eir office.

"Yes. Digging in that silt could be almost as bad as working in
quicksand."

Mr. Swift's deep-set blue eyes took on a thoughtful gleam. "Speaking of
silt, son, I've found the ideal spot for my secret deep-sea farm."

"You mean for growing those plants you use in making Tomasite?" Tom
asked.

The elder scientist nodded. Tomasite, a revolutionary plastic which Mr.
Swift had developed, possessed amazing insulating properties against
both heat and radiation. One of its secret ingredients came from certain
plants found only in Far Eastern waters. Mr. Swift hoped to transplant
them locally.

"The site is near Fearing Island--about fifty feet in depth," he added.

"You may have a tough time finding gardeners, Dad," Tom pointed out.
"Men can't work that far down for very long at one time."

"It'll be a problem," Mr. Swift conceded. He finished his coffee, then
looked up with a twinkle in his eyes. "How about figuring out a solution
for me, Tom?"

"A new kind of air lung?" Tom was intrigued!

CHAPTER IV

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
anoth