devise some means to
free that line from the shaft, we are in a pretty tight fix!"

"How near the surface can you bring the boat, Harry?" asked Frank.

"The gauges show that we're about two and a half fathoms down at
present," replied Harry. "I have pumped a lot more water out than would
ordinarily be required to bring us to the surface."

"Then we must be held by that line!" declared Ned.

"Let's try some other maneuver with the ship before we give up!" put in
Jack. "We're not half though our experiments yet!"

"All right, what'll you try?" asked Ned in a despairing tone.

"I don't know," was the answer. "But we're going to do something to help
get us out of this fix. How would it do to fill the tanks to sink us as
far as we can go? Then we could empty them in a hurry, which would make
the boat rise swiftly. The jounce would perhaps break the line and let us
up so we could get some fresh air."

"If we don't get some fresh air pretty soon, we'll have to do something
desperate. The reserve tank is nearly exhausted!"

In compliance with Jack's suggestion, the ballast tanks were again
filled. Gradually the "U-13" descended to the bottom. As the deck began
to tilt forward, as it had done when the craft was first stopped, Harry
threw into operation every pump that could be used to empty the water
from the ballast tanks. The boat rose rapidly.

With a jerk that nearly threw the boys off their feet, the "U-13" came to
a rest. The gauges still showed the same depth as before.

Ned's face turned ashen as he sank upon a locker. The others gathered
around him, expressing sympathy. The boy was clearly distressed.

"Never mind, Ned!" spoke up Frank. "We're coming out all right! The only
trouble is that we haven't tried the right thing yet!"

"But I can't seem to think of a thing to do in this case," protested the
other. "I'm all out of ideas! I'm sorry that we tried to follow that
other submarine. I wish we had taken Jimmie's advice!"

"Never mind that now, Ned. We're close to the surface. If it becomes
necessary, I will volunteer to be shot out of the torpedo tube. I can
rise to the surface, swim about until I get my wind again, and then dive
and cut the rope. That will release the whole ship!"

"Jimmie, that's awfully good of you to offer that, but I feel that I
should be the one to do it," was Ned's reply.

"No, sir!" declared Jimmie promptly. "You're in no condition to attempt
anything like that. You're worried,