"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.