rew who had not been carried down
by the sinking unterseeboot were too shaken by the concussion to make
any great effort to save their lives. Attempting to keep afloat in
that oil-covered water added to their difficulties, for whenever the
head of a swimmer disappeared he did not rise again.

"Kick off your boots, old man," exclaimed Ross.

"Where are the lifebuoys?" asked Vernon as he carried out his friend's
advice.

One buoy had disappeared; the other was supporting a seaman, the only
survivor of the crew.

"A case of finding's are keeping's," announced Ross. "We can't sling
him out of it. It might support two people. We could take turns at
hanging on."

"Stop!" exclaimed Vernon as Ross began to strike out towards the buoy.
"There'll be trouble if we get mixed up in that oil. It's much lighter
than water. I doubt whether we could swim in it. Do you think the
_Tremendous_ will put back?"

"Not likely," replied Trefusis.

He looked in the direction of the fast-vanishing battleship, half
hoping that she would slow down and lower a boat. As he did so,
something caught his eye: a cloud of grey smoke apparently issuing from
the sea.

"What's that?" he asked, pointing in that direction.

"Torpedo, perhaps; one that has finished her run," suggested Vernon;
but his chum waved aside the explanation.

"If U77 did fire a torpedo, you can bet your bottom dollar it wasn't
one with a dummy head!" he said. "Only practice torpedoes send up a
calcium light when their compressed air has given out. By Jove, I
believe it's one of those patent buoys! Let's make for it."

The lads swam strongly, making powerful and comparatively slow
breast-strokes. The water was warm. They were in no immediate danger
of cramp.

As they skirted the patch of oil they noticed that the seaman holding
on to the buoy had turned round. His face was now in their direction.
The man was Hans Koppe.

"Are you all right, Hans?" shouted Ross.

"Yes, mein herr," replied the man. "I've found a buoy."

"Thanks to us," thought Trefusis; then raising his voice: "You had
better kick out and get clear of the oil," he advised. "We are making
for yonder buoy."

By the time the swimmers reached the Kisbie the emission of calcium
smoke had ceased. They found that not only did the buoy support them
both, but that it was so constructed as to allow them to maintain a
sitting position without having to hold on with both hands. Glad of a
seat