es passing vertically through them, and weighted at the
lowermost ends to give the necessary stability, served as periscopes.

"There's a real submarine knocking about, I'll swear," said the
skipper. "Put a shot into those barrels, Morgan."

One shell was sufficient. Little more than a hundred chips floating on
the surface was left of the decoy.

The _Capella_ was about to resume her course when a warning cry was
heard:

"Torpedo coming, sir!"

From a point bearing half a mile on the vessel's port quarter, the
track of the on-coming torpedo was clearly discernible. The _Capella_,
being without way, would undoubtedly have fallen a victim had it not
been for her light draught, for before she could forge ahead the
missile passed under her keel. Its track could be followed as far as
the eye could reach, which showed that it was a modern weapon propelled
with superheated air and having a range of about five miles.

Straight for the source of the missile, tore the British craft, but her
effort to grapple with the unterseeboot was in vain. The submarine had
dived immediately. No sounds betrayed her presence in the vicinity.
Had the U-boat been moving, the churning of her propellers would have
been distinctly audible.

"She's got away, worse luck," growled Sub-lieutenant Fox. "I wonder
how she did it? It's too deep for her to sound, and she can't be
moving under her own power."

"We'll have her right enough," rejoined Barry, the optimist. "A light
haze and a calm sea is what we want. We'll run her down in less than a
week, you mark my words."

Four days passed. The _Capella_ kept her station almost without
incident. Ship after ship, deeply laden with troops and munitions,
entered the sand-banked estuary of the Seine, having been escorted thus
far by destroyers. Ship after ship, more lightly burdened, left the
river, homeward bound. Amongst them were hospital ships, clearly
distinguishable by their broad green bands and conspicuous red crosses
on both bows and quarters. A big action had taken place "somewhere in
France", and the passing of the Red Cross vessels was the aftermath of
a dearly-bought victory.

Yet nothing occurred to threaten the constant stream of shipping. It
seemed reasonable to surmise that either the U-boat had met with an
accident or else that she had transferred her energies to another area.

Meanwhile Ross and Vernon had been working hard, improving their
seamanship. Under the