uld suggest that you get
busy with your wireless outfit and see what you can find out."

The three boys gazed curiously at Cub's father and then at one another in
a puzzled manner.

"Haven't I given you enough hint?" asked Mr. Perry. "I don't want to do
the work myself--in fact, I couldn't if I wished to, for I can't send a
wireless message; but if I could, I know exactly what I'd do."

"We might send a broadcast to all other amateurs and find out if any of
them can help us," Hal suggested.

"How could they help us?" asked Bud skeptically.

"I'm sure I can't tell you," replied Mr. Perry. "But you have a dandy
field to work on. All you need is a little imagination; then begin to do
a little head-work, and before you know it you'll have a lead to work on.
And let me add something more. There are two things in this world, which,
working together, can knock a mystery into a cocked hat more successfully
than anything else in the world that I know of."

"I bet I know what they are," Cub volunteered, eagerly.

"Mathematics and imagination," almost shouted Hal in a wild scramble of
mind to beat Cub with the answer.

The latter cast a wrathful glance at the saucy youth who had broken in
ahead of him.

"Tee-hee!" laughed Bud with fitting imitation of Hal's characteristic
vocal merriment.

As for Tee-hee, that worthy individual preserved his dignity for
the nonce.

"Well," laughed Mr. Perry; "You've hit the nail on the head, but I
venture to say you can't explain why mathematics and imagination can put
a mystery to rout."

Hal confessed he was unable to explain.

"It's too much highbrow for me," he said. "And I bet it's too much
highbrow for Cub."

The latter said nothing. Evidently he was thinking hard. He leaned back
in his camp chair and hoisted his feet upon the rail again.

"Well, let's quit the highbrow field and get down to business," suggested
Mr. Perry. "If we're able to put this thing through along mathematical
lines, I bet you boys will have enough imagination to tell me why
mathematics and imagination can put any mystery on earth to rout."

"I'm goin' to get busy with the spark gap," Cub announced suddenly, as he
sprang to his feet.

"You've got a big thing ahead of you, boys," announced the owner of the
Catwhisker. "I venture to say there are some big surprises in store for
you. For instance, you're likely to find the newspapers of the United
States and Canada giving considerable space to this af