"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 shouted to Ralph.
The latter raised up from his crouching position, with his revolver now leveled full in the faces of the two frenzied men. Before Ralph had reached the upper step both men in the hold fired, fortunately, without doing any damage.
The moment Ralph gained the deck the captain jumped out of the hatch and slammed it down.
"Now, quickly, boys; tie this rope to the railing close to the periscope tube, and arm yourself with the life preservers; there, you will find them under that couch," said the captain, as he quickly threw back the cover from the couch and handed out four preservers.
"Why do you want four?" asked Ralph, as he hastily buckled one of them around himself.