ton, no flash of livid flame and shattering of the wonderful
structure of steel they had hoped to destroy. A death-like stillness
prevailed.

"You've failed!" choked out Berghoff.

His companion's eyes flashed in the darkness like a cat's. He swallowed
convulsively.

"There is only one explanation," he snarled.

"And that is?"

"That they have discovered the mine. My friend, we had better be leaving
as soon as possible. It will not be good for us to be found in this
vicinity."

At that very moment two boys were standing with horror-stricken eyes on
the deck of the submarine. In his hands Rob held a peculiar looking
cylinder of steel. From one end of it hung two severed wires. It was so
weighted and balanced as to float a distance of about five feet under
the surface of the water.

"If I hadn't found those wires and cut them," Rob said, in an
awe-stricken voice.

But Merritt did not answer. He could only clasp his companion's hand.
The realization of the fearfully narrow limit by which they had escaped
death almost overcame him. The night was hot, but both boys shivered as
if stricken with the ague. It was some minutes before they could give
the alarm to those on shore. Then the rapid blowing of the whistle used
by the submarine when on the surface signalled their companions.

Some fifteen minutes later two pale-faced, wild-eyed lads were
explaining to an absorbed group the foiling of the diabolical plot
against Uncle Sam's diving boat. It was not long after, that the
submarine was rushing through the water for the nearest harbor.

"If we can arouse the police along the coast we may yet be able to
capture the authors of this outrage," exclaimed the ensign, as at full
speed the _Peacemaker_ clove through the waters.

"Yes; it's hardly probable that they had as swift a boat as this,"
agreed Mr. Barr. "If we can get ashore ahead of them, we can cause a
police net to be spread that they can scarcely break through."

But it was decreed that the fate of Berghoff and his companion should be
a different one. Suddenly, off to port of the _Peacemaker_, the night
was split by a roar and a red flash of flame.

"Great Scott! What was that?" gasped out Ensign Hargreaves.

"The searchlight--quick!" cried Mr. Barr.

In an instant the great beam of white light was cutting the night like a
fiery sword. Suddenly its rays concentrated on a dark object not far
distant from the _Peacemaker_.

Within the radiant circle was