troyer were not at target practice. Yet they seemed to
have found a target in the middle of that circle the destroyer was
furrowing through the sea.

At last they saw an answering shot fired from the midst of the circle.
The destroyer was traveling at top speed and her own guns continued to
keep up a wicked cannonading of the central object.

"A Hun submarine!" shouted somebody. "They're circling it, and they are
going to get it, too!"

"If it is a submarine why doesn't she sink?" demanded Torry the
sceptical.

"I see why," Whistler said. "If the U-boat goes down the destroyer will
dart in and drag depth bombs. Then--good-_night_!"

"Wow, wow!" cried Frenchy. "She's so fast she can cut circles around the
U-boat, eh?"

"Sure as you live!" said Torry. "My! that's a pretty fight. If that
destroyer was the old _Colodia_, and we were only aboard of her! What
fun!"

The destroyer was narrowing her circles; the U-boat was in a pocket, and
unless the Hun put a lucky shell into the destroyer's engines, she
seemed doomed to capture or destruction.

The cutter raced nearer. Her course would take her directly into the
circle of battle unless her helm was changed.

CHAPTER XXIII

UNDER SPECIAL ORDERS

It was like bombarding a whale with bomb lances. One after another the
shells from the destroyer's guns shrieked over the sea to fall around
the more sluggishly manoeuvring U-boat.

The captain of the submarine handled his craft with skill; but his
gunners were poor marksmen. They kept both the U-boat's deckguns
smoking; but the shots went wild.

Torpedoes could not be used against the destroyer, for the latter was
steaming too swiftly. Around and around she went, and each time she
finished a lap the circle had narrowed.

The spectators on the revenue cutter were highly interested. They
climbed upon the upperworks and cheered and yelled in their excitement.
At last a shell from the destroyer dropped fairly upon the deck of the
U-boat, just abaft the conning tower.

The submarine rocked, dipped, and seemed about to sink. The helm of the
destroyer was changed instantly and she shot straight for her quarry.

"She'll sink her! She's going down!" yelled Al Torrance, clinging to a
stay beside Whistler, as the cutter bobbed through the rather choppy
seas.

But the Germans had no desire for a glorious death. Up went the white
flag, and the men on her deck put up their hands, signifying that they
had surrendered.