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 shore 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 abo