at the dock. Breaking
into a run, Tom hastened to the boathouse. The ARROW was not in there,
and a look across the lake showed only a few rowboats in sight.

"That's mighty funny," mused the youth. "I wonder--"

He paused suddenly in his thoughts.

"Maybe Garret took it out to try and see that it worked all right," he
said hopefully. "He knows how to run a boat. Maybe he wanted to see
how the rudder behaved and is out in it now. He got through dinner
before I did. But I should have thought he'd have said something to me
if he was going out in it."

This was the one weak point in Tom's theory, and he felt it at once.

"I'll see if Garret is in his shop," he went on as he turned back
toward the house.

The first person he met as he headed for the group of small structures
where Mr. Swift's inventive work was carried on was Garret Jackson, the
engineer.

"I--I thought you were out in my boat!" stammered Tom.

"Your boat! Why would I be out in your boat?" and Mr. Jackson removed
his pipe from his mouth and stared at the young inventor.

"Because it's gone!"

"Gone!" repeated the engineer, and then Tom told him. The two hurried
down to the dock, but the addition of another pair of eyes was of no
assistance in locating the ARROW. The trim little motor craft was
nowhere to be seen.

"I can't understand it," said Tom helplessly. "I wasn't gone more than
an hour at dinner, and yet--"

"It doesn't take long to steal a motor-boat," commented the engineer.

"But I think I would have heard them start it," went on the lad.
"Maybe it drifted off, though I'm sure I tied it securely."

"No, there's not much likelihood of that. There's no wind to-day and
no currents in the lake. But it could easily have been towed off by
some one in a rowboat and then you would not have heard the motor
start."

"That's so," agreed the youth. "That's probably how they did it. They
sneaked up here in a rowboat and towed the ARROW off. I'm sure of it."

"And I'll wager I know who did it," exclaimed Mr. Jackson energetically.

"Who?" demanded Tom quickly.

"Those men who were sneaking around--Happy Harry and his gang. They
stole the boat once and they'd do it again. Those men took your boat,
Tom."

The young inventor shook his head.

"No," he answered, "I don't believe they did."

"Why not?"

"Well, because they wouldn't dare come back here when they knew we're
on the lookout for them. It would be too risky."