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 enemy 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.