TOM SWIFT AND HIS DEEP-SEA HYDRODOME
By VICTOR APPLETON II
No. 11 in the Tom Swift Jr. series.

From the inside cover:
From the moment Tom Swift finds himself tossed about helplessly in an 
undersea geyser to the time he faces possible death at the hands of his enemies, 
the young scientist lights to overcome many obstacles in putting his two latest 
amazing inventions to use.
When Torn discovers that helium on the ocean bottom had caused the 
geyser, he plunges into the task of building an underwater city of derricks and 
pipe lines to capture the gas. His astounding new water-repelling machine and 
phenomenal hydro-dome make the gigantic operation possible.
While at work at the undersea mountain site, Torn and his pal Bud Barclay 
uncover what seems to be pirate treasure, but find in the leaden chests a cache 
of death-dealing destruction. Time and again the young scientist's plans are 
nearly wrecked. A sinister, hooded figure attacks him in his laboratory, and a 
mysterious submarine nearly costs him his life.
How Tom outwits his ruthless enemies and saves his country from grave 
danger makes a nerve-tingling story, packed with swift, tense action and high-
voltage suspense.

THE NEW TOM SWIFT JR. ADVENTURES
TOM SWIFT AND HIS DEEP-SEA HYDRODOME
BY VICTOR APPLETON II

The Tom Swift Jr. series:
1 Tom Swift and his Flying Lab (1954) 
2 Tom Swift and his Jetmarine (1954) 
3 Tom Swift and his Rocket Ship (1954) 
4 Tom Swift and his Giant Robot (1954) 
5 Tom Swift and his Atomic Earth Blaster (1954) 
6 Tom Swift and his Outpost in Space (1955) 
7 Tom Swift and his Diving Seacopter (1956) 
8 Tom Swift in the Caves of Nuclear Fire (1956) 
9 Tom Swift on the Phantom Satellite (1956) 
10 Tom Swift and his Ultrasonic Cycloplane (1957) 
11 Tom Swift and his Deep-Sea Hydrodome (1958) 
12 Tom Swift in the Race to the Moon (1958) 
13 Tom Swift and his Space Solartron (1958) 
14 Tom Swift and his Electronic Retroscope (1959) 
15 Tom Swift and his Spectromarine Selector (1960) 
16 Tom Swift and the Cosmic Astronauts (1960) 
17 Tom Swift and the Visitor from Planet X (1961) 
18 Tom Swift and the Electronic Hydrolung (1961) 
19 Tom Swift and his Triphibian Atomicar (1962) 
20 Tom Swift and his Megascope Space Prober (1962) 
21 Tom Swift and the Asteroid Pirates (1963) 
22 Tom Swift and his Repelatron Skyway (1963) 
23 Tom Swift and his Aquatomic Tracker (1964) 
24 Tom Swift and his 3D Telejector (1964) 
25 Tom Swift and his Polar-Ray Dynasphere (1965) 
26 Tom Swift and his Sonic Boom Trap (1965) 
27 Tom Swift and his Subocean Geotron (1966) 
28 Tom Swift and the Mystery Comet (1966) 
29 Tom Swift and the Captive Planetoid (1967) 
30 Tom Swift and his G-Force Inverter (1968) 
31 Tom Swift and his Dyna-4 Capsule (1969) 
32 Tom Swift and his Cosmotron Express (1970) 
33 Tom Swift and the Galaxy Ghosts (1971)

ILLUSTRATED BY GRAHAM KAYE
GROSSET & DUNLAP
© BY CROSSET & DUNLAP, INC., 1958 ALL RIGHTS R E S E R V E D
PRINTED IN THE UNITED STATES OF AMERICA


CONTENTS
1 An Exciting Discovery
2 Secret Mission
3 Undersea Rover
4 The Mysterious Chests
5 Atomic Patrols
6 The Stalking Sub
7 A Hooded Figure
8 Telltale Threads
9 Up Elevator!
10 Deep Freeze
11 Mountain Cache
12 A Surprising Dinner
13 Niffman's Story
14 A Baited Trap
15 Dome Test
16 A Perilous Picnic
17 The Star Mark
18 A Hazardous Rescue
19 Tom Is Kidnapped
20 A Hidden Weapon



CHAPTER I
AN EXCITING DISCOVERY

"Swing that searchlight around, will you, Dad? I see something unusual!"
Tom Swift's blue eyes lighted up with excitement as he steered the Sea 
Hound, his latest model of the diving seacopter, through the inky depths of the 
Atlantic Ocean.
"Port or starboard?" asked Mr. Swift.
"Starboard, just a few degrees," Tom replied.
The lanky, blond-haired inventor was cruising with his distinguished scientist 
father about a hundred feet above the ocean floor near an undersea mountain. 
They were in the realm of eternal night, far below the depths at which the sun's 
rays penetrate.
Mr. Swift gasped in surprise as he swiveled the powerful searchlight. In its 
glare a myriad of huge bubbles could be seen billowing upward in a steady 
stream from the ocean bottom.
"Great Scott! This is unbelievable!" the scientist exclaimed.
i
2 DEEP-SEA HYDRODOME
"I've never seen anything like it!" Tom agreed, as he stared in fascination.
On an earlier cruise in his first seacopter, the Ocean Arrow., Tom Swift Jr. 
had discovered an underwater city of gold on the same mountain range. Now he 
and his father were making a return trip to explore the strange sunken civilization, 
and conduct underwater tests there.
"Dad," Tom said, after making some quick calculations, "those bubbles might 
be helium gas!"
"You mean because of the tremendous speed with which they're rising?" 
remarked Mr. Swift, who was as excited as his son.
"Yes," Tom replied. "Other bubbles we've seen so far have been just lazily 
drifting up."
"You have a point there," his father admitted. Knowing that helium, because 
of its low density, is very buoyant, both Swifts realized that this would account for 
the bubbles' fast-streaming action.
The elder inventor's keen eyes glinted as he added, "Son, if your hunch is 
right, this could be a discovery of top scientific importance!"
Eighteen-year-old Tom nodded tensely. "I know. At present our country can 
get helium only from certain natural gas wells in Texas and Kansas, and those 
sources don't produce a great deal. If scientists had an unlimited supply from 
under the ocean-"
Father and son looked intently at each other as Mr. Swift laid a hand on 
Tom's shoulder.
"Don't get your hopes up too soon," he cau-
AN EXCITING DISCOVERY 3
tioned. "The gas is still deep in the ocean. And we don't even know that it is 
helium."
Tom grinned. "Right. It could be hydrogen, or argon or neon or other gases. 
But," he declared, "I intend to find that out right now!"
Mr. Swift frowned. "How?"
"I'll go out in a Fat Man suit, collect a sample, and test it!"
Pulling a lever on the control panel, Tom cut the directional jets. The sleek 
craft slowed to a halt, as its whirring central rotor held the sea-copter suspended 
motionless in the ocean depths.
Powered by atomic reactors, the Sea Hound was one of Tom's most thrilling 
inventions. Like the Ocean Arrow, it could be used as a helicopter or as a 
submarine. The unique craft was equipped with tractor treads which could be 
extended like a plane's landing gear for crawling along the ocean floor.
"Take over, will you, Dad?" Tom asked eagerly.
Mr. Swift stepped to the controls and glanced at the dials and gauges. "You'll 
need a float balloon in case you want to send up a marker," he suggested over 
his shoulder.
"Good idea. I'll take one."
Tom unlocked a stowage compartment and took out one of the "balloons," 
which actually was a hollow metal sphere containing compressed air. Using a 
short length of nylon cable, he attached the sphere to a laboratory vacuum flask 
in which he would collect the gas sample.
4 DEEP-SEA HYDRODOME
"Now to climb into a Fat Man suit," the young inventor murmured.
The Sea Hound carried two of these escape suits just inside the ship's air 
lock, located at the rear side of the forward compartment. Shaped like huge 
dinosaur eggs, each Fat Man suit had a heavy quartz-glass view plate, 
pantograph arms and legs operated by inner controls, and a seat for the 
operator. Months ago, Tom had invented the Fat Man devices to help him track 
down a gang of undersea pirates in his jetmarine.
"Watch your step in the ooze out there," Mr. Swift warned as Tom squirmed 
into one of the suits through the open view plate and sat down.
"Roger!"
Clamping the view plate shut, Tom switched on his air supply. Then he 
picked up the balloon and flask with one of the mechanical arms and stepped 
into the pressure chamber.
His father shoved the control wheel forward and the seacopter descended 
gently to the bottom. A moment later the hatch in the ship's hull opened and Tom 
stepped out.
Waddling cautiously through the muck, he made his way forward into the 
glare of the searchlight. Guided by its beam, he headed toward the source of the 
bubbles.
The ocean floor was completely barren of vegetation at this depth. 
Occasional flashes of eerie light from strange-looking fish and other sea 
creatures were the only signs of life.
The bubbles seemed to issue from the ledge
AN EXCITING DISCOVERY 5
on which he stood. The ooze seethed like a giant stewpot.
Tom tested each step with the Fat Man's pantograph legs, at the same time 
probing the sea floor with his own built-in searchlight. Finally he came within 
reach of the bubbling area.
Maneuvering the mechanical arms, he upended the vacuum flask just as a 
bubble was forming and caught some of the gas neatly inside.
"So far, so good," the young scientist muttered. "Only hope it is helium." After 
the self-sealing bottle had capped itself, he started back toward the Sea Hound.
Suddenly the Fat Man began to wobble. It teetered perilously on its 
mechanical legs for a moment, then righted itself as the gyro brain brought the 
egg-shaped monster back into balance.
"Hey, what goes on here?" Tom wondered, feeling a slight twinge of alarm.
The next instant a violent lurch almost threw him out of his seat. Quickly Tom 
pressed his face against the quartz-glass window to see what was happening. To 
his horror, the ocean bottom was shuddering in a violent upheaval!
"Good night! I'd better get out of here fast!" Tom muttered to himself.
He gunned the air jet to propel the device forward. But an upsurge of bubbles 
caught the Fat Man, rocking it from side to side.
Frantically Tom worked the controls, trying to keep the escape suit upright. 
Then came another
6 DEEP-SEA HYDRODOME
jolt as the whole sea floor seemed to explode.
An immense geyser of water and mud erupted with the force of a dynamite 
blast. It struck the Fat Man and the seacopter, and hurled them upward.
Tom barely had time to glimpse the Sea Hound's searchlight beam sweeping 
in a crazy arc, when he was thrown from the operator's seat. His head crashed 
against the inner wall of the steel egg. With a moan of pain, the young inventor 
blacked out. When Tom regained consciousness, he found himself in total 
darkness. Only the glow of the instrument dials relieved the black gloom of the 
ocean depths.
The water around him was quiet now. Tom theorized that the geyser had 
been caused by the

AN EXCITING DISCOVERY 7
sudden release of a tremendous quantity of gas held under pressure inside 
the mountain.
Whether he had been unconscious for a few seconds or several minutes, 
Tom did not know.
"Where was Dad blown to?" he asked himself worriedly. "And how is he?"
Tom pressed the Fat Man's light switch, then flipped it back and forth in 
desperation. There was no response.
"Oh, no!" Tom groaned. His searchlight was out of commission!
Outside the quartz-glass window, there was no sign of the Sea Hound's 
beam. A wave of fear surged through Tom.
"Steady, boy!" he told himself. "Getting panicky won't help."

8 DEEP-SEA HYDRODOME
From the weight indicated on the pantograph controls, Tom could tell that the 
vacuum flask had been wrenched from his grasp by the undersea geyser. His 
valuable sample was gone, too. But there was no time to worry about that.
Working the controls cautiously, Tom maneuvered the Fat Man through a 
complete 360-degree turn. There was not a glimmer of light from the Sea Hound.
"Maybe I can make contact by sonarphone," he thought.
Switching on his two-way set, Tom spoke hopefully into the mike. "Dad, can 
you read me? . . . Fat Man calling the Sea Hound!"
Again and again he repeated the call. Getting no response, he finally gave up 
and turned off the transmitter.
"Now what?" Tom wondered fearfully.
He pondered the situation for a moment. Without help from the mother ship, 
his own plight was serious and his father's might be worse. In any case, Tom 
decided, there was no point in lingering on the ocean bottom.
"Well, here goes," he determined.
Opening a valve, he blew his ballast tanks and prepared to surface. An 
elevator feeling in the pit of his stomach told him the Fat Man was zooming 
upward through the murky depths.
Slowly the blackness outside his view pane lightened into gray. Then the 
water took on greenish tinges, which finally deepened into a rich blue-green. 
Fishes of all description darted
AN EXCITING DISCOVERY 9
past. Seconds later he broke through the surface.
"Oh, boy, that old sunshine looks good!" Tom exulted.
Peering around, he gave a cry of joy. Less than a hundred yards away, the 
Sea Hound was wallowing in the waves. The float balloon, with the vacuum flask 
attached, was also in sight.
After retrieving the gas sample, Tom steered the Fat Man toward the 
seacopter. A chill of foreboding came over him when he failed to glimpse his 
father inside the cabin window.
Tom rapped on the ship's hatch. After a pause, he knocked again. There was 
no response from inside!
CHAPTER II
SECRET MISSION
THIS time, there was no avoiding the fearful thoughts that hammered in 
Tom's mind. Something must have happened to his father when the Sea Hound 
was hurled upward by the undersea geyser. Was he lying helpless and seriously 
injured inside the seacopter?
Frantically Tom tried the hatch to no avail. The opening mechanism was 
jammed! And he had no tools with which to force an entrance.
What to do now? Bobbing about in his Fat Man suit, Tom was alone at sea, 
hundreds of miles from the nearest point of land. And he was not in a sea lane 
for ships.
"It looks as if the radio is my only hope," Tom decided grimly. He switched to 
the special frequency used by employees of Swift Enterprises. This was the 
sprawling experimental station in Shopton, the Swifts' home town, where Tom 
and his father developed their numerous inventions.
10
SECRET MISSION 11
"Tom Swift Jr. calling Enterprises! Can you read me? . . . Come in, please! . . 
. Tom Jr. calling Swift Enterprises!"
Suddenly his heart gave a leap of joy as a reply came faintly over the 
earphones. "Enterprises to Tom. What goes, skipper?" It was the voice of 
George Billing, communications chief at Enterprises.
"We're in trouble, George-stranded at seal" Tom said urgently. "Send help 
pronto, including Doc Simpson!"
He gave their position and Billing started to reply. But after two or three 
words, the signal faded out.
Again and again Tom tried to re-establish contact but without success. At last 
he gave up in despair. Had Billing heard the position?
For the time being, there was nothing for Tom to do but wait and hope. As 
the minutes dragged by, the young inventor thought ruefully of the many times 
when he had come face to face with death, not only at sea, but in the frozen 
wastes of the Antarctic and the bleakness of outer space. In his latest adventure, 
with his ultrasonic cycloplane, he had outwitted a fiendish scientist seeking long-
lost riches in the New Guinea jun-gle.
Now, under the blazing sun of the open Atlantic, the Fat Man was becoming 
uncomfortably hot. Even the asbestalon insulation and air-changing equipment 
could not prevent the tempera-
12 DEEP-SEA HYDRODOME
ture from rising inside the egg-shaped escape suit.
To offset this, Tom submerged several times to cool off. Each time he 
reappeared, the stranded inventor looked hopefully for help. But all he saw were 
flying fishes which leaped into view every now and then. Several times a deadly-
looking shark fin went streaking past, and once he sighted a school of playful 
porpoise.
It was midafternoon when a faint roar from the sky drew his attention. Off to 
the northwest, a silver speck was winging into view.
"The Sky Queen!" Tom thought hopefully. "Thank goodness!"
A few minutes later the sleek, swept-wing air giant stood overhead. Atomic-
powered and completely equipped for scientific research anywhere in the world, 
this three-decker Flying Lab was Tom's first major invention. Jet lifters enabled it 
to land or take off vertically.
"Fat Man to Sky Queen! Boy, are you a welcome sight!" Tom said into his 
mike.
"Be right with you, skipper!" came the reply.
Using the lifters, the huge plane lowered to a hovering halt just above the 
water a short distance from the Sea Hound. Swiftly Tom propelled the Fat Man 
alongside and clambered aboard through the open hatch. Anxious faces greeted 
him as he crawled out of the escape suit.
"Are you all right, pal?" asked Bud Barclay. The same age as Tom, the 
husky, dark-haired boy was his closest chum.
SECRET MISSION 13
"Never mind me," Tom replied. "We must see about Dad!"
"Where is he? What happened?" demanded Hank Sterling, the Swifts' 
square-jawed chief pat-ternmaking engineer and trouble shooter.
Quickly Tom described their undersea disaster and how his father had failed 
to respond when he knocked on the Sea Hound's air lock.
Hank said promptly, "Pull up alongside, Slim, and I'll open it!"
Slim Davis, a company test pilot who had flown the Sky Queen from 
Shopton, hurried back to the controls. With a slight kick on the main jets, he 
maneuvered the big plane close to the seacopter.
Then Arv Hanson, a hulking six-foot, engineer-craftsman who turned out the 
small, sleek models of all Tom's inventions, got to work. He threw a mooring line 
over to a cleat on the seacopter's hull to grapple the two craft close together.
Working with a powerful cutting torch, Hank and Bud soon forced open the 
door of the Sea Hound's air lock. Tom, with Doc Simpson, Swift Enterprises' 
physician, led the way into the sea-copter. The crewmen scrambled aboard 
behind them.
In the rear of the forward cabin, they found Mr. Swift laying in a crumpled 
heap on the deck.
"Dad!" cried Tom in a stricken voice, as he rushed to his father's side.
Doc Simpson followed. "Your dad must have been jolted off his feet and 
knocked out," he said,
14 DEEP-SEA HYDRODOME
examining an ugly bruise on the scientist's forehead. "Help me carry him to a 
bunk."
The young medic worked over Mr. Swift for several minutes but failed to 
restore him to consciousness.
"What do you think the trouble is?" Tom asked anxiously.
"I'm afraid that he may have a concussion," Doc replied gravely. "I'm hoping 
I'm wrong, but we'd better get him to a hospital as quickly as possible."
Tom took over the controls for the return flight, and soon the huge, atomic-
powered Sky Queen was streaking in a northwesterly course across the ocean at 
twice the speed of sound. Meanwhile, Hank Sterling and Slim Davis had 
remained aboard the seacopter to pilot it home. In little more than an hour, Tom's 
Flying Lab was nearing an island off the United States coast.
"We'll land at Fearing to save time," the young inventor told Doc Simpson.
Moments later, they came in sight of the tiny stretch of sand dunes and 
scrubgrass lying not far off the Atlantic coast. This was Fearing Island, the Swifts' 
rocket base, closely guarded by drone planes and radar.
Tom radioed for clearance, and an ambulance was waiting when they 
landed. Mr. Swift was carried off the plane on a stretcher and rushed to the island 
infirmary. Here, with Tom, Bud, and Doc at his side, he finally regained 
consciousness.
SECRET MISSION 15
"W-what happened?" he asked weakly.
"Take it easy, Dad," Tom soothed him. "Everything's okay and we're back on 
Fearing."
X rays had revealed a slight concussion and bone bruises. Doc Simpson said 
that it would be necessary for Mr. Swift to remain in the hospital for two to three 
days.
"I'm afraid this fouls up our trip to the city of gold, son," the scientist said with 
a wry smile.
"Never mind that, Dad," Tom replied. "The important thing is that you'll soon 
be all right, and we may have found an important new source of helium!"
"You've tested the sample?" asked Mr. Swift eagerly.
"Yes, and the Swift spectrograph proves that it is definitely helium."
"Fine, fine," his father said. He drummed his fingers on the white bedspread, 
then added, "Tom, we'd better notify the government of this at once. It's too 
important to keep to ourselves."
"I certainly agree, Dad," Tom replied earnestly. "Whom should I contact?"
"Bronson at the Bureau of Mines. He's in charge of all helium production."
"I'll call him right away," Tom promised.
In a jeep Torn hurried to the base headquarters building and put through a 
long-distance call to Washington. When he reported the undersea discovery, the 
government official was very enthusiastic.
"If we can find a way to tap this source of
16 DEEP-SEA HYDRODOME
helium, it would really expedite our space-flight program!" Bronson declared.
"The space-flight program?" Tom puckered his brow. "What's the connection, 
sir?"
"Can't go into it over the phone, but I'll send two men up to your rocket base 
first thing in the morning."
"We'll be waiting for them," Tom replied.
Early the next morning an Air Force jet streaked down on the Fearing airfield. 
Two passengers disembarked-one a rugged, balding man of about fifty with a 
tanned, weather-beaten face. The other, in his late twenties, was dark-haired and 
wiry.
The older man, Dr. Arthur Clisby, was a well-known Bureau chemist. "And 
this is my associate, Bob Anchor," Dr. Clisby said, introducing his companion.
"Glad to know you," said Tom, shaking hands. "And this is Bud Barclay. 
Would you like to have a look at that helium sample right away?"
Bob Anchor grinned. "More than you realize!"
With Bud at the wheel of a jeep, the group sped off to the main laboratory 
building. Here the two chemists eagerly assisted Tom in repeating his analysis 
with the spectroscope. When they finished, the visitors' faces were tense with 
excitement.
"Incredible!" gasped Dr. Clisby. "This is almost one hundred percent pure 
helium!"
Bob Anchor ripped off his rubber apron and said jubilantly, "If we could 
organize production
SECRET MISSION 17
on a large scale, it would revolutionize half a dozen fields of research!"
"Yes," Dr. Clisby said. "Cargo-carrying balloons would be much cheaper than 
the present planes and they could make use of the jet air stream."
"Also," Tom remarked, "Mr. Bronson mentioned the space-flight program. Is 
the government planning to use helium balloons?"
Dr. Clisby nodded, pausing to light a huge meerschaum pipe. "Right! On 
some of the future rocket and satellite launchings, helium balloons will be used 
as a booster stage. In other words, the launching platform will be raised to the 
outer limits of the atmosphere by means of these balloons."
"That will save fuel," Tom agreed, "but it will take immense quantities of 
helium if the method is used for all rocket experiments."
"That's just it!" put in Bob Anchor. "We need a new source of helium in a 
hurry and this undersea bed could be the answer!"
Bud, who was looking on, grinned at Tom. "How soon do we take off, 
skipper?"
The young inventor smiled. "We could leave almost immediately, if these 
gentlemen agree."
"You mean to make a preliminary survey?" Dr. Clisby asked.
Tom shook his head. "I'd start drilling operations, using my atomic earth 
blaster."
"Great!" said Dr. Clisby and Bob Anchor nodded. Both men were familiar with 
Tom's
18 DEEP-SEA HYDRODOME
earth blaster, which he had invented to tap a new source of iron at the South 
Pole. "However," the senior chemist went on, "what about capping the flow if the 
drilling proves successful?"
"I've thought of that," Tom replied. "My gadget must be strong enough to 
stand up against a geyser. Last night I had a special well-capping device rigged 
up in the base machine shop. Here's the principle."
Pulling out a pencil, he made a quick sketch of his arrangement. Both 
government chemists gave admiring approval.
"Should work perfectly!" said Dr. Clisby. "Well, I'm in favor of leaving as soon 
as possible to find out the extent and depth of these wells. Of course the 
expedition must be kept secret until the United States has staked an official 
claim."
"So far, no one outside Swift Enterprises and the Bureau of Mines knows 
about the discovery," Tom assured him. "And we'll keep it that way!"
Within half an hour, the Fearing rocket base was bustling with activity. A crew 
of mechanics swarmed over the Sea Hound to repair the hatch damaged by the 
undersea geyser. Every part of the craft, which could wing its way through the air 
as easily as it could navigate to great depths under water, was tested. After the 
check was complete, supplies and equipment were loaded aboard, including 
Tom's well-capping device and an extra Fat Man suit.
Meanwhile, an atomic earth blaster was flown
SECRET MISSION 19
in from Shopton. Shaped like a gleaming torpedo, it was radio-controlled and 
had a launching rig capable of withstanding great pressure. Its nose tip was 
designed to smelt the hardest rock.
By noon this, too, had been loaded aboard and the seacopter was ready for 
take-off. Tom lunched with his father at the infirmary. Then, assured that Mr. 
Swift's progress, though slow, was satisfactory, Tom sped to the airfield by jeep. 
Bud Barclay, Dr. Clisby, and Bob Anchor were waiting for him.
"All set, skipper?" Bud greeted him eagerly.
Tom grinned back. "We're on our way!"
All four climbed aboard and Tom took his place at the controls. As he gunned 
the throttle, the rotors whirred into life and the sleek craft rose skyward.
In a few seconds both ocean and distant coastline were far below. Then Tom 
cut in the forward jets and the Sea Hound streaked off toward the South Atlantic.
Bob Anchor, who had served a post-college hitch in the Air Force, was 
impressed. "Tom, if your new helium strike pans out half as well as this baby, it'll 
be a rip-snorter!" he exclaimed.
"Wait'll you see this hound dive!" Bud told him with a chuckle.
Reaching the site of the helium bubbles, Tom brought the seacopter down on 
the water and reversed blade pitch. Then he shoved the control wheel forward 
and the Sea Hound plummeted downward into the ocean depths.
20 DEEP-SEA HYDRODOME
Dr. Clisby marveled at the strange, phosphorescent fishes that darted past 
the cabin window. "Fantastic scene!" he exclaimed.
Soon the seacopter settled onto the ocean floor at the site of the helium. 
Climbing into Fat Man suits, Tom, Dr. Clisby, and Bob Anchor went out to explore 
the bubbling area while Bud manned the controls.
After selecting a spot for drilling, they unloaded the launching platform 
through the ship's air lock and fastened it into the rock below the ooze with 
spread anchors. Next, the earth blaster was maneuvered into place and quickly 
set up.
Then, the men worked on the capping device. To keep it in place, they shot 
rocket anchors into the bedrock. The nozzle, which would be open at first, was 
protected from the sea water. It would close gradually, until the device sealed 
itself.
"All set now. Stand back!" Tom warned his two companions by sonarphone. 
"I only hope we don't start another geyser!"
When the men signaled back an okay, Tom switched on the power. As the 
blaster bored into the sea floor, the three scientists turned off the searchlights in 
their Fat Man suits. In the yellow glare of the seacopter's giant beam they 
watched the flow of gas from the end of the blaster.
Suddenly the Sea Hound's light blinked off and on, as if in a warning signal. 
Surprised, Tom asked over his mike, "What's wrong, Bud?"
SECRET MISSION 21
He stopped short as the searchlight went off again-and stayed off. Instantly 
Tom sensed danger. He turned off the blaster, which by now had completely 
disappeared under the sea floor. Then Tom told his companions to keep their 
lights out.
Everyone waited tensely.
CHAPTER III
UNDERSEA ROVER
A FEW seconds later Tom's sonarphone detected sounds that made him 
stiffen with apprehension. An underwater craft was coming rapidly toward them 
from the south!
Tom was puzzled. He was sure no one from Enterprises would be coming 
from that direction, and he had never heard of any submarine besides the 
seacopter that could dive to this depth.
Of one thing he was sure: He did not want to be seen at the secret project! 
Over his mike he told his companions:
"Lie down! Camouflage yourselves! Don't move!"
Obediently the two grotesque-looking Fat Men followed Tom's example as he 
worked the controls of his suit so that it stretched out into a mass on the ocean 
bottom.
As they waited in worried silence, the strange submarine came on steadily 
and passed within a few hundred yards of the three prospectors. In
22
UNDERSEA ROVER 23
a moment its searchlight disappeared from view and the throb of its engines 
dwindled off in the distance.
Tom now turned on his light and slowly worked the pantograph arms and 
legs to bring his Fat Man upright again. The other two were soon standing up 
also. To Tom's amazement, the Sea Hound was gone!
"Where did it go?" he puzzled.
Over the sonarphone Dr. Clisby asked urgently, "What about that sub? 
Whose was it?"
"Can't even guess," Tom replied.
As he spoke, another light flashed on and drew closer. Tom's heart leaped 
with relief as he recognized the outlines of the Sea Hound!
"Everyone okay?" Bud inquired.
"I think so," Tom told him. "How about you, Bob?"
The young chemist responded that he was all right but thoroughly mystified 
by the unknown submarine.
"Aren't we all!" Bud chuckled. "That's why I ducked out of sight. Tom, do you 
think it was someone who got wind of our operations and was trying to find you?"
"Could be," Tom admitted in a worried voice. "As far as I could make out, the 
sub had no marks of identification. However, we went into hiding ourselves when 
you ducked out of sight, and I think our helium secret is safe. So let's get on with 
the drilling."
"Rogerl"
24 DEEP-SEA HYDRODOME
"First we'll put the capping device in place," Tom said.
The men labored with their mechanical arms to lower the tube-shaped device 
into the hole already cut by the blaster. The power was turned on and the capper 
ground itself into the rock. Tom adjusted the main valve to an open position so as 
not to restrict the flow of vaporized rock from the well.
Once again Tom switched on the power, and the blaster resumed its 
downward boring into the sea floor. Several minutes later a hissing roar, deep 
and muffled, could be heard over the sonar-phones.
"We've struck gas, I think!" Tom cried out to his companions.
Reversing the controls deftly, he brought the blaster zooming up backward 
out of the shaft. There was a pinging noise, like a cork being pulled from a bottle, 
as the blaster cleared the surface of the sea floor. Then a terrific geyser of helium 
gas shot upward!
"You've done it, skipper! Nice going!" Bud cheered from the Sea Hound.
Tom turned the controls that closed the well, stopping the flow of gas from 
the undersea mountain.
"Tom, this is wonderful! We have that new supply of helium right in our 
grasp!"
"Fine so far," Tom agreed with a smile. "But we must still-"
His words were cut short by a strangled cry
UNDERSEA ROVER 25
over the sonarphone. "Help! S-something's gone wrong with my air supply!" It 
was Bob Anchor's voice. "I can't b-b-breathe!"
The call died away in a choking gasp!
"Quick! We must get him back to the ship!" Tom urged Dr. Clisby.
In agonized suspense, the two waddled through the water as fast as they 
could to their friend's side. Through the view pane, they could see Bob's eyes 
bulging, his face turning reddish purple!
"We must hurry!" Tom urged.
He and Dr. Clisby grasped the helpless form and carried it to the seacopter. 
The air-lock hatch swung open, and Bob was shoved aboard. Entering 
themselves, they soon had the gasping figure safely inside the Sea Hound's 
cabin.
"I'll get him out!" Bud offered.
Swiftly he undamped the suit's view pane and hauled out the nearly 
unconscious man. Bob Anchor's mouth hung open and his chest heaved 
spasmodically as he gulped in lungfuls of air.
Stretching him out on the deck, Tom applied artificial respiration for several 
minutes. When Bob's breathing became more quiet and regular, the dark-haired 
young chemist was moved to a bunk.
Dr. Clisby got a bottle of smelling salts from the first-aid locker and waved it 
under Bob's nose. Soon his color became normal and he was able to talk.
"Man, what a close call!" the young chemist gasped with a wry smile.
26 DEEP-SEA HYDRODOME
"What went wrong?" Bud queried.
"Something happened to his air supply," Tom replied.
Taking a small kit of tools, he crawled inside the defective Fat Man and 
tinkered for several minutes.
"Flutter valve was jammed shut," he announced as he emerged from the suit. 
"But it's fixed now."
The near-tragic accident was temporarily forgotten when the group excitedly 
discussed the helium strike on the mountain shelf.
"Judging by the quantity of gas bubbles, this whole area is loaded with 
helium!" Bob Anchor declared.
"Fine," said Bud. "But what method are you going to use to get the stuff two 
miles up to the ocean surface?"
There was a spurt of comments and suggestions from the two chemists. 
Then Dr. Clisby flashed a quizzical smile at Tom.
"Some of our ideas may be usable," he said. "But I think we're going to have 
to rely on those famous Swift brains to supply the best answer. How about it, 
Tom?"
The young inventor grinned. "I'm already working on something at 
Enterprises that may help us," he admitted. "Tell you about it later. But first let's 
get the blaster on board and start back to Fearing."
Bob Anchor wanted to help, but Tom insisted that he rest. Bud, of course, 
was needed at the

28 DEEP-SEA HYDRODOME
controls to maneuver the seacopter. Though it was a difficult task, Tom and 
Dr. Clisby managed to release the launcher and blaster. Then, with the help of a 
hoist, they brought them in through the air lock.
Moments later, the Sea Hound rose slowly from the ocean depths. As it 
broke surface, Bud reversed the blade pitch and gunned the rotors to high speed. 
Like a huge flying fish, the craft soared off above the waves.
Tom stood at the cabin window, wrapped in deep thought, as they streaked 
through the sky toward Fearing Island.
"Look at that furrowed brow," Bud teased. It's a sure sign that genius boy is 
cooking up something big! Right, pal?"
The young inventor chuckled. "All right. You wanted to know how I propose 
getting the helium in large quantities. I believe the only feasible way is to sink a 
huge air bubble over our drilling setup. We could maintain a breathable 
atmosphere inside the bubble and work there."
"A huge air bubble?" Dr. Clisby frowned. "I'm afraid I don't understand. How 
could such a bubble be formed?"
"That's where my new invention comes in," said Tom. "It's a selective matter 
repeller. I've named it the repelatron. If it works out successfully, we could use it 
to repel the water all around us, thus creating a livable air space."
"How does your repelatron operate?" Bob Anchor inquired, greatly intrigued.
UNDERSEA ROVER 29
Tom grinned. "Well, here's the principle. As you know, matter is made up of 
molecules, which in turn are composed of atoms. And each atom has a central 
nucleus with one or more electrons orbiting around it, like tiny planets going 
around a sun."
As the young inventor paused, Bud Barclay said, "I get the idea so far. But 
keep it simple."
"Well, the inner arrangement of these atoms is different in each kind of 
matter. For instance, iron has one kind, carbon another. And because their atoms 
are different, they each give off a distinct type of radiation, which can be seen 
under a spectroscope."
"Quite so," agreed Dr. Clisby. "And by studying the color spectrum of its 
radiation, we can identify what kind of matter we're looking at."
"Sort of a chemical fingerprint in technicolor." Bud chuckled. "Is that right?"
"Precisely," Dr. Clisby replied.
"The molecules in sea water," Tom went on, "are made up of various kinds of 
atoms, each of which gives off its own special radiation, as I just explained. If I 
can pick up and analyze the radiation at the helium wells, and then generate a 
counterradiation wave, I can repel the sea water."
"That's right," said Bob. "This counterradiation will be exactly out of phase 
with the incoming radiation-and thus exert a repelling force on the sea water."
"Right."
30 DEEP-SEA HYDRODOME
Dr. Clisby and Bob Anchor were amazed at the idea, though somewhat 
dubious about the outcome.
"It's terrific, all right," said Bob. "But will it work?"
Bud Barclay, who had never known Tom to fail, said loyally, "Listen! If Mr. 
Brain Wave says the plan figures, it's in the bag! Only thing is," he added with a 
grin, "the contraption's way over my head. I never got beyond being a pilot."
"But what a pilot!" Tom exclaimed. "The world's best! And look, Bud. You 
remember that resistorizer gadget I cooked up down in New Guinea?"
Tom was referring to the adventures that he and Bud had experienced in his 
ultrasonic cy-cloplane when the inventor had to cope with a deadly knockout ray 
developed by an unscrupulous scientist.
"Sure." Bud nodded.
"Well, that gadget was a radiation neutralizer because it changed the 
knockout waves that were fired at us into heat. What my new repelatron will do is 
simply to hurl back any source of incoming radiation waves. In other words, the 
two opposing rays will repel each other, just like two similar poles of a magnet."
Bud scratched his head. "It sounds like a neat trick." He brooded for a 
moment, then burst out, "Say, wouldn't the same idea work on other stuff besides 
water?"
"Yes," said Tom, "if I can iron out the bugs.
UNDERSEA ROVER 31
Later on, if my first model proves to be successful, I'd like to build repelatrons 
to repel other substances, like iron, aluminum, and so on."
The young scientist got up and paced the deck excitedly.
"Just think!" he exclaimed. "In time, I might even design special repelatrons 
to be used as motive power for rocket ships and aircraft."
The others were carried away by the sweeping picture which his words 
painted.
"Tom," said Dr. Clisby, "this could be a terrific achievement. You could 
manufacture repelatrons to be used as military force rays and protective screens 
to defend our country against attacking missiles!"
The young inventor grinned. "One job at a time, Doctor," he said simply.
When the travelers sighted Fearing Island, Tom signaled for clearance. A few 
moments later the Sea Hound hovered down and landed on the airfield.
"The old place looks pretty good," said Bud. "First thing I'll do is-"
He never finished the sentence, for at that moment the island rocked violently 
and everyone was thrown to the ground.
"An earthquake!" Dr. Clisby cried out.
CHAPTER IV
THE MYSTERIOUS CHESTS
AS THE earth tremor continued, Tom realized that a tidal wave would surely 
follow. He looked around for a place to which he and the others might escape.
At that instant came a deafening crash from across the island. A huge cargo 
rocket whose needle nose loomed against the sky in a launching platform had 
toppled, bringing a gantry crane down with it in a mass of tangled wreckage!
Tom groaned. But he was relieved to see that the dispatcher's tower, though 
swaying, was still standing. He cried out, "Men, get to the tower fast!"
All of them started off at top speed, for already they could see a wall of water 
about to inundate the island. The group reached the building with only seconds to 
spare.
As they raced up the stairs, the dispatcher's voice could be heard calling 
orders through the
32
THE MYSTERIOUS CHESTS 33
mike. "Attention! Danger! Tidal wave!" he warned. "Everyone take to a high 
place!"
From the windows Tom and his friends could see workmen running to higher 
ground. By now the quaking of the earth had ceased, but the sea water was 
rolling over the island in a mighty ten-foot-high wave. The tower trembled and the 
men held their breaths, hoping that the building would stay erect.
"I hope everyone's safe," Tom said in a low voice, thinking particularly of his 
father. The infirmary was on the first floor of a low building.
As the water began to recede, Tom grabbed up binoculars to survey the 
damage. In relief he noted that no men seemed to have been caught outdoors. 
He now trained his gaze on the infirmary. Every door and window had been 
closed and fortunately were unbroken. The same condition existed, so far as 
Tom could see, in every building on the grounds.
"Your warning paid off," Tom told the dispatcher.
"Thank goodness!" the man said.
Tom asked him to get a report from each section and in a few minutes 
learned that everyone was safe and the damage slight.
As soon as travel outside was feasible, Tom and his friends went out on the 
field. To their relief, the Sea Hound had withstood the onslaught. The men 
uprighted an overturned jeep which started with a roar, water pouring out of the 
exhaust pipe.
34 DEEP-SEA HYDRODOME
"I guess she'll take us to the administration building," Tom said. "Hop in."
Tom stopped for a few minutes at the infirmary. His father declared that he 
was none the worse for the scare of the earthquake, but Tom thought he looked 
very pale and thin.
"Are you sure you're all right, Dad?"
"Of course. Stop worrying and go find out what happened on the island."
"Right away."
When he and his friends reached the base headquarters, Bud took Dr. Clisby 
and Bob Anchor to a reception room, and Tom went hurriedly to his office. Here, 
phones were ringing and the clerical staff was in confusion.
"You got back just in time, skipper!" said Hank Sterling, who had been left in 
charge during Tom's absence. "Reports are coming in."
Sliding into a chair, the young inventor grabbed a phone and listened as 
each unit gave an account of what had happened. Some electronic gear had 
been damaged in the communications center, as well as various other machinery 
not gyroscopically mounted. Luckily, the delicate rocket-tracking equipment, well-
protected in this manner, was in perfect condition.
Aside from cuts and bruises, no one on the island had been hurt. At last Tom 
put down the phone and ran his fingers through his blond crew-cut.
"We can be thankful the damage was no worse,
THE MYSTERIOUS CHESTS 35
Hank. Take a salvage crew, will you, and see about the rocket that went 
over."
"Right, skipper!"
As he left, another man clumped through the doorway in high-heeled boots. 
He was fat, bow-legged Chow Winkler. A former Texas ranch cook, Chow was 
now head chef on Tom's expeditions. In between trips he served Tom and his 
father when they were not going home to a meal.
At the moment his bald head and fancy cowboy shirt were streaked with 
flour, his trousers were soaked, and his leathery face bore the mournful, 
disgusted look of a sick steer.
"Hi, pardner!" he said. "I'm sure glad to see yo', but I cain't face that galley o* 
mine. No siree! Reckon it'll take a salvage crew to clear up that mess!"
"What happened, Chow?" asked Tom, almost grinning in spite of the 
situation.
"What didn't happen? Brand my biscuits, that place looks worse'n a one-
wheel chuck wagon that's jest been hit by a Texas twister!"
Overcome, the stout cook slumped into the nearest chair.
"Pretty bad, eh?" said Tom sympathetically.
"Bad!" Chow shook his head. "When the quake hit, I was up on a stepladder 
reachin' fer a bag o' flour on the shelf. First thing I knew, the ladder crashed over 
an' the bag split wide open. Then a twenty-pound cheese come rollin' down on 
my head!"
36 DEEP-SEA HYDRODOME
Rubbing his sore bald spot, the Texan added, "That was only the beginnin'. 
By the time things stopped shakin', I was swimmin' in about four gallons o' oyster 
stew the boys asked me to make. Hot oyster stew!"
The picture Chow painted was so funny that Tom roared with laughter. "Don't 
worry, Chow," he said, slapping the cook on the back. "I'll be around with a mop, 
just as soon as I get a work gang busy on that rocket!"
After Chow went off, Tom picked up the phone again. "Please get me 
Professor Quinn at Grandyke University," he told the operator.
Professor Quinn, an old friend of the Swifts, was one of the country's 
foremost seismologists.
When he answered, Tom said, "Professor, did you get a fix on that tremor we 
felt here at Fearing Island about half an hour ago?"
"We certainly did, Tom! Our seismograph showed it was centered on your 
island."
"What!" the young inventor exclaimed. He was worried. There might be more 
trouble ahead!
While he was talking with Professor Quinn, Bud walked in and Tom waved 
him to wait. Presently Tom thanked the professor for the information, then hung 
up.
Turning to Bud, he asked, "Are you game for another undersea workout?"
"You name it, skipper. What's the deal?"
"The quake was centered here, which could mean we might have another," 
Tom explained.
THE MYSTERIOUS CHESTS 37
"I'd like to check around the island below the water line and see if we can 
spot any fault."
"Let's go!" said Bud promptly.
Commandeering a truck, the two boys loaded two Fat Man suits aboard and 
headed for the north dock. Here they climbed into the steel escape suits and 
descended.
Fearing Island, near the end of the continental shelf, was a rocky pinnacle 
that rose almost straight up from a great depth. Tom figured that the eruption had 
taken place at least fifty feet below the surface, so at this point he and Bud began 
to work their way around the rocky mass which was coated with sea growth.
For over an hour, they probed the island's foundations inch by inch with their 
searchlights, without seeing any sign of a crevice. Then Tom spotted an 
immense indentation. It was new! Completely devoid of sea growth!
"Bud! Come here! Look!" he cried out.
The opening was large enough for one Fat Man to get into. Tom told Bud he 
was going to do a little investigating.
"Well, for Pete's sake, be careful," Bud urged.
Tom was not gone long. Returning, he startled Bud by reporting that it was 
his guess that the earthquake had not been a natural one.
"Someone put an explosive in there and set it off!" Tom said grimly.
Bud was shocked into silence for a moment, then asked, "An old enemy or a 
new one, Tom?"
"I wish I knew, pal. At any rate, let's look some
38 DEEP-SEA HYDRODOME
more and see if we can pick up a clue as to who was responsible."
There were no pieces of telltale metal in the vicinity, so the boys continued 
their search around the island, with Bud twenty feet above Tom. They had almost 
reached the spot directly under the north dock when a shout came over Tom's 
headphones. Bud cried excitedly, "Pirate treasure!"
"What!"
"On the level, skipper! Come up here and see for yourself!"
Blowing his ballast tanks, Tom rose to the same depth as Bud. To his 
surprise, he found his partner perched in a cavelike opening in the rock.
"Look!" Bud exclaimed. He aimed his suit's searchlight so as to illumine the 
interior of the cave. The yellow glow revealed a number of large dull metal chests 
piled inside.
"Good night!" Tom gasped. "You really stumbled on something!"
"I'll bet there's enough gold in those chests to buy a bank!" Bud babbled on. 
"Let's get a blowtorch, Tom, and open one!"
"Not so fast," Tom cautioned. He extended one of his Fat Man's pantograph 
arms and scratched the surface of the nearest chest. "That stuff looks like lead to 
me-and it hasn't been down here very long, either!"
"You mean-" Bud hesitated.
THE MYSTERIOUS CHESTS 39
"There's no telling what's inside. Let's not take any chances."
Bud stared through his view plate. "You mean just leave 'em here?"
"No," Tom retorted. "We'll haul one up to the surface first, and then 'Open 
with Care'!"
Most of the chests proved to be too heavy to maneuver. But finally the boys 
picked out the smallest of the lot and managed to shove it to the ledge of the 
cave opening.
Here they each gripped one end with the mechanical arms of their Fat Men, 
and then blew their ballast tanks. Slowly the steel eggs rose to the surface, 
gripping their prize securely.
After the boys had beached the chest, Tom radioed the base machine shop 
to send a truck and crane. Twenty minutes later the heavy object was deposited 
safely in his island laboratory.
Doc, Slim Davis, Hank, and Arv Hanson, who by this time had heard about 
the strange find, gathered around eagerly to witness the opening.
"I'm still hoping this chest is full of gold-or silver at least," Bud remarked.
Tom, not daring to use any electronic tools for fear of sparks, began to chisel 
through the welding that fastened the lid to the chest. Finally he pried it open with 
a special cutting chisel.
"Atomic warheads!" gasped Hank.
"Great heavens!" murmured Doc. "There must be enough destructive power 
in this one chest to blow up the whole island!"
40 DEEP-SEA HYDRODOME
"Which might easily have happened," said Tom tersely. He told the group the 
grave fear he had expressed to Bud, and added, "I have an idea an atomic 
warhead went off by mistake on the other side of the island."
"By mistake?" said Bud. "I thought it was done on purpose."
"I've changed my mind," Tom replied with a worried frown. "Furthermore, I 
believe the hiding of these warheads is all part of a big and sinister plot against 
our government."
CHAPTER V
ATOMIC PATROLS
THE MEN in the laboratory stared at Tom as the full import of his words 
struck them.
"You mean," Slim spoke up, "that the planting of the atomic warheads is the 
work of saboteurs hired by a foreign country-some country unfriendly to the 
United States?"
As Tom nodded, Hank remarked, "That figures. No private individual would 
have access to atomic warheads."
Tom went on, "That's not the worst of it, either. I'd be willing to bet they have 
caches of these warheads hidden under water at any number of strategic points 
in our oceans!"
"Planted by subs, of course," said Bud. "Say Tom, do you think the sub that 
passed us at the helium field could be mixed up in this job?"
"Could be!" Tom replied. "Bud, you and I are lucky we were in those Fat Man 
suits during our search. They're radiationproof and those
41
42 DEEP-SEA HYDRODOME
waters around this island aren't, thanks to that explosion."
Knowing there was no time to lose, Tom gave instant orders for a half mile of 
ocean around the island to be off limits for anyone not wearing a Fat Man suit. 
Then he said:
"It's dangerous to leave those other chests down there. We must get them up 
right away."
"But how?" Bud asked.
"I'll use Dad's vacuum lifter," Tom said, then turned to Arv Hanson. "Call 
Enterprises, will you, Arv, and have them fly one over."
"Right away!" Arv hurried off to the communications building to put in the call 
to the mainland.
Meanwhile, under Tom and Hank's direction, a winch and boom were set up 
on a rocky out-thrust near the point where the boys had brought the first chest 
ashore. By the time it was ready, a big cargo jet from Swift Enterprises was 
already touching down on the island airfield.
The vacuum lifter was quickly unloaded and trucked to the beach. Hank 
rigged it to the boom and connected the power cables to a portable generator. 
When everything was ready, Tom and Bud would go below in Fat Man suits to 
guide the vacuum lifter to the chests.
"How about you two going out in a boat right now and pinpointing the right 
spot for the lifter to go down?" Hank asked Tom and Bud.
"Right away," Tom agreed.
A rowboat and oars covered with radiation-
ATOMIC PATROLS 43
proof paint was brought to the dock. Tom and Bud stepped in. A few strokes 
of the oars brought them to a spot which they both felt was approximately above 
the cave opening.
"Okay. Right here!" Tom called.
Hank flicked on power to swivel the boom into position. As the boys watched 
it swing out over the water, they were suddenly horrified to see the hoisting 
cables part! The heavy machine came whipping toward Tom and Bud like a giant 
octopus about to strike!
"Jump!" yelled Tom.
In the nick of time, he and Bud plunged headfirst into the water. They came 
to the surface twenty yards away, shaking the water from their eyes.
Bud managed a grin. "Good thing our reflexes were working or we'd be 
deader than mackerels by now, genius boy!"
"Hurry, Bud! Out of the water! We must get to Doc right away and have him 
run us through a check for radiation!"
They climbed into the boat, pulled to shore, and set off for the infirmary. Two 
hours later the cable was repaired and the boys returned to the project.
"How about it?" Hank asked.
"We're pure as strained honey," Bud answered, "and ready for another 
plunge. Where's my Fat Man?"
He and Tom climbed into their suits. "Give us a while to get down there and 
then lower
44
DEEP-SEA HYDRODOME
away on signal," Tom ordered Hank, then locked his view plate.
Opening valves to flood their suit tanks, the two boys settled back in their 
steel eggs. In a moment they were plummeting downward.
As soon as the cave opening became visible to them, they closed the valves 
and propelled themselves toward the undersea cliff wall.
The chests were gone!
"Tom!" gasped Bud over the sonarphone. "Someone's beat us to it!"
"Yes," said Tom. "And there's no doubt in my mind who it was-the men who 
planted them!"
"Do you think they found out we were going to bring the chests up?" Bud 
asked.

ATOMIC PATROLS
45
"I'm sure of it. They've been spying on us." Tom's jaw set grimly. "Let's look 
around."

46 DEEP-SEA HYDRODOME
But the cave proved to be barren of clues. Aside from the fact that the chests 
were gone, the unknown marauders had left no sign of their visit. More worried 
than ever, Tom gave orders to surface.
Back on land, he drove to the infirmary and gave a detailed account to his 
father. Mr. Swift was dismayed by the news.
"Better report this at once to our friend Admiral Hopkins at Navy Intelligence," 
he suggested.
When the long-distance call was placed to Washington, Admiral Hopkins 
promised instant action. "I'll order out every available sub to comb our coasts for 
other caches," he told the young inventor. "Thanks to your warning, we may be 
able to prevent a terrible disaster!"
Tom promised that his own seacopters would assist in the hunt in lower 
waters, beyond the operating depth of conventional undersea craft. One of his 
jetmarines would also patrol the waters around Fearing Island to prevent any 
more chests from being secreted.
Shortly before six the next evening, Tom, Bud, and Mr. Swift, now able to 
travel, said good-by to Dr. Clisby and Bob Anchor who would remain at Fearing 
while the others made a trip home. From the Enterprises landing field they drove 
to the Swift home in Bud's red convertible.
Tom's slim, pretty mother and his blond, blue-eyed sister, Sandra, greeted 
them at the front door.
ATOMIC PATROLS 47
"Oh, I'm so glad to have you all safely home again," said Mrs. Swift, 
embracing them.
"Glad to see me, Sandy?" Bud asked with a wide grin.
"Any girl likes to see her date show up, doesn't she?" Sandy retorted 
impishly. With a mischievous twinkle in her blue eyes, she added, "You were 
coming to dinner tonight, I believe?"
In the big, cheerful living room, another girl was waiting to greet the 
homecomers-Sandy's school chum, Phyllis Newton. Phyl, dark-haired and 
beautiful, with laughing brown eyes, was the daughter of Mr. Swift's long-time 
associate, "Uncle Ned" Newton. Like Sandy, she was a year younger than the 
two boys. Phyl was Tom's favorite date and the two couples often went to parties 
and dances together.
"Did you boys bring Phyl and me any treasure from your deep-sea dive?" 
asked Sandy gaily.
"No pearls that deep," Tom answered. "But Bud will tell you about the pirate 
chests he found. Before he could bring you any of the gold doubloons, somebody 
stole them."
Over a delicious dinner of roast turkey and apple pie a la mode, Mr. Swift and 
the boys described their adventures. But they refrained from telling of the atomic 
warheads planted under Fearing Island, for fear of worrying Tom's mother and 
the girls.
"I do hope this new helium project won't take you away from home too 
much," said Mrs. Swift.
48 DEEP-SEA HYDRODOME
Mr. Swift smiled fondly at his wife. "Don't worry, Mary dear. No expedition will 
ever keep us away a day longer than necessary!"
Early the next morning Tom drove to his laboratory at Swift Enterprises. Here 
he plunged feverishly into work on his repelatron.
The electronic circuits for his first model had been designed before he left 
with his father on their cruise to the city of gold. But his mind was already 
teeming with ideas for changes and improvements.
After sketching out the new circuit diagrams, Tom set to work with an array of 
tubes, transistors, wires, condensers, and resistors.
Shortly before eleven o'clock Bud joined him. Though he seldom fully 
understood Tom's inventions, the young flier never ceased to wonder at the 
amazing products of his friend's fertile brain.
"How're you coming, skipper?" he inquired.
Tom laid down his soldering gun and wiped the perspiration from his 
forehead. "Almost done -with the improved pilot model, anyhow. Keep your 
fingers crossed."
Bud stared at the compact but tangled mass of electronic parts and shook his 
head. "Looks like spaghetti to me."
Tom burst out laughing. "Actually it's quite simple. There are only six main 
parts to the gadget."
"Go ahead and name 'em-just to confuse me," Bud retorted.
ATOMIC PATROLS 49
"Well, first, this is the detector, to pick up the radiation from whatever we 
want to repel-in this case, water. Then there's an analyzer to break down the 
radiation into its separate components; an amplifier to boost the strength of the 
signal; and a phase inverter to put the radiation exactly out of phase."
Tom paused and grinned at Bud, whose eyes were already assuming a 
glazed look. "Next is the power amplifier to produce the output wave. And last is 
the radiator which sends out the radiation to repel the water."
Bud gave a deep sigh. "You lost me on the booster," he said.
Tom chuckled. "Never mind, Bud, you'll see when it works. Which reminds 
me, I have a job for you."
"At your service, boss!" Grinning, Bud snapped a smart salute.
"Hop over to Fearing and get the seacopter ready for another trip. We'll be 
taking a full crew from Enterprises this time, including a photographer."
"What are we after?" asked Bud, his face turning serious. "More helium 
samples?"
"No. Sea water samples from around the helium area," Tom explained. "I'll 
have to analyze the water's exact molecular structure in order to plan my full-
scale repelatron properly."
"What's the matter, skipper? Couldn't you make a solution good enough to 
use?" Bud asked.
"Salt water," Tom answered, "differs from one
50 DEEP-SEA HYDRODOME
place to another. The repelatron must have an exact sample of what it is to 
repel."
Bud nodded. "Right, pal. I'm on my way!"
As he hurried off to the Enterprises airfield, Tom went back to work. It was 
nearing noon when the pilot model of his new machine was finally ready for a 
tryout with fresh water. Tom had installed the electronic chassis in a metal case, 
and the radiator was housed in a shiny silver sphere.
Switching on the power, he lowered the sphere into a tank of distilled water. 
To his delight, it worked perfectly! On all sides of the sphere, the water drew 
away, leaving it dry and untouched in its surrounding air space!
Just then, the wall phone rang. Leaving the repelatron in operation, Tom 
walked over and lifted the receiver.
"Tom Swift Jr.," he began.
But his words turned into a startled gasp as he heard a sound of shattering 
glass behind him!
CHAPTER VI
THE STALKING SUB
TOM whirled around from the telephone to see what had happened. Water 
had flooded out of the tank, over his workbench, and splashed across the floor! 
Other bottles of distilled water in the room had been hurled against the wall and 
crushed. Walls and floor had been showered with water and broken glass.
"Can't talk now! Call back, please!" Tom cried out. Putting the phone back on 
the hook, Tom dashed to the laboratory table and switched off the repelatron.
In spite of the mess and breakage, the young inventor could not restrain a 
pleased grin. His device, with its improvements, worked even better than he had 
hoped! It not only repelled the water around the radiator sphere, but it had 
literally hurled it from the tank, and even acted on bottles of water ten feet away!
"Man alive"-Tom chuckled to himself-"if it works this forcefully at the helium 
wells, I'd better watch out. It might cause a tidal wave!"
51
52 DEEP-SEA HYDRODOME
As he started to clean up the broken glass, Chow Winkler came galloping 
into the laboratory.
"Brand my atomic saddle, what's goin' on?" the old Westerner panted. 
"Sounded like there was a loco steer loose in here I Where is he? I'll git him!"
"Relax, old-timer." Tom grinned. "It was only my new repelatron."
"Your new w/miz-atron?"
"Repelatron," Tom repeated.
The stout cook glowered suspiciously. "If that means a new janitor, you'd 
better fire him pronto before he breaks somethin' else!"
Tom slumped down on a stool, shaking with laughter. "Don't worry, Chow, it's 
not alive. It's just an invention of mine."
"Per smashin' things up? Must be a funny sort o' contraption!" Chow stared 
at the odd-looking device on the workbench. "Reckon you're jest pullin' my leg, 
ain't you, Tom?"
"Not really, Chow," the young inventor replied. "The purpose of this device is 
actually to repel water."
"Well, it sure works fine!" Glancing around at the dripping walls and puddles 
on the floor, the cook scratched his balding head. "But why in the name o' prairie 
grass d'you want to fuss around with a thing like that? Wouldn't a squirt gun do 
jest as well?"
"Afraid not, Chow," Tom answered. "You see,
THE STALKING SUB 53
I'm trying to figure out a way to get helium gas from some wells located about 
two miles underneath the ocean. And in order to carry out such large-scale 
operations there, we'll have to create a big air space so we can work on the 
mountainside."
"You mean it'll be like a giant bubble?"
"That's right," Tom nodded. "We'd be inside it-and not get wet!"
Chow's weather-beaten face, tanned brown as leather by the desert sun, 
gaped in amazement. "Well, I'll be a bang-tailed bronc! Jest think o' that-folks 
livin' inside a bubble!"
"Shouldn't bother an old space-puncher like you," said Tom with a smile. "Not 
after living up on Little Luna with no air at all!"
The Texan chuckled as he recalled their recent space voyage to the phantom 
satellite. "Brand my asteroids, that was really somethin'! But I reckon livin' in a 
bubble might be a bit nerve-janglin' jest the same! What if a whale comes pokin' 
his nose in the galley?"
"You might offer him a cup of tea," Tom quipped.
"That ain't all," Chow grumbled. "On a stormy day it might even rain cat-and-
dog fish on us!"
The young inventor roared with laughter. "Seriously, Chow," he admitted, "we 
will need some kind of fish screen for our helium city. But so far I've been 
concentrating on my repelatron
54 DEEP-SEA HYDRODOME
for holding off large quantities of sea water. If that works, I'll put a protective 
covering over us."
"You figurin' on buildin' a whole city down there?" the cook asked, amazed.
"It'll have to be a pretty big setup," Tom conceded. "Besides a full-scale 
repelatron, there will be the drill rigs, crew's dormitory, gas tanks-"
"How about some kind o' cook shack?"
"There'll be one," the young inventor promised. "But you'll have to figure out 
some new angles on cooking."
"How's that, partner?"
"No salt in the water. It might make a solution similar to the ocean around 
us," Tom explained tersely. "Then the repelatron would hurl it right out of the 
airdome."
Chow looked unhappy. "But how in tarnation d'you expect me to run a decent 
galley? How'll things taste?"
"I'm sure you can manage." Tom grinned. "You can still bake and fry, or use 
a can opener."
Chow merely snorted contemptuously, as Tom went on, "Any liquids which 
aren't pure water or salt water can be used. Like milk, cocoa, or fruit juice, for 
example. And for washing or cleaning, we can use ultrasonic equipment as they 
do in many industrial plants."
The old cowpoke considered. "Well, mebbe. But how about me? I sure don't 
want to be shot out o' that there bubble, an' I got plenty o' salt water in my blood."
THE STALKING SUB 55
"That's different," said Tom. "It's not like that in the ocean, so you're safe."
Chow felt reassured and stomped off.
After a lunch of ham sandwiches and tomato soup which Chow brought in on 
a lunch cart, Tom went back to work on his repelatron. By changing the design of 
the power amplifier, he was able to perfect the control of the repelling force, with 
no further accidents to his workshop.
Getting up from his lab stool, Tom stretched his cramped muscles. "Well, at 
least the new pilot model works okay," he reflected with satisfaction. "Now to go 
back to the wells and do some work."
Picking up the phone, he called one of the hangars on the Enterprises 
airfield. "Get a plane ready for take-off, Mike," he told the crew chief. "Make it one 
of our Pigeon Specials. I want to fly over to Fearing Island."
Then he rang up Scotty McGurk, the small, red-haired Scotsman, who was 
the plant's photographer. "Bring the deep-sea camera out to Hangar B," Tom 
said. "We're going on a sea-copter cruise. You'll get pictures of a mysterious 
underwater mountain while the rest of us look over the spot with a view to 
building a small city there."
"Aye-aye, skipper!" replied Scotty, delighted.
Twenty minutes later they were on their way in the sleek two-place aircraft 
which Tom had chosen for the trip. Produced by the Swift Construction Company 
under Uncle Ned Newton's
56 DEEP-SEA HYDRODOME
management, the Pigeon Special had become one of the most popular light 
planes on the market.
After landing at the rocket base, Tom and Scotty hurried over to the 
sprawling hangar where four of the Enterprises' seacopters were usually berthed. 
Here they found Bud working with a team of mechanics on the Sea Hound.
"Everything shipshape?" Tom asked.
"We can take off as soon as they finish checking the rotor bearings," Bud 
reported.
"Good work! I'll line up a crew."
Besides Bud, Scotty, and the two government chemists, Tom picked out 
three of his best sea-copter men from among those stationed at the base.
Before leaving, Tom talked to Admiral Hopkins to tell him about his plans and 
to ask if any Navy subs would be in the area.
"No," the admiral replied. "By the way, our men haven't found any caches of 
warheads yet. Thanks for calling and have a good trip," he said, then hung up.
Soon Tom and his fellow travelers were soaring eastward across the Atlantic 
in the Sea Hound. About a hundred miles from the helium site, Tom submerged 
so Scotty could shoot some pictures of the undersea life-his favorite hobby.
"Mon, whut a picture that'll be!" he exclaimed, catching a wing-finned 
monster that flashed into view with its mouth agape.
"It's an angelfish." Tom grinned.
Suddenly Bud, watching the sonarscope, sang
THE STALKING SUB 57
out, "I see a submarine! It's trailing us, skipper!"
Tom frowned. It must be a foreign craft. Was it a friendly one? He stepped to 
the scope to watch the blip himself.
"How long since you first noticed it?" Tom asked.
"Just a few minutes. But she's holding steady on the same course."
Dr. Clisby joined them, his forehead creased in a worried frown. "If it 
continues to follow us, Tom, we'll lead it straight to the helium beds and give 
away the secret!"
"Maybe we can shake it." Tom gunned the jets to high speed. "How about it, 
Bud?" he called as the indicator needle crept to a hundred knots.
"Still on our tail!" Bud reported.
Tom throttled back to half speed, and the mystery sub did likewise. At ten 
knots it still lagged behind.
Exasperated, Tom opened throttle again- forty knots, fifty, sixty, seventy, 
eighty. Still the undersea stalker refused to be shaken off.
"What're they doing? Playing tag?" growled Bud.
"If they are, they'll get no free tickets to jump our claim!" Tom gritted his 
teeth.
Swinging the helm to starboard, he veered sharply off course and headed 
away from the helium fields. After ten minutes the unknown sub was still 
following them closely.
Tom switched on the sonarphone and spoke into the mike. "Sea Hound 
calling strange sub-
58 DEEP-SEA HYDRODOME
marine! Can you read us? . . . Come in, please! . . . Sea Hound calling the 
submarine just astern!"
Receiving no answer, he tried a ship-to-ship challenge in International Code. 
Still the mysterious craft made no response.
"Looks as if they're not eager for a friendly chat," observed Bob Anchor 
grimly.
"I'm going way down and see what happens," Tom muttered.
With a flick of his hand, he cut in more power from the atomic reactor. Then, 
as the rotors hummed at increased speed, he shoved the control wheel forward. 
Like a stone, the seacopter plummeted downward.
Tom was hoping to maneuver under the mystery submarine and then return 
to his original course after shaking it off. But to his dismay the sonarscope 
showed that their pursuer was still in contact.
"Okay, we'll give 'em a real workout!" Tom decided. "I'd like to find out what 
that sub can do. It may give me a clue as to what country owns it."
Holding the wheel forward, the young skipper continued the descent. Down, 
down they plunged. Outside the cabin window the waters grew darker. Still the 
unidentified submarine dogged their wake.
"Wow! How much deeper can they go?" Bud wondered.
Soon both were nearing the ocean bottom.
THE STALKING SUB 59
Tom felt a chill of foreboding. Some foreign power had a submarine capable 
of going to the same depth and performing the same hydrobatics! But the United 
States Government was not aware of this, he knew.
"Ready on camera, Scotty!" Tom snapped, deciding to double back and take 
the submarine by surprise but avoid any encounter with it.
Plunging downward suddenly, he brought the seacopter around in a fast turn. 
As it swept past the mystery submarine, he stabbed the murk with the Sea 
Hound's searchlight.
"Got 'er!" yelped Scotty.
"Now we'll let them think we've left for home!" Tom told him, gunning the jets 
to full power.
CHAPTER VII
A HOODED FIGURE
THE SEACOPTER rose out of the ocean and set off in a straight line for 
Fearing Island. Soon the South Atlantic was left behind.
"Are we going all the way back?" Bud questioned.
"Depends on whether we can shake that sub," Tom answered. "I'm going 
down again now and find out."
He dived and started back for the helium area. After going many miles, he 
sighed in relief. There had been no sign of the mystery submarine.
"I guess we've lost contact," he said finally.
A cheer of relief burst from the Sea Hound's crew.
"Wonderful, Tom!" cried Dr. Clisby. "I guess our helium secret is still safe!"
"Let's hope so," said Tom. Secretly he felt none too certain about this, now 
that he knew the commander of the mystery submarine was interested in him.
Meanwhile, Scotty had developed his photo-
60
A HOODED FIGURE 61
graph of the craft. The film was chemically processed within the housing of 
the camera itself and a print made in a minute. The photographer, not wanting to 
interrupt Tom, had waited until now to show it to him.
"Take a look, skipper!"
The others gathered around to peer over Tom's shoulder. The mystery craft 
was whale-shaped, with a tail design that showed it was obviously jet-propelled. 
Not the slightest mark of identification was visible.
"What a monstrosity!" remarked Bob Anchor, noting its squat, bulging 
contours.
"Let's call it the Mad Moby," joked Bud.
"It may look funny," Tom said seriously, "but don't forget that baby can travel-
and dive! I can see that she's designed to carry plenty of cargo, too."
"Such as atomic warheads?" Dr. Clisby suggested.
"No telling," he said, but was reminded of the cache at Fearing Island.
In thoughtful silence the group continued their undersea cruise. There was 
no sign of the Mad Moby. After reaching the helium fields, Bud and Bob Anchor 
donned Fat Man suits and proceeded to collect numerous samples of sea water 
at various depths throughout the bubbling area.
In the meantime, Tom maneuvered the Sea Hound as close to the 
underwater mountain as he dared, and with Dr. Clisby's help roughly sketched 
the topography of the site.
62 DEEP-SEA HYDRODOME
When the work was finished, Tom left the area, still elated that they had 
outwitted the mystery submarine. Soon they were air-borne again and heading 
back to Fearing Island. When they landed at the rocket base, Dr. Clisby and Bob 
Anchor hurried at once to Tom's island laboratory to analyze the samples of sea 
water.
Meanwhile, Tom arranged to have the photograph of the whale-shaped 
submarine transmitted immediately to the Defense Department in Washington 
over the Swifts' private video network. Half an hour later an urgent phone call 
came back from Navy Intelligence.
"Tom, we've checked every possible source," Admiral Hopkins reported, "but 
so far we have no clue to that sub's identity. There's nothing like it listed in the 
latest issue of Jane's Fighting Ships or any other authority. And we've never had 
word on such a craft from any of our secret agents abroad."
The young inventor flashed a worried look at Bud, seated close by, then said, 
"Admiral, judging by the mystery ship's performance, she can outdo any military 
sub in the world. It can dive as deep as our seacopters, and, as for speed, we 
barely managed to outrun it!"
Admiral Hopkins' voice was grave. "This is serious news. I'll warn all our 
patrols to be on the lookout for it!"
After hanging up, Tom told Bud about the Navy's failure to identify the 
mysterious craft. A moment later Bud smiled wryly. "Tom, if that
A HOODED FIGURE 63
sub can't be traced, maybe your space friends have managed to arrive on 
earth and taken to sub travel!"
"Wish I could believe that," the young inventor retorted. "It would make things 
a lot easier."
Tom thought back to the time when a black missile from outer space had 
landed at Enterprises. The object had contained a message from beings on 
another planet. Tom and his father had finally succeeded in establishing 
communication with the senders, who hoped eventually to come to earth 
themselves. First, however, the problem of penetrating Earth's atmosphere would 
have to be overcome.
During the space beings experiments to accomplish this, they had sent a 
second rocket containing specimens of their planet life. Later, they had moved a 
small asteroid into orbit around the earth. But so far they had not been able, 
apparently, to translate the Swifts' messages telling them about Earth's 
atmosphere and what to expect when they arrived here.
Tom flew back to Enterprises with Bud. They took with them the analysis of 
the samples of sea water from the helium area.
It was past seven in the evening when they landed at the sprawling 
experimental station. Most of the working staff had gone for the day, and only a 
few men were still on duty at the airfield.
"Come on, I'll treat to a steak somewhere in
64
DEEP-SEA HYDRODOME
Shopton," Bud suggested, heading for his red convertible.
Tom shook his head. "Thanks, but I have work to do on my repelatron. I'll get 
something later."
Tom slid behind the wheel of a jeep and drove to his private laboratory. He 
immediately went to work on the problem of adjusting his repelatron for the 
molecular structure of the sea water from the helium area.


66 DEEP-SEA HYDRODOME
"Hmm, it looks as if I may have to redesign the radiation detector 
completely," he muttered.
Soon his workbench was littered with sketches, scribbled calculations, and a 
jumble of electronic parts. Tom became so absorbed in his work that he 
completely forgot about eating.
Hours went by. Outside, the moon glided across the sky and soon the night 
was half over. Finally Tom paused in his work and stretched wearily.
"Good grief, it's ten to three!" he noticed, glancing at the wall clock.
Getting up from his workbench, he went over to check an equation on one of 
his small analog computers. It was standing on a bank of electronic equipment.
Behind him, the door to the laboratory opened silently. Unseen by Tom, a 
hooded figure in a long gown crept into the room. Whisking out a hammer from 
under his robes, the intruder dealt a smashing blow at the repelatron!
Tom whirled at the resounding crash of the hammer on metal. Before he 
could move, another blow completed the wreckage!
Enraged, Tom hurled himself at the hooded figure. With one hand he 
grabbed wildly at the intruder, with the other hand he groped on the workbench 
for something with which to defend himself.
Before he could find a weapon, the figure brought down the hammer with 
stunning force
A HOODED FIGURE 67
on Tom's head! The young inventor groaned and slumped to the floor.
Regaining consciousness, Tom shook his head groggily. His eyes focused 
with effort on the wall clock. Finally he could see the time clearly.
"Only five to three!" he muttered. "I wasn't out long. If I act fast, maybe 
there's still time to catch that fiend!"
Staggering to his feet, Tom made his way over to the wall panel of the public-
address system. His thumb stabbed a switch button, setting off an alarm all over 
the Enterprises experimental station.
"Hear this!" he gasped. "Everyone alerted to -an enemy-on the grounds. A 
hooded figure!"
The words were barely out of his mouth when Tom's last ounce of strength 
gave out. He toppled dizzily to the floor!
CHAPTER VIII
TELLTALE THREADS
WHEN Tom awoke, the first thing he noticed was a faint odor of ether and 
antiseptic. His eyelids flickered open and he saw a white coverlet and the rungs 
of a metal bedstead. With a start, Tom sat bolt upright. He was in the Enterprises 
infirmary!
"Thank heavens you've regained consciousness, son!" murmured a voice 
nearby. Mr. Swift gripped Tom's hand. Then the young inventor realized that his 
whole family was clustered around the bedside, with Doc Simpson in the 
background. Tom managed to grin wanly at them as he felt the bandage on his 
head.
"We've been so worried about you, dear!" his mother said, bending down to 
kiss his cheek. "Even though Doc Simpson says that you'll be all right."
The young medic smiled reassuringly. "Yes, he will, Mrs. Swift." Then, 
grinning, he added, "Being a hardheaded scientist, Tom won't have any 
aftereffects from that bump on his skull."
68
TELLTALE THREADS 69
Stepping forward, the young physician took Tom's wrist and glanced at his 
watch. Seconds later he said, "Pulse rate normal. Feel hungry?"
"I could eat a horse!" Tom chuckled. "Just remembered-I didn't have supper 
last night."
"No supper!" Doc Simpson clucked his tongue reprovingly. "That explains 
your condition. No food and no rest. It wasn't only that blow on the head that kept 
you unconscious so long. It was nature forcing you to recharge your batteries." 
Pressing a button beside the bed, he added, "With a good lunch inside you, you'll 
feel like a new man."
"Lunch!" Tom exploded. "Hey, what time is it?"
Doc grinned. "Almost noon."
"Well, good grief, I can't stay here all day!" Throwing off the covers, the 
young inventor started to jump out of bed, but Sandy pushed him back firmly.
"Now stay put. Do you want to bring on a relapse?"
"But that hooded figure-the guy who conked me!" Tom said insistently. "Was 
he caught?"
Mr. Swift shook his head. "I'm afraid not, son. A night watchman found you, 
and the security guards searched every inch of the plant. But there was no sign 
of a stranger anywhere on the grounds."
Tom stared at his father in dismay and groaned. "That means we must have 
a subversive right on our own staff!"
70 DEEP-SEA HYDRODOME
"I know," said Mr. Swift gravely. "It's not veiy pleasant to think one of our own 
men is working against us, but we'll ferret him out. In the meantime, you take it 
easy."
Overruling Tom's anxious protests, his family joined in urging him to lie back 
and rest. With a sigh, the young inventor, realizing he still felt shaky, obeyed.
Soon a nurse brought in a tray of food with an appetizing aroma. Tom's 
family watched with smiling approval as he ate the meal with relish. Then, hoping 
he would sleep for a few more hours, they left him.
Tom waited until they were gone, then grabbed up the phone from the night 
table by his bed. He dialed Harlan Ames, chief of the Enterprises security 
division.
"It's Tom, Harlan," he said. "Any clues yet on last night's saboteur?"
"None so far," the security boss admitted glumly. "If you feel well enough to 
talk, I'd like the whole story."
Tom gave him the facts briefly.
"Looks like an inside job, all right," Ames commented. "I've had your lab 
locked up until we could go over it together."
"Be there right away!" Tom promised. He assured Ames that he felt much 
better. "Food fixed me up fine."
Next he called Bud Barclay. "Get a jeep over here, pal," he requested 
urgently. "The patient is ready for an airing."
TELLTALE THREADS 71
"How about that clout on the head?" Bud countered in a worried voice. "Did 
Doc Simpson say it was all right for you to get up?"
"Don't worry about me. I'm okay," Tom assured him. "And I'll feel a lot better 
if I'm sure that masked figure didn't steal my repelatron drawings and formulas!"
Slipping into his clothes, Tom hurried down the hall. As he ducked out the 
front door of the infirmary, Bud pulled up in a jeep.
"Swell patient you are!" Bud grinned wryly. "I'll bet Doc Simpson crowns me 
when he finds out I helped you escape!"
"Move over and stop fussing." Tom chuckled. "You can tell him I 
overpowered you with a hypodermic syringe!"
Taking the wheel, Tom sped past the north airstrip toward the sleek, glass-
tiered laboratory building. Harlan Ames, dark-haired and slim, was waiting 
outside the door of Tom's private lab.
"Glad you're okay, skipper," he greeted them. "How's the head?"
"Few sizes too big, but still there." Tom opened the door and they went 
inside.
The smashed repelatron was still lying on his workbench, along with his 
scribbled calculations and hasty sketches.
"Apparently your assailant didn't take anything," Ames remarked.
"This stuff wouldn't do him much good," Tom replied. "What I'm worried about 
are the original plans."
72 DEEP-SEA HYDRODOME
Taking an electronic key from his pocket, Tom flicked a combination and 
beamed it at a steel wall cabinet. As the door slid open, he reached in and drew 
out a sheaf of blueprints.
"Still here!" the young inventor exclaimed in relief.
Satisfied that the secret of Tom's new invention was safe, Ames began to 
dust the laboratory for fingerprints. Unfortunately the doorknob had been handled 
by the night watchman and others, and any visible footprints on the rubber-tiled 
floor had been obliterated by the rescuers who had gone to Tom's assistance.
Suddenly the security chief heard a cry of excitement from the young 
inventor.
"Find something?" he inquired.
Tom held out a small wad of tangled threads that looked as if they might 
have been torn from a piece of fabric.
"Where did you find this?" Ames asked.
"Here on the floor, right by the workbench," Tom replied. "Probably got ripped 
off when I struggled with that intruder. Wait a second. I'll put it under a 
microscope!"
Going over to another table, Tom slipped the strands into place under the 
lens, then peered through the eyepiece and twirled the adjusting knob.
"Take a look," he said a moment later.
Both Harlan Ames and Bud examined the find. Apparently the fabric had 
been woven from dark blue and white cotton threads.
TELLTALE THREADS 73
"Any idea where they might have come from?" Tom asked.
Ames frowned. "Not a regular suit." His eyes widened and he snapped his 
fingers. "What about the airfield mechanics? Their coveralls are woven out of 
stuff like this!"
The suggestion upset Bud, who had many friends among the hangar crew. 
But he agreed with Tom that they should make an immediate check.
After consulting the work-assignment schedules at the main building, Tom 
made two phone calls. One was to the control-tower operator who had been on 
duty from midnight until six a.m., and the other to the ground-crew chief who had 
been in charge of the airfield. Both were old-timers in the Swift organization.
Piecing together their accounts, it soon became clear that only three 
mechanics might have had an opportunity to sneak away from their jobs 
unobserved. Their names were Smith, Tonas, and N iff man. All three were 
employed at Hangar E, where the experimental planes were berthed.
When he hung up the phone, Tom relayed the news to his two companions.
"Want me to haul 'em in for questioning?" Ames asked.
The young inventor shook his head thoughtfully. "Better not. If one of them's 
guilty, he might become suspicious and try to leave town. Let's wait until they 
come on duty tonight."
That evening, after dinner at the Swift home,
74 DEEP-SEA HYDRODOME
Tom and Bud drove back to the plant. The three mechanics were due to 
report with the late shift at ten o'clock. Half an hour after the time for punching-in, 
the two boys picked up Harlan Ames at the security building, then drove over to 
Hangar E.
As they walked in, Doke Smith, a sandy-haired, husky young fellow of 
twenty-three, was tinkering with the afterburner of a sleek racing jet.
"Hi, skipper!" he greeted Tom cheerfully. Catching sight of Bud, he grinned. 
"What're you doin' here, fly boy?"
"Planes-I can't keep away from "em," Bud bantered. "Where'd you get that rip 
in your coveralls?"
"What rip?" Smith looked surprised as he noticed a tear along one leg. "Oh, 
that. Search me. Caught it on an engine cowling, I guess."
The other two mechanics were busy in different parts of the hangar. Tom, 
Harlan, and Bud quizzed each of the three men in turn, keeping their questions 
casual and friendly.
It was hard to believe that any of them might be guilty of the brutal assault on 
Tom. But the fact remained that none could provide a complete alibi. The huge 
hangar was crowded with planes and equipment, with the result that most of the 
time the men were not even in sight of each other. All three claimed to have gone 
dashing wildly out on the field when the alarm sounded the night before.
A search of their lockers revealed no trace of
TELLTALE THREADS 75
the hooded cloak. Yet, Tom concluded, it would have been impossible for the 
culprit to have smuggled it past inspection at the main gate when coming on or 
going off shift.
Acting on a sudden hunch, Ames asked Milt Tonas if the planes now in the 
hangar had been there the night before.
"Far as I know," said Milt, a quiet-spoken, middle-aged man.
"Were any planes taken out during the day?"
"Don't think so. But you can check the flight sheet over there on the wall."
With Tom and Bud helping, the security chief began checking every ship in 
the hangar. A few minutes later Bud stuck his head out the hatch of a newly 
designed cargo jet.
"Eureka!" he hissed, holding up a black-hooded robe. He explained that the 
sinister-looking garment had been tucked out of sight under the engineer's seat. 
It had two eyeholes cut in the hood.
"Wait a second!" whispered Ames, after examining the cloak and passing it 
to Tom. He hurried back to check the flight schedule again, and returned a 
moment later, his face grim.
"This job's due for a test flight at two a.m., and Reuben Niffman's down as 
flight engineer."
There was a tense, uneasy silence as the two boys and the security chief 
looked at one another. Was N iff man their man? On the test flight, he could 
easily dispose of the robe by jettisoning it through the cargo hatch.
76 DEEP-SEA HYDRODOME
"Well, let's get it over with," said Tom quietly. He had little relish for the 
prospect of having a once-trusted employee arrested.
N iff man looked up from his work as the three approached. He was a tall, 
slender man in his late twenties.
"Ever seen this before?" Ames asked him, holding up the cloak.
Niffman's face went ashen. His eyes seemed to glaze with fear as he stared 
at the telltale garment. Before anyone could stop him, he jerked a pistol from the 
pocket of his coveralls.
"Stop!" he screamed. "You won't take me alive! Don't come any closer or I'll 
shoot!"
CHAPTER IX
UP ELEVATOR!
TOM and his two companions fell back in horror as Niffman waved the pistol 
wildly. The trusted mechanic had suddenly turned into an armed madman!
"Put that gun down!" Harlan Ames commanded. "Hurry! Drop it!"
"You can't bluff me!" Niffman shrilled in a high-pitched voice. "This gun's 
loaded, I tell you! Try anything and I'll kill everyone in this hangar!"
Hearing his screams, Doke Smith and Milt Tonas dropped their work and 
came rushing to see what was happening. But at sight of the threatening 
weapon, they froze in their tracks.
"Now look, Rube," Tom spoke quietly. "You have nothing to be afraid of. We 
want to talk to you. Hand over the gun and I promise you we won't press any 
charges."
Casually Tom took a step forward, holding out his hand.
77
78 DEEP-SEA HYDRODOME
But Niffman again brandished the pistol. "I'm warning you. Don't come any 
closer," he screeched, "or I'll shoot!"
Determined not to show any fear, Tom advanced another step, then another. 
Ames and Bud held their breaths.
"You had your warning!" Niffman yelled. He was waving the gun around, his 
finger on the trigger.
Crack! One shot, then a series of them. Bullets sprayed wildly about the 
hangar.
Tom ducked for cover behind the nearest plane, then hurled himself at the 
crazed mechanic, grabbing for his gun hand.
Niffman fought back, trying to wrench his wrist from Tom's steely grasp. Bud 
and Harlan leaped to Tom's assistance. In a few seconds their combined 
strength brought Niffman to his knees. Tom and Bud forced his arms together 
and Ames snapped on a pair of handcuffs.
Realizing he was now helpless, the mechanic broke down completely and 
began weeping hysterically. Then he babbled wildly:
"Tom Swift, you're trying to wreck the laws of nature! You can't repel water-
the whole world would be flooded! Human life would be wiped out!"
As Niffman glared at the inventor, his three captors realized that he was 
beyond all reasoning and made no attempt to reply to his accusation.
"What do you think we should do with him, Tom?" Harlan Ames asked.
UP ELEVATOR! 79
Tom replied, "No sense having him arrested while he's in this condition. We'd 
better take him over to the infirmary."
He, Bud, and Ames carried the mechanic, who now was too weak to walk, 
and drove to the Enterprises medical building. Here Doc Simpson took charge 
and injected a tranquilizing drug.
Out of the patient's hearing, Tom asked, "Do you think we'll be able to get 
any sensible answers from him?"
Doc Simpson shook his head. "I doubt it. He'll probably fall into a deep sleep 
soon. The shock of being discovered has evidently unbalanced his mind. Could 
be days before he's able to talk lucidly."
In glum silence Tom left the infirmary with Bud and Harlan. Tom's brain, 
meanwhile, had been dwelling on a new worry. Niffman had spoken about 
"repelling water," which meant that he knew the purpose of Tom's latest 
invention. But how had he found out? Besides the two government chemists and 
a few highly trusted men working on the project with Tom, only the young 
inventor's family and closest friends had been told about the repelatron!
Tom mentioned this to Bud and Ames as they drove to the main gate.
"I'll check on Niffman right away," Ames promised. "Maybe his friends or 
neighbors can give us a lead on what he's been doing lately outside of business 
hours."
"Okay. See you tomorrow, Harlan. Thanks!"
80 DEEP-SEA HYDRODOME
Tom and Bud transferred to Bud's convertible for the ride to the Swift home 
and tumbled wearily into bed. The following morning Tom went to check up on 
the building of the giant repela-tron to be used at the underwater helium wells.
"It's almost ready to have the delicate instruments installed," the foreman 
reported.
"Great!" said the young inventor, smiling.
Next, Tom went to see Art Wiltessa, a young project engineer for Swift 
Enterprises, who would design the special pressureproof, transparent dome to 
enclose the undersea air bubble and keep out fish or other foreign objects. The 
dome would be made of Tomasite, a plastic, radiation-proof material, which was 
extremely strong and durable, and had been invented by Mr. Swift.
For a few days Bud saw little of his chum. One morning, looking for Tom, he 
strolled into the small machine shop on the ground floor of the laboratory 
building. Complete with forge, casting equipment, and machine tools, the shop 
was often used by Tom when he was constructing the first models of new 
inventions. Right now the young scientist was hard at work on a new invention.
Bud stared at it and said, "Don't tell me what this is for. Let me guess."
The object in question consisted of a metal platform, about five feet square, 
with fins or vanes extending out on each side of it. In the center was a shiny 
metal sphere.
UP ELEVATORI 81
"Go ahead." Tom chuckled at the baffled look on his friend's face.
"Well," drawled Bud, "I'll say it's an elephant's back-scratcher."
Tom grinned. "Not quite. It's an undersea elevator."
"How's that?"
"An undersea elevator for hauling things up or down between the airdome 
and the surface of the ocean," Tom explained. "It'll slide on cables."
Bud shook his head in silent amazement, then asked, "What makes it go?"
"A repelatron. This metal ball in the center is the radiating part of the 
machine."
Bud said quickly, "I thought the repelatron was to repel water to create a 
living and working space."
The main repelatron will do that," Tom said. "This one will create a bubble 
space around the elevator."
"But you just got through saying it would make the elevator go up and down."
"It'll do that, too, by altering the bubble's buoyancy."
"Better draw me a diagram," Bud declared.
"Okay." Tom rapidly sketched a small ship. "Suppose this ship is built out of 
metal weighing a thousand tons. It floats. But what would happen if you 
squeezed the ship into a solid hunk of metal-like this?"
82 DEEP-SEA HYDRODOME
"She'd sink."
"Right. The solid hunk of metal wouldn't weigh any more than the ship, but it 
would displace a lot less water. In other words, if you shrink something down so it 
takes up less space in the water, it also becomes less buoyant-or more sinkable, 
you might say."
Bud nodded. "So?"
"So we'll do the same thing with the bubble around the elevator," Tom 
explained. "By cutting down the force of the repelatron, we make the bubble 
shrink to a smaller size. Since we're now displacing less water, the elevator will 
automatically tend to sink."
"Fine, but how about getting back up again?" Bud demanded.
"Turn the repelatron up full force. The bubble now becomes larger, displacing 
more water, so the elevator starts to rise."
"Well, I'll be a scootin' sky ghost!" Bud shook his head in admiration. "Don't 
know how you do it, genius boy, but it sounds terrific. How about these fins 
sticking out on each side?" he added. "What are they for?"
"Stabilizers to keep the elevator steady as it rides up and down. And here on 
the bottom are shock absorbers to cushion the jolt when the elevator reaches the 
landing stage."
"Nice work, pal!" Bud clapped his friend on the back. "I hereby grant you the 
official Barclay seal of approval! How soon do we give it a try-out?"
UP ELEVATOR! 83
"Tomorrow morning." Tom grinned. "Want to come along?"
"It's a date!"
Later that afternoon the young inventor put through a long-distance call to 
Washington. Speaking to Admiral Hopkins, he asked if any Navy submarines 
would be cruising in the vicinity of Fearing Island during the next twenty-four 
hours.
"Don't think so, Tom, but let me check and make sure." Calling back a short 
time later, he reported there would be none in that area.
"Why? Has something new come up?" Admiral Hopkins asked.
"I have an undersea experiment scheduled," Tom explained. "Just wanted to 
make sure no submarine commander would mistake us for enemy saboteurs and 
let fly with a torpedo!"
Next morning the elevator device was loaded aboard a cargo jet and Tom 
and Bud took off with it to Fearing Island. Doc Simpson accompanied them on 
the flight in case of any mishaps during the experiment.
"How's Niffman?" Tom asked.
"About the same. Sleeps a lot and keeps babbling when he's awake. Doesn't 
make any sense yet," the physician replied. "But I feel his condition is 
temporary."
After landing at the rocket base the elevator was transferred to a small tug. 
Tom had invited Dr. Clisby and Bob Anchor to witness the trial and all climbed 
aboard.
84 DEEP-SEA HYDRODOME
The tug steamed to a point not far from the island where the fathometer 
showed a depth of about a hundred and fifty feet. Here a boom was swung out to 
support the elevator cables. These were then reeved through pulley blocks and 
payed out into the water, with a heavy framework attached to anchor them firmly 
on the bottom of the ocean when Tom reached it.
"Okay, let's rig the elevator!" Tom ordered.
While this was being done under Hank Sterling's direction, Bob Anchor 
begged to go along on the first descent.
"Sure." Tom grinned. "But it won't be like riding down in a skyscraper 
building!"
As soon as the elevator guides were clamped in place around the cables, 
Tom, Bud, and Bob went aboard the platform. The elevator was then lowered by 
winch until it touched the surface of the water. With his heart racing nervously, 
Tom murmured, "Here goes!" and switched on the repelatron full force.
An awed gasp burst from the watchers on the tug. A huge hollow depression, 
like a giant dimple, had opened up in the surface of the water, directly below and 
around the elevator!
"Cast off the winch lines!" Tom ordered, feeling a thrill of excitement at this 
first success.
A moment later the elevator hung poised above the water dimple, sustained 
entirely by the force of the repelatron.
"We're going down!" Tom reversed the switch slowly, cutting down the action 
of the repelatron.
UP ELEVATOR! 85
As the repulsion force decreased, the elevator began to sink. At the same 
time, the dimple grew smaller. As the trio slowly descended below the waves, the 
water closed in above their heads. They were enclosed in the air bubble!
Bob gasped, "Whew! What a feeling!"
"Weird," agreed Bud, as they sank down, down through the greenish waters.
In a short while the ocean floor became visible below, with its tangled mass 
of green vegetation. Tom could not suppress a pleased grin at the elevator's 
operation.
Suddenly Bud let out a cry of alarm. "Tom! Look!" he pointed.
A whale-shaped craft was heading straight toward them at terrific speed!
"The mystery sub! It's going to ram us!" Bob yelled.
White-faced, Tom slammed the switch lever to full power. The elevator shot 
up just in time! With a shuddering wake, the submarine roared past below them!
As the elevator broke the surface, pains were shooting through Tom's chest. 
Bob and Bud were leaning over and writhing in agony.
"Quick! Get them aboard!" Doc Simpson cried to the horrified tug crew. "They 
have the bends!"
CHAPTER X
DEEP FREEZE
IN FRANTIC haste Tom, Bud, and Bob Anchor were hauled up onto the deck 
of the tug. Every crew member realized the boys were suffering the deadly 
cramps brought on by a too-sudden change of pressure. Doc Simpson at once 
gave them injections to ease their pain.
"We must get them back to the island!" the medic ordered. "They'll need 
treatment immediately!"
"But my invention!" Tom protested in spite of his agony. "We can't just 
abandon it!"
"We'll stay here and unrig the setup, skipper," Hank promised. "You four take 
the motorized lifeboat."
This was lowered, with the three victims propped comfortably inside. Doc 
Simpson took the helm and raced back to Fearing Island. Meanwhile, the tug had 
radioed news of their mishap and an ambulance was waiting on the south dock.
86
DEEP FREEZE 87
From here the boys were rushed to the infirmary and wheeled into the 
operating room.
"What happens now?" asked Bud, looking askance at huge tubs of ice 
standing in readiness.
"Hypothermia," said Doc Simpson tersely.
Bud grimaced. "Sounds horrible."
"Relax," Doc said. "We're just going to freeze you, that's all."
"Freeze us?" echoed the three patients.
The physician nodded as he hastily prepared anesthetizing equipment. "We'll 
lower your body temperature to 75 degrees and keep you that way until your 
circulatory system gets back to normal. You won't feel a thing."
"I'm numb already!" Bud groaned.
Luckily the boys' condition, though painful, was not serious, since they had 
submerged only a hundred feet. By the following day Tom and his friends were 
recuperating comfortably in a three-man hospital room.
"Some visitors just flew in," the young physician told them when he dropped 
by to check their progress. "Like to see them?"
"Sure, bring them in!" said Tom, who was growing restless at inactivity.
"Hold on!" warned Bud. "If it's Dr. Clisby or other government experts, don't 
start figuring chemical equations or I'll have another pain!"
Doc chuckled. Opening the door, he ushered in Mrs. Swift, Sandy, and Phyl.
"Wow! I feel better already!" Bud exclaimed, beaming at Sandy.
88 DEEP-SEA HYDRODOME
"Well, don't get frisky," she warned, her eyes dancing, "or I'll tell the doctor to 
put you back in deep freeze!"
The lighthearted banter cheered everyone. Phyl said, with a special smile for 
Tom, "You boys look fully recovered, thank goodness!"
She and Sandy distributed fruit and cookies they had brought from Shop ton.
Tom, meanwhile, was saying to his mother, "How's Dad?"
"Completely recovered," Mrs. Swift reported. "He's at The Citadel right now 
on a special research problem." The Citadel was the Swifts' atomic energy plant 
in the Southwest. "Dad said you'll have to carry on with the helium project pretty 
much on your own."
"With Bob and Bud here, and Dr. Clisby to help, it shouldn't be too tough," 
Tom said, smiling.
"You're lucky to have such fine people to work with," his mother agreed 
warmly. "But do take care of yourself and get some rest!"
"I'll keep an eye on Tom," Bob Anchor spoke up. Like everyone who knew 
her, he was touched by Mrs. Swift's quiet charm.
Then, in answer to Sandy's and Phyl's questions, the boys described their 
recent mishap but did not mention the submarine which they thought had 
planned to ram them.
"The elevator worked to perfection," Tom explained. "I just brought it up a 
little too fast."
"Now tell us what you girls have been doing,"
DEEP FREEZE 89
said Bud. "Turning down all other dates, I hope."
"My, what an optimist!" Sandy teased.
Phyl laughed, her dark eyes sparkling. "After all, we had you two on ice!"
"You're licked, fellows!" Bob Anchor chuckled as the two boys pretended to 
fume.
Next day, since they were much better, Doc Simpson released them from the 
hospital. Tom and Bud said good-by to Bob, who would continue work on some 
reports for the Bureau of Mines. The young inventor and his pal took off for 
Shopton.
As they winged over the water toward the mainland, Bud remarked, "Do you 
suppose that sub was the same one that trailed us the other day, or is there a 
whole fleet of Mad Mobys?"
Tom looked grim. "I wish I knew the answer to that one, Bud. Whether it was 
the same one or not, I wonder if it carried atomic warheads."
"You mean," said Bud, "that the sub was planning to hide warheads in this 
area again, and just happened to spot us by accident?"
"Could be," Tom agreed. "I hope we stopped them! Anyway, our patrol is 
pretty efficient."
The young inventor was silent for a moment, then he said, "You know, Bud, 
there's another spot I'm even more worried about."
"For instance?" queried his pal.
"That mountainside near the helium fields," Tom replied. "If our enemies 
cached some warheads there, and they detonated by accident, the explosion 
could wreck our whole operation!"
90 DEEP-SEA HYDRODOME
Bud gave a low whistle. "Brother, and how! Maybe we ought to take a look-
see, skipper."
"I intend to," Tom vowed. "We'll leave tomorrow if I can get things organized 
here."
As soon as they landed at Enterprises, Tom hurried to his worktable. A host 
of problems connected with the helium city were pressing-an air-purification 
plant, the gas-bottling process, and construction of buildings inside the dome.
Under pressure, the young inventor's mind seemed to work at top speed. 
Hour after hour he hunched over his bench, testing parts and circuit hookups, 
sketching out ideas, dashing off memos, and taking phone calls.
One of these was from Miss Trent, the Swifts' cool, efficient secretary. She 
asked Tom to drop by later to sign a batch of letters in his father's absence.
"Be there at three," he promised.
Tom left his work and in a company jeep drove to the Enterprises main 
building where he shared a big modern office with his father. The spacious room 
was fitted with huge desks, gleaming models of their inventions, cushioned 
leather chairs, and push-button drawing boards.
After signing the letters, Tom hurried to the door, giving Miss Trent a smile.
"If anyone calls, I'll be over at the Swift Construction Company. I want to see 
about some magnesium girders for the helium project."
Hopping into his sports car, Tom sped across
DEEP FREEZE 91
town to the construction company. Its manager, Ned Newton, had worked 
side by side with Tom Swift Sr. through their youthful years.
As he drove through the gate onto the company airfield, Tom was startled by 
a sleek little plane stunting crazily overhead. It was a Pigeon Special.
"Hope that's not Sandy!" Tom gasped. He recalled that she had mentioned 
she might demonstrate the plane to a prospective customer.
Tom waited no longer. He sped to the control tower and raced upstairs, two 
steps at a time.
"Who's in that Pigeon Special?" he asked.
"Your sister, but I'm afraid she's in trouble."
Tom snatched up a pair of earphones. Then he said into the mike, "Sandy! 
What's going on?"
"Oh, Tom, it's you! I don't know. The plane's out of control. I'm trying to right 
it, so I can land. But it keeps banking. I can't straighten it out."
"Sis, can you climb a little and parachute?"
"No, Tom. I-I can't do anything with these controls!"
"Then I'll come up and drop you a ladder to climb into my plane!"
The words were hardly out of his mouth when the plane suddenly started 
downward. "I think I can land," said Sandy.
Tom and the dispatcher gaped in horror as the plane went into a spin. But a 
moment later Sandy pulled out of it and managed to make a pancake landing!
92 DEEP-SEA HYDRODOME
"Good night!" the dispatcher gasped, his shirt drenched with perspiration. "If 
Sandy has-"
Tom did not hear the rest. He was already halfway down the tower stairs. As 
he dashed out on the field, he saw his sister emerge from the plane, shaken but 
unhurt.
"Thank goodness!" he cried.
Sandy was glad to fall into her brother's arms. She was shaking like a leaf, 
but in a few moments recovered her poise.
"Tom!" she cried out suddenly. "Do you know what I think? That the man I 
was going to demonstrate the plane to ruined it."
"But why? Where is he?" Tom demanded.
"I left him at the hangar. He wanted me to go up alone so he could see how 
the Pigeon looked in the air."
"Let's find him," Tom urged. "But what makes you think that he damaged the 
plane?"
"Well, just before we were to go up, a phone call came for me," Sandy 
explained. "It was from a man who wanted an appointment for a demonstration. 
He kept me talking a long time."
Sandy paused and gazed toward a hangar. "I left him right there," she said.
Inquiry brought out the fact that the man had left the premises the instant 
Sandy was in the air. And also, that while she was at the phone, the stranger had 
been in the cockpit at least ten minutes.
"Guess your hunch was right, Sis," said Tom. His eyes narrowed. "The man 
on the phone was
DEEP FREEZE 93
probably an accomplice and the two of them tried to kill you! But I'll catch up 
with them, and when I do-"
Sandy took her brother's hand. "Tom, don't get mixed up with dangerous 
characters like that. Or," she warned, "you may never get that helium city built!"
Tom calmed down a bit and called the police. Sandy gave the chief a 
description of the suspect -a tall, slender man with blond hair that he wore rather 
long on the sides. He had given the name Paulus White. The telephone caller, 
who had a rather high-pitched voice, was Firth Webster.
When the telephone conversation ended, Tom said, "Come on, Sis. I'm 
driving you home right away."
On the way they tried to figure out why anyone would want to harm Sandy. "I 
hope it has nothing to do with my present work," Tom said.
"How could it?" Sandy asked.
Tom was grim as he answered, "If anything had happened to you, it would be 
a long time before I'd feel like continuing the project. And perhaps that was what 
those two scoundrels were counting on."
The police found no trace of White or Webster under those names and 
decided they had been assumed. After a long night's sleep Sandy declared she 
felt fine.
Tom, relieved, could not resist teasing his sister just before he left the house. 
"You can't keep a good woman down on earth-or up in the air,
94 DEEP-SEA HYDRODOME
either. Well, happy landings today! Now I'll go see my other patient."
He drove to the Enterprises infirmary to see Doc Simpson.
"How's Niffman coming?" Tom inquired.
"Not too good. I'm forced to keep him under sedation. When I don't, he 
becomes violent."
"What's your diagnosis?"
The medic groaned. "Hard to say exactly. He shows definite schizophrenic 
symptoms."
"Does that mean that he was mentally unbalanced even before this 
happened?" Tom asked.
"Not necessarily. It could have been brought on by drugs, such as lysergic 
acid or one of the adrenalin derivatives. I have a hunch someone may have 
doped him, in order to give him enough courage to smash your invention."
Tom asked how soon the effects of such drugs would wear off.
"It should be fairly soon now," Doc replied. "Perhaps within the next day or 
two."
Tom was thoughtful as he drove home that evening. The worried inventor 
hoped that Niffman would be ready to talk by the time the cruise to the undersea 
mountain was over.
"And then I'll find out more about those men, White and Webster-the fiends!"
The next morning Tom and Bud flew to Fearing Island, where the Sea Hound 
was ready for take-off. A cargo plane would accompany them, carrying the giant 
vacuum lifter machine and a dozen empty lead cases the size and shape of 
those
DEEP FREEZE 95
which had contained the atomic warheads. It was Tom's plan, if he found a 
cache, to substitute the new cases.
Soon the Sea Hound was headed over the Atlantic, followed by the cargo 
craft. Bud was at the seacopter's controls. As they neared their destination, he 
submerged and guided the vessel toward the helium area. Soon their searchlight 
was sweeping the plateau on the mountainside.
Suddenly Bud cried out, "Tom! The gas is gone!"
Not a bubble of helium rose through the water!
CHAPTER XI
MOUNTAIN CACHE
THE whole crew of the seacopter crowded to the cabin window. Looks of 
dismay appeared on the men's faces as Tom played the searchlight back and 
forth, probing the inky waters with its yellow glare. Nowhere could they glimpse 
any trace of the helium bubbles, nor of the capped well.
"What a tough break!" Bob Anchor groaned. "The helium deposit must be 
played out!"
"It can't be-not so soon." Tom scowled. "Maybe this isn't the right location."
"Sure it is," said Bud. "Look at the chart. And there's the undersea peak up 
ahead."
"That doesn't necessarily prove it," Tom insisted. "If we're off course, we 
might be in a spot that looks like the other one. Let me check the automatic 
navigator."
Tom had invented this device especially for the Sea Hound. It measured the 
change in frequency of sonar pulses to determine the ship's
96
MOUNTAIN CACHE 97
speed and drift over the sea floor. A computer translated this information, 
along with the compass course, into latitude and longitude readings which 
showed up on twin dials.
Pulling his emergency tool kit from a locker, the young scientist unscrewed 
an inspection plate. Then he checked the electronic circuits inside and tested 
various parts.
"Anything wrong?" asked Bob, noticing the puzzled look that furrowed Tom's 
brow.
"I'm not sure, but I have a hunch the ocean water around here may be 
throwing the readings off. It might be due to the extreme pressure at this depth, 
or possibly some kind of electrochemical action on the pulse transmitter."
Tom decided to run some tests on it when they got back to Fearing Island. In 
the meantime, he ordered Bud to cruise along the slope of the undersea 
mountain while he maneuvered the search beam.
A few moments later Bob Anchor cried out, "There's the helium spot! I can 
see the bubbles!"
Cheers went up from the crew as they gazed at the steady upsurge of gas.
"Boy, what a relief!" Bob exclaimed. "I was really worried there for a while!"
"And I!" Tom relaxed and grinned.
"Now what, skipper?" Bud asked.
Tom took over the controls. "We'll comb the whole mountainside to look for 
any hidden chests. You beam the searchlight, pal, and everyone look for 
warheads."
98 DEEP-SEA HYDRODOME
For over an hour Tom guided the seacopter in first a descending, then an 
ascending course. The slope of the nearby peak proved to have more likely 
hiding places than the rest of the area.
Suddenly one of the crewmen shouted, "Bring the spot over to starboard a 
little, Bud, and raise it a few degrees. Think I saw something in an opening!"
Tom throttled back on the directional jets, and Bud maneuvered the 
searchlight. As the yellow beam stabbed through the murk, it settled on a crag 
jutting out from the main peak. A small shadowy aperture was visible in the cliff 
face.
Tom brought the seacopter around and steered in closer. As it approached 
the cliff, the Sea Hound's probing beam revealed a cave. Inside were a cluster of 
grayish-black chests!
"Nice going, Jerry." Tom clapped the crewman on the back. "This looks as if 
it's what we've come to get!"
Turning the controls back to Bud, Tom climbed into a Fat Man suit and went 
out through the air lock. Propelling himself toward the cave, he found a foothold 
on the rocks and waddled inside.
"How about it, skipper-more lead cases?" called Bud on the sonarphones.
"Ten of them!" Tom reported.
Returning to the Sea Hound, he gave the order to surface so they could 
make contact with the cargo plane.
MOUNTAIN CACHE 99
To everyone's amazement, the weather had suddenly changed. Mountainous 
whitecaps greeted them as the seacopter emerged. Angry dark clouds obscured 
the sky, and sheets of rain lashed the cabin window under winds of gale velocity.
"Jumpin* jets!" Bud gasped, clinging to a stanchion. "Break out the oilskins, 
me hearties! We're in for a real blow!"
A jagged bolt of lightning lit up the cabin, followed by a peal of thunder that 
made the craft quiver. The Sea Hound wallowed and pitched like a nervous 
dolphin!
"What's the matter, fly boy?" Tom teased Bud. "Lost your sea legs already?"
Bud's rollicking grin had faded fast as his face took on a slight greenish tinge. 
"My legs are still here," he gulped, "but I seem to have misplaced my stomach!"
Tom and the other crewmen scanned the overcast, but the cargo jet was 
nowhere in sight.
"I'll try the radio," Tom decided.
Switching on the transmitter, he called over the mike:
"Sea Hound to Swiftjet! Can you read us?"
The static was so bad it was impossible to make out any response. Rather 
than waste time in a futile search that might leave the whole crew seasick, Tom 
decided to submerge and stand by until the storm subsided.
In half an hour he surfaced. The skies had cleared and the sea calmed down. 
There was no
100 DEEP-SEA HYDRODOME
sign of the cargo plane, but before long it was sighted in the distance.
"We got blown off course," Arv Hanson reported by short wave. "Find any 
warheads?"
Bud described the cache they had located in the undersea peak, adding, 
"Get the vacuum lifter ready. We'll guide you into position."
In a few minutes the Sea Hound reached a point directly over the cave.
Tom picked up the mike. "Use us for a target and start lowering," he ordered. 
"Current's pretty strong near the bottom, so we may run into trouble. Don't switch 
on power till I give the signal."
"Aye-aye, skipper!"
The cargo plane was equipped with hovering jets, similar to those on the Sky 
Queen. Arv jockeyed the craft until it was lined up directly over the seacopter, 
then locked the controls. A hatch opened in the plane's belly and the giant lifter 
disk dropped into view, supported by steel cables.
While waiting for the disk to descend within a few feet of the Sea Hound's 
hull, Tom took out a buoy. To it was attached a cable which connected with the 
seacopter's sonarphone. It would relay messages from the seacopter to the 
plane's radio.
"We're going to submerge," Tom radioed. "Give us a few seconds, then 
resume lowering."
With his keen blue eyes fixed on the instrument dials, Tom eased the control 
wheel forward. The Sea Hound plummeted straight to-
MOUNTAIN CACHE 101
ward the bottom. From the plane overhead, Arv and his flight crew watched it 
disappear beneath the waves.
"Okay. Lower away!" Hanson told his men.
Fathom after fathom, the seacopter sank into the depths. Meanwhile, the 
lifter cables were steadily unreeling just above them.
Reaching the cave in the undersea peak, Tom used the reversing jets to 
back off a little, so that the search beam could illumine the area of operations.
"Hey, what happened to the lifter disk?" Bud muttered, when it failed to 
appear.
"The current's probably sweeping it out of range," Tom replied. "Swing the 
searchlight around."
Bud complied and they finally sighted the machine about a hundred yards to 
port, dangling at the end of its cables. The subocean current had swung the disk 
like a pendulum.
"Avast on the winch up there!" Tom signaled. "You have enough cable payed 
out."
"Are we on target?" Arv responded.
"The disk isn't, but we'll attend to that. Just stand by."
Chip Kelly, an experienced seacopterman, took over the controls while Tom, 
Bud, and Bob Anchor each squirmed into a Fat Man suit. Waddling into the air 
lock, they emerged a moment later through the outside hatch.
Guided by the brilliant glare of the Sea Hound's search beam, they propelled 
their steel
102 DEEP-SEA HYDRODOME
eggs toward the vacuum machine. The ocean current pressed hard against 
them and the disk. Bud and Bob, who reached the lifter ahead of Tom, found it 
hard to maneuver the device with their mechanical arms.
"The thing's temperamental." Bud chuckled over his sonarphone. "Wants its 
Uncle Tom!"
"Be right with you, pals," Tom responded.
Between them, the three boys got a firm grip on the disk. Then, gunning their 
propulsion jets at full force, they managed to push it. Heading across current, 
they steered toward the cave opening in the cliff face.
As the boys moved through the water, the Sea Hound swiveled its search 
beam so as to keep them constantly illuminated.
"Now conies the ticklish part," said Tom.
Maneuvering the lifter device through the cave entrance, they brought it close 
to one of the chests. Segmented feelers extended out from the rim of the disk, 
like the tentacles of an octopus. Each one had a series of holes through which 
the vacuum pumps would exert their gripping force as the lifter took hold.
The boys set the disk flat on top of the chest and arranged its tentacles in 
gripping position. Then Tom signaled the Sea Hound by sonar-phone:
"Okay. We're all set. Notify the plane to switch on power and hoist away!"
In a moment the vacuum lifter gave off a loud,
MOUNTAIN CACHE 103
humming noise. Then the steel cables started reeling in.
As the chest was dragged out of the cave, it scraped against the rock, 
knocking loose one of the tentacles. Bob Anchor reached out his pantograph arm 
to place it back in position.
A second later he let out a scream. "Help! I can't get loose!"
Dangling from the lifter disk, Bob was swinging back and forth in his steel 
egg, powerless to move. The chemist was being dragged upward along with the 
lead chest!
"Avast heaving!" Tom cried, and the Sea Hound relayed his signal.
Slowly the cables were payed out again, and after much maneuvering the 
unwieldy load was deposited on the lip of the cave. Then the power was turned 
off so Bob could free himself.
"What were you trying to do-a one-arm trapeze act?" Bud quipped.
"Sure," said Bob. "How'd you like the underwater circus?"
Once again the power was switched on. This time the chest was hoisted up 
through the water without incident. When the disk was lowered again, it bore an 
empty lead case to be substituted for the one removed.
The whole operation seemed painfully slow, since Tom, Bud, and Bob had to 
return to the Sea Hound twice for a rest and to replenish the oxygen supply in the 
Fat Men.
104 DEEP-SEA HYDRODOME
"Okay, that's it," Tom reported to the plane. "Let's start for Fearing."
When the seacopter surfaced, Bud radioed a final message to the cargo jet. 
"Race you back to Fearing, Arv! Last one home gets the water cure!"
"If that means a chance to dunk you, you're on, fly boy!"
As the jet streaked off through the blue, Bud gunned the rotors and sent his 
craft spearing skyward in hot pursuit. Neck and neck, they raced across the 
ocean, but the Sea Hound finally pulled ahead and came in first.
"Ah, now for the payoff!" Bud gloated, as the jet arrived thirty seconds later 
on the island airfield.
Arv good-naturedly acknowledged himself the loser. All hands were eager to 
watch the dunking, so a truck was commandeered to carry both crews to the 
south dock.
After they had piled out on the pier, Arv said, chuckling, "Okay. Toss me in!"
Looking at the burly six-footer, Bud suddenly realized he had bargained for 
more than he had anticipated. Sweating and grunting, he tried to pick Arv up in 
his arms. No use! In the end, both pilots landed in the water with a mighty splash.
"A photo finish!" Tom howled, as the crewmen roared with laughter.
Meanwhile, the lead chests were being transported to a lead-lined concrete 
bunker on the rocket launching area. Twenty minutes later

106 DEEP-SEA HYDRODOME
Tom, Bud, Arv, and the two government chemists, wearing radiationproof 
suits, prepared to open them.
Nine of the cases proved to contain the same type of atomic warheads as 
were planted under Fearing Island. But as Tom pried up the lid of the last one, 
his face blanched.
"Run, everybody!" he yelled. "This may explode!"
CHAPTER XII
A SURPRISING DINNER
PANIC hit the little group of observers! In a wild rush they stampeded out of 
the blockhouse. It was not until they were some distance away that the men 
realized Tom was not with them.
"What's he doing?" Bud cried in alarm and started running back. "Tom! Come 
here! Tom!"
Meanwhile, the young inventor, holding his breath, had carefully closed down 
the lid of the chest, which, he had noted at a glance, was filled with deadly 
nuclear sticks of fissionable material!
"Probably exposed as soon as I opened the chest. It must have some type of 
contact device," Tom reflected tensely. "Better get this thing sealed up fast!"
Working with cool precision he scooped the chest onto a dolly and relayed it 
into a huge lead container. Turning a lever, he sealed it off from the rest of the 
bunker.
"That should do it," he decided, heaving a sigh of relief.
107
108 DEEP-SEA HYDRODOME
Next, he plugged in the radiation absorption machine and set the timer. An 
alarm bell would ring over the intercom when the contamination fell to a safe 
level.
A few hundred yards beyond the concrete bunker, Tom's friends waited 
anxiously. They had persuaded Bud not to return to the blockhouse. Finally, to 
their relief, Tom appeared. He locked the door securely, pocketed the electronic 
key, and came toward them.
"You all right, pal?" Bud inquired.
"I'm okay," Tom assured them, "but the bunker's hotter than a stove." Briefly 
he explained about the radiation sticks in the chest.
"This is even more fiendish than the warheads!" Dr. Clisby exclaimed angrily.
Tom nodded, tight-lipped. "I'll report our find to the Navy right away," he said.
With Bud at the wheel, he drove off in a jeep to the headquarters building. 
Here he asked the telephone operator to contact Admiral Hopkins in Washington 
on the Swifts' private line. Tom and Bud went into the office to wait.
"Just found another cache of warheads, sir," Tom told him when the admiral 
came on the line. I thought you'd want to be notified immediately."
"Yes, indeed, Tom. Where was the cache located?"
"Near the undersea helium beds which we're planning to tap," the young 
inventor replied. "There were ten chests. One of them contained
A SURPRISING DINNER 109
nuclear sticks designed to give off very dangerous radiation when opened."
Over the phone Tom could hear a furious but stifled mutter. Apparently the 
admiral was having a hard time holding back some salty quarterdeck remarks 
about the unknown enemy who had secreted the chests.
Aloud the Navy officer said, "Tom, if we ever lay hands on the scoundrels 
responsible for this, they deserve to be treated like mad dogs!"
Tom smiled, then sobered again. "I wonder if they have caught on to the fact 
that we're looking for their stuff, and hoped to annihilate me and some others."
"It's a good guess," said Admiral Hopkins, "especially since one of our subs 
found another cache just last night. The chests were filled with bombs."
"Where were they?" Tom asked. "On the East Coast?"
"No, in the Caribbean near one of our biggest defense bases. The chests 
weren't planted very far down under the island. If the bombs had gone off, 
thousands of people would have been wiped out!"
Tom shuddered at the thought of such terrible havoc. "Another thing, 
Admiral," he went on. "We planted dummy chests in place of the ones we 
removed."
"Excellent idea, Tom. I'll have the Navy subs do the same, so as not to tip off 
the enemy that we're locating their devilish equipment."
110 DEEP-SEA HYDRODOME
After the young inventor finished his conversation with the officer, Bud asked, 
"More bad news?"
Tom nodded. "Another cache. I won't rest until we find out who's back of this, 
Bud!"
"Don't worry, skipper. We'll find 'em!" Bud's words carried such a ring of 
determination that Tom felt renewed hope. But the elusiveness of the opposing 
force had him baffled.
"What's the next item on the program?" Bud asked.
"Back to Shopton. Let's get over to the airfield and hop a plane."
When they reached Enterprises, Tom asked Bud to assist him in his private 
lab.
His pal grinned. "Guess I can do the monkey-wrench work," he replied.
Tom plunged into the job of finishing a small portable repelatron which might 
adjust itself to various types of salty solutions. The boys were still hard at work at 
closing time when most of the employees went streaming out through the main 
gate.
Some time later Chow Winkler stuck his bald head through the doorway. 
"Some folks never know when to take a break," the old cook remarked.
Tom looked up in surprise. "Hi, Chow! Say, what time is it?"
"Nigh onto seven o'clock."
Tom gave a whistle. "Gosh, I had no idea! Guess we'd better get home to 
dinner, eh, Bud?"
A SURPRISING DINNER 111
"Suits me," said the husky young pilot, laying down a Phillip's-head 
screwdriver.
"Hold on now, partners!" Chow interposed. "You fellers ain't goin' nowheres. 
Why, brand my propeller-trons, seems like I hardly get a chance to see your 
faces lately! Besides, I figured you'd sure be here all night a-workin', so I fixed up 
some real fancy vittles to line your insides with."
The old Westerner spoke so earnestly that the two boys were touched by his 
thoughtfulness.
"Thanks, Chow, that's swell." Tom smiled. "I could sure use one of your 
super-deluxe specials!"
"Comin* right up!" beamed the cook happily.
"But watch out for these newfangled contraptions around here," Bud teased. 
"They might subatomize the molecular frumzoid content of the food particles, 
especially if cooked at less than super-duper degrees centigrade."
"Never you mind, Buddy boy," the cook said, grinning back. "You're kiddin' 
me, an' anyways, I reckon there ain't no invention yet kin spoil the taste o' good 
Texas-style grub!"
Still beaming, Chow hurried off to the plant kitchen.
Tom immediately phoned his mother and explained why he would not be 
home. Then, having completed work on the small repelatron, he went to a far 
corner of the laboratory to look at some construction plans he had promised his 
father he would deliver to Arv Hanson.
112 DEEP-SEA HYDRODOME
Meanwhile, Bud did a quick cleanup job. He put away tools and sorted out 
the jumble of electronic parts strewn over the workbench. Presently the boys 
heard a shrill whistle on a bosun's pipe just outside the laboratory.
"Chow down!" boomed a foghorn voice, and the roly-poly sun-bronzed cook 
appeared, wheeling a tiered cart loaded with covered dishes.
The meal was to be served in a small dining room just off the laboratory. 
Chow laid the table with a snowy white cloth, dishes, glasses, and silverware. 
Then he lifted the lid of a soup tureen. Out floated a cloud of steam, bearing with 
it an appetizing aroma.
"Mmm! Smells delicious!" Tom said. "What is it?"
"Armadillo soup," Chow replied proudly as he ladled it out. "Reckon you'll say 
it's the finest you ever tasted!"
Tom had turned a bit pale. "Don't know that I ever tried any before," he said 
cautiously, not wanting to hurt the Texan's feelings.
"Course you ain't never had any o' this kind before," said Chow, " 'cause I 
jest got the idea the other day."
Bud stared at his soup dish suspiciously. "You mean you stewed up one of 
those armor-plated critters one sees in the zoo?"
"Oh, I took the shell off," Chow assured him. "Jest cooked the pink tender 
meat-folks like the flavor fine down on the Rio Grande. You will, too, when you 
taste it. Go ahead and try some."

114 DEEP-SEA HYDRODOME
"Well, okay," said Bud. "But I sure hope the molecular frumzoid content 
hasn't been subat-omized."
"Quit your funnin', boy, an' spoon in. I want to see the look on your face when 
you-"
Chow's words ended in a shriek as the soup suddenly flew from the dishes.
"Great jumpin' Jehoshaphat!" The cook turned white as a ghost as he stared 
at the empty dishes and spattered walls. "What was that you was say in' about 
subatomizin' the frumzoid tadpoles?" he quavered weakly.
Both boys were shaking so hard with laughter they could hardly talk. Finally 
Tom managed to find his voice.
"Don't worry, Chow. Something tells me Magician Barclay is back of this!"
Reaching down, he brought out the new portable repelatron from a shelf 
under the table. Bud confessed to being the culprit and explained that he had 
flicked on the switch just an instant before. He had put one spoonful of the soup 
into the repelatron as a sample.
"Brand my boot heels, I might 'a' known that varmint was up to somethin'!" 
Chow groaned, mopping his forehead.
Finally the meal proceeded. Though the taste of the armadillo soup was 
unusual, both Tom and Bud found it delicious. The rest of the meal proved to be 
equally appetizing. Chow looked happy when the boys praised his cooking in 
glowing terms.
A SURPRISING DINNER 115
"Guess I kin take a joke long as I'm cookin' fer folks who 'predate good grub!" 
he beamed.
While Tom took the construction drawings to a far part of the building where 
Arv's office was located, Bud helped Chow clear away the dishes, then sponge 
off the spattered soup from the walls. The old Texan hung around for a moment, 
chatting idly, but finally went off, wheeling his cart.
Bud carried the repelatron back to the lab and set it down. He began to 
amuse himself by making a costume jewelry pin for Sandy out of a piece of 
copper.
Gradually a strange feeling crept over him. His throat seemed dry and 
painful. Dropping his work, Bud slumped down on a stool. The whole room was 
swimming before his eyes.
"Tom!" he called anxiously. His voice came out in a hoarse croak.
There was no answer, and Bud's nerves grew taut as he fought down a 
surge of fear. He tried to get up from the stool but he staggered and his legs 
gave way. What was happening to him?
"Help!" the young pilot cried out in panic.
CHAPTER XIII
NIFFMAN'S STORY
TOM was just coming down the hall on his way back to the laboratory when 
he heard Bud's call for help. Startled, he broke into a run.
"Bud! What's wrong?" he cried, bursting into the laboratory.
His friend was sagged against the worktable, his head drooping. Tom threw 
an arm around Bud's shoulders and raised him so he could see his face. Both of 
Bud's eyelids were fluttering weakly. His skin was flushed, hot, and dry.
"Bud, talk to me! For Pete's sake, tell me what happened!" Tom pleaded.
"I ... I ... don't know . . ." The words trailed off. Bud could hardly move his jaw 
and his mouth hung open. Tom noticed with alarm that his pal's tongue was dark 
and swollen.
"Good night, what's wrong with him?" the young inventor wondered 
desperately.
Plucking a paper cup from the wall container,
116
NIFFMAN'S STORY 117
Tom tried to fill it at the lab faucet. To his amazement, nothing came out!
A sudden thought struck Tom. The repela-tron! Maybe it was turned on, 
repelling all water from the room as well as from Bud!
Dashing across the laboratory, he checked the repelatron which Bud had 
brought back from the dining room and laid on a workbench. The device was 
switched on to low power!
"Poor Bud's dehydrated!" Tom exclaimed aloud.
He turned off the switch, then hurried back to the sink and tried the faucet 
again. This time, after a few coughs and gurgles, water came out.
Tom filled the large paper cup and held it to Bud's lips. He swallowed it down 
in greedy gulps and mumbled for more. After complying, Tom eased him back 
gently against the worktable.
"We'll soon have you fixed up, Bud!" he tried to reassure his friend. "I'll get 
Doc Simpson."
He phoned the infirmary, spoke a few moments with the physician, then 
called Chow in the plant kitchen. "Hop to it, Chow, and get some salt over here! 
Lots of it!"
"Sure, boss. Is somethin' wrong?"
"Bud's ill. Please make it snappy!"
By the time Chow arrived, lugging several bags of salt, Tom had filled a huge 
experimental vat with warm water and was stripping off Bud's clothes.
"Great snakes! What's happened to him?" the cook gulped in a frightened 
voice.
118 DEEP-SEA HYDRODOME
"The repelatron was on. Something went wrong with its detector. It was 
sending out a very general radiation. Too much moisture was taken out of Bud's 
tissues," Tom explained. "Pour the salt into the water and we'll let him soak for a 
while."
Hands trembling with nervousness, Chow slit open the salt bags with his 
jackknife and dumped the contents into the tub. Then he helped Tom ease the 
scarcely conscious victim into the water up to his chin.
As they held him there, Doc Simpson arrived, checked Bud's temperature, 
pulse, and respiration.
"You reckon he'll pull through?" quavered Chow.
"Sure," Doc replied. "He just needs a chance to replace the moisture he's 
lost."
Bud was also given water to drink and the bottle of smelling salts from the 
first-aid cabinet was waved under his nose. Half an hour later Bud felt better and 
insisted upon getting out of the bath.
"Whew! What a dopey trick I pulled!" Bud said. "I must have clocked the 
switch on accidentally when I set the thing down."
While Bud was pulling on his clothes, Doc insisted that he go to the infirmary 
for rest and a further checkup.
"Will you come along, Tom?" Doc requested. "Reuben Niffman's mind is 
clear and he's ready to talk."
NIFFMAN'S STORY 119
"Good!" said Tom.
After Bud had been put to bed, Tom and Doc went to Niffman's room. They 
found the mechanic sitting up in bed. He looked rested, and his eyes had lost 
their weird, glassy stare.
"I sure am sorry for what happened," he said to Tom, reddening. "I'll do 
everything I can to make up for it."
"I'm glad you're better, Rube," the young scientist told him kindly. "Was 
someone else responsible for your condition?"
"Yes. A doctor named Calvin Klevalog."
N iff man explained that Dr. Klevalog had introduced himself in a local 
restaurant one evening. During their conversation N iff man had told the doctor of 
a sprained muscle that was bothering him. The physician had offered to give him 
free treatments and pills. Instead, he had apparently used the opportunity during 
his visits to Niffman's apartment to establish hypnotic control over the mechanic.
"I didn't realize all this until just now," Rube added, "for over a period of time I 
became convinced that everything Klevalog said was true. He told me that you 
had invented a water-repelling machine that would wipe out humanity, and kept 
repeating that I must destroy it and steal the plans. Finally my will power and 
reasoning ability became so weakened that I said I would.
"But after I smashed your machine and knocked you out that night, I felt 
dizzy and was afraid to hang around and look for the blueprints. I rushed
120 DEEP-SEA HYDRODOME
back to the hangar and took some more pills. Then I went back to work."
"Have you any idea what this Klevalog's plans are?" Tom asked him. "Or 
how he found out about my water-repelling machine?"
"No."
The young inventor was sure that the hypnotist's concern for his fellow men 
was merely a pretext. But what was back of it?
"Doc," he asked, "have you ever heard of Klevalog?"
Doc nodded. "He acquired a rather shady reputation in another city from 
misusing hypnotism, so the state medical society had him barred from practice. 
But I had no idea he was carrying on the same thing here in Shopton."
"Is Klevalog listed in the telephone directory?" Tom asked.
"No, I've looked," replied the plant physician. "While Niffman was delirious, I 
heard him mention Klevalog, so out of curiosity I phoned the medical society. 
They had no information on his whereabouts."
Niffman was able to give a good description of his tormentor. "He's a heavy-
set guy, about five-ten, with a reddish mustache," the mechanic reported. "Eyes 
are sort of yellow green, and they really bore into you when he uses that 
hypnosis business!"
"I'll pass the description along to Harlan Ames," Tom said. "No telling what 
Klevalog may try next."
NIFFMAN'S STORY 121
Suddenly Niffman snapped his fingers. "Wait a minute! What day is this?"
When Tom told him, he went on, "I've just remembered something. I'm 
supposed to hear from Dr. Klevalog tomorrow evening. He phones me every 
Thursday. Since he missed me last week, I'm sure that he'll call tomorrow to 
learn how I made out about getting the plans."
"What time?"
"I don't know exactly," Rube replied. "He said he'd call me at home sometime 
before I left for work on the night shift."
"Good! Maybe we can set a trap!" Tom said.
It was arranged that Niffman would remain in the hospital overnight, and a 
plan for capturing Klevalog devised with Harlan Ames before he was released.
Early the next morning Tom set to work on the problem of providing his 
undersea airdome with an atmosphere. A group of engineers met in his office to 
talk over the matter.
"Seems to me the simplest way would be to bring in tank oxygen," said Art 
Wiltessa. "Then we could remove the carbon-dioxide waste by the usual soda-
lime method and recirculate the same air over and over again."
Jack Grady, who had worked on the air-conditioning setup for Tom's space 
station, offered another suggestion. "Water is made up of hydrogen and oxygen," 
he pointed out. "So how about producing the oxygen we need right from the sea 
water by electrolysis?"
122 DEEP-SEA HYDRODOME
Tom nodded thoughtfully. "That's a clever idea, Jack, but it would take an 
awful lot of power and waste the hydrogen, too."
"Hmm. Guess you're right, skipper."
Tom frowned and ran his fingers through his hair. "I think Art's idea of using 
tank oxygen would be good for small domes in undersea exploring. But for our 
big permanent dome, maybe we could imitate the fishes."
"How do you mean?" Art asked.
"To breathe, they absorb the oxygen from air dissolved in the water, and give 
off their waste carbon dioxide in exchange."
"You mean you're going to fit everyone on the expedition with a pair of fish 
gills?"
Tom smiled. "No. I think we could do it with a special air-conditioning 
machine."
Going over to a blackboard, Tom sketched out his idea. "We'll pump in sea 
water and extract its dissolved oxygen by osmosis through a membrane-like this. 
Then we dry the oxygen in a dehumidifier and pump it into the dome through a 
heating and decompression unit. The stale air is then drawn out by a 
compressor, and the waste carbon dioxide is given off to the same sea water in 
exchange for the oxygen we removed. Of course there would be constant 
circulation of both sea water and air."
The engineers were enthusiastic. "Tom, I think you have the answer right 
there!" Jack declared. "What'll you call this latest invention of yours?"
NIFFMAN'S STORY 123
Tom smiled. "An osmotic air conditioner describes it, I guess. But there's one 
danger to such a setup," he added.
"What's that?"
"If the surrounding sea water should become polluted, it might have a serious 
effect on living conditions inside the dome."
"A guard system would prevent that," Art suggested.
Tom nodded thoughtfully. He said nothing about a grim possibility that had 
just occurred to him. What if the pollution were caused at long range by a clever 
enemy?
CHAPTER XIV
A BAITED TRAP
AS THE meeting among Tom and his engineers broke up, Art Wiltessa came 
over to speak to the young inventor.
"The plastic dome's almost finished, skipper," he reported. "Like to see it?"
"Sure would, Art. Let's go right now."
Outside the Enterprises main building, they hopped on motor scooters and 
rode across the grounds to a sprawling workshop. Blue-white flashes of welding 
arcs glimmered through its long stretch of glass windows, and the noisy chatter 
of riveting hammers and humming lathes came drifting out.
Tom and Art drove their motor scooters inside onto a conveyor belt. It 
whisked them rapidly to a room at the far end, where they hopped off, leaving 
their scooters to be parked automatically.
"Here she is, skipper!" Art announced proudly as they approached the dome.
The experimental dome was constructed of
124
A BAITED TRAP 125
shimmering, translucent Tomasite plastic. Hemispherical in shape, the dome 
was a hundred and fifty feet in diameter. Four hoisting rings at the top provided 
the attachments for lowering it by cable to the sea bottom.
"Looks swell, Art!" Tom commented. "Let's take a peek inside."
A zipper flap had been opened and thrown back to provide entrance to the 
dome. The two young engineers stepped inside, where several workmen with 
rivet guns were putting the finishing touches on the framework.
The dome was braced by a spider web of slender magnesium rods. 
Lightweight floor struts provided a mounting for the repelatron which would be 
installed later, just before the dome submerged.
"Art," said Tom, scanning the details with a critical eye, "I'd say you've done 
an excellent job!"
"The dome will be portable, of course," Wil-tessa explained. "And those joints 
you see will enable the structure to be folded up."
"Nice work!"
"There's only one thing that bothers me," said Wiltessa. "Too many ribs to 
make transporting the dome easy."
"Yes, you're right," Tom agreed. "Since the air pressure inside the dome will 
hold it against the water and there'll be no pressure on it from the outside, we 
ought to get along with fewer supports."
126 DEEP-SEA HYDRODOME
Art scratched his head, with a slight look of chagrin. "You're right, Tom. Why 
didn't / think of that!"
"No one person can think of everything, Art, but this job comes mighty close 
to being perfect! You did it in record time, too." Tom gave the engineer a friendly 
slap on the back. "How soon will she be ready?"
"Tomorrow noon at the latest. I'll take out all unnecessary supports."
"Fine! We'll give it an underwater test as soon as possible," Tom decided. "If 
no bugs show up, we'll build the giant dome of the same design for the helium 
city."
Happy at the progress of work so far, Tom hurried over to the Enterprises 
security office. He had already relayed N iff man's story to Harlan Ames over the 
telephone, and now he was eager to arrange the details of their plan for trapping 
Dr. Klevalog.
"I've given his description to the police," Ames reported. "They have a 
dragnet out for him, but that bird's probably too wily to let himself be picked up by 
the cops. It'll take some clever planning to catch him off guard."
"Suppose we give N iff man some phony blueprints and formulas for the 
repelatron," Tom suggested. "Then when Klevalog phones this evening, Rube 
can say he has the plans. Klevalog probably will want to see them right away. 
When he shows up, we'll nab him!"
Ames nodded approvingly. "Swell idea! But
A BAITED TRAP 127
we'd better arrange a phone call check with Rube and have him use some 
kind of a code in case anything goes wrong."
Tom agreed that this was a wise precaution, so Ames jotted down four 
signals. Whichever one N iff man used in answering the phone would indicate 
what was going on at his apartment.
"Good. That should cover everything," said Tom, after reading the signals.
A short time later Tom and Ames drove to the infirmary, where Bud, now fully 
recovered, was being discharged. Doc Simpson and Bud accompanied them to 
Niffman's room.
"Hi!" the mechanic greeted them eagerly. "Got a plan figured out yet?"
"I think so," Tom replied. He dumped a sheaf of blueprints and papers on the 
bed. "Here's the bait we'll use for trapping Klevalog."
After explaining the plan, he asked Niffman to repeat it to him, to make sure 
he understood every step.
"When Klevalog calls me this evening, I'll tell him I have the plans for your 
repelatron," said the mechanic. "I'll ask him to come to my apartment and pick 
them up. If he says okay, I'll phone you here at the plant immediately so you can 
nail him when he arrives."
"Check!" said Tom.
"Now then," said Ames. "It may be that he won't give us time to set your trap. 
In other words, he may come straight to your place without phoning first."
128 DEEP-SEA HYDRODOME
"What do I do in that case?" asked Niffman, looking a bit worried.
"If we haven't heard from you by nine o'clock," the security chief explained, 
"we'll call your apartment to find out what's happening."
"But how can I talk if Klevalog's right there?" the mechanic objected.
"We've thought of that," Ames said. "You'll have to slip us the information by 
means of a code message. Here are four groups of words that I want you to 
memorize. Use one of them in your reply."
He handed Niffman a slip of paper containing the four code signals:
Answer number one would contain the words "feel all right" and would mean 
"Klevalog came here to my apartment without phoning." Answer number two, 
"nice day" would mean "He didn't come, but a friend of his is here." Number 
three, "okay with me" would mean "Klevalog isn't coming, but I'm afraid someone 
is watching my apartment." Answer number four would be "before going off" and 
would mean "I can't talk and you'd better come here quick."
"Okay. I've got "em," Niffman said, after studying the list. "I may have to shift 
the words around a little in case Klevalog seems suspicious."
"That's right. If we don't catch on, we'll ask you to repeat it."
When the mechanic had changed into his street clothes and was ready to 
leave, Tom shook hands.
A BAITED TRAP 129
"Good luck, Rube! We'll be waiting to hear from you!"
"Thanks, skipper," Niffman replied fervently. "And I'm glad of the chance to 
help you. Let's hope there aren't any slip-ups!"
That evening, Tom and Bud ate dinner at the Swift home and then drove 
back to the plant before seven o'clock. Doc Simpson and Harlan Ames were 
waiting at the security office.
"It may be a while yet before we hear from him," said Harlan Ames.
An hour dragged by, then another, with frequent glances at the clock. As the 
deadline approached, Ames grew fidgety.
"Three minutes to go," he muttered, checking his wrist watch. "Somehow I 
have a hunch we're in for trouble!"
At nine o'clock Doc Simpson picked up the phone and dialed N iff man's 
number. Instead of Niffman, a stranger answered. The voice sounded muffled, as 
though the speaker was trying to disguise it.
Instantly Doc was alarmed but tried to sound casual as he said, "I'd like to 
speak to Reuben Niffman, please."
"Sorry, but he can't come to the phone right now," the stranger replied. "May 
I take a message?"
Doc Simpson frowned. What now? He decided there was only one thing to 
do.
"Yes. Ask Mr. Niffman this question, please.
130 DEEP-SEA HYDRODOME
I'm Dr. Simpson at Swift Enterprises. I'm calling about a mechanic named 
Tonas who works at Hangar E. Understand he's a buddy of Niff-man's. He 
collapsed this afternoon with a high fever and I wonder if Mr. Niffman could tell 
me whether he showed any symptoms of illness last night?"
"Er-just a moment. I'll ask him."
There was a pause. Then the stranger's voice came back on the line. 
"Niffman says Tonas complained of a stomach-ache just before going off shift."
"Hmm, thanks very much." Doc hung up the phone and turned to his 
companions. "I got answer number four. Niffman used the words 'before going 
off.' That means he can't talk and we're to come there on the double quick."
"Let's go!" said Ames, jumping up from his chair.
Bud's convertible was waiting outside. The three sped off through the night to 
N iff man's address. It was a plain-looking brick apartment house.
"You boys stay here and watch the door while Doc and I go inside," Ames 
ordered.
As they hurried off, Tom and Bud remained parked in the shadows, a few 
yards from the entrance, which was lighted. Scarcely a moment later the door 
burst open and a man with a reddish mustache came running out.
"It's Klevalog!" Tom cried out.
CHAPTER XV
DOME TEST
BUD was about to leap out of the car and give chase, but Tom stopped him. 
"Hold it, pal! Let's trail Klevalog and see where he goes. He might lead us to 
somebody else who's in this scheme!"
"Smart thinking, chum!"
Klevalog had darted across the street and was climbing into a low-slung 
green sedan of foreign make. Switching on his lights, he swung out from the curb 
and took off with a roar.
Bud waited a moment, then whirled his convertible in a fast U-turn and sped 
after him. Up ahead, at the end of the block, they could see Klevalog's taillights 
turning left into a one-way street.
Bud reached the corner, braked for the stop sign, then turned left in hot 
pursuit. There was enough traffic to give them cover, while still keeping their 
quarry in plain view. Fortunately, the street lights and neon business signs made 
the green foreign car easily visible.
131
132 DEEP-SEA HYDRODOME
Half a mile farther on, Klevalog turned right, this time onto a darkened side 
street. Bud rounded the corner a few seconds later.
"Tough break!" Tom muttered. "On a street like this, he'll spot us following 
him!"
"He just did, I think!" Bud replied tensely. "Look at him go!"
The green sedan ahead put on a fresh burst of speed. As Bud followed, it 
roared along for several blocks, then turned again and began weaving in and out 
through a maze of connecting streets.
"Trying to shake us, all right!" Tom said.
They were rapidly approaching the outskirts of Shopton. Suddenly Klevalog's 
car shot through a yellow light. The boys had to brake to a lurching stop as the 
signal changed to red.
"O-oh, what luck!" Bud seethed, drumming nervously on the wheel.
Far ahead, they could see Klevalog's taillights making another turn. By the 
time the boys reached the same spot, the turn-off street loomed dark and empty.
"We've lost him!" Bud groaned.
"Maybe not," Tom snapped. "I have a hunch he's heading for the lake road. 
Let's try it!"
Taking a short cut, they sped along a curving thoroughfare which made a 
juncture with the Lake Carlopa road just north of the city limits. Just as they 
reached the highway, a low-slung green sedan went streaking by.
"This time he won't shake us!" Bud vowed, as he sent the convertible roaring 
off in pursuit.
DOME TEST 133
At this time of night there were few motorists on the highway. Except for the 
moments Kleva-log was passing a trailer truck or disappearing around a curve, 
the boys were able to keep his taillights in view.
"He's turning again!" Bud exclaimed suddenly.
Moments later they followed their quarry up a winding dirt road. Soon it 
became little more than a rutted track. Trees and shrubbery on both sides helped 
to deepen the gloom as their headlights carved a yellow path through the 
darkness.
"There's his car!" Tom whispered.
It was pulled over into the brush with all lights off. Bud parked and the boys 
sprang out to inspect it.
"Empty!" Tom cried.
"He must have gone that way!" Bud exclaimed, pointing to a narrow path. 
Overgrown with weeds, it was barely visible in the darkness.
Arming themselves with a flashlight apiece, the two boys hurried to explore 
the path. It led away from the road for about a hundred yards into a tiny clearing 
fringed with willows and old fruit trees. Beyond stood a ramshackle, weather-
beaten farmhouse, obviously long deserted.
"So that's his hide-out!" Tom murmured as they flicked off their flashlights.
"What'll we do, skipper? Try to rush the place?"
"Too risky. He may have a gun. I'll contact
134 DEEP-SEA HYDRODOME
the police back in Shopton." Pulling his pencil radio from his pocket, Tom 
flicked the switch button. "Tom Swift to Shopton Police! . . . Tom Swift calling 
Shopton Police!"
In a few moments the radio operator at police headquarters responded. Tom 
asked to speak to the chief, who promised to send help immediately.
"By the time they get here, Klevalog will be gone!" Bud fumed. "It's a cinch 
he's not going to wait around to be captured!"
"What else can we do?"
"Listen! I have an idea!" Hastily Bud explained his scheme, and the young 
inventor agreed that it was worth a try.
Taking a flashlight in each hand, Tom held his arms outstretched and 
switched on both flashlights. Then he began circling the edge of the clearing. The 
boys hoped that in the darkness this would give the impression that they both 
were moving off to reconnoiter the house from the rear. Bud, in the meantime, 
had remained where he was.
As soon as Tom played the beams around at the back of the house, the front 
door burst open and a man dashed out. Bud immediately tensed for action as the 
running figure dashed across the clearing.
When the fugitive reached the fringe of trees, Bud launched himself through 
the air in a flying tackle. With a grunt, the man went down!
"Got him!" yelled Bud. "Here's Dr. Klevalog!"
DOME TEST 135
Tom rushed to his pal's assistance. The prisoner fought back with vicious 
kicks and blows. But in a few minutes the two boys had him subdued. While Tom 
held the fugitive, Bud tied the man's hands tightly behind his back with his belt.
"What's the meaning of this outrage?" Kleva-log stormed. "You have no right 
to lay hands on me! I've done nothing wrong!"
"Oh, no?" Tom retorted dryly. "Then how come you were making such a fast 
getaway from Reuben Niffman's apartment?"
"I don't even know anyone by that name!" Klevalog snapped.
"And I suppose you were just playing tag with us back in Shopton?"
The prisoner scowled. "I saw you trailing me, so I got frightened. Who 
wouldn't? I thought you might be gangsters or holdup men!"
"So instead of heading for a police station, you take the darkest side streets 
and wind up out here in the woods!" Tom eyed him scornfully.
He reached into Klevalog's inside coat pocket and pulled out a handful of 
papers, among them the folded blueprints and formulas for the repela-tron. 
Klevalog turned pale and refused to say another word. Tom leafed through the 
rest of his papers and suddenly stopped with a gasp.
"Find something?" Bud inquired.
"Yes-a driver's license for Mr. Firth Webster!"
Bud was flabbergasted. "You mean the man
136 DEEP-SEA HYDRODOME
who got Sandy to talk on the phone while his pal sabotaged her plane?"
As Tom nodded, their prisoner gave a convulsive start but said nothing. Bud 
doubled up his fists and glared at the man as if he would like to punish him right 
then and there for his part in the near tragedy. Instead, he and Tom escorted the 
man to the cars. A few minutes later a sedan full of state troopers arrived.
"Caught your man, eh?" said Captain Rock, an old friend of the Swifts. "Who 
is he?"
"Calls himself Dr. Klevalog," Tom replied. "But I think he's also Firth 
Webster." Tom showed the driver's license. "I suspect he's mixed up in 
something big. In the meantime, you can hold him for practicing medicine without 
a license, conspiracy to commit assault, theft of blueprints of mine, and being an 
accomplice in trying to kill my sister!"
Rock turned a cold eye on the prisoner and started to question him. When 
Klevalog remained tight-lipped, he thumbed him toward the car. "Okay, haul him 
in, boys!"
Half an hour later, Tom and Bud were back at the Enterprises security office. 
Here they listened as Ames and Doc Simpson told what had happened after they 
entered the N iff man apartment.
"Klevalog must have ducked out of sight just before we came in," said Ames. 
"We found Niff-man tied up in his apartment. He says he heard
DOME TEST 137
Klevalog tell his guard out in the hall to run- someone named White."
"White!" Tom exclaimed. "The plane saboteur!"
"Too bad he got away," said Ames.
"Well, boys, our evening's work paid off," said Ames. "Now maybe your 
inventions are safe."
"I doubt it with that man White still loose," Tom replied.
Next morning, while Tom was busy in his office, one of the older Swift 
engineers, Gib Brow-nell, walked in.
"I'd like to ask a favor, skipper," he said. "It may be a good bit of trouble but 
there's a lot at stake-a two-million-dollar industrial plant, in fact."
"Sounds interesting," said Tom. "Sit down and tell me about it."
Brownell pulled up a chair. "Do you recall reading about the sinking of a ship 
called the Funs ton some miles off the Jersey coast?"
"Sure do. It's lucky that most of the passengers were saved."
"Well, my uncle was on board," Brownell continued, "but he died of injuries 
before they could get him to a hospital."
Brownell went on to explain that his uncle's dispatch box had been left in the 
safe, and had gone down with the ship. In it were a revised will, together with 
various letters and other papers relating to the industrial plant.
138 DEEP-SEA HYDRODOME
"Unless that dispatch box is recovered," Brow-nell concluded, "the plant will 
pass into new hands. Unfortunately, the Funston is lying too deep for regular 
salvage operations. But if you could go down in a Fat Man suit, Tom, the 
company would pay you a big fee."
Tom smiled thoughtfully, drumming his fingers on the desk. "Forget the fee, 
Gib. It happens I'm just about to test our new undersea airdome. This will give 
me an opportunity to kill two birds with one stone."
"You'll do it?" said Brownell eagerly.
"Sure, be glad to. Have the company wire me all the details about the ship's 
depth and location, and also how to open the safe."
"Tom, I'll never forget this!"
After Brownell left, Tom went to his private laboratory. He was eager to make 
some new refinements on his repelatron before the test took place. He worked 
steadily until noon, when Chow interrupted, wheeling in a lunch tray of steaming 
chili con carne and egg sandwiches.
"You fussin' with that propeller-tron o' yours again?" asked the cook, as Tom 
tackled the food with a hearty appetite. "Thought you had that gadget all worked 
out perfect."
"It works all right, but not perfectly by a long shot," said Tom between 
mouthfuls. "I'm adding an automatic molecule detector."
"A molly-cule detector?" Chow scowled intently. "Molly-cules are them lil bitty 
specks that everything is made out of, ain't they?"
DOME TEST 139
"You might put it that way," Tom agreed. "Trouble is, when the machine's 
working, it stirs up the water and causes changes in density. And when water is 
under different pressures or at different temperatures, its natural radiation varies 
slightly. On top of that, sea water contains all kinds of dissolved mineral salts, 
which also change the radiation."
To make the repelatron repel all the molecules under these conditions, Tom 
explained that he was adding a tube through which samples of the sea water 
could be drawn into the machine continually. The detector would then adjust the 
machine's action automatically, whenever it found any changes in the make-up of 
the sea water.
"Brand my coyote stew," said Chow, "that gadget's goin' to do everything but 
talk, afore you're done with it, boss!"
"Might be a good idea if it did." Tom chuckled. "Then it could warn us if 
anything goes wrong!"
The test was set for the following evening. Tom preferred to carry out 
operations after dark, to avoid any mention of his repelatron getting into the 
newspapers. It might arouse the interest of enemy agents eager to get the 
invention!
The collapsible plastic dome and the repelatron were loaded aboard the Sky 
Queen. Tom, Bud, and a crew including Gib Brownell took off. Half an hour later 
the huge plane was hovering over the exact spot of the Funston wreck. The 
plane's cargo hatch opened. The airdome in-
140 DEEP-SEA HYDRODOME
flated itself and with Tom and Bud inside was lowered on steel cables.
The repelatron had already been mounted on a platform in the dome, with its 
two ends protruding outside. There were four powerful spot-

DOME TEST
141
lights. Just before the boys reached the surface of the waves, Tom opened 
the switch to full power.
"Wow! Look at that!" Bud exclaimed. "It's repelling the water for at least fifty 
feet around this dome!"

142 DEEP-SEA HYDRODOME
Tom grinned, highly pleased. He reversed the switch slowly and they 
descended. Fortunately, the Funston had settled upright in the mud, so its deck 
provided a level landing stage.
"Okay. You stay here, chum, and tend the controls," Tom told his friend. "I'll 
go get the dispatch box."
As he unzippered the exit flap, Tom felt a glow of satisfaction over the 
invention. The repelatron was working superbly, and the large, transparent 
plastic dome was holding up to perfection.
"It's great, Tom!" said Bud enthusiastically.
Tom stepped out onto the deck. It was a strange, unearthly feeling to be 
walking on board a sunken hulk at the bottom of the ocean, with no water even 
touching its hull or superstructure. The white glare of spotlights lit up the weird 
scene.
Tom made his way to the captain's cabin without incident and opened the 
safe, using the combination which the company had provided. Inside, along with 
a number of other valuables, was the dispatch box, plainly stenciled.
Tom took it, locked the safe, and emerged onto the ship's deck. He gave a 
gasp of horror. The air bubble in which he stood was being pushed out of shape 
by the water. It looked as if the repelatron was working only on one side. The 
bubble was being flattened out.
Soon there would be no air space! The dome and its passengers would be 
crushed!
CHAPTER XVI
A PERILOUS PICNIC
TOM raced toward the platform. Bud was wide-eyed with panic.
"What's happening, skipper?" he cried. "Is the repelatron losing power?"
"Don't know yet, but we'll soon find out. Here, take this dispatch box!"
Neither boy dared think of the awful consequences if the ocean should close 
in around them. Tom grabbed the switch lever and opened it several notches. 
The air bubble expanded a little and the dome began rising, but the water 
pressure was still flattening the bubble.
Suddenly the answer flashed through Tom's mind. "Bud, I have it!" he 
exclaimed, as they continued rising. "Must be some kind of pollution in the water. 
The automatic molecule detector should be adjusting our radiation to 
compensate for it. But it's not taking effect!"
"My brain's fogged, skipper. Tell me what all
143
144 DEEP-SEA HYDRODOME
that means in plain English!" Bud begged nervously.
"It means we'd better get topside fast-or as fast as we dare, anyhow!"
"Then give 'er the gun and let's put on more speed!" the pilot urged.
Tom shook his head grimly. "Can't. Not unless we want another attack of the 
bends. Flicking on the radio, he called the plane. "We're coming up, Hank. Start 
reeling in the slack!"
By the time they had risen two hundred feet, the flattening of the air space 
had subsided. "Relax, Bud," Tom said, breaking into a smile of relief. "We're out 
of the pollution area."
Bud blinked hard. "A sinking boat is bad, but I'd take that to a waterlogged 
bubble!"
Soon the two-man salvage team emerged from the dome. It deflated and 
was hauled into the Sky Queen. Then the boys went aboard.
"You did it!" cried Gib Brownell, seeing the dispatch box.
The engineer was jubilant at the success of the mission. "Tom, I don't know 
how to thank you! You'll be getting a nice fat check from the company board 
whether you like it or not!"
"Never mind that." Tom grinned. "Just tell them to say nothing about how we 
reached the ship. Might give our enemies some more ideas about stealing the 
repelatron!"
"I'll warn them to keep quiet," Gib promised.
Despite this, reporters picked up the story. They had already been covering 
the dramatic
A PERILOUS PICNIC 145
fight for control of the industrial plant. Two days later, at a stockholders' 
meeting, the victory of the Brownell group was announced. At once the newsmen 
started digging out the facts.
The following morning, Tom was dismayed as he read the Shopton Bulletin 
while eating breakfast with his mother and sister. Blaring headlines proclaimed:
daring deep-sea salvage crew reaches funston
Did Divers Use Secret Invention by Tom Swift?
The story said that a Swift engineer, named Gibson Brownell, was known to 
be involved in the salvage job, since the purpose was to recover documents 
belonging to his uncle. This, in turn, led to speculation that a new "mystery 
device" invented by Tom Swift had been used, since the Funston was lying too 
deep for ordinary diving methods.
"Good night!" Tom groaned.
"Does it really matter so much?" Sandy asked.
Tom shrugged. "Maybe not, if they don't run any follow-ups on the story."
The telephone rang constantly at the plant that day. Wire services and 
newspaper reporters clamored for more information about Tom's new deep-sea 
invention. They were given none.
Tom shut himself in his private laboratory, with only Bud to assist him. He 
struggled doggedly to correct the flaws in his automatic mole-
146 DEEP-SEA HYDRODOME
cule detector. The boys worked until almost midnight, then slept on cots at 
the lab. They started again at eight o'clock the next morning.
Shortly before noon someone knocked lightly on the door. Bud opened it. 
"Sandy! Phyll"
Grinning, the girls walked in, wearing gay sun-back dresses. Sandy 
announced that her car was loaded with a picnic hamper and a portable record 
player.
"We knew it was hopeless waiting for you two to take us out on a date, so we 
decided to come and get you!" Phyl added.
"Looks as if they have us trapped, Tom."
The youthful inventor grinned at their two pretty visitors. "What's on the 
schedule?"
"A cruise to Cave Island, followed by swimming and a super-duper picnic 
lunch," said Sandy.
Bud, greatly tempted, looked at Tom. "The detector's practically finished, 
skipper," he said persuasively.
"Okay. Since they're twisting our arms, we'll go."
The boys changed their clothes, then the young people piled into Sandy's 
blue convertible. With the top down, they drove to the Shopton Yacht Club on 
Lake Carlopa. Here the Swifts' sailboat, a sleek little craft, was moored. It had 
been christened Mary Nestor, Mrs. Swift's maiden name.
In a few minutes Tom had cast off and they were skimming out across the 
green expanse of
A PERILOUS PICNIC 147
water. Cave Island lay in the center of the lake, about two miles distant.
"Isn't it a beautiful day!" Phyl exulted. Her long, dark hair was flying in the 
breeze, and she was trailing her hand in the cool waves as they glided along.
"It's perfect," Tom agreed. "We should do this more often!"
After anchoring in the shallows, they waded ashore onto the white, sandy 
beach. The girls picked a pleasant picnic spot, shaded by overhanging trees. 
Then they hurried off to a cave to change into swim suits.
By the time they were ready, the boys had put on swimming trunks and were 
cavorting like porpoises in the water.
"Come on, you scaredy cats!" yelled Bud, as the girls tested the water 
delicately.
"Okay," said Sandy, "but don't you try any-"
Her words ended in a shriek as Tom sent a sheet of water flying toward 
them, splashing both girls from head to foot!
For over an hour they swam, laughed, and sunned themselves. Then when 
Tom and Bud announced that they had worked up ravenous appetites, they 
decided it was time to open the picnic baskets.
As the two couples strolled along the beach, they heard the sound of a plane 
and glanced up.
"Hey, what's that hotrock up to?" Bud cried out.
The plane, a small gray one, was heading
148 DEEP-SEA HYDRODOME
straight for the island. Tom watched the craft through narrowed eyes. His 
scalp prickled with a sudden sense of impending danger.
As it neared the island, the plane suddenly swooped down, roaring in so low 
that the picnickers instinctively dived to the sand. The plane circled sharply and, 
with an ear-splitting whine, buzzed the beach again.
"If I ever get my hands on that rockhead-" Bud stormed as he leaped to his 
feet.
"Look out! He's coming back!" cried Phyl in terror.
This time, as the plane whipped past, it sprayed the beach with a heavy 
vapor. In a twinkling, the stifling gas began to diffuse over the island.
"Quick! Into the cave!" Tom yelled. "Grab your clothes, Bud!"
Hands over their faces, the four picnickers raced across the beach. When 
they reached the cave, Tom and Bud hastily barricaded the entrance with rocks 
and stuffed up the chinks with their shirts, trousers, and sweaters.
"Tom! Something's happened to Phyl!" Sandy gasped in a panic-stricken 
voice.
Her brother's face went white as he saw that the dark-haired girl had 
slumped unconscious on the cave floor, evidently overcome by the gas.
"Oh, what'll we do?" cried Sandy fearfully.
Tom racked his brain. Suddenly he recalled that one long, sweeping branch 
of a giant cedar tree reached inside the cave.
A PERILOUS PICNIC 149
"Chafe her wrists, Sandy!" he ordered.
Groping in the gloom, Tom stripped the needles from the branch, crushed 
them between his strong fingers, and held them under Phyl's nostrils. Soon the 
pungent, aromatic scent revived her.
"Wh-what happened?" she murmured.
"That gas sprayed from the plane made you black out," Tom replied. "But 
don't worry, Phyl. You'll be okay and we're safe in here."
Fortunately, a strong breeze soon dispelled the vapor and in twenty minutes 
they were able to venture out. There was no sign of the strange plane. Sandy 
gazed dejectedly at their picnic lunch, which was spoiled.
"Let's go home and eat," she suggested with a sigh, and the others agreed.
As soon as they arrived in Shopton, Tom phoned Harlan Ames at the plant 
and reported the incident.
"Any idea where the plane came from?" asked the security chief.
"None at all," Tom replied. "It had no marks of identification, and we couldn't 
see the pilot."
"Okay, I'll notify the CAA. Maybe the Air Patrol can spot it."
No word came, but the next morning Tom received a long-distance call from 
Admiral Hopkins. The officer reported that a Navy sub had found another cache 
of warheads and substituted empty chests in their place.
"We'd like you to be on hand when the chests
150 DEEP-SEA HYDRODOME
are opened, Tom," the admiral went on. "Could you fly down to Norfolk this 
afternoon?"
"Yes, I could, sir. I'll leave right after lunch."
Taking off in a company jet, Tom landed at Norfolk and was driven to an 
underground safety laboratory. Here he found Admiral Hopkins waiting with a 
group of officers and civilian experts.
"You're in charge, Tom," said the admiral. "You've already had experience 
with these confounded things."
"Right, sir."
The others waited anxiously as Tom pried off the lid of the first chest. It 
proved to contain warheads like those they had seen before. But the second 
chest held a strange-looking cylinder punched with holes, as well as a warning 
note printed by hand in several languages. In English it read:
ANY PERSON WHO OPENS THIS WILL NOT LIVE LONG!
As the group looked at one another, puzzled and worried, they heard a faint 
hissing sound from inside the chest I
CHAPTER XVII
THE STAR MARK
THE HISSING sound was obviously coming from the perforated cylinder.
"It must be a bomb!" cried one of the civilian experts.
A fearful tension clutched the group and everyone turned pale with alarm. If 
the cylinder contained a nuclear device, it would not only disintegrate the 
laboratory but probably wipe out part of the town!
How many seconds remained before it might go off?
Tom's thoughts were racing. "Bring a vacuum pump here and hook it up 
fast!" he yelled. As two Navy men rushed to comply, Tom said, "I believe the 
bomb mechanism was started by exposure to air. Our one chance is to seal up 
the chest again and exhaust it before the chemical fuse finishes reacting!"
"Let's hope you're right!" said the admiral
151
152 DEEP-SEA HYDRODOME
fervently. Turning to one of his aides, he barked, "Rawley, you and Jones 
start broaching some oil drums. We'll fill up that vat over there and dump the 
chest in!"
Within half a minute the pump had been set up, the chest lid tightly sealed, 
and a valve fitting attached through which the air could be exhausted. The pump 
throbbed into action.
As soon as the gauge needle showed a high vacuum, the valve was snapped 
shut and the pump disconnected. Then the chest was lifted by a chain fall and 
plunged into the huge glass vat.
A deathly silence had settled over the laboratory. Everyone left and went 
aboveground. Twenty minutes later Tom said:
"I'm sure that the fuse's reaction was stopped in time, or there would have 
been an explosion by now. The danger is over."
There were audible sighs of relief and several of the men came to shake 
Tom's hand.
"The Navy owes you a tremendous debt," said Admiral Hopkins. Turning 
back to his aides again, he smiled. "Fly that chest out to sea and give it the deep 
six!"
Tom did not smile, however. "The men who are planting the chests have 
found out we're tampering with their caches. This warning note practically proves 
it."
"But we've substituted dummy chests. Surely that will mislead them."
"It might, unless they have started identifying their own cases," the young 
inventor pointed
THE STAR MARK 153
out. "Let's see if the ones we have here are marked."
Everyone returned to the underground laboratory. Examining the first chest 
which Tom had opened, they found a barely discernible star pressed into the 
back of it. The other chests bore the same identification. There were no other 
clues to its maker.
"Hmm." Admiral Hopkins frowned gravely. "We'd better send a sub back to 
mark those dummy cases we planted!"
The remaining chests contained no more surprises, and by 3:30 that 
afternoon Tom was on his way back to Shopton. As he landed on the Enterprises 
airstrip, a call came from the tower:
"Tom Swift wanted by Harlan Ames," and a few seconds later the security 
chief came speeding across the field in a jeep.
"What's up, Harlan?" asked Tom as he climbed out to greet him.
"I think the Air Patrol has located that mystery plane," Ames reported. "I 
mean the one that attacked you on Cave Island. The FBI found it abandoned in a 
field up north of Hainesville. Want to go take a look at it?"
"Sure," said Tom eagerly. "Let's fly the heli-plane."
This craft was another of Tom's inventions. It had rotors for take-off and 
hovering, but these folded into the fuselage during flight, when the ship was 
being operated as a conventional jet.
Ames had marked the location on a map, and
154 DEEP-SEA HYDRODOME
Tom found the field without difficulty. An Air Patrol officer and two men in 
civilian clothes were standing beside the abandoned plane.
"Hi, Wes!" called Tom to one of the FBI agents. He was Wes Norris, who had 
worked with the Swifts in preparation for their expedition to the phantom satellite.
"Hello, Tom," he said. "Is this the crate that buzzed you and sprayed the 
gas?"
"Certainly looks like it." Tom noticed that the plane's identification numbers 
had been painted over. "Have you traced the owner?" he asked.
The agent nodded. "It was reported stolen yesterday morning. And I have a 
strong hunch who's responsible. A member of a subversive group we've been 
checking on. One of them is a pilot."
"I see," said Tom. "Where do they come from?"
Norris held up some charred remnants of colored cloth. "This is what's left of 
a certain foreign flag. You can guess which country. We found this inside the 
plane."
Tom gave a low whistle. "Wow! This bunch must be in cahoots with Klevalog 
and the others who are trying to steal my inventions, and if they've found out 
about the helium, they probably want it for themselves."
"Yes," said Ames. "And it may explain where the atomic warheads are 
coming from!"
THE STAR MARK 155
"They're a dangerous group, all right," Morris agreed. "However, the Bureau's 
pressing a search all over the country for them."
"Fine, Wes! Let us know the minute anything develops."
That evening Tom relaxed at home in front of the TV set with his mother and 
Sandy.
"I sure wish Dad would get back from The Citadel," he said. Tom missed the 
wise, cool-headed advice which Mr. Swift could always be depended upon to 
provide at crucial stages of a new undertaking.
"Sandy and I do, too," Mrs. Swift spoke up wistfully.
Tom said he thought another inspection trip to check the undersea gas beds 
would be a good idea before the expedition got underway to build the helium city.
Mrs. Swift looked at her son fondly. "You will be careful, won't you, dear?"
"Promise," he said, hugging her as he said good night.
In the morning he called Hank Sterling at the Fearing Island base. "Get the 
Sea Hound and one other seacopter ready for a cruise, will you?"
"Will do, skipper. What's the program?"
Tom outlined his plans, then hung up and put through another call, this time 
to Admiral Hopkins. He invited the chief to accompany him on the cruise the next 
day, along with a picked group of officers and civilian experts.
156 DEEP-SEA HYDRODOME
"Could you make it by ten o'clock tomorrow morning, sir?" Tom went on. 
"We'll be taking off from our Fearing rocket base."
"We'll be there!" Admiral Hopkins promised.
When Chow Winkler wheeled Tola's lunch tray into the laboratory at noon, 
the cook's leathery face had a worried look.
"This true what I hear about you leavin* on another ocean cruise, boss?"
"That's right, Chow. Is anything wrong?"
"Well, blame it all, ain't you goin' to need a cook?" the old Texan asked in an 
aggrieved voice.
Actually Tom had made no such plans, figuring that box lunches would be 
the simplest answer to the commissary problem. However, he hastily replied, 
"Sure we are, Chow! You're coming along, aren't you?"
The chef's face broke into a grin. "Brand my tops'l, you bet I am, skipper! An' 
jest you wait. I'll wrassle you up some seafood that'll make the fishes sit up an' 
take notice!" Humming "Blow the Man Down," Chow waddled off happily to figure 
out his deep-sea menu.
The following day the Navy group landed on Fearing Island in a plane. At 
once Tom escorted them aboard the seacopter. Tom would pilot the Sea Hound 
with Chow, Bob Anchor, and Dr. Clisby on board, along with Admiral Hopkins 
and a rocket expert, Dr. Albert Prentiss. The rest of the group would accompany 
Bud Barclay in the other ship.
After demonstrating the seacopter's jet flight
THE STAR MARK 157
features above the Atlantic, Tom submerged about two hundred miles out to 
sea. Bud followed close in his wake.
Admiral Hopkins marveled at the Sea Hound's performance. "It'll be a great 
day when the Navy puts some of these into commission, Tom!"
When the two seacopters reached the helium fields, Dr. Prentiss was 
amazed and excited at sight of the myriad of huge gas bubbles pouring up from 
the ocean bed.
"This source of helium should supply all our rocket needs for years to come!" 
he said.
"How soon can we start drilling, Tom?" put in Dr. Clisby.
"I see no reason why we shouldn't begin outfitting the expedition at once," 
Tom decided.
When Admiral Hopkins asked to be shown where the cache of warheads had 
been planted, Tom steered the Sea Hound in that direction. Suddenly a shout 
came from Bob Anchor at the sonarscope.
"I've picked up something, Tom!" he reported. "On the starboard quarter!"
Tom's heart pounded with a thrill of alarm. "Is it a sub?" he asked.
Bob peered at the scope tensely. Then he cried out, "From the terrific speed, 
it must be a missile! And it's heading our way!"
CHAPTER XVIII
A HAZARDOUS RESCUE
WITH NOT even a fraction of a second to lose, Tom gunned the jets of the 
seacopter and threw the wheel hard aport. The Sea Hound streaked out of 
danger.
A second later came a muffled bo-o-o-om on the sonarphone and the craft 
rocked. Tom had to grab the wheel to keep from being thrown to the deck.
"They've hit Bud's ship!" Bob Anchor yelled in a stricken voice.
Tom froze with dread. Had his best friend been killed and all the men with 
him?
Before he could shake off the feeling of horror, there was fresh cause for 
alarm.
"More missiles coming!" Bob cried out.
Gritting his teeth, Tom pulled himself together. His slim, sinewy hands flew 
over the bank of controls as he sent the Sea Hound racing for cover in the lee of 
the undersea mountain.
Tom switched off the seacopter's searchlight, 158
A HAZARDOUS RESCUE 159
and the craft lay in darkness on the ocean floor. A rocky outcrop at the foot of 
the mountain provided partial protection from a direct hit.
Boom! . . . Boom! . . . Boom! The Sea Hound shuddered and vibrated 
repeatedly as the missiles exploded all around it.
Peering at the sonarscope, the young inventor saw a dim blob of light, which 
showed where the other seacopter was lying, several hundred yards away. 
Apparently it had settled straight to the bottom after being hit.
"Oh, if only those men are alive!" Tom thought.
Gradually the last vibrations died away, and the ocean became silent. 
"Guess they've ceased fire," Bob Anchor muttered.
Chow had emerged from the galley. "If them sidewindin' rats has harmed any 
o' our pals," he growled, "I hope they get bio wed sky-high by one o' their own 
torpedoes!"
Tom waited a while to make sure the cease fire was not a trick to lure him 
into revealing the Sea Hound's position. Finally, his heart pounding, he called 
over the sonarphone:
"Sea Hound to Swiftcopter. Can you read us, Bud?"
There was a brief, terrifying silence. Then a feeble reply came back, "Right 
here, skipper. You fellows all right?"
It was Bud's voice! Tom felt like shouting for joy. "Sure we're all right!" said 
Tom. "How about you?"
160
DEEP-SEA HYDRODOME
"Not so hot, pal. That missile nailed us amidships and smashed the rotor 
blades. On top of that, the escape hatch is jammed and water's seeping in."
"How long can you hold out?" Tom inquired.
Bud paused. "Maybe three or four hours, if the leak doesn't get 1 any worse."

A HAZARDOUS RESCUE
161
"All right, plug it up as best you can and stand by. I'll get help pronto!"
Hurrying back to the controls, Tom surfaced the Sea Hound and beamed an 
SOS to Shopton, telling George Billing what had happened.
"Have Hank load a big repelatron and Dad's giant magnet on the Sky Queen, 
and get here fast!" he told George. "Every second counts. And have Arv Hanson 
follow in another seacopter."
"Right, Tom!"
Time was growing short for the trapped men when the huge silver-winged 
plane came streaking into view of the Sea Hound. Only a few minutes before, 
Bud had radioed that the water in their cabin was now waist-high.

162 DEEP-SEA HYDRODOME
"They're here!" Tom told him over the sonar-phone. "Hang on! We're going to 
lower a repela-tron."
Feverish activity followed, as the repelatron was lowered on steel cables to 
the surface of the water. As Tom started to step onto the platform, Chow begged 
to go along.
Tom looked into the old cowpoke's worried eyes. "Sure, Chow. I can use 
your help."
Equipped with acetylene torch, chisels, and crowbars, the two began their 
descent. Soon they were plunging downward, enclosed in a giant air bubble.
"On target!" Tom signaled, as the repelatron settled squarely into position 
above the disabled seacopter, sending the water back from the craft for fifty feet.
Through the cabin window, Bud and the Navy men could be seen, waving 
and whooping in wild relief. Twenty minutes of work on the air-lock hatch brought 
the near victims rushing out to freedom. They clapped Tom and Chow on their 
backs in thanks.
Cheers from the Sea Hound and the Sky Queen greeted the men when they 
rose to the surface. After a brief rest Tom instructed Hank to lower the giant 
magnet. With this, he hoped to bring up the disabled seacopter.
In the meantime, Arv Hanson arrived and the young inventor ordered him to 
remain at the undersea mountain and patrol the area until the salvage operation 
was completed.
A HAZARDOUS RESCUE 163
"But if you pick up any sign of the enemy, radio an alarm to us and run for 
home!" Tom warned.
"Don't worry, Tom." Arv chuckled. "We're not hankering for a torpedo hit!"
Two hours later the Sky Queen started back to Fearing at a lumbering pace, 
with most of the Navy men aboard and the disabled seacopter grappled to her 
hull. Bud preferred to make the return trip in the Sea Hound with Tom.
Darkness had fallen when they landed on Fearing. Admiral Hopkins and his 
companions boarded a waiting Navy transport, and Tom and Bud flew back to 
Shopton.
"An exciting cruise." Bud chuckled as the boys prepared for bed. "Another 
one like it, and we'll all rate campaign ribbons!"
Two mornings later Tom had just arrived at the plant when Miss Trent asked 
him to talk to Harlan Ames by phone.
"Hello, Harlan. What's up?" Tom asked.
"The FBI found Mrs. Paulus White," Ames reported excitedly. "The wife of the 
man who tried to wreck Sandy's plane."
"How about her husband?"
"She doesn't know where he is-said he kept all his business dealings secret. 
But she was able to give the FBI one lead on a man named Menarsky."
Tom jotted down the name. "Ever heard of him?"
"I sure have," said Ames. "He's one of the big
164 DEEP-SEA HYDRODOME
wheels in that subversive group Norris mentioned."
Tom gave a whistle. "I guess that ties things up pretty tight! Keep me posted 
on all developments, Harlan."
The morning was spent in a flurry of phone calls, rapid-fire orders, and rush 
trips to various parts of the plant. By noon, cargo planes were taking off on 
shuttle trips, hauling equipment and supplies to Fearing Island for the expedition 
to the helium wells.
Later that day Tom and Bud took off by heli-plane for the rocket base to 
check final preparations. A few minutes after leaving Shopton, Tom felt a nudge 
from his copilot.
"Say, space boy, look over there at three o'clock! Ever see a plane like that 
before?"
A strange, sleek-looking jet was arrowing in from seaward. "Some kind of a 
fighter," Tom said with a frown. He focused a pair of binoculars. "Good night! It's 
a robot! And coming this way!"
Tom nosed upward, shooting for altitude. The robot soared after them. "This 
is no joke!" he cried, opening the throttle wide.
He looped, rolled, and sent the heliplatfe into a screaming dive, but the robot 
followed every maneuver as if by magic. In desperation, Tom waited to pull out 
until he was almost scraping the treetops, then banked sharply and roared 
skyward again. But he still could not shake the needle-nosed demon off their tail!
Heading out to sea, Tom went through every
A HAZARDOUS RESCUE 165
acrobatic trick that his father and Rip Hulse, a wartime fighter ace, had taught 
him. After ten minutes, both boys were white-faced and streaming with 
perspiration. At times it seemed that only a split second saved them from 
disaster!
Then, just as they streaked past a rocky stretch of coast, the pursuing robot 
ran out of fuel. With a screaming whine it plunged, hit the water, and exploded in 
a terrifying burst of flame.
Both boys slumped weakly in their seats. Bud murmured hoarsely, "Where in 
Jupiter did that baby come from? Was it land-controlled or operated from another 
plane?"
Tom could only shrug. "One thing I do know. We've never had a worse 
enemy than the one who tried this fiendish trick."
As soon as they landed at the rocket base, Tom ordered an immediate 
search for the robot's launcher by every available plane, both at Fearing and 
Enterprises. He also notified Admiral Hopkins.
Though worried, Tom determined not to let the terrifying incident stop the 
preparations for the trip. An hour later he paused in his work to phone the control 
tower.
"Any results yet from the search planes?"
"No, Tom," the operator replied. "You want the pilots to keep at it?"
"I guess it's hopeless," Tom decided. "Tell them to return to base."
At eight the next morning the great move toward the undersea mountain 
finally got under-
166 DEEP-SEA HYDRODOME
way. A fleet of eight huge cargo planes, including the Flying Lab, lined up on 
the airfield to be loaded with the repelatron, folded plastic dome, and the heavy 
construction gear. Smaller equipment would be transported by seacopter.
Tom took off first in the Sea Hound, accompanied by Bud, Chow, Dr. Clisby, 
Bob Anchor, and the crewmen. He was followed immediately by Hank Sterling 
piloting the Sky Queen, and a cargo jet with Slim Davis at the controls.
"We're off to that mystery mountain despite our enemies!" Bud chortled as 
the trio of aircraft streaked in V-formation high across the heaving waters of the 
Atlantic.
"My first experience founding a city," Dr. Clisby spoke up.
Reaching the site of the helium beds, Tom brought the Sea Hound down to 
the surface of the water, while the two planes hovered close by. Operations had 
been planned to the last detail.
Tom would go first with the giant repelatron and set up the osmotic 
atmosphere conditioner. Then would come the enormous plastic dome, and 
finally the rigging for the wells and the prefabricated dormitory, galley, and office. 
All the latter equipment would descend by elevator in air bubbles created by 
small repelatrons.
Three crewmen went down with Tom on the first trip, and the platform of the 
repelatron was set on the great plateau of the mountainside. Until everything was 
in working order, it would not be detached from its elevator.
A HAZARDOUS RESCUE 167
"This is amazing!" remarked one of the engineers, Pete Elliot, as the 
atmosphere conditioner began to function, bringing about a perfect balance with 
the helium bubbling up from the ocean floor.
"A little more work and we'll be ready to send for the other equipment," said 
Tom, walking off to determine whether they had selected the best spot for 
anchoring the repelatron. "Pete, bring me a rock tester."
When there was no answer, Tom glanced around. He saw that the three 
crewmen were weaving dizzily, about to collapse!
"What's wrong?" Tom cried out. At the same moment he felt a wave of 
giddiness. "The atmosphere conditioner isn't operating!"
Tom instantly realized that chemical pollution in the water was poisoning the 
air supply. The action of the repelatron might also be affected!
"Quick! Into the elevator!" he gasped.
Staggering and helping one another, the four clambered onto the elevator 
landing stage. Tom groped for the switch lever. Then everything blurred before 
his eyes!
CHAPTER XIX
TOM IS KIDNAPED
WHEN TOM'S vision cleared, the water outside the elevator bubble was blue 
green. They were rising steadily!
"Whew!" he shuddered with relief. "We're near the surface. I must have 
worked the lever even though I almost blacked out!"
His three companions were stirring groggily. Moments later, when the 
elevator broke surface, the sunshine and fresh salt air quickly revived them.
"What happened?" Bud asked, as willing hands helped them aboard the Sea 
Hound.
"Something was polluting the water down there. It fouled up the atmosphere."
A worried frown appeared on Dr. Clisby's face. "Another move by our 
enemy? Or was the pollution just caused by an ocean current?"
"It was carried by an ocean current," Tom said grimly. "Where it came from is 
another question."
168
TOM IS KIDNAPED 169
A stir of alarm ran through the crew. One man asked, "You mean this gang 
we're up against is trying to poison the air we'll breathe?"
Tom was pacing back and forth, scowling thoughtfully. "Could be, Dave," he 
muttered.
Striding over to the radio, Tom picked up the mike and called Arv Hanson's 
seacopter. "There's a pollution current around the wells, Arv. It may mean 
someone's doctored the water. How about submerging to see if you can pick up 
anything on your sonar?"
"Sure thing," Arv replied. "Which direction is it coming from?"
Tom consulted an oceanographic chart. "The general current flow is 
approximately from the northeast. But that may not mean too much along the 
bottom. Better scout the whole area within a ten-mile radius."
"Roger!"
As the young inventor switched off the radio, Bud asked, "Suppose we can't 
trace the source, Tom? Anything we can do about it?"
Tom puckered his brow. "Sure. We can set up a purification plant to filter out 
any chemicals or foreign material. But that would take time. It could ruin our 
whole construction schedule."
After a hasty conference on board the Sky Queen, Tom reached a decision. 
He would have Billing rush a shipment of gas masks by plane. As soon as they 
arrived, operations would continue under Hank Sterling's direction, with the two 
sea-copters constantly patrolling the area.
170 DEEP-SEA HYDRODOME
"Okay," Hank nodded. "But how about you, skipper?"
Tom replied that he and Dr. Clisby would fly back to Enterprises immediately 
in the Sea Hound to design the antipollution setup. "Which reminds me," he 
added, "I'd better radio Admiral Hopkins in Washington to send up some Navy 
engineers. They can probably give us some valuable help on the job."
By the time he landed in Shopton, the Navy engineers had already arrived. 
The young inventor and Dr. Clisby went into a huddle with them. The meeting 
lasted until eight that night. By midnight a design had been worked out which 
seemed to answer the problem.
Draftsmen, machinists, and production men were standing by to translate the 
design into actual "nuts and bolts." Working all night and into the next day, they 
had the equipment ready by noon. Next step was to test it in operation.
"We'll use the submarine test tank," Tom told the engineers. This mammoth 
concrete tank was set in bedrock on the Enterprises grounds.
The new equipment was installed and hooked up. Then Tom spun the valves 
and water gushed in through a row of four-inch nozzles.
A thick steel door slid shut, sealing the tank. Pressure was gradually built up 
equal to the two-mile ocean depth at the helium beds.
"Now to feed in the chemicals," Tom murmured.
Dr. Clisby had mixed several drumfuls of toxic
TOM IS KIDNAPED 171
solutions. These were pumped in, one at a time, while Tom and the 
engineers studied a cluster of gauges. When the test was over, all were jubilant.
"Works like a charm!" said Commander Gray-ton, one of the Navy experts. 
"With this setup in operation, Tom, the atmosphere in your airdomes should be 
safe at all times."
To make absolutely sure, Dr. Clisby ran a series of chemical tests on a final 
water sample.
"Not a trace of impurities!" he announced.
"We're certainly grateful for your help," Tom told the Navy engineers. "If 
possible, I'd like all of you to come along and inspect our operations."
The invitation was accepted with enthusiasm. Less than two hours later, the 
men were flying toward the undersea helium beds. As they approached the area, 
Dr. Clisby observed, "It looks as if Hank is really making progress."
"He's a man that gets things done!" Tom agreed. More than once in the past, 
his own life and the success of a Swift expedition had depended on the blond, 
square-jawed chief engineer.
The whole surface of the ocean for almost a mile around was bustling with 
men, seacopters, and hovering aircraft. Two Navy supply ships, a Swift tanker, 
and a tug operated by the Bureau of Mines had also arrived on the scene.
"Let's go below and take a look," Tom invited his guests.
He dived the Sea Hound to the mammoth dome, set inside the giant air 
bubble. The sea-copter was parked in the vacuum beyond the
T72 DEEP-SEA HYDRODOME
dome and the passengers walked through the zippered entrance.
The helium city was already taking shape. At the moment a crew of riggers 
was erecting the derricks.
"Tom," said one of the Navy men, "this is the most unusual experience of my 
life!"
Work proceeded quickly. Tom checked the exact direction of current flow by 
means of radioactive tracers. A site for the antipollution station was then 
selected, about two miles from the helium wells, and a repelatron and a dome 
were lowered over the spot.
The purifying equipment was brought down in sections by elevator. In less 
than an hour, Tom and the Navy engineers had it set up and operating.
Chow, who had come along for what he called a "look-see," asked, "How's it 
work?"
"It's fairly simple," Tom explained. "This big pipe will be channeling water 
through the dome at all times. If the slightest trace of impurities shows up, this 
electronic device will detect it. The equipment will then begin its purifying action, 
which will affect the water for miles around."
"Brand my octopus soup," said Chow, goggle-eyed, "this thing's got a sink 
strainer beat all hollow!"
The engineers broke into roars of laughter.
Forty-eight hours later, the helium city was an established fact. Inside the 
dome were a mess hall,

174 DEEP-SEA HYDRODOME
dormitory, laboratory, gas tanks, and drilling equipment.
Tom made a final inspection with Hank Sterling. The place hummed with 
activity, as crewmen swarmed about the drill rigs, while others tended valves or 
stood by the control panel of the central power supply. The helium gas was being 
piped into a huge storage tank, to be bottled later.
"It's a terrific achievement, skipper," said Hank quietly.
"Without your help, it couldn't have been done, Hank," Tom replied.
As night closed over the ocean, the scene became quiet. Below the surface, 
all the men had gone to bed, except a few watchmen and gauge tenders. High 
overhead, the sky blazed with stars.
Tom was restless and unable to sleep, after his weeks of intense work under 
almost constant pressure. He got up, walked around, and suddenly stood still. 
Did he detect a tiny light inside the Sea Hound?
"No one is supposed to go in there," Tom told himself and decided to 
investigate.
But once inside he found no one. "Guess I was wrong," he thought.
Tom was about to leave when the urge came over him to do some 
experimental work.
He smiled to himself as he entered the laboratory. "That's one sure way to 
relax!"
Under the soft light of a fluorescent lamp, he began to design a brand-new 
repelatron. This
TOM IS KIDNAPED 175
one, instead of repelling water, would work against metal. Tom chose 
aluminum as the material for his experiment.
For an hour he remained hunched over his worktable, amid a jumble of 
electronic parts and test gear. Finally the job was done. By means of transistors 
and a flashlight-sized solar-charged battery, he had been able to assemble the 
device in a case small enough to be held in one's hand.
Tom tested the device on several aluminum disks and found that it worked to 
perfection.
"Not bad for one night's work," he yawned. Then he glanced at his wrist 
watch. "Wow! Two o'clock! I'd better get some shut-eye."
Slipping the tiny repelatron and disks into his pocket, Tom left the lab and 
stepped out into the passageway.
To his amazement, the air-lock doors opened. Two strange men, holding 
deadly-looking automatic pistols, entered. One man had a short black beard; the 
other was burly and shaven-headed.
"Surprised, my friend?" asked the bearded man. He spoke in a heavy foreign 
accent.
Tom had frozen in dismay. These must be his mysterious enemies! 
Recovering, he asked, "Who are you and how did you get in here?"
"We too have a few clever devices, including an antisonar machine and 
some undersea suits that got us here from our subs. We left them in the air lock." 
The bearded man waved his gun curtly. "And now kindly step into the control 
cabin, Tom Swift, with your hands up!"
176 DEEP-SEA HYDRODOME
Tom obeyed. When they reached the cabin, his captor snarled a guttural 
order. Instantly the shaven-headed man stepped to the controls, which he 
seemed to understand perfectly.
The hum of the rotors altered slightly as he raised the seacopter from the 
ocean floor. Then, with a flick of the throttle, he sent the Sea Hound knifing 
forward through the inky waters!
Tom's thoughts were in a whirl. What was happening outside? Would anyone 
come to his rescue?
"I can read your mind, my friend." The black-bearded foreigner smirked. "At 
this moment my men are taking over your helium city. And thanks to your 
ingenious inventions, we will reap the rewards of all your efforts!"
Tom tried not to show the rage that was boiling inside him. The priceless 
helium he had worked and striven for-now it would become the prize of an enemy 
power!
"You, my dear Tom Swift," his captor went on, "will be held as our hostage, to 
make sure your crewmen surrender peacefully. Then, of course, you will be put 
to death!"
The black-bearded man threw back his head and chuckled mirthlessly.
"Unless," he added, "you care to make a bargain with us."
"Name the terms," Tom said.
"Quite simple. You will have your father turn over to me the complete plans 
for all your Swift inventions!"
CHAPTER XX
A HIDDEN WEAPON
TOM clenched his fists so hard that his nails bit into the flesh of his palms. 
So the scoundrels were offering him a chance to save his own life! But at what a 
price! All the Swift inventions, many of them for government use only.
"You expect me to accept a bargain like that?" Tom demanded in a choking 
voice.
"Why not?" His captor smiled suavely. "It is never pleasant to die, especially 
when one is so young. And I assure you that your manner of death would be 
most unpleasant!"
Tom could hardly keep from smashing out at the leering black-bearded face 
that smiled back at him so mockingly through the soft gloom of the Sea Hound's 
cabin.
Controlling himself, Tom asked, "And suppose I did accept your terms. What 
then? Would I be allowed to go free?"
The enemy agent chuckled again. "Alas, I fear we could hardly afford to be 
so generous. A brain
177
178 DEEP-SEA HYDRODOME
such as yours is far too valuable to us. You would, of course, be allowed to 
live. But you would remain a prisoner and go on developing new inventions-to 
serve our cause."
"I'll think about it," Tom muttered, playing for time.
"I suggest you do so, my friend-very seriously!"
Tom's face was a mask. "In the meantime, may I put my hands down before 
they drop off?"
"Very well. But no tricks. At such close range, a burst from this automatic 
pistol would leave you in very regrettable shape!"
As Tom eased his aching arm and shoulder muscles, his mind was racing for 
a way to escape from his dilemma.
While the seacopter rose in a slant through the pitch-dark waters, Tom 
engaged the men in conversation. He pretended to show a calm scientific 
curiosity about the undersea equipment they had used in carrying out their plot.
The shaven-headed man said little, except for occasional grunted comments. 
But his black-bearded companion became talkative.
"Allow me to introduce myself," he said. "My name is Menarsky."
"I've heard it before," said Tom grimly.
"Ah, yes." The bearded man bared his teeth in a smirking smile. "I am, of 
course, well-known to your stupid FBI. And this bald one here is my second-in-
command, Klaus Sturko."
A HIDDEN WEAPON 179
"I take it you don't expect me to say I'm happy to meet you," Tom snapped.
"Ha-ha! That is good-very good!" Menarsky roared. "I am so glad to see that 
you have not lost your sense of humor!"
Presently Sturko switched off the power and eased the Sea Hound to a stop. 
Tom could see the ghostly outlines of a whale-shaped submarine, rolling gently 
among the waves alongside.
"We will now transfer to our own flagship," Menarsky announced. "And once 
again I warn you, Tom Swift-no tricks!"
Sturko went first. He picked up the two bulky deep-sea suits which the 
enemy agents had worn entering the Sea Hound. To Tom's amazement, the suits 
appeared to be made out of some tough but flexible woven-metal fabric-perhaps 
designed to be inflated and pressurized like space suits-allowing complete 
freedom of movement.
Scrambling out of the hatch to the whale-shaped sub, Sturko led the way, 
with Tom next. They entered through a small conning-tower hatch and climbed 
down a steel ladder. Another amazing discovery awaited Tom. There appeared 
to be no crewmen aboard!
"You are surprised, no?" Menarsky chuckled. "Our automatic pilot is of very 
advanced design. We do, of course, carry a crew, but as I told you, they are now 
busy taking over your helium city!"
Tom looked around at the neat tiers of folded bunks, the missile tubes, the 
clusters of control
180 DEEP-SEA HYDRODOME
dials and gauges, the shielded housing of the atomic reactor. It was obvious 
that the craft had been planned by a master designer!
Menarsky watched Tom's reaction with gloating pride. "Since you are being 
so reasonable, perhaps you would also like to see the ship's laboratory and 
scientific equipment," he offered.
"I would, very much," said Tom, quite sincerely.
Menarsky led the way aft and opened a steel door, while Sturko followed 
close behind. As Tom stepped into the laboratory, his eyes widened in 
admiration.
With the exception of his own setup on the Flying Lab, probably no other 
craft on earth was so thoroughly equipped for scientific research.
Tom whistled. "This is amazing!"
"You like it, eh?" Menarsky replied. "Well, you can work here too, my young 
friend, if you care to join us."
Pleased by Tom's reaction, he began pointing out other pieces of equipment. 
Sturko, too, was obviously very proud of the setup. From time to time, he threw in 
a guttural comment when Menarsky failed to mention some feature of the 
laboratory's resources.
Tom pretended to be thoroughly absorbed in what they were saying. 
Meanwhile, his mind was working at top speed. Both men had hung their 
weapons in a rack, apparently confident that Tom Swift was safely their prisoner.
Suddenly a breath-taking idea flashed through
A HIDDEN WEAPON 181
Tom's mind. He had a secret weapon of his own, all but forgotten in the 
excitement of his capture!
"And now let me show you an interesting biological experiment I have been 
carrying on," Menarsky went on. "Observe these queer-looking webs which result 
when a spider is injected with certain drugs-drugs which I later intend to use on 
human beings."
Skillfully, Tom managed to get between the two men. As they bent over the 
worktable, he took the aluminum disks out of his trouser pocket and slipped them 
into the pockets of the two men on either side of him. Then his fingers probed 
back into his own pocket and flicked on the switch of his miniature repelatron.
Suddenly Tom made a dash for the door!
"Halt!" screamed Menarsky.
He tried to reach for his pistol from the rack, while Sturko endeavored to 
lunge after the young inventor. To their dismay, neither could move from the 
spot! They strained forward frantically, but found themselves held back as if by 
an invisible wall of glass!
"What have you done to us?" Menarsky shrieked, as his shaven-headed 
companion poured out a stream of guttural oaths.
"A little secret weapon your spies failed to inform you about," Tom jeered 
from the doorway.
"They will die for this!" Menarsky howled, almost purple with rage.
"That will depend on a United States judge and jury!" Tom retorted coolly.
182 DEEP-SEA HYDRODOME
Stepping quickly into the passageway, he slammed the watertight door, then 
latched it with its steel dogs, locking the men in securely.
Taking no chances, Tom grabbed a hammer from the engine compartment 
and smashed the ship's controls beyond repair. Then he raced up the ladder to 
the escape hatch and made his way aboard the Sea Hound.
A moment later he had warmed up the radio and was beaming an urgent call 
to Shopton on the Swifts' private wave length.
Billing's assistant was thunderstruck by the news. "I'll round up help here and 
also notify Admiral Hopkins at once. Roger!"
Within half an hour a government flying boat reached Tom. He and the Navy 
men went aboard the Mad Moby.
Tom's prisoners tried to put up a fight with their automatic pistols, but Tom 
quickly subdued them with his aluminum repelatron. They were handcuffed, then 
ordered to talk.
At first the men refused, but when they heard that Klevalog was in jail and 
that Paulus White was about to be captured, Sturko talked freely. Menarsky tried 
to stop him, but his henchman hoped for a lighter sentence if he told the truth.
His country had secreted atomic warheads and bombs along the Atlantic 
coast to be used by their subs. "We could not carry enough at one time from our 
own land for the big attack that was planned," Sturko explained.
The prisoners were flown off in the flying boat.
A HIDDEN WEAPON 183
Tom set off by air for the helium site. On the moonlit surface of the ocean 
below, he could see the cluster of ships and seacopters that tended the needs of 
the dome crews. Grim silence reigned-evidence that all had been captured swiftly 
and efficiently by the sneak attack. Half a dozen of the whale-shaped subs which 
had brought the attackers were moored alongside.
"Wish I could go down there and capture those thieves!" Tom reflected. But 
knowing that he could not do it singlehanded, he continued his flight westward.
As dawn broke, he sighted a speedy United States destroyer, a light cruiser, 
and a baby flattop rushing to the scene at full steam. Soon a squadron of jet 
Skyhawks took off from the carrier's flight deck. Tom followed them.
When the first wave of aircraft reached the captured helium ships, they were 
greeted by a frantic hail of tracers and rockets. Fortunately, none of the 
Skyhawks was hit.
The Navy pilots roared in low, sweeping the decks with a warning fire that 
sent the unprotected enemy gunners scurrying for cover! Realizing they had no 
chance against such overwhelming force, the gang of subversives radioed a 
quick surrender.
Two of the whale-shaped subs, which evidently had stand-by crews aboard, 
tried to make a getaway by submerging. But they were promptly dive-bombed in 
warning before their conning towers were awash. Rather than risk certain 
destruction, they surfaced and also surrendered.
Tom now landed and manned the first elevator carrying fighters to the helium 
city. Taken by surprise, the subversive guards soon gave up against such 
overpowering odds. They were taken to the surface and herded into the brigs of 
the Navy vessels.
When it was all over, Tom rushed to release Bud and the others from the 
dormitory in which they had been locked.
"Boy, am I glad to see you!" Bud gave his pal a bear hug. "I thought both of 
us had had our last adventure."
"Not us," Tom told him with a grin.
His words proved to be prophetic, for very soon Tom and Bud were 
engrossed in an even more exciting adventure, Tom Swift in the Race to the 
Moon.
Admiral Hopkins, who had arrived by this time, slapped Tom on the back. 
"Magnificent work, Tom. Your country owes you a great debt of gratitude. You'll 
be in for a hero's welcome back in the States!"
Tom, who disliked the glare of publicity, groaned. Then he turned to Chow. 
"Lend me a ten-gallon hat and one of your loud cowboy shirts, will you?"
"What fer, boss?"
"I'll pretend I'm a Texas wrangler who just came along on this expedition to 
round up some sea cows!"


THE END
TOM SWIFT AND HIS DEEP-SEA HYDRODOME
By VICTOR APPLETON II
No. 11 in the Tom Swift Jr. series.