with
your Uncle Sam's U-boat _Dewey_," vouchsafed Bill Witt as he stood
surveying the mine field into which they had stumbled.

In response to the warning from the lookout forward, Lieutenant
McClure had stopped the submarine and was taking account of the
dangers that beset his ship. The sea was running high and it was
hard to discern the mines except when they were carried up on the
swell of the waves.

Swept along thus with the rise and fall of water, one of the floating
missiles seemed now bearing down upon the _Dewey's_ port bow. Lieutenant
McClure saw it just as a huge wave picked up the whirling bomb and
carried it closer up toward the submarine.

"All hands below; ready to submerge!" he called out sharply, at the same
time directing Executive Officer Cleary to get the _Dewey_ under way.

"Stay here with me a moment," continued McClure, addressing Jack. They
were standing alone on the forward deck.

Another wave brought the mine dangerously close.

"You armed?" called out Lieutenant McClure.

"Yes, sir," replied Jack, as he drew his heavy navy automatic.

"Shoot at that mine, boy," commanded the officer. At the same time
the young lieutenant drew his own weapon and began blazing away. He
hoped thus to explode the deadly thing before it was hurled against
the _Dewey_.

Jack followed suit. The target, however, was so buffeted about by the
waves that it was next to impossible to sight on it. The only thing
to do was to fire at random, hoping against hope that a lucky shot
would result in the detonation of the mine.

"It's no use," shouted McClure above the crack of the firearms and the
roar of the sea.

Their shots were rattling harmlessly off the metallic sides of the
mine.

By now Cleary had swung the _Dewey_ around until she was pointed almost
directly at the nearest mine, it being slightly off the port quarter.
The engines had been reversed and started, and the submarine was
drawing away.

"We ought to clear this one and then be able to dive and get out of
here," said McClure.

But as he spoke a huge wave lifted the mine again and flung it full in
the path of the submarine. As though drawn by some mysterious magnet
the floating explosive seemed following the _Dewey_ at every
turn---an unrelenting nemesis bent on the destruction of the American
vessel.

"Quick, Jack; grab that wireless upright forward!" commanded the young
lieutenant.

With alacrity Jack flung himself upon the steel