tered an exclamation of astonishment.

"Of all the remarkable things I ever saw!" he ejaculated.

Frank and Jack were equally astonished; and the reason was this: both
torpedoes had gone true and the periscope of each vessel fell away.

"There'll be no more diving," said Lord Hastings quietly.

Now the fighting submarines, both upon the surface, launched torpedo
after torpedo at each other. A shot from the pirate struck her adversary
a glancing blow on the bow and the head of the little craft ducked a
trifle. But she bobbed up serenely again a moment later and returned the
fire.

This time her aim had been true and the torpedo grazed the top of the
conning tower. _The Vulture_ also ducked, but came up again.

"It all depends upon who gets in the first square shot," said Lord
Hastings, and at that moment the square shot struck.

_The Vulture_, swerving suddenly, barely escaped a torpedo from her foe,
while the pirate's next torpedo struck the enemy squarely upon the
bridge. There was an explosion and the German craft seemed to leap from
the water. A moment later she came down in pieces, blown to atoms.

"It's all over," said Lord Hastings quietly. "Now it is time for us to
put an end to that troublesome craft."

He led the way below and gave the order to submerge.

But it appeared that Davis, instead of fleeing as Lord Hastings and the
two lads had expected him to do, had determined to square accounts with
his British enemies. _The Vulture_ headed toward the U-6.

Before Lord Hastings could give the command to launch the first torpedo,
a missile from the enemy carried away the periscope of the U-6.

Lord Hastings gave an exclamation of dismay.

"We'll have to fight it out on the surface," he said quietly.

Now the U-6 launched her first torpedo and missed. A missile from _The
Vulture_ struck close to port. Again the U-6 missed and swerved just in
time to escape another torpedo from the enemy.

Then suddenly Lord Hastings gave the command to submerge.

The command was obeyed quickly and he explained to the lads.

"We'll try and run closer to him while we're below. They'll be expecting
us to go the other way, and if we are not seen the moment we come up
we'll take them at a disadvantage. Of course, it's a long chance, but we
must do something."

Ten minutes later he gave the order to rise again. There was no
response. Again Lord Hastings gave the signal and still the U-6 failed
to rise.

"What's the m