unded in their ears.

"There goes our late rescuer!" announced Jimmie presently.

"Where?" asked Frank. "Whom do you mean?"

"The Sturmvogel!" answered Jimmie, pointing toward the harbor, where
could be seen the speedy destroyer slipping quietly out to sea.

"Here's hoping you have a good voyage, friend!" said Frank.

"Yes," added Jimmie, "we'll see you a little later!"

"That reminds me," put in Ned, "we might as well get back to the 'U-13'
and begin work. There's no use delaying the game!"

"That's right," agreed Harry. "These fellows are probably in a hurry for
that submarine. We might as well be decent."

"Wait a minute," suggested Jimmie. "You've given me an idea! Your mention
of the name of a certain undersea craft started a train of thought in my
alleged brain. Take it easy for a moment!"

"Yes," cried Jack, in mock sympathy, "stand back! Give him air! If Jimmie
is really going to think, let's give him lots of room!"

"Aw, you go on!" scorned Jimmie. "I've got a right to think if I want to,
haven't I? I guess that's my privilege!"

"Not unless you have a union card!" protested Jack, laughing.

"That's all right," retorted Jimmie with a grin as he wrinkled a freckled
nose at the other. "I was going to think about a scab, anyhow, so I don't
need a card. Besides, this is on overtime!"

"All right, you win!" declared Jack, submissively. "Go ahead!"

"If you'll promise to never, never tell, I'll let you in on the scheme!"
whispered Jimmie, glancing about to make sure that no strangers were
within earshot. "Do you solemnly promise?"

"I do!" answered the boys in chorus, anxious to receive the news.

"Then here it is: If we could paint the name 'U-13' on that tub there's
nothing to prevent our getting away in it!"

"Hush, Jimmie!" cautioned Ned, in a startled tone.

"Hush nothing!" declared the other boldly. "It's now or never! The
destroyer's gone--everything's gone that could chase us. Mackinder's
loose on this island. He'll make us trouble if we stay. If we go now we
are safe from pursuit until another German boat comes in unless they
flash the news by wireless. In that case, we have an even chance of
getting away. If we don't go now tell me when we can get home?"

"I guess you're right, Jimmie, but how are you going to work it?"

"Simply putter along this afternoon," explained the lad, "fixing the
wiring and so on. If necessary, rip out some and replace it. We can get
in one another's way enoug