and Tom decided to make an early start.

The night passed without incident, though Tom, who kept the gun Mr.
Duncan had given him in readiness for use, got up several times,
thinking he heard suspicious noises. After an early breakfast, and
having once more cautioned the engineer and housekeeper to be on their
guard, Tom started back in the ARROW.

As it would not be much out of his way, the young inventor decided to
cut across the lake and stop at the sanitarium, that he might inquire
about Mr. Duncan. He thought he could speed the ARROW up sufficiently
to make up for any time he might lose, and, with this in mind, he
headed out toward the middle of Lake Carlopa. The engine was working
splendidly with the new spark plugs, and Tom was wondering if there was
any possible method of getting more revolutions out of the motor. He
had about come to the conclusion that a new propeller might answer his
purpose when he heard the noise of an approaching boat. He looked up
quickly and exclaimed:

"Andy Foger again, and Pete and Sam are with him. It's a wonder he
wouldn't go off on a trip instead of cruising around so near home.
Guess he's afraid he'll get stuck."

Idly Tom watched the RED STREAK. It was cutting through the water at a
fast rate, throwing up curling foam on either side of the sharp bow.
"He seems to be heading this way," mused Tom. "Well, I'm not going to
race with him to-day."

Nearer and nearer came the speedy craft, straight for the ARROW. The
young inventor shifted his helm in order to get out of Andy's course,
but to his surprise he saw that the red haired lad changed the
direction of his own boat.

"Guess he wants to see how close he can come to me," thought our hero.
"Maybe he wants to show how fast he's going."

The RED STREAK was now so close that the features of the occupants
could easily be distinguished. There were grins on the faces of Andy
and his cronies.

"Get out of the way or we'll run you down!" cried the bully. "We've
got the right of way."

"Don't you try anything like that!" shouted Tom in some alarm, not that
he was afraid of Andy, but the RED STREAK was getting dangerously near,
and he knew Andy was not a skillful helmsman. The auto-boat was now
headed directly at the ARROW and coming on speedily. Andy was bending
over the wheel and Tom had begun to turn his, in order to get well out
of the way of the insolent, squint-eyed lad and his friends.

Suddenly Andy uttered