ed on the terrace overlooking the sparkling blue waters of Lake
Carlopa.

The young inventor's spirits were high when he finally returned to his
laboratory and buckled down to work.

"I'll lick this problem yet," he muttered. "Those enemies of ours are
clever, but if they can produce an undetectable sub, there's no reason
why I can't do the same."

Deep in thought, Tom idly fingered a microphone on his workbench.

"In fact," the young inventor mused, "why not go them one better? I'll
invent a submarine that's not only invisible to sonar, but equipped to
_see them_!"

CHAPTER XI

SQUARE-DANCE HOAX

Random hunches and circuit diagrams flashed through Tom's brain. "The
job will boil down to blotting out sonar waves and piercing the enemy's
own 'wave-trap defense,'" the young scientist concluded.

As Tom struggled with the problem, he lost all track of time. A door
swung open and high-heeled boots clumped on the floor tiles. Tom looked
up and saw the portly, aproned figure of Chow Winkler entering.

"Hi, boss! Can I borrow a radio?" Chow asked. "Kinda like a lil music
while I wrassle them pots an' pans in the galley."

"Sure, pardner." Tom pointed toward a portable radio on a shelf nearby.

Chow's leathery face broke into a grin as he picked it up. "One o' them
slick lil transistor doodads, eh?"

The cook flicked on the dial knob and the twangy strains of Hawaiian
guitar music came throbbing out. A split second later the volume swelled
as the same music echoed back to them from the two-room apartment
adjoining the lab, where Tom ate and slept when engaged in some
round-the-clock experiment.

Chow was startled by the blare. "You got a stereo hookup here, boss?" he
inquired.

"Not exactly." Tom explained that the music had merely been picked up by
the mike on his workbench, then fed into the adjoining apartment and
amplified over a speaker there.

Chow grinned, snapping his fingers to the catchy melody. "Comes out even
louder'n it does from the radio!"

"Yes, but the sound quality's not so good," Tom said. "You'd notice the
difference with real stereo."

Chow walked out with the portable, crooning contentedly to the music.

Tom frowned, trying to get his train of thought to focus once more on
the submarine problem. But for some reason the business with the
microphone and the speaker in the next room kept lingering in his mind.

Suddenly Tom exclaimed aloud, "Say! I wonder if that's how the enem