across the sea in the direction of the swimmers. One man produced
a glass and levelled it in their direction. Then he turned to the
others and they could be seen to gesticulate excitedly.

"One wants to save us and the others don't," declared Frank.

For some moments the men continued to argue. One shook his finger in
the faces of the others and pointed in the direction of the swimmers.

"You're all right," declared Frank, speaking of the one man. "Wish I
were there to lend you a hand. But I'm afraid the others are too much
for you."

At this juncture the man who opposed the others produced a revolver and
made an angry gesture. He was ordering the others to the aid of the
three friends in the water.

"By Jove!" said Harris. "He's all right. I'd like to be able to do him
a good turn."

And the chance was to come sooner than he expected.

Apparently the men aboard the German vessel had decided to obey the
order of the man who would save the three swimmers. A boat was lowered
over the side.

Three men stood ready to leap into it. The hopes of the three friends
in the water rose high; but they were shattered a moment later in a
sudden and unexpected manner.

A dull rumbling roar came suddenly across the water. Instantly all
became confusion aboard the German vessel. Officers shouted hoarse
commands and struck out with the flat of their swords as members of the
crew rushed for the rails.

"An explosion!" cried Frank. "Swim back quickly."

The others understood the significance of that strange rumbling aboard
the German vessel as quickly as Frank, and turning rapidly, they struck
out as fast as they could.

An explosion such as that dull roar indicated could have but one result
and the lads knew it. Evidently there had been a fire on board--that
accounted for the strange activities of the men on the ship--and the
flames had reached the vessel's magazine.

A second and a louder roar came now. Men jumped into the sea by the
scores and struck out vigorously that they might not be pulled under by
the suction when the ship sank.

Then there came an explosion even louder than the rest. The great ship
parted in the middle as though cut by a knife. A huge tongue of flame
shot high in the air. Hoarse cries from aboard, screams and frightful
yells. Split in twain, the vessel settled fore and aft.

A second huge tongue of flame leaped into the sky; and then the vessel
disappeared beneath the sea.

Giant waves leaped