynamo. Then, after the message had been
clicked out as usual Tom would begin his weary waiting.

They found that the earthquake shock had slightly disturbed the
apparatus, and it took them half an hour to adjust it. As there had
been a delay on account of the landslide, it was eleven o'clock
before Tom began sending out any flashes, and he kept it up until
midnight. But there came no replies, so he shut off the power, and
prepared to get a little rest.

"It looks pretty hopeless; doesn't it?" said Mr. Fenwick, as he and
Mr. Damon were on their way back to the sleeping shack.

"Yes, it does. Our signal hasn't been seen, no ships have passed
this way, and our wireless appeal isn't answered. It does look
hopeless but, do you know, I haven't given up yet."

"Why not?"

"Because I have faith in Tom Swift's luck!" declared the eccentric
man. "If you had been with him as much as I have, up in the air, and
under the water, and had seen the tight places he has gotten out of,
you'd fe