the now motionless propeller being well clear of the
water.

For quite a minute she remained thus, then with a quick yet almost
gentle movement slid under the waves. The last seen of her was the
weather-worn red ensign still fluttering from the truck.

The periscope's bowl showed nothing but an expanse of sea and sky, and
the two boats rising buoyantly to the waves.

A grim chuckle brought Ross and Vernon back to their surroundings.
Herr Rix was rubbing his hands and grunting with evident satisfaction.

"Goot!" he ejaculated. "Now, how you like dat? Now you see how we
German make blockade, hein?"

"A brave deed," replied Ross scornfully, and, gripping Vernon by the
arm, led him back to their uncomfortable quarters in the alley-way.

CHAPTER VII

On the Bed of the Sea

For the next twenty-four hours nothing exciting occurred. The U-boat
kept to the surface as much as possible, running under her petrol
motors at fifteen knots. To exceed that pace would mean too great a
consumption of fuel, and already the vessel was short of petrol.

Kapitan Schwalbe was prone to act on the side of extreme caution.
Having sunk one vessel, he would not tackle another in the same
vicinity. He invariably put at least a hundred miles between him and
the scene of his latest ignominious exploit before attempting another
act of kultur.

Three times during that twenty-four hours he dived: twice on sighting
what were unquestionably Bristol Channel pilot-boats, and on the third
occasion when a Penzance lugger under motor-power (for it was a dead
calm) crossed his track.

All this time a regular stream of shipping was passing up and down the
Bristol Channel, as unconcernedly as in the piping days of peace. To
anyone but a bumptious German, the sight would have told its own tale;
for the British Mercantile Marine, used to danger and difficulties, was
not to be deterred by the "frightfulness" of von Tirpitz's blockade.
On the contrary, the possibility of falling in with a hostile submarine
gave an unwonted spice to the everyday routine of the toilers of the
sea.

After breakfast on the following morning Ross and Vernon were told to
go on deck. The sea was still calm, and the submarine, now running
awash at full speed, was cleaving the water with practically dry decks.

The lads soon realized what was in progress. A couple of miles away
was a large ocean cargo-boat, outward bound, and U75 was in pursuit.

Trefusis and h