Chapter VIII. The Mud Bank - Page 2

rudders in the proper position.

A submarine moves under water by means of electric motors, the current of which is supplied by storage batteries. On the surface when the hatches can be opened, oil or gasolene engines are used. These engines cannot be used under water because they depend on a supply of air, or oxygen, and when the submarine is tightly sealed all the air possible is needed for her crew to breathe. While cruising on the surface a submarine recharges her storage batteries to give her motive power when she is submerged.

There are many types of submarines, some comparatively simple and small, and others large and complex. In some it is possible for the crew to live many days without coming to the surface.

Tom Swift's reconstructed craft compared favorably with the best and largest ever made, though she was not of exceptional size. She was very strong, however, to allow her to go to a great depth, for the farther down one goes below the surface of the sea, the greater the pressure until, at, say, six miles, the greatest known depth of the ocean, the pressure is beyond belief. And yet is possible that marine monsters may live in that pressure which would flatten out a block of solid steel into a sheet as thin as paper.

"Well, we are as deep down as it is safe to go in the river," announced Tom, as the gauge showed a distance below the surface of a little less than twenty-nine feet. "Now we'll move into the bay. How do you like it, Mr. Hardley?"

"Very well, so far. But it isn't very exciting yet."

"Bless my accident policy!" exclaimed Mr. Damon, "I hope you aren't looking for excitement."

"I'm used to it," was the answer. "The more there is the better I like it."

"Well, you may get your wish," said Tom.

He turned a lever, and those on board the submarine became conscious of a forward motion. She was no longer sinking.

She trembled and vibrated as the powerful electric motors turned her propellers, and Tom, having seen that all was running smoothly in the main engine room, called Mr. Damon, Ned, and Mr. Hardley to him.

"We'll go into the forward pilot house and give Mr. Hardley a view under water," he announced. "Of course, you'll see nothing like what you'll view when we're in the ocean," added the young inventor, "but it may interest you."

The four were soon in the forward compartment of the craft. She could be directed and steered from here when occasion arose, but now Tom was letting his navigator direct the craft from the controls in the main engine room. A conning tower, rising just above the deck of the craft, gave the pilot the necessary view.

"Here you are!" exclaimed Tom, as he switched out the lights in the cabin. For a moment they were in darkness, and then, with a click,