Tom Swift and the Electronic Hydrolung - II Appleton Victor (great books of all time .TXT) 📗

soon took off in the diving seacopter. Landing on the water, they submerged and began the undersea detection test.

Tom manned the sonarscope personally, eager to conduct as careful a search as possible.

"Getting any blips, skipper?" Hank called out from his post at the Sea Hound's controls.

"Not a ping, Hank. The system seems to be working out even better than I'd hoped."

Tom felt a glow of satisfaction. He explained, however, that the jetmarine's transparent nose pane—which had to be left unprotected for the pilot's visibility—offered one vulnerable spot to sonar detection.

"But a little smart maneuvering can cover up that angle," Tom added. "Try the hydrophones, Arv, and see if you can hear 'em."

The chief modelmaker slipped on the earphones and listened intently. For another ten or fifteen minutes they probed about with no sound trace of the "invisible" jetmarine.

But presently Arv snapped his fingers to catch Tom's attention. "Got her, skipper!"

Tom took over the hydrophones. Sure enough, his ears could make out the faint hum of the jetmarine's atomic turbines. Tom directed Hank toward the sound, then ordered him to switch on the Sea Hound's powerful search beam.

The light cut a path of radiance through the murky dark-green waters. Dead ahead, the jetmarine could be seen gliding across their field of view.

"Your system blinded our sonar okay, skipper," Hank commented, "but this proves she could still be spotted by enemy listening devices."

Tom refused to be discouraged. He ordered Hank to return to base and wait for Bud. Meanwhile, the young inventor applied himself to the problem of how to mask the sub's noise.

"How about it, pal?" Bud asked, when he reported aboard the seacopter a while later.

Tom explained the results of the test and the need for an added safeguard against hydrophone detection. "Think I see a simple way out, though," he added with a pleased chuckle.

"Natch! With a brain like yours, it's a cinch," Bud quipped. "Explain, professor."

"Well, we can never do away with the noise of a sub's propulsion machinery," Tom began. "That goes without saying. So we'll have to camouflage it—lose it in the underwater jungle noises, so to speak."

Bud scratched his head. "How do we do that?"

"By amplifying the natural undersea sounds all about it," Tom explained. "Fish and all forms of underwater life make a background noise over the hydrophones, you know."

As Bud nodded, Tom went on, "So we simply step up the volume till the sub's own noise gets drowned out or 'wasted' in all the racket."

This could be done, he concluded, with fairly simple amplifying equipment. Bud, Hank, and Arv were jubilant at the idea.

"Nice going," Bud said. "How soon can we give it a try?"

"Soon as I can rig up the amplifier," Tom promised.

In less than two hours they were ready to submerge again. Zimby Cox joined the crew. Bud suggested taking along hydrolungs in case of any need for tinkering with the transducers or amplifying equipment.

This time, the jetmarine scored perfectly on the test, successfully eluding all the Sea Hound's efforts to detect it. Tom returned happily to base, feeling that the antidetection problem was now solved. The jetmarine, however, failed to appear.

"That's funny. The test was over at four-fifteen," Tom murmured.

"Maybe Bud surfaced out at sea somewhere," Arv Hanson suggested.

Repeated radio calls brought no response. Tom, now seriously worried, took the seacopter down again for another search, hoping that Bud would have switched off the antidetection gear by this time. But neither sonarscope nor listening devices revealed the slightest clue.

Tom, Hank, and Arv exchanged fearful glances. Had the jetmarine foundered on the ocean bottom—perhaps fouled somehow by Tom's new invention? Or had Bud and his crew fallen victim to the enemy?

CHAPTER XIII

ENEMY FROGMEN

At the end of the test period, Bud had prepared to bring the jetmarine to the surface. But just as he was about to blow the ballast tanks, Mel Flagler sang out a warning from the sonarscope.

"Whoa! Hold it, skipper! I think we have company on the starboard beam!"

Bud jerked his head around in surprise. "You mean the Sea Hound?"

"No, she surfaced," Mel reported. "Can't make this out yet, but it could be another sub."

Bud turned the controls over to Zimby Cox. Then he rushed to the scope and examined the blip. "Seems to be moving away from us on a westerly course. It's about two miles from here."

He donned the hydrophone earset and listened. "It's no seacopter, nor a jetmarine either," he announced presently.

"A Navy sub, maybe?" suggested Zimby.

Bud shrugged. "Let's find out." He ordered a change of course, hard to the right, and gunned the jets to bring the jetmarine directly on the mystery object's trail.

"It's a sub, all right," he said a short time later, listening again over the hydrophones.

"Pretty close to Fearing Island, isn't it?" put in Mel Flagler. "That's a government-restricted area."

Bud nodded grimly. "But staying just out of sonar range from the base."

The jetmarine closed steadily on its quarry. In a few minutes they were able to make it out dimly through the cabin window, dead ahead.

"That's sure no U.S. Navy sub that I know of," Bud said. "Probably an enemy snooper."

"What if they spot us?" Zimby asked.

Bud chuckled. "That's the beauty of it, pal! Don't forget. With this new antidetection gear we're invisible to them. At least as long as they don't run into us or we into them," he added.

"Or unless they have superdetection equipment we don't know about," cautioned Mel Flagler.

As they talked, the unidentified submarine was bearing steadily toward the mainland. Fathometer soundings showed it was on a steep upward slope of the continental shelf.

Presently a foaming gush of bubbles showed that the sub ahead was blowing its tanks. The jetmarine followed as it surfaced and Bud hastily manned the periscope.

"What're they up to?" Mel asked tensely.

"Don't know yet, but the hatch is opening," Bud reported. Suddenly he gave an excited gasp. "Jumpin' jets! They're sending out a couple of frogmen!"

Bud's companions were electrified by the news.

"Spies!" Zimby exclaimed.

"What do we do now?" piped up Mack Avery, the third man in Bud's crew. "Hadn't we better radio the Coast Guard and the FBI?"

Bud wrenched away from the eyepiece. "I have another idea! Any of you fellows game to go with me and capture those spies?"

All three of his companions volunteered eagerly. Bud chose Mel Flagler, then took another sight through the periscope.

"The sub's submerging again," he reported. "That'll give us a clear field. Zimby, you and Mack keep an eye on that baby while we're gone, and be plenty careful she doesn't spot you!"

"Roger! And take this roll of wire to tie up your prisoners."

Hastily Bud and Mel changed into swimming trunks and donned hydrolungs. They went out through the air lock, plunged into the bracing salt water, and switched on their ion-drive units.

"Can you see 'em?" Mel asked over his mike.

"Not yet. Let's speed up before we lose 'em completely!"

Both pushed their ion drives to capacity, scanning the water ahead in all directions.

"There they are!" Bud exclaimed presently. He pointed to two tiny figures, barely visible in the distance.

"Wow! They're sure not wasting any time!" Mel muttered. "Let's step on it, Bud! They'll be ashore in a minute!"

A darting school of sea bass screened the figures briefly from view. As the fish flickered past, Mel and Bud saw the frogmen breast-stroke up toward the surface and break water.

Bud and Mel followed. Ahead lay a barren stretch of beach, humped with sand dunes. It was skirted beyond by a thick fringe of trees.

"They certainly picked a perfect spot for a sneak landing!" Bud thought. The beach seemed totally deserted, with no sign of human habitation.

By this time, the frogmen were scrambling ashore. Within moments, Bud and Mel were on their heels. The raiders whirled in dismay as they caught the sound of footsteps rushing up behind them through the sand.

Bud and Mel hurled themselves forward, each dropping a man with a flying tackle. All four went down in a struggling, kicking tangle of arms and legs.

The battle was rough but short. Bud and Mel had the advantage of surprise, and soon pommeled and grappled their foes into submission.

Bud, astride his opponent's chest with knees pinning the man's arms, unlooped from his belt the wire he had brought.

"Here! Take some of this and wire your man's wrists together!" Bud told Mel.

When the frogmen were safely bound, Bud and Mel allowed them to stand up. Neither captive tried to escape.

"Now, my sneaky friends, talk!" Bud snapped. "What kind of a sightseeing trip did you plan?"

The frogmen's jaws remained tightly clamped. Both looked flushed and sullen as they faced their captors.

"Got their lips zipped, I guess," Mel said disgustedly.

Bud decided to try another tack. "Doesn't matter," he said carelessly. "We know they're pals of the Mirovs."

Both men started as if they had been stung. Bud followed up quickly, hoping to prod them into some unguarded remark.

"Just as we thought!" he snarled. "A couple of low-down Brungarian rebels! And up to their usual amateurish spy stunts!"

The raiders' eyes blazed, but they maintained silence. Both, however, kept darting looks of keen interest at the Americans' hydrolung gear.

Just as Bud was wondering how he could get the prisoners to the nearest police headquarters, a jeep came bouncing into view across the sand.

"Hey! Police!" Mel exclaimed with a happy grin.

"We're in luck," Bud said. "They can take these creeps off our hands."

The jeep braked to a halt a few yards away, and two uniformed officers hopped out.

"What's going on here?" said one, who was wearing a sergeant's stripes. The jeep had the words BEACH PATROL stenciled on it in white paint.

"We just nailed these two Brungarian frogmen," Bud explained. "A sub put them ashore—probably as spies or saboteurs. They won't talk to us, but maybe you can pump them at headquarters."

The startled sergeant turned a cold eye on the two prisoners. "Got anything to say for yourselves?" When neither answered, he unholstered his revolver and covered them. "Better take off those wires and put bracelets on them, Mike," he told his fellow officer.

The frogmen were handcuffed with cool efficiency and bundled into the jeep. Meanwhile, the sergeant turned back to Bud and Mel.

"You fellows come along too," he ordered.

"But we haven't got time," Bud protested. "Our own sub's waiting right offshore and we want to tail the sub that brought those guys here! We're from the Swift rocket base."

"Any identification?" the sergeant asked.

"How could we have in this getup?" Mel retorted.

"That's what I thought. So get moving," the sergeant barked.

Reluctantly, Bud and Mel hopped onto the running board and clung to the bouncing jeep as it sped to the nearby town of Sandbank. At headquarters they were questioned by the local police chief.

"If you'll call Swift Enterprises at Shopton, sir, Mr. Swift—or Harlan Ames of the plant security department—will vouch for us," Bud said.

The chief picked up the telephone and soon had Mr. Swift on the line. After speaking to him briefly, he passed the phone to Bud so the scientist could identify his voice.

"That's Bud Barclay, all right. He's one of our most trusted employees," Mr. Swift told the chief after hearing Bud's story.

The officer promised to release Mel and Bud at once. Before doing so, however, he took them into the adjoining office where the two frogmen were being questioned.

"Any luck?" the chief asked the sergeant.

Sergeant Gryce shook his head in disgust. "Not much. They did admit they came in a sub, but they claim it didn't wait to pick them up."

The police chief shot a few questions of his own at the men, but they answered either in curt monosyllables or not at all.

"Look, sir," Bud put in, "if they're telling the truth about their sub not waiting, our jetmarine may have chased it. That means Mel and I are stranded here. Could you have your men wait for us on the beach till we find out?"

"Gladly," the chief replied. "You two have done a fine day's work."

After the prisoners had been locked up to be handed over to the