As in all submarines, it was necessary to let water into ballast tanks in order to make her sink, and to rise it was only necessary to pump out this same water, by means of compressed air. But Dr. Klauss had made many improvements even in this simple and fundamental principle.
The propulsion of the Sonderbaar was by means of twin screws at the stern, and each screw had its own engine—a gasoline one when running on the surface, and an electrical motor, run by a new type of storage battery, when submerged. The propeller shafts passed through the armatures of the motors, which were mounted directly on the shafts, revolving with them, and acting as flywheels when the gasoline engines were being used. At such times the circuits of the field windings were open, and no current was generated.
There were also dynamos for the making of electric illumination and charging the storage battery, and small motors to work pumps and other devices. In fact the craft was complete, mechanically.
She was steered by two rudders, one to guide her to port or starboard—or left and right, as the new navy regulations specify—and another rudder to send her to the surface or toward the bottom of the sea.
All this Dr. Klauss showed the boys, explaining many things, for he saw they were greatly interested; but, of course, there were some secrets he did not reveal. And one of these was the method of firing the deadly torpedoes.
The ship could be controlled from the engine room, or from the pilot house, in the bow, and here there was a perfect maze of levers, wheels, switches and other devices. Gages told of the boat’s speed, of her depth, and gave all the information it was necessary for the pilot to know.
“And now I think you need rest,” said the inventor, when the tour of the boat was completed. “I shall see you in the morning.”
“You have a marvelous boat, Dr. Klauss,” said Jerry, sincerely. “I congratulate you.”
“Thank you, my lad. I am sorry we had to leave your own air craft at the mercy of the sea, for, from what Mr. Sheldon told me of her, in our conversations after I rescued him, I understand it was a wonder of its own kind. But I had my own reasons for not lingering longer there.”
“Oh, well, it couldn’t be helped,” said Jerry, but he could not refrain from sighing.