Only an instant was needed for the full meaning of this information to sink into the minds of all. Jerry and his chums rushed into the corridor after Ted.
“We must recapture him!” cried Mr. Sheldon. “He is capable of doing all some terrible harm after what we did to him!”
“How did he get out of the chains?” asked Bob.
“No time to think of that now!” panted Ned. “The question is how to get him back in them again. Come on, fellows!”
“Grace, go to your stateroom!” commanded her father, quickly. “There may be some danger——”
“I’ll look after her,” volunteered Professor Snodgrass.
“All right,” assented Bob’s uncle. They knew they would hardly need Professor Snodgrass’s assistance in the coming struggle, and it was better to have someone at hand to look after Grace, in case the two German friends of Dr. Klauss should take it into their heads to render him aid in his mad project.
All this time (comparatively short, though it may seem long in the telling) the Sonderbaar was behaving in a peculiar manner. She was rolling, pitching and tossing, though she continued to sink toward the bottom of the sea on a long slant.
“What’s his game?” queried Jerry.
“We’ll have to stop it, whatever it is,” answered Ted.
They made a rush toward the pilot house, while Professor Snodgrass closed the door of the cabin containing himself and Grace.
Dr. Klauss, who was still busy manipulating the various levers before him, turned at the sound of rushing feet. A sneer showed around his cruel mouth, and he laughed.
“Ha!” he cried. “You thought you had me a prisoner! But I fooled you! Now who is master? I am going to put an end to all of you. Had you let me alone, you would, at worst, have been but captives. Now you shall all die!”
“Not if we know it!” cried Jerry, bravely.
“Rush him!” yelled Ned, and tragic as the situation was, he could not, for the life of him, help thinking that it was like an impending scrimmage on the football field.
But the refugees were not destined to capture the insane commander as easily as they had before. With a mocking laugh Dr. Klauss shoved over a lever and the steel sliding door of the pilot house closed. It was locked from within.
“There!” cried Ted. “Why didn’t I think he’d do that? I should have wedged that door open. Now we can’t get at him!”
“Isn’t there any way of opening the door from the outside?” asked Jerry, pausing, crestfallen, with his companions.
“No, he can lock it securely from within,” answered Bill Burke.
“Well, we can’t stop him now!” exclaimed Tom Flynn. “We’ll have to batter it down. That maniac will send us all to the bottom and keep us there!”
Indeed there was grave danger of this. The submarine, under the influence of the mad commander, was plunging downward at a terrific rate.
“Batter down the door!” cried Tom. “I’ll get a sledge hammer——”
“No!” interrupted Jerry. “We might damage the ship, or spring the plates and cause a leak. Isn’t there any other way?”
“Stop the motors!” cried Ned. “We can do that from the engine room and then he can’t do us any harm. Disconnect them from the pilot house control.”
“That’s it!” agreed Ted. “Come on, boys!”
The submarine was now rolling at a sickening angle. It was as though she was in the trough of the sea, on top, but the boys knew she was several hundred feet down. A glance at an auxiliary depth gage told them that.
“It’s he who is doing it!” cried Ted. “He’s crazy—he doesn’t know what he’s doing. He’s filling the ballast tanks unequally, and she’s got a bad list to starboard. And he’s set the port and starboard planes at different angles, which makes her go down this way. Oh, he’s surely crazy! He’ll kill us all!”
White-faced they stared at one another. It seemed that the end had come.
Suddenly they all became aware of a peculiar odor—a choking, suffocating smell, while there seemed to be floating about them a vapor of greenish-yellow tint. They began to gasp for breath.
“What—what is it?” panted Bob. “I—I can’t breathe!”
“None of us will in a few minutes!” choked Jerry. “It’s chlorine gas! Some sea water must have gotten into the sulphuric acid of the storage battery solution. That will make chlorine!”
“That—that’s right, lad!” gasped Ted. “That’s what happened. I’ve smelled it before when we had an accident on board Uncle Sam’s submarines. There’s a leak near the storage tanks!”
“What—what can be done?” queried Mr. Sheldon. “That gas will soon be deadly.”
“It’s getting worse,” spoke Ned in a low voice. Bob, whose stoutness made him more susceptible to the effects of the chlorine gas, was staggering about weakly.
“Quick!” cried Jerry. “We must stop the motors, and then see if we can’t force the ship to the surface. Fresh air is the only thing that will save us now. We must get rid of the chlorine gas!”
Staggering they made their way to the engine room. The motors were humming away at top speed, being controlled and regulated by Dr. Klauss, shut up in the pilot house. The pointer of the depth gage showed that the Sonderbaar was going swiftly down. Already she was nearing a thousand feet, and as this was close to the margin of safety there was no telling when the terrific weight of the water would crush her like an egg shell.
True, she was strongly built, and might be able to stand the pressure, but it was a terrible risk that the madman was taking, and all realized it save himself.
Weak from the effects of the gas, which constantly grew thicker, filling the interior of the submarine with its sickly, greenish-yellow tint, Jerry reached up, and pulled out the switch that stopped the main motor—the one connected with the propellers. This at once halted the progress of the craft. But she was still far below the surface.
No sooner, however, had Jerry stopped the motor than Dr. Klauss, in the pilot house, made an attempt to start it again, there being an auxiliary arrangement for doing this.
“The madman!” cried Ted, and reaching for a hammer with one blow he broke the connection leading to the pilot house. That rendered it impossible for Dr. Klauss to operate the motor from his position.
“Empty the ballast tanks! Get us to the surface!” cried Mr. Sheldon. “We are suffocating!”
It took but an instant to open the valve that forced compressed air into the tanks containing the tons of water. The air forced out the liquid ballast, and, while the boys and the others watched eagerly, the needle of the depth gage began moving backward.
“We’re going up!” cried Ned.
“Thank heaven for that!” murmured Mr. Sheldon, earnestly.
“Get up—as high as you can—near the ceiling!” cried Jerry. “Chlorine is nearly two and a half times as heavy as air. There may be some fresh air near the ceiling.”
Choking and gasping, they all climbed up on various parts of the machinery. The air higher up was better, but even there it was hard to breathe.
However, the submarine would be at the surface in a few moments, and none too soon, either.
“I—I hope Grace is all right,” gasped her father.
“I’ll go tell her to get up as high as she can,” volunteered Bob.
“Professor Snodgrass will know enough for that,” declared Jerry. “He knows the smell of chlorine and how to avoid it. Stay where you are.”
“Yes, do,” assented Mr. Sheldon. “Take no unnecessary risks, Bob.”
“Hark!” cried Jerry, motioning for silence. They heard someone rushing along the steel-floored corridor leading to the motor room, and the next instant Dr. Klauss staggered in on them.
“What—what does this mean?” he cried. “You are interfering with my boat. We are going—to the—bottom of—the sea!”
His voice trailed off into nothingness, and he fell unconscious on the floor.
“The chlorine!” said Ted. “That did it! We’ll be out of it in another minute, though.”
Up shot the Sonderbaar. They could all tell when she reached the surface and bounded out into the open sea. In an instant Jerry had pulled the lever that removed the hatch cover. In rushed the fresh air, quickly reviving the sufferers. But Dr. Klauss still lay in a faint on the floor of the motor room.
“We must get him on deck,” said Jerry. “We can’t let him die, even if he is a maniac and sought our lives.”
It was hard work, but they managed to get the unconscious form up the hatchway. Mr. Sheldon quickly ascertained that Grace and Professor Snodgrass, though suffering, were safe.
As Jerry and his chums lifted the limp form of the insane commander out into the open, they gave a cry of surprise. For there, directly before them, and so close to the submarine that a few yards would have rammed her into it, lay a lonely island—an island in mid-ocean.