“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.