dge scanned the tossing, glittering sea. His keen eye
detected a triangular, black membrane steering leisurely through the
waves a hundred yards ahead.

"Fin on the starboard bow! Keep her off, Throppy!"

In a short time the _Barracouta_ was close behind the unconscious fish.

From the bowsprit end burst a shout of disgust:

"No good! I can see him plain! Tail's too limber! Only a shark! Swing
her off, Throppy!"

"How can I tell a shark from a swordfish?" Budge called down to Jim.

"Shark's back fin is shorter and broader, and he keeps his tail-fluke
whacking from side to side. Swordfish has two steady fins, stiff as
shingles; front one is long and slender and curves back on a crook; the
after one is the upper tail-fluke. Try again!"

Five minutes passed. Then an excited yell:

"Fin to port!"

Following Budge's shouted directions, the sloop gave chase. Soon they
were near their quarry.

"Swordfish!" breathlessly announced Jim. "And a big one! Put me on top
of him, Budge!"

Leaning against the mast-hoop that encircled his waist, he lifted the
long lance and poised it for the blow. The tail of the fish was almost
under his feet when he launched the harpoon with all his strength.

Unluckily, at just that moment the sloop dipped and met a big sea
squarely. Her bowsprit dove under, burying Jim almost breast-deep,
spoiling his aim. The dart struck the fish a glancing blow on the side
of the shoulder. Off darted their frightened game.

Jim gave a cry of disappointment.

"Too bad! Ten feet, if he was an inch! Well, better luck next time!"

A quarter-hour passed. Budge strained his eyes, but no fin! The breeze
was shifting to the northeast. Jim cast a practised eye about the
horizon.

"If the wind swings round much farther it'll bring the fog again. See
anything, Budge?"

"No--yes! Up to starboard! Right, Throppy! Keep her as she is!"

The fish was swimming at a moderate rate, and the sloop had no trouble
in catching up with him. The two stiff fins betrayed him.

[Illustration: LEANING AGAINST THE MAST-HOOP THAT ENCIRCLED HIS WAIST,
HE LIFTED THE LONG LANCE AND POISED IT FOR THE BLOW]

"Swordfish all right!" muttered Jim. "Not quite so big as the other one,
but too good to lose! Steady, Throppy!"

Foot by foot the _Barracouta's_ bowsprit forged up on their prospective
prey. Nobody spoke. Jim's grip on the pine staff tightened; his eye
measured the distance to the dull-blue shoulder.

Six inches furthe