s,
all of which, fortunately, was aboard the WHIZZER, he could produce
a powerful spark.

"I had to make a key out of strips of brass, to produce the Morse
characters," the lad said. "This took considerable time, but it
works, though it is rather crude. I can click out a message with
it."

"That may be," said Mr. Hosbrook, who had been considering
installing a wireless plant on his yacht, and who, therefore, knew
something about it, "you may send a message, but can you receive an
answer?"

"I have also provided for that," replied Tom. "I have made a
receiving instrument, though that is even more crude than the
sending plant, for it had to be delicately adjusted, and I did not
have just the magnets, carbons, coherers and needles that I needed.
But I think it will work."

"Did you have a telephone receiver to use?"

"Yes. There was a small interior telephone arrangement on Mr.
Fenwick's airship, and part of that came in handy. Oh, I think I can
hear any messages that may come in answer to ours."

"But what about the aerial wires for sending and receiving
messages?" asked Mr. Nestor.

"Don't you have to have several wires on a tall mast?"

"Yes, and that is the last thing to do," declared Tom. "I need all
your help in putting up those wires. That tall tree on the crest of
the island will do," and he pointed to a dead palm that towered
gaunt and bare like a ship's mast, on a pile of rocks in the centre
of Earthquake Island.

CHAPTER XXI

MESSAGES INTO SPACE

Tom Swift's announcement of the practical completion of his wireless
plant brought hope to the discouraged hearts of the castaways. They
crowded about him, and asked all manner of questions.

Mr. Fenwick and Mr. Damon came in for their share of attention, for
Tom said had it not been for the aid of his friends he never could
have accomplished what he did. Then they all trooped up to the
little shack, and inspected the plant.

As the young inventor had said, it was necessarily crude, but when
he set the gasolene motor going, and the dynamo whizzed and hummed,
sending out great, violet-hued sparks, they were all convinced that
the young inventor had accomplished wonders, considering the
materials at his disposal.

"But it's going to be no easy task to rig up the sending and
receiving wires," declared Tom. "That will take some time."

"Have you got the wire?" asked Mr. Jenks.

"I took it from the stays of the airship," was Tom's reply, and h