in Mentor. "You don't mean to say that you
have been building a boat up there in your little shack, do you?"

"Not a boat," replied Tom, "but I think I have a means of sending
out a call for help!"

"Oh, Tom--Mr. Swift--how?" exclaimed Mrs. Nestor. "Do you mean we
can send a message to my Mary?"

"Well, not exactly to her," answered the young inventor, though he
wished that such a thing were possible. "But I think I can summon
help."

"How?" demanded Mr. Hosbrook. "Have you managed to discover some
cable line running past the island, and have you tapped it?"

"Not exactly." was Tom's calm answer, "but I have succeeded, with
the help of Mr. Damon and Mr. Fenwick, in building an apparatus that
will send out wireless messages!"

"Wireless messages!" gasped the millionaire. "Are you sure?"

"Wireless messages!" exclaimed Mr. Jenks. "I'll give--" He paused,
clasped his hands on his belt, and turned away.

"Oh, Tom!" cried Mrs. Nestor, and she went up to the lad, threw her
arms about his neck, and kissed him; whereat Tom blushed.

"Perhaps you'd better explain," suggested Mr. Anderson.

"I will," said the lad. "That is the secret we have been engaged
upon--Mr. Damon, Mr. Fenwick and myself. We did not want to say
anything about it until we were sure we could succeed."

"And are you sure now?" asked Captain Mentor.

"Fairly so."

"How could you build a wireless station?" inquired Mr. Hosbrook.

"From the electrical machinery that was in the wrecked WHIZZER,"
spoke Tom. "Fortunately, that was not damaged by the shock of the
fall, and I have managed to set up the gasolene engine, and attach
the dynamo to it so that we can generate a powerful current. We also
have a fairly good storage battery, though that was slightly damaged
by the fall."

"I have just tested the machinery, and I think we can send out a
strong enough message to carry at least a thousand miles."

"Then that will reach some station, or some passing ship," murmured
Captain Mentor. "There is a chance that we may be saved."

"If it isn't too late," gloomily murmured the scientist. "There is
no telling when the island will disappear beneath the sea."

But they were all so interested in Tom's announcement that they paid
little attention to this dire foreboding.

"Tell us about it," suggested Mr. Nestor. And Tom did.

He related how he had set up the dynamo and gasolene engine, and
how, by means of the proper coils and other electrical apparatu