portion sank like a stone. The after part reared itself high in the
air, revealing the curiously shaped stern, the two propellers, and the
complication of rudders. Then, before the cloud of smoke and spray had
time to drift inboard, the _Tremendous_ was over and beyond the
ever-widening circle of iridescent oil that marked the ocean grave of
yet another of the would-be blockaders of Britain's shores.

Even in the midst of his great responsibility Bourne's keen eye
discerned two heads bobbing up and down in the water. The midshipman
noticed them too.

"They are those fellows who hauled down the white flag, sir," he
exclaimed. "They are quite youngsters, too, and we daren't stop."

"No, we dare not," agreed the Lieutenant. For aught he knew, another
unterseeboot might be in the vicinity, reserving her torpedoes in the
hope that the battleship would slow down to investigate. "Pass the
word to the sentry to let go the Kisbie. It's the best we can do."

With a splash the patent lifebuoy was dropped from the cage at the
extremity of the navigation-bridge. It bobbed up again under the
battleship's quarter, emitting a dense cloud of calcium smoke as it did
so. By the time the marine had dropped the Kisbie the ship was a
quarter of a mile away from the two swimmers.

"It's the best we can do," repeated Bourne as he closed the eyepiece of
his telescope. "They may fetch it, they are swimming strongly."

"Well done, Mr. Bourne!" exclaimed a deep voice.

Turning, the Lieutenant faced the Captain standing beside him.

"A smart manoeuvre!" continued the skipper approvingly. "We can now
only carry on; but we'll wireless the Commander-in-Chief Devonport, and
report that there are survivors from the rammed submarine. He'll have
a destroyer patrol on the spot within an hour, and I hope it won't be
too late."

Bourne stepped to the extremity of the bridge and glanced astern. His
effort to distinguish the heads of the two swimmers was fruitless, for
a thin haze, the smoke from the ship's funnel, spread far in her wake,
completely obliterating the spot where Ross Trefusis and Vernon Haye
were swimming for dear life.

It will be necessary to set back the hands of the clock in order to
follow the fortunes of Ross and his chum.

"Is she slowing down?" whispered Vernon anxiously, as they stood on the
deck of U75 awaiting the approach of the _Tremendous_.

"I don't think so," replied Ross. "But now's our time."

T