"If one of them pill boxes bumps us on the water line it's all day with your Uncle Sam's U-boat Dewey," vouchsafed Bill Witt as he stood surveying the mine field into which they had stumbled.

In response to the warning from the lookout forward, Lieutenant McClure had stopped the submarine and was taking account of the dangers that beset his ship. The sea was running high and it was hard to discern the mines except when they were carried up on the swell of the waves.

Swept along thus with the rise and fall of water, one of the floating missiles seemed now bearing down upon the Dewey's port bow. Lieutenant McClure saw it just as a huge wave picked up the whirling bomb and carried it closer up toward the submarine.

"All hands below; ready to submerge!" he called out sharply, at the same time directing Executive Officer Cleary to get the Dewey under way.

"Stay here with me a moment," continued McClure, addressing Jack. They were standing alone on the forward deck.

Another wave brought the mine dangerously close.

"You armed?" called out Lieutenant McClure.

"Yes, sir," replied Jack, as he drew his heavy navy automatic.

"Shoot at that mine, boy," commanded the officer. At the same time the young lieutenant drew his own weapon and began blazing away. He hoped thus to explode the deadly thing before it was hurled against the Dewey.

Jack followed suit. The target, however, was so buffeted about by the waves that it was next to impossible to sight on it. The only thing to do was to fire at random, hoping against hope that a lucky shot would result in the detonation of the mine.

"It's no use," shouted McClure above the crack of the firearms and the roar of the sea.

Their shots were rattling harmlessly off the metallic sides of the mine.

By now Cleary had swung the Dewey around until she was pointed almost directly at the nearest mine, it being slightly off the port quarter. The engines had been reversed and started, and the submarine was drawing away.

"We ought to clear this one and then be able to dive and get out of here," said McClure.

But as he spoke a huge wave lifted the mine again and flung it full in the path of the submarine. As though drawn by some mysterious magnet the floating explosive seemed following the Dewey at every turn--an unrelenting nemesis bent on the destruction of the American vessel.

"Quick, Jack; grab that wireless upright forward!" commanded the young lieutenant.

With alacrity Jack flung himself upon the steel aerial and wrenched it loose. It was a long tubing very much like an ordinary length of gas pipe set up usually forward as one of the wireless supports, and folding down into the deck plates when the Dewey was stripped for undersea navigation.

"I am going to take a chance on exploding that one mine that seems to be our hoodoo," shouted Lieutenant McClure.

Jack waited anxiously to see just what his lieutenant was doing. Taking the wireless upright in hand after the manner of a track athlete throwing the javelin, the young commander drew it well back and then launched it full upon the mine floating not more than fifteen or twenty feet from the Dewey.

"Hit it!" exclaimed McClure as the improvised battering ram left his strong right arm.

It did, and with the desired result. The impact of the long steel tubing directly upon the shell of the mine was sufficient to explode the deadly thing. A terrific detonation rent the air and immediately a column of water was hurled high, towering over the Dewey like a geyser, and then engulfing the little submarine. Jack and his commander were swept off their feet in the deluge. As though some unseen hand had suddenly clutched them with a grip of steel the pair were flung from the deck of their craft into the seething foam.

It seemed an endless eternity to Jack as he was carried down into the depths. The roar of a million cataracts throbbed in his brain and before his mind flashed the panorama of his life. Home--Winchester--Brighton--all the old chums and the "profs!"

Death seemed so near to the youth as ho felt his strength giving way. His senses reeled. In his ears pealed the medley of a thousand bells. In this horrible abyss he knew he could not long survive.

Then, just when it seemed life was gone, his head shot up out of the water and he found himself swimming free and breathing normally again. Above, the same old blue sky. Turning over on his back and paddling thus until he floated, the boy remembered gain the submersible and the fearful mine explosion that had cast him into the sea.

He looked for the Dewey and in a moment beheld it still riding the waves. Yes, the old sub had survived the mine explosion, or at least, was still afloat, if damaged.

But what about Lieutenant McClure? Now Jack recalled his gallant commander and how he, too, had been cast from the deck in the deluge. Was "Little Mack" still alive?

The Dewey was slowly picking her way among the other mines. Jack shouted to her, but getting no response he started to swim with vigorous strokes. He had gone but a few yards when an object appeared on the crest of the water directly in front of him. It took only a glance to convince him that it was the form of Lieutenant McClure. With a supreme effort Jack drove himself forward with mighty strokes toward the inert form of his commander.

Glancing up for a moment, what was the delight of the youth battling with death to see the Dewey bearing down upon him!

Some one had seen him and they were coming to his rescue.

The sight renewed his strength. After what seemed a long while Jack was able to clutch the collar of his chief officer. "Little Mack" was unconscious.

By degrees Jack succeeded in turning over the limp form until it floated face upward. Locking his left arm securely around the neck of the apparently lifeless officer so that the face was held above the surface of the water, and using his strong right arm and legs, Jack began swimming as best he could in the general direction of the submarine that he knew to be not far away.

The weight of the lieutenant's body dragged heavily upon his left arm. His strength was ebbing away fast. His arm became numb and his senses chaotic.

Instinctively the lad closed his eyes. It seemed he must let loose the burden tugging in his arms and himself slip away into the depths and into that long sweet sleep that seemed just now so alluring, so compelling.

"Catch the rope when I fling it"--the words were borne into his stifled senses. It sounded like the voice of his good chum.

Was it Ted? Again came the call, seemingly closer at hand. It was Ted, now faintly, now more clearly. The sound of that voice galvanized the youth in the water.

Jack flung out his free limbs in a frenzy of muscular energy. Something loomed up in the blue of the sky near him and he beheld for one instant the periscopes of the Dewey.

She was drawing closer to the pair in the water!

On the deck stood a number of the crew disregarding the floating mines that had been engaging their attention. Someone was whirling a rope, aiming to throw it to the pair in the water. Every one seemed to be yelling at the same time.

"Hold on--we are coming--don't let go--catch the rope!" Jack heard the calls from his shipmates.

Out over the water spun a coil of rope--only to fall short of the desired mark and trail off into the sea many yards from the floating pair. Yes, it was Ted, winding frantically again, and yelling encouragement to his chum.

"Hold 'em!" Ted shouted over and over again, just as the Brighton lads had been wont to yell in unison at their football games when the opposing eleven was smashing its way toward Brighton's goal. Once again the coil was ready; once again it was flung outward from the deck of the Dewey. This time it fairly lashed Jack's face. The sting of the hemp seethed to whip new courage into him. Making one last frantic effort he clutched and held the precious rope, just as Ted sprang from the submarine and dived to the rescue.

Jack remembered no more. When he came to he was stretched in his bunk in the hold of the Dewey. Ted was bending over him.

"Thank God you are alive, Jack, old chum!" Ted was murmuring, with glad tears brimming from his eyes.

Jack strove to raise himself on one elbow but fell back limply, weak from the terrible struggle through which he had passed.

"How about 'Little Mack'?" he managed finally to ask faintly.

"Alive but yet unconscious," replied Ted, "They have gotten most of the water out of his lungs and are using the pulmotor."

Jack closed his eyes again and murmured a prayer of thanks for his safe deliverance and for the life of his lieutenant.

"Was the Dewey damaged by the mine explosion?" he asked.

Ted replied that so far as could be determined no serious damage had been inflicted, although Officer Cleary had expressed some apprehension as to the condition of the port seams forward on the under side of the hull. The examination was still in progress.

For an hour Jack rested quietly in his bunk. The Dewey had submerged after taking aboard the half-drowned commander and his rescuer, and at a safe depth gotten safely out of the zone of danger. Now she had come to the surface again for further examination of her hull.

Jack and Ted were conversing in low tones, when Bill Witt stumbled along the passageway leading into the men's quarters and stopped beside Jack. His face was stern.

"What's the matter, Bill--you seasick?" queried Ted.

"Wish that's all it was," muttered Bill.

"Tell us, what's up?" pressed Ted.

"Isn't very cheery news for a fellow knocked out like Jack after making such a plucky fight for his life and saving his lieutenant," answered Bill with a shrug of his broad shoulders.

Jack smiled.

"If I survived that, I guess I can hear what's troubling you," was his reply.

"Well, it's bad news, boys--mighty bad," went on Bill. "Chief

Engineer Blaine reports a leak in the main oil reservoir to starboard.

That mine explosion loosened up the seams and the fuel stuff is slowly

but steadily streaming into the deep blue sea!"