wed in the direction Jack indicated. Although Bob
was still distant there was a purposefulness about his stride and
about the way he waved a response to their greetings that caught his
chum's attention.

"Bob's got something on his mind," he said, with conviction. "Wonder
what it is?"

"Maybe, he found something, hiking along the beach."

"Maybe, he did," agreed Frank. "I didn't feel like hitting it up with
him this morning, felt kind of lazy, as if I had spring fever. It
would be just my luck to have him make a discovery on the one morning
I wasn't along with him."

Bob's figure disappeared in a fold in the sandhills, and Frank
remembering Jack's disgust over interference in the radio receivers,
began to question him about it while waiting for Bob to arrive.

"What was it like this time, Jack?" he asked.

"Just the same, only worse," answered Jack. "Tune up to 1,375 meters
for receiving and then comes that snarling, whining, shrieking sound.
It's steady, too. If it were dot and dash stuff, I might be able to
make something out of it. But somebody somewhere is sending a
continuous wave, at a meter length, too, that is practically never
used. From 1,100 meters to 1,400 meters, you know, is reserved and
unused wave territory."

"I wonder what it can be," said Frank.

Bob by now had approached within calling distance, and he was so
excited that he began to run.

"What's the matter?" called Frank.

"Somebody chasing you?" asked Jack, as the big fellow ploughed through
the sand and halted before them.

Bob grinned tantalizingly.

"What would you give to know?"

"At him, boys. At him," cried Jack, making a flying tackle.

His arms closed about Bob's waist. At the same time, Frank who had
been standing to one side, dived in. His grip tightened about Bob's
legs below the knees. All three lads rolled over in the sand in a
laughing, struggling heap. Presently, Jack and Frank bestrode the form
of their big chum and Frank, who sat on his chest, gripped Bob's
crisply curling hair.

"Now will you tell?" he demanded in mock ferocity. "If you don't----"

"All right, you big bully," answered Bob. "Why don't you pick on a
fellow your size?"

With which remark, he gave a mighty heave--as Frank afterwards
described it "like a whale with a tummyache"--and Frank and Jack went
sprawling. Then he stood upright, brushing the sand from his khaki
walking clothes.

"Oh, is that you down there?" he asked. "Why, where did yo