r phones. "I'm going to see if I can get any of those fellows
we talked with on the way up here."

"Get that amateur with the radio compass who proved Mr. Perry's
mathematical theory," suggested Bud.

"All right I remember his call and wave length; so here goes."

Hal tuned for several moments and sent the call of the Canadian amateur
in question. Then suddenly he gave a little gasp of surprise. Only Mr.
Perry felt a curiosity as to what it meant, for the other two boys knew
as soon did the boy at the transmitting key. Someone was calling them and
the call he gave as his own was the Canadian V A X. Then came the
following message:

"Have you not given it up yet, boys? I did not mean to carry the joke so
far. Better go back home."

Mr. Perry was waiting patiently for an explanation of the tense interest
manifest in the attitudes of the three boys. Presently Cub gave it to
him, thus:

"We're on the trail again, dad. This fellow we've got is posing as Hal's
cousin and he's advising us to go back home."

CHAPTER XVI

Running Down a Radio Fake

"You say you are V A X?" dot-and-dashed Hal to the amateur who had thus
represented himself.

"Yes," was the reply.

"What is your name?"

"Alvin Baker."

"Where do you live?"

"At Port Hope."

"Where are you now?"

"On the river with some friends."

"Have you any relatives in the United States?"

"Yes."

"Where do they live?"

"In New York."

"New York City?"

"No--State."

"What city?"

"I have forgotten."

"Is it Rochester?"

"I do not know."

"Is it Oswego?"

"I am not certain."

"Have you a cousin named Hal?"

"Yes."

"What is his last name?"

"Baker."

"Have you any relatives named Stone?"

"I think so."

"Is the name Hal Stone familiar to you?"

"Never met the gentleman."

"Then your name is not Alvin Baker?"

"Maybe you know my name better than I do."

"No, but I know just as well as you do that you are not Alvin Baker."

"How do you know that?"

"Because Alvin Baker is my cousin. I am Hal Stone, and I live in Oswego,
New York."

"I do not believe you. You are an impostor."

"Let me tell you a secret. I have penetrated your plot. You are an enemy
of my cousin. There was no wager between him and you, but you don't want
us to find him. You had better keep out of the atmosphere or I will have
you arrested on a charge of disorderly conduct in the air."

No answer.

"V A X, V A X, V A X," called Hal.

St