o down to
the dock to make sure he had shut off the gasoline cock leading from
the tank of his boat to the motor. It was a calm, early summer night,
with a new moon giving a little light, and the lad went down to the
lake in his slippers. As he neared the boathouse he heard a noise.

"Water rat," he murmured, "or maybe muskrats. I must set some traps."

As Tom entered the boathouse he started back in alarm, for a bright
light flashed up, almost in his eyes.

"Who's here?" he cried, and at that moment someone sprang out of his
motor-boat, scrambled into a rowing craft which the youth could dimly
make out in front of the dock and began to pull away quickly.

"Hold on there!" cried the young inventor. "Who are you? What do you
want? Come back here!"

The person in the 'coat returned no answer. With his heart doing beats
over-time Tom lighted a lantern and made a hasty examination of the
ARROW. It did not appear to have been harmed, but a glance showed that
the door of the gasoline compartment had been unlocked and was open.
Tom jumped down into his craft.

"Some one has been at that compartment again!" he murmured. "I wonder
if it was the same man who acted so suspiciously at the auction? What
can his object be, anyhow?"

The next moment he uttered an exclamation of startled surprise and
picked up something from the bottom of the boat. It was a bunch of
keys, with a tag attached, bearing the owner's name.

"Andy Foger!" murmured Tom. "So this is, how he was trying to get
even! Maybe he started to put a hole in the tank or in my boat."

CHAPTER VI

TOWING SOME GIRLS

With a sense of anger mingled with an apprehension lest some harm
should have been done to his craft, the owner of the ARROW went
carefully over it. He could find nothing wrong. The engine was all
right and all that appeared to have been accomplished by the unbidden
visitor was the opening of the locked forward compartment. That this
had been done by one of the many keys on Andy Foger's ring was evident.

"Now what could have been his object?" mused Tom. "I should think if
he wanted to put a hole in the boat he would have done it amidships,
where the water would have a better chance to come in, or perhaps he
wanted to flood it with gasoline and--"

The idea of fire was in Tom's mind, and he did not finish his
half-completed thought.

"That may have been it," he resumed after a hasty examination of the
gasoline tank, to