John was perhaps a hundred and fifty yards from sh.o.r.e now. Slowly he was nearing land and safety, but could he reach it? The great shark still circled around and around the unfortunate boy, evidently waiting for some moment when John should be off his guard to give him an opportunity to strike. John was determined that this should not happen, however, and he watched the shark just as closely as he himself was watched. First he swam on one side and then on the other, then on his back and then on his stomach. Not for a second did he relax his watchfulness.

"Look at Sam go!" exclaimed Grant. "He's a marvelous swimmer."

"He's that all right, but I wish he would get there."

"There goes the shark," cried Grant, and as he spoke the big fin could be seen to shoot with lightning-like rapidity in close to the spot where John was. A great splashing immediately followed and then the fin appeared once more some ten or twelve yards distant.

"Whew! That was close," gasped Grant, his lips ashen with terror.

"He's getting desperate," said Fred. "He knows that unless he can get John before he comes much closer to sh.o.r.e his chance is gone."

"Hurry, Sam!" shouted Grant with all his strength. "Keep it up, John!"

he called. "You'll be all right in a minute!"

"He will not," said Fred in a low voice. "He'll be gone in a minute."

"No he won't," cried Grant. "Sam is almost there."

"Forty yards is a lot."

"Hurry, Sam! Hurry!" begged Grant. "You must hurry!"

"Look!" cried Fred. "The shark must have seen him. He's going away."

"Not 'away,'" Grant corrected. "He's just backing up a little."

Sure enough the shark moved out a little toward the ocean and the fin stood almost still as if it might be debating what should be done next.

Evidently the arrival of a second foe had puzzled him. Sharks are not known especially for their bravery. Rather they are scavengers that feed on the ocean's refuse, and they must be very hungry indeed to attack a man unless they have him at a disadvantage. Grant and Fred were aware of this fact, but they feared that this particular shark was very hungry and that he did have John at a disadvantage.

"Maybe he'll go away now that there are two of them," said Fred hopefully.

"Don't be too sure," warned Grant.

"He'll attack soon if he's going to, though."

"Yes, he'll have to. The water gets pretty shallow in a little closer."

"Look at Sam," exclaimed Fred. "He's sending John on ahead of him."

"John must be pretty tired now."

"I should think so."

"He'll be all right in a minute, though. A few more yards and he'll be out of danger."

"There goes the shark again," cried Fred suddenly. "This is about his last chance and it won't be so easy to drive him off this time."

Around and around the two swimmers the shark circled. He moved with amazing rapidity, and it seemed as if the two hard-pressed and tired swimmers must become dizzy if they followed his every move.

"He'll fly around them like that," said Grant, "until he sees a good chance and then you'll see him strike like lightning."

"They mustn't give him a chance," muttered Fred doggedly.

"They won't if they can help it, you may be sure of that."

"There he goes!" cried Fred. "No, not yet," he corrected himself.

"He'll strike, all right. Just watch him."

"If Sam can only use that knife."

"Maybe he won't attack Sam."

"They're awfully close together now," said Fred. "If he goes for John, Sam can stick him and if he goes for Sam, why he has the knife right there."

"The old knife will never go through that shark's hide," exclaimed Grant. "It's almost as hard as sheet steel."

"Here's the test anyway," cried Fred, and as he spoke the giant fin could be seen darting suddenly towards the two swimmers. Just before it reached them it disappeared beneath the surface of the water.

"He has turned bottom side up to bite," muttered Grant, fully understanding just what was taking place.

Sam and John had noted the approach of their enemy and both realized that the crisis of the whole affair was now at hand. If they could elude him this once, the chances were that they could reach shallow water where the shark would not dare to follow them. They both began to kick violently and splash as much as possible with their hands; they shouted and yelled; they did everything which they thought might possibly aid them in scaring the great ugly fish away.

Grant and Fred on the sh.o.r.e held their breath while all this was taking place and their hearts almost stopped beating. With feverish anxiety they awaited the result of the battle taking place before their very eyes.

"There's John," cried Grant suddenly. "Where's Sam?"

"I don't see him. I don't see the shark either."

"The splashing has stopped. Sam must have been killed."

"Oh, no," exclaimed Fred. "Don't say that. It can't be."

"Where is he then?"

"Look!" cried Fred.

The water some five or ten yards behind John was suddenly churned into froth. Red, b.l.o.o.d.y froth it was and evidently some gigantic struggle was going on. All at once, just on the outside of the miniature maelstrom, appeared a small round, black object.

"There's Sam!" shouted Grant.

Sure enough. Sam was still alive and without wasting a moment he struck out boldly for the sh.o.r.e. John was ahead of him, but he was soon overhauled by the powerful negro and side by side the two swimmers plowed through the sea. Behind them the waters were still churned by the struggles of the great shark, but they were rapidly becoming weaker.

"Sam killed the shark," exclaimed Fred, almost overcome by the suddenness and the unexpectedness of the event.

"It looks so," agreed Grant. "I didn't think it was possible."

"Nor I. Imagine the nerve he had, and that old knife certainly did do the work after all."