iciently 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---a