"after adequate doses of your space vitamin, dad, a skin diver could tackle almost any undersea job in my hydrolung!" tom exclaimed. "he wouldn't be subjected to any antiosmosis troubles with his body tissues."
his father nodded. "for the first time, man might become a truly marine creature!"
"wow! think of it!" bud gasped excitedly. "with tom's hydrolung and a knife to hunt his own food, he could practically live in the sea!"
"that's no farfetched dream, bud." tom's steel-blue eyes flashed at the thought of new fields of scientific conquest. "this discovery of dad's and doc simpson's opens up some really amazing possibilities."
most important at the moment, the vitamin would be a great boon in carrying out search and digging operations for the jupiter prober. with fresh enthusiasm, tom returned to his laboratory to work on the new sonar gear. in his own mind, he had already named it a "quality analyzer sonar," since that exactly described the way it would function.
"hmm, let's see," tom mused as he settled down at his workbench, pencil in hand. "besides a regular sonarscope, i'll need at least three units for the gear."
first, he would need an oscillator to produce the complex pulse. next, of course, an oscilloscope to check the pulse as it was beamed out. last—but highly important—a correlation calculator.
this latter unit would compare the original pulse with the returning echoes. if an echo had a high enough "standard of acceptance"—that is, if its quality was very near the original pulse, it would show up on the screen in the normal way. if the echo came back blurred, or if "shadow echoes" showed up, these would be separated and appear on the screen colored red.
"whew!" tom sighed as he realized the complicated job of circuit design that lay ahead. "this sure is going to burn some midnight oil!"
the young inventor worked all afternoon at a furious pace, breaking off toward dinnertime to telephone his mother that he would be staying overnight at the lab. after a hasty meal, he resumed his layout job at the drawing board and by midnight had finished designing his quality analyzer sonar.
whipping off his eyeshade, tom went into the apartment next door and stretched out to snatch a few hours' sleep. but as usual when in the midst of an exciting new project, he was too keyed up to rest for long.
before daylight, tom was back at his workbench ready to begin assembling the units of his new sonar gear. later he phoned chow but scarcely paused to eat when the cook arrived with his order.
"brand my solar stovepipe!" chow scolded. "take time to eat your vittles properly, boss!"
"hmm?... oh, sure." tom looked up and grinned.
the stout old texan stomped out, shaking his head.
as the morning wore on, the pace at which tom had been working began to tell on the young inventor. his head nodded again and again. gradually he fell forward into an exhausted doze.
the next thing tom knew, he was sailing through the air, high above swift enterprises. lake carlopa was a tiny blue puddle below, and the town of shopton a mere cluster of toy buildings in the distance.
"good grief!" tom exclaimed with a gulp. "what's keeping me up?"
he was floating freely, without the support of any aircraft—or even one of his amazing force-ray repelatrons!
the discovery triggered off disaster. like a character in a movie cartoon, now that he knew he had nothing to support him, tom instantly went plunging downward—down, down, straight into the lake!
splash!
tom gasped and shuddered and shook his head like a drenched terrier.
another splash! as tom brought his eyes into focus, he realized he was back at his workbench in the laboratory. chow was standing in front of him, holding a half-empty pail of water, ready to splash him again!
"hey! cut it out!" tom cried out, jerking bolt upright. then, as he saw the disturbed look on chow's face, tom burst out laughing. "okay. relax, old-timer! guess i was dreaming."
"brand my snake oil!" chow said. "you looked so pale an' pasty, you had me plumb scared, tom! i couldn't wake you nohow!" worriedly the cook added, "what you need is a good beefsteak and some sunshine. you been under water too long."
"in more ways than one!" tom chuckled as he grabbed a towel and dried himself off.
the beefsteak, with crisp golden-brown french fried potatoes, was already at hand on chow's lunch cart. tom ate with a hearty appetite and the stout chef went off, secretly plotting to arrange the second half of his prescription.
when he reached the galley, chow plucked the wall phone off its hook and called bud at an airfield hangar. after a brisk conversation, he hung up, grinning contentedly.
at one o'clock bud came bursting into tom's laboratory. "snap to, skipper!" he announced. "you have company!"
tom looked up from his work in surprise.
"ta-daaa!" bud sang out, imitating a trumpet flourish.
sandy and phyl newton marched in, smiling.
"boy, this is a surprise!" tom got up to greet them. "a mighty pleasant one. but what's the occasion?"
"the occasion is that you're coming on a mountain hike with us, out in the nice fresh air and sunshine!" sandy informed him.
"and please don't argue," phyl said with a giggle. "it's for your own good—not to mention ours."
"i suppose chow winkler put you up to this." tom grinned.
"never mind that," sandy said sternly. "just come along quietly. it's a beautiful day."
tom glanced at his workbench cluttered with drawings and electronic gear. "well, okay, since you're twisting my arm," he agreed. "i guess it might clear my brain at that."
"now you're talking." bud clapped tom on the back and propelled him toward the two girls, who promptly seized his arms before he might change his mind.
on their way to the door, however, the telephone rang. tom insisted upon answering it, in spite of the girls' scolding.
"tom swift jr. talking."
"this is chief slater, tom," said the voice at the other end of the line. "dimitri mirov wants to see you. i don't know what's up, but he might be ready to tell something worth while. could you drop by?"
"sure thing, chief. right away!" tom hung up, excited by the thought that the brungarian might be about to reveal an important secret. "mind stopping by police headquarters first?" he asked his friends.
minutes later, bud's red convertible pulled up in front of the gray stone building. tom jumped out and dashed up the granite steps.
"i've had mirov transferred to a cell by himself," chief slater said as he took tom back to see him. "figured he might talk more freely away from his pals."
the prisoner, however, showed no eagerness to do so at tom's arrival. he remained slouched on his bunk as the young inventor pulled a chair up to the cell bars. his only response was a slight curl of the lips.
"have you heard about my country's new submarine?" mirov inquired after chief slater left.
tom nodded curtly.
"when are you going to build one?" mirov prodded slyly.
"look!" tom snapped. "you asked to see me. here i am. what is it you want?"
mirov shrugged with a look of amusement. "to make a bargain with you," he replied casually. "i know the secret of that sub. get me and my friends released and i'll give it to you."
tom had no intention of doing so, but he parried the offer, hoping to draw mirov out further. the prisoner, however, would say nothing more.
at last tom gave up and rose to leave. "i'll think over your proposition," he said.
he heard mirov chuckle as he walked away. somewhat puzzled, tom reported the conversation to chief slater and also telephoned the plant to inform ames.
then he hurried back to the car. bud frowned upon hearing tom's story.
"do you think he's on the level?"
tom shrugged as they headed out into the countryside. "i may be wrong, but the whole thing sounded fishy."
"now look!" sandy said severely. "if we're going to enjoy this hike, we're not going to talk about brungarians or inventions or that lost missile. from now on, it will cost anyone five cents every time he breaks the rule!"
the boys chuckled and agreed. but agreeing proved easier than keeping the rule. again and again, either tom or bud would inadvertently drop a remark about their submarine experiments or the search in the south atlantic. by the time they had parked in the hills and started climbing, sandy's and phyl's pockets were jingling with coins.
"what are you going to do with it all?" bud asked jokingly.
"give it to us!" snapped a strange voice.
as the four young people turned with a start, they saw two men burst from the shrubbery just behind them.
both were holding guns!
