mention a single word about this
whole occurrence to another soul. If any one should question you, with a
seeming knowledge of what happened here to-night, report the matter to
me at once."

"Yes, sir," the three boys responded, saluting, and the captain
departed, motioning Lieutenant Mackinson to accompany him.

By this time Joe was stiff and sore in every joint. Jerry and Slim
insisted that he retire immediately, and helped him off with his
clothing.

Nor was there any objection from Jerry, whose turn in the wireless room
was to begin then and last until one o'clock in the morning, when Slim
suggested that he would stay on with him, "just to talk things over."

"All right," said Jerry, "and then I'll stay on during your shift, until
Joe relieves us in the morning. We can get a good sleep to-morrow,
anyway."

And so the long night began. The dull song of the engines, far, far
below, became like the monotonous droning of giant bees, and the wash of
the salt water against the side of the ship was a constantly recurring
swash-h-h--swish--swash-h-h--swish as the vessel plowed on and on
through the darkness, toward the submarine zone and Europe and the
battlefields and the trenches and the men--millions of them--of the
Allied armies.

It was near midnight, and the boys had fallen silent, Jerry with the
wireless headpiece over his ears, Slim standing near the porthole,
gazing out at the lone swaying light that indicated the position and the
progress of the cruiser convoy on the port side.

Suddenly Slim whirled around, his face pale, his muscles tense, and with
a motion to Jerry signaled silence. As the latter removed the gear from
his head, Slim tiptoed across the room to him. Placing his lips close to
Jerry's ears he said: "I thought I heard someone in the battery room.
Listen!"

There was no doubt of it this time. Both boys heard the sound. It was of
someone softly feeling about, as though in doubt as to his exact
position.

"Quick!" hissed Slim into Jerry's ear. "You get the captain and
lieutenant; I'll wait here."

And as Jerry disappeared through the room in which Joe was sleeping, so
as not to give suspicion to the man in the battery room, Slim slid into
Jerry's chair and centered every faculty upon listening to the almost
inaudible movements in the next chamber.

He could tell instinctively that the man was feeling about the walls
with his hands. And not unnaturally, recalling Joe's experience only a