"It belongs to the Australian line," replied the captain.

"Aren't we in the barred zone?" asked Alfred.

"I was about to remark a moment ago that it does not seem as though the
German edict of a restricted zone makes much difference in the sailing
of vessels," replied the captain.

While speaking, the submarine seemed to slow down, and the captain
turned toward the conning tower. "I wonder what is up now?" he asked.

Alfred's head appeared at the door and shouted: "They don't seem to
answer my signals."

The captain entered the tower, and pulled the lever, _Attention!_ There
was no response to the signal below the word. He again rang, with the
same result.

[Illustration: _The Periscope_]

"I will open the hatch," said the captain.

It was quickly swung open. The sub-lieutenant appeared at the hatch with
haggard face and staring eyes. "The captain has gone mad!" he shouted.

"I will go down if you want me to; I am not afraid," said Ralph.

The captain looked at him for a moment, and glanced down into the
hatchway. "Why do you not obey my signals?" he asked.

The sub-lieutenant stared at the captain, but did not make a reply.
"Answer my question!" shouted the captain.

The officer raised his face, threw up his hands, and fell back across
the low railing, which served as a guard at the foot of the stairs.

"You may go down, and ascertain what is the matter, but use caution,"
said the captain.

Ralph stepped into the open hatch, and, as he did so, the captain laid
his hand on his shoulder, and said: "Take out your revolver; do not
trust those men for a moment, under any consideration; we know them too
well."

Ralph quickly drew the weapon and held it in his hand, then cautiously
descended. He passed the inert form of the officer on the rail, and not
until he reached the last step did he see the doctor and the chief
machinist by the side of the dynamo.

The doctor held a revolver, which he pointed straight at Ralph. "Drop
that revolver!" shouted the doctor. "The lieutenant is dead, and the
time fuse will soon send this ship to the bottom."

The moment he saw the revolver and heard the voice, Ralph dropped behind
the stanchions to which the stairway was attached. The doctor's revolver
was fired. Instantly the captain divined the cause. Without waiting for
a warning cry from Ralph, he leaped into the open hatch, and saw the two
men with their weapons. He covered them with his revolver.

"Come up!" he