AERIAL ATTACK
"Yes, son," Mr. Swift went on. "What's needed is a new type of breathing
device--one that will eliminate bulky air tanks and permit a skin diver
to stay down for long periods."
"Quite an order, Dad."
Grabbing a pencil, the young inventor began sketching. In both his Fat
Man suits and his osmotic air conditioner, Tom had already perfected
ways of drawing oxygen from sea water.
"But a small gadget for skin divers," he said, "will take a fantastic
job of electronic miniaturization." After a pause he added, "It could
really speed up recovery of the Jupiter prober, though."
Lunch over, Tom hopped a jet scooter and sped off to his private
laboratory. The modernistic glass-walled structure--designed by Tom
himself--had every tool of modern scientific research, from electronic
microscope to helium cryostat.
As always, whenever he was absorbed in a new idea, Tom was eager to get
to work. "Let's see what I'm shooting for. A small container, slung
around the diver's neck?... No, too dangerous. Better hook it to his
weight belt, with a tube to his face mask."
Using a plastic foam "breadboard," Tom began experimenting with various
circuit designs. He worked through the afternoon and returned to the
problem early the next morning.
He was interrupted by a message from Art Wiltessa, reporting no luck so
far in finding the missile. Later, shortly before lunch, Tom received
another call, this time from Admiral Walter. "Just wanted to keep you
posted, Tom. Our task force reports no success on their part in finding
the buried missile. No sign of the enemy, either."
"They'd probably hesitate to attack any official U.S. Navy units," Tom
said. "Or it might mean they've already found the missile themselves."
"That's what I fear," Admiral Walter confessed gloomily. "However, we'll
continue searching."
Tom promised to fly down to the site at the first opportunity, saying he
was developing a new device that might assist in the search. After
snatching a hasty lunch, Tom returned to work.
Arv Hanson machined several parts and molded the plastic face mask to
Tom's specifications. By evening the new device was completed.
"Now for a test," the young inventor said to himself.
Sandy Swift and Phyl Newton were eager to watch the test, so the next
morning they drove to the plant in Phyl's white convertible. Tom, clad
in swim trunks, was waiting for them with Chow near the edge of a
mammoth concrete tank. Set in bedrock, at one end of the Enterprises
grounds, the tank was used for submarine testing.
When Sandy saw the power unit strapped to Tom's weight belt, she
exclaimed, "_That_ little gadget will supply all the air you need? Why,
it's no bigger than a pocket transistor radio!"
Tom grinned. "I hope it will. That's what I intend to find out."
"How does it work?" Phyl asked, fascinated.
Tom explained, "Actually its function is to replace the carbon dioxide
that I exhale with fresh oxygen drawn from the water. Otherwise,
although the carbon dioxide I'd breathe out would be a very small amount
at a time, it soon would make the air unfit. The nitrogen, which makes
up much of the air we breathe, is chemically inert and can be used again
and again."
He pointed to a round screen on one side of the unit. "This is the water
intake," Tom went on, "and this other screen is where the water comes
out after we've removed its oxygen."
Near the forward end of the unit, a semirigid plastic tube was
connected, leading up to the face mask. At the rear was a power port for
inserting a small solar battery.
"What about this little tuning knob?" Sandy asked.
"That's the rate control for adjusting the output frequency to the
wearer's breathing rate." Tom added, "I've decided to call the whole
apparatus an 'electronic hydrolung.'"
Chow pushed back his ten-gallon hat and scratched his head dubiously.
"Wal, I'm keepin' a net handy to drag you out, boss, just in case."
Tom chuckled and fitted the mask over his face, then made a clean dive
into the tank. For the next ten minutes the girls and Chow watched
wide-eyed as he swam, walked around, and went through vigorous exercises
at the bottom of the tank without once coming up for air.
"Whee!" Sandy exclaimed when Tom finally climbed out. "Make me one, so I
can take up skin diving!"
"It's wonderful!" Phyl added admiringly.
Tom took off his mask. "I'm pretty pleased with it myself," he admitted,
grinning.
The girls stayed at Enterprises for lunch. Then the group, accompanied
by Doc Simpson, flew to Fearing Island so Tom could test his invention
in deep water. Boarding a small motor launch, with Doc at the helm, they
cruised out to a suitable depth and dropped anchor.
"Don't become too confident, Tom," Doc warned. "I'll drop a signal line
over the side in case of emergency."
Tom buckled on his equipment belt and adjusted the face mask. Then he
held up crossed fingers and back-flipped over the gunwale into the
water. Chow, Doc, and the girls watched his plummeting figure fade from
view.
Tom, an expert skin diver, had never before felt such a sense of ease
and freedom under water. He was moving, light and self-contained, in a
green, magical world. With no air tanks chafing his back, he felt akin
to the fishes themselves.
"Wish I'd brought a hook and line along." He chuckled, as a school of
mackerel darted past.
Now came the real test. Deeper and deeper, Tom cleaved his way downward.
Reaching bottom, he prowled about the ocean bed for a while, then
started up again. Suddenly a stab of pain shot through his chest--a
warning of nitrogen bubbles forming in his blood!
Tom swam toward the signal cord, dangling dimly in the distance. By the
time he reached it, his muscles were knotting with cramps.
"It's the bends again, all right!" Tom realized. Gritting his teeth, he
yanked hard on the line, then summoned his strength to hang on.
Doc and Chow hauled up frantically. Tom's face was contorted with pain
when they finally got him aboard and stripped off his mask.
"Oh! How awful!" Phyl gasped.
Sandy cradled Tom's head in her lap, and Phyl held his hand
sympathetically, while Doc Simpson injected a hypodermic to ease the
pain. Chow steered the launch back to shore, and Tom was rushed to the
base infirmary in an ambulance.
Here he was placed in a decompression chamber for several hours and
later transferred to a hospital bed. Bud Barclay came to visit him.
"We're a fine couple of fish," he said.
Tom chuckled wryly. "_Live_ fish, anyhow."
"In my case, thanks to you," Bud said.
"Forget it, pal. The score's about even, I should think," Tom said,
recalling the many life-or-death adventures they had shared.
Bud was thrilled to hear of Tom's electronic hydrolung. The young
inventor spent the evening sketching out an improved design to eliminate
future accidents.
"I'll install a special device to remove the nitrogen as the wearer
exhales," Tom explained. "Then a valve will feed in helium to replace
it. Since helium doesn't dissolve in the blood like nitrogen does, it
will not bubble out when the pressure is reduced. Should have thought of
that before!"
"But you'll need a tank for the helium, won't you?" Bud objected.
Tom shook his head. "Enough can be compressed into a small capsule to
supply the wearer's needs. Remember, it can be used over and over
again."
"Pretty neat," Bud commented.
By morning Tom felt thoroughly recovered. He insisted upon flying back
to Enterprises to make the necessary changes in his hydrolung. Bud
accompanied him, eager to get back on the job.
In a few hours Tom had added a small fitting to his power unit to
provide for helium substitution. Then the two boys hopped back to
Fearing for a second deep-water test. This time, Tom was delighted to
find that he could operate comfortably at great depths, as well as rise
or descend suddenly without ill effect.
Bud was aglow with enthusiasm. "Boy, we can really explore now!"
After the boys had returned to Enterprises, Tom phoned Arv Hanson and
asked that a duplicate of the hydrolung be turned out in the shop as
soon as possible. It was ready the following Monday morning, so Tom
suggested to his father that the two visit the proposed underwater site
and make some sample plantings.
"Great idea, son," Mr. Swift agreed. "I want to try out your new diving
apparatus myself. If it's successful, we'll be able to tackle two
problems at once--recover the Jupiter prober and start the 'sea farm.'"
They flew to Fearing, then went by boat to the farm site, about half a
mile offshore. Each carried several of the valuable Far Eastern plants.
[Illustration]
The silt beds which Mr. Swift had selected were just deep enough to
keep the plants from being discovered, yet enable them to receive
sufficient sunlight.
Tom and his father started their planting. But no sooner had the first
plants been embedded than fish darted in to nibble them. Even the roots
disappeared into their greedy maws.
[Illustration]
"Looks as though we'll have to build some sort of net enclosure around
and over our farm," Mr. Swift said, after they had climbed back into
the boat. "But at least your hydrolung device is a great success, son!"
Tom was thoughtful. "Dad, I wonder if the fish would eat those plants
from space which you've been growing under salt water?"
Tom was referring to certain strange plants rocketed to earth by unknown
space friends with whom the Swifts had been in communication.
"I have a hunch," Tom went on, "that the fish might be repelled by the
unusual scent of those space plants. If so, we could scatter them among
the earth plants to keep the fish away."
Mr. Swift was impressed by Tom's idea. As soon as they had returned to
Enterprises, he proposed that the experiment get under way.
Tom volunteered to undertake the job at once with Bud. While the young
inventor phoned his copilot, Mr. Swift went to his own laboratory to
prepare the plants for shipment.
Twenty minutes later the boys took off in a jet. The plants had been
parceled in transparent plastic film. Glistening with a red metallic
sheen, they looked somewhat like tulips with honeycombed centers.
"Scarecrow plants to drive off fishes," Bud joked. "What will scientists
think of next!"
Tom laughed, then abruptly frowned. "Hey! What's that character up to?"
he said. "Trying to buzz us?"
A sleek gray jet without markings was arrowing in on them from three
o'clock. Bud flicked on the radio and barked a warning. The plane made
no response. As it kept coming, Tom increased speed--then rolled, dived,
and changed course, but failed to shake off their pursuer.
Bud, meanwhile, was frantically calling Enterprises and a nearby
airport, but getting no response. Yet their radio was working, for a
voice suddenly crackled:
"_Follow the mystery plane for a landing and you won't be harmed!_"