pe so," Tom said.

A ten-hour sleep that night proved a fine tonic. Tom awoke the next
morning feeling entirely refreshed, and after a hearty breakfast,
hurried off to the plant. Here he plunged into work on his quality
analyzer sonar.

Much of the circuitry was assigned to the electronics department. The
finished boards and sub-assemblies were fed back to Tom in his private
laboratory. He himself assembled the major units.

At lunchtime, over a bowl of chili and crackers, Tom recalled another
problem. "We'll need an undetectable sub to test my analyzer," he mused.
"That means a repeat job of rigging all those transducers. Whew! I'd
better get busy on that plastic sheathing."

As soon as he had eaten, Tom phoned Arv Hanson, who arrived at the lab
in a few moments.

"You remember that idea I mentioned to Danny about molding all the
transducers into a single continuous plastic sheet?" As Arv nodded, Tom
went on, "Let's try it, using Tomasite as the plastic."

Tom picked up a pencil and quickly sketched out the production steps.
By machine-spacing the transmitting and the receiving transducers as
closely together as possible, with minimum clearance, the plastic
coating could do an even better job of absorbing sonar pings than the
hand-rigged model.

"And the leads from all the transducers can be combined into a single
flat tape," Tom ended. "That'll make it simple to hook up with the
electronic control unit inside."

"Got it, skipper," Arv said tersely. "It'll take overtime to set up the
job in the plastics department. But we ought to be rolling out the
sheeting Tuesday."

"That's swell, Arv! Thanks!"

By midmorning Tuesday, Tom had his quality analyzer sonar completed and
was showing Bud how the units worked.

"Boy, it looks simple enough the way you explain it, prof!" Bud said
admiringly. "How soon can we try it?"

"Depends on Arv," Tom replied. He picked up the phone and called the
plastics department. To his delight, the sheathing was already being
rolled out in quantity. Arv promised that by noon he would have enough
of it available to coat a jetmarine.

"Nice going!" Tom said. "Shoot it out to the cargo-jet hangar as soon as
it's ready!"

Soon after lunch, Tom, Bud, and Arv took off for Fearing Island. When
they arrived at the base, the plastic coating with its myriad tiny
"mikes" and "speakers" was speedily applied to a jetmarine under Arv's
supervision. Tom, meanwhile, wired the control unit and