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 aerial and wrenched
it loose. It was a long tubing very much like an ordinary length of
gas pipe set up usually forward as one of the wireless supports, and