crush the strong steel. Still it might have
sprung the joints, and water would have entered, which would have been
as fatal as though the sailor had been swallowed by the shark. Tom
realized this and, moving as fast as he could through the water, he
came up behind the monster and drove his steel bar deep into it.

The sea was crimsoned with blood, and the savage creature, opening its
mouth, let go of the captain. It turned on Tom, who again harpooned it.
Then the fish darted off and began a wild flurry, for it was dying. The
rush of water nearly threw Tom off his feet, but he managed to make his
way over to his friend, and assist him to rise. A confident look from
the sailor showed the lad that Captain Weston was uninjured, though he
must have been frightened. As the two turned to make their way back to
the submarine, the waters about them seemed alive with the horrible
monsters.

It needed but a glance to show what they were, Sharks! Scores of them,
long, black ones, with their ugly, undershot mouths. They had been
attracted by the blood of the one Tom had killed, but there was not a
meal for all of them off the dying creature, and the great fish might
turn on the young inventor and his companion.

The two shrank closer toward the wreck. They might get under the prow
of that and be safe. But even as they started to move, several of the
sea wolves darted quickly at them. Tom glanced at the captain. What
could they do? Strong as were the diving suits, a combined attack by
the sharks, with their powerful jaws, would do untold damage.

At that moment there seemed some movement on board the submarine. Tom
could see his father looking from the conning tower, and the aged
inventor seemed to be making some motions. Then Tom understood. Mr.
Swift was directing his son and Captain Weston to crouch down. The lad
did so, pulling the sailor after him. Then Tom saw the bow electric gun
run out, and aimed at the mass of sharks, most of whom were congregated
about the dead one. Into the midst of the monsters was fired a number
of small projectiles, which could be used in the electric cannon in
place of the solid shot. Once more the waters were red with blood, and
those sharks which were not killed swirled off. Tom and Captain Weston
were saved. They were soon inside the submarine again, telling their
thrilling story.

"It's lucky you saw us, dad," remarked the lad, blushing at the praise
Mr. Damon bestowed on him for killing th