nk goodness that's over!" gasped Donald. "At the rate we were
going up we'd have bounced clean out of the sea."

"I guess we're all right now," remarked Merritt.

The words had hardly left his lips when there came a jar and a bump that
shook the submarine in her every frame and rivet.

The boys were thrown from their feet and hurled about the cabin. At the
same instant the engines stopped and the submarine began to back, but
slowly, like a stricken animal.

"We've rammed something!"

"We're sinking!"

These and a hundred other exclamations came from the alarmed boys.

Mr. Barr poked his head down into the cabin.

"Are you all right below?" he asked.

"Yes; but what has happened?"

"Have we been badly damaged?"

"Are we sinking?"

The above questions were all shouted at once in the tense excitement.

Barton, his face white as ashes, came out of his engine room.

"What did we hit?" he demanded in a frightened voice.

"I don't know; but we struck something, possibly a sunken wreck, a hard
blow," was the inventor's reply. Although his face was deadly pale, his
voice was without a tremor as he spoke.

"We must make an examination at once," he went on. "Andrews, Higgins,
and Ross," addressing the three sailors who had appeared from forward,
"make an examination forward at once and see if any of the plates have
started. If you find a suspicion of a leak report to me at once."

The sailors, trained in naval discipline, saluted, and hastened off on
their errand.

"If we are leaking, what are we to do?" demanded Rob.

"Meet death as bravely as we can," was the reply in steady tones;
"submarines carry no boats and we must go to the bottom unless we can
find some way to stop the leak."

Small wonder that the boys were stricken aghast. Barton, the machinist,
flung himself face downward on a couch and began whimpering.

The inventor looked at the man with contempt.

"Stand by your engines, Barton," he commanded sternly; "the first man to
shirk his duty in this emergency will have to settle with me."

Barton rose to his feet unsteadily. He was pasty yellow with terror. In
his eyes was a wild look. But under the inventor's stern gaze he
reentered the engine room, shaking like a leaf.

It was then that Rob noticed that a revolver was in the inventor's hand
as he stood at the top of the cabin ladder.

CHAPTER XV.

THE STRANGE FLAG.

After ten minutes of the most painful suspense that any of the b