orning and
round him up, if he is here."

"I--er--I don't think much of your plan," murmured Nat, and seemed
much disturbed.

In about a quarter of an hour the boys reached the island shore, at
the spot where Nat's motor-boat was tied up. They helped him get in
and start up the engine. He had been told how they had come to the
island.

"If you want to, you can tie your boat fast to the stern and ride back
with me," he said.

"All right, Nat, we'll do it," answered Dave. "It is getting rather
late and it's a pretty stiff row to the school."

The motor-craft was started up and sent along in the direction where
the boys had left the Oak Hall rowboat. Their course took them past
the spot where the wild man's boat had been tied up.

"Why, look, it's gone!" cried Gus, standing up and pointing to the
place.

"True enough," answered our hero. "He must have gone off in it while
we were up to the cabin."

"He can't be very far away, Dave."

The boys looked up and down the river, but could catch no trace of the
missing rowboat or the wild man. In the meantime, the motor-craft was
moving forward, where the other boat had been beached among the
bushes.

"That is gone, too!" ejaculated Dave. "He has taken our boat!"

"Oh, do you really think so?" asked Gus. He felt that he was
responsible for the craft, as he had taken it from the school
boathouse.

"I certainly do think so," said Dave. "It was a neat trick to play."

"It's a wonder he didn't take the motor-boat, too."

"Maybe he didn't know how to run the boat and it was too heavy to
start without the engine."

"I guess you are right!" came suddenly from Nat. "Look here!"

He had stooped down to pick something up from the grating on the
motor-boat's bottom. If was a torn and dirty bandanna handkerchief.

"The wild man's!" cried Dave. "I remember it."

"I am glad he didn't get away with my boat," returned the
money-lender's son, drawing a deep breath. "I'll keep this
handkerchief to remember him by."

"Is it marked in any way?" questioned our hero. "Perhaps it has his
name or initials on it."

"Oh, I don't think so," returned Nat. "Let us hurry up and get back to
the school. If we are late, old Haskers will be after us."

"Go on and run the boat as fast as you please, Nat," answered Dave.
"But I want to look at that handkerchief."

Rather unwillingly, the money-lender's son passed the bandanna over.
It was now growing so dark that Dave could see but lit