It was now more than twelve hours since the Dewey had submerged after the exciting events of the preceding night and the air supply was still sufficiently impregnated with oxygen to enable the imprisoned crew to breathe free and normally. The boys knew that the Dewey could continue thus for at least thirty-six hours before her officers would commence drawing on the reserve oxygen tanks.

In an atmosphere of suspense the long afternoon dragged into evening. Every effort to free the vessel had been tried, but to no avail. Evening mess was served amid an oppressive silence varied only by the valiant efforts of bluff Bill Witt to stir a bit of confidence in his mates. Another and final effort to get away was to be tried at midnight with high tide. And then—-if nothing availed—-the boys knew full well that with the morning Lieutenant McClure would resort to some drastic measures.

Efforts at sleep were futile for the most part, although dauntless spirits like Bill Witt and Mike Mowrey turned in as usual and dozed away as peacefully as though no danger existed. Midnight and high tide kindled fresh hopes as "Little Mack" steeled himself for a last try with the Dewey's hardworked engines. Jack and Ted had spent the long evening in the wireless room with Sammy Smith, hearing not so much as a trace of a passing vessel. Eagerly they awaited the last herculean effort for freedom. At ten minutes to one the engines were set in motion again and the signal given to back away as before. Lieutenant McClure had resorted to the expedient of shifting everything movable within the Dewey to the bow bulkhead in the hope that the submarine might be tilted forward at the supreme moment. Now he ordered every man aboard ship, except the engineering force necessary to operate the engines, into the torpedo chamber forward.

"Whirr-r-r!" the roar of machinery reverberated throughout the hold.
The Dewey struggled again in mad convulsion—-but all to no avail.
The shifted cargo of humans and equipment made no difference; the
submersible remained fast.

There now was no doubt of the Dewey's serious dilemma. No spoken word was necessary to impress upon the men the critical situation. Sleep was out of the question. Jack rambled into the wireless room, where he tried to calm his restless spirits by rattling away on the key at the code alphabet. Lately he had been giving much attention to mastering the operation of the wireless apparatus and under the direction of Sammy Smith had been making excellent progress.

He nervously fitted the microphone receivers to his ears—-and the next moment sat bolt upright. He was startled to hear the clicking sound in the listeners that indicated the proximity of a moving vessel.

"Quick! Listen here!" he called out to Sammy Smith. The wireless chief dashed down the receivers and hurried to find Lieutenant Mcclure.

"Ship approaching from the southwest," said Smith hurriedly. "Coming up the coast and apparently about two miles away."

"Little Mack" adjusted the receivers and stood listening to the revolving propellers of the craft that approached and passed overhead. For a moment he debated the idea of releasing a torpedo that might be noticed by the crew of the unknown vessel. But such a plan was not feasible, for the ship would think only of being attacked and would stand ready to repel an enemy rather than look for a submarine in distress. Furthermore, such an expedient was out of the question; for, gazing at his watch, he found that it was only four o'clock and hardly light enough for a torpedo to be seen unless it passed very close to the oncoming ship.

"There is one thing we might do," spoke up Jack Hammond. "Lieutenant, I have a plan to suggest. We seem to be in a desperate situation that demands some prompt action. That vessel up there may be an American or British destroyer. It is up to us to find out while there is yet a chance for our lives. Shoot me out the torpedo tube, sir. I'm a good strong swimmer and I may be able to attract their attention. The thing has been done before and I'm perfectly willing to take a chance."