y sub
blinds our sonar?"

The idea certainly seemed feasible. Suppose the submarine used a great
many "microphones"--or receiving transducers--to pick up the sonar
pulses beamed out by another craft trying to detect it? These impulses
could then be passed on and sent out by speakers on the opposite side of
the sub, and relayed along on their underwater path of travel.

Thus the sonar waves would appear to be striking no obstacle--and no
echo would return to the sonarscopes on the search craft!

"Jumping jets!" Tom thumped his fist on the workbench in his excitement.
"I'll bet that's the answer, all right!" He grinned. "Brand my boot
heels, it's partly due to good old Chow!"

He grabbed a pencil and began sketching his idea on paper. It would be
necessary to spot the receivers and transmitters all over the hull of
the submarine. Diagrams and pages of scribbled computations followed the
rough sketches.

An invisible sub--one that sonar pulses would seem to pass right
through, as if nothing were there! "Seems so simple now that I have the
key!" Tom said to himself elatedly.

Hours ticked by while he analyzed the wave action mathematically, then
worked out a typical hookup for one of his jetmarines in a set of
precise schematic drawings.

Finally the young inventor dropped his pencil, picked up the telephone,
and dialed Bud Barclay.

"Hop over here, fly boy," Tom told his chum. "Something hot on the
griddle!"

Bud arrived in a few moments. Tom showed him the drawings and explained
his plan for dodging underwater detection. He also related how Chow's
remarks about the radio music had sparked the idea.

His chum slapped him on the back. "Good going, Tom!"

"Let's fly right over to Fearing and see how it works on a jetmarine!"
Tom proposed enthusiastically.

Bud grinned but made no move. He stood looking at Tom, arms folded and
feet wide apart.

"Well, let's go, pal!" Tom urged impatiently, puzzled by Bud's lack of
response.

"What about the square dance?"

Tom stopped short, feeling like a punctured balloon. He stared in dismay
at his smiling, dark-haired copilot. "Good night! I forgot again!"

With a sigh, Tom added, "You're right, of course. We sure can't let the
girls down twice. But at least let's get together all the gear we'll
need when we _do_ go to Fearing."

"I guess we'll have time for _that_," Bud conceded with a sympathetic
grin.

Tom assembled a mass of electronic equipment and phoned var