“No, dad, don’t,” exclaimed the young inventor quickly.  “I can fight my own battles with Andy.  I don’t fancy he will bother me again right away.”

Tom found it more of a task than he had anticipated to get the motor in shape to run the arrow back under her own power.  The magneto was out of order and the batteries needed renewing, while the spark coil had short-circuited and took considerable time to adjust.  But by using some new dry cells, which Mr. Hastings gave him, and cutting out the magneto, or small dynamo which produces the spark that exploded the gasoline in the cylinders, Tom soon had a fine, “fat” hot spark from the auxiliary ignition system.  Then, adjusting the timer and throttle on the engine and seeing that the gasoline tank was filled, the lad started up his motor.  Mr. Hastings helped him, but after a few turns of the flywheel there were no explosions.  Finally, after the carburetor (which is the device where gasoline is mixed with air to produce an explosive mixture) had been adjusted, the motor started off as if it had intended to do so all the while and was only taking its time about it.

“The machine doesn’t run as smooth as it ought to,” commented Mr. Hastings.  “No, it needs a thorough overhauling,” agreed the owner of the arrow.  “I’ll get at it to-morrow,” and with that he swung out into the lake, towing his rowboat after him.

“A motor-boat of my own!” exulted Tom as he twirled the steering wheel and noted how readily the craft answered her helm.  “This is great!”

He steered down the lake and then, turning around, went up it a mile or more before heading for his own dock, as he wanted to see how the engine behaved.

“With some changes and adjustments I can make this a speedy boat,” thought Tom.  “I’ll get right at it.  I shouldn’t wonder if I could make a good showing against Mr. Hastings’ new Carlopa, though his boat’s got four cylinders and mine has but two.”

The lad was proceeding leisurely along the lakeshore, near his home, with the motor throttled down to test it at low speed, when he heard some one shout.  Looking toward the bank, Tom saw a man waving his hands.

“I wonder what he wants?” thought our hero as he put the wheel over to send his craft to shore.  He heard a moment later, for the man on the bank cried: 

“I say, my young friend, do you know anything about automobiles?  Of course you do or you wouldn’t be running a motor-boat.  Bless my very existence, but I’m in trouble!  My machine has stopped on a lonely road and I can’t seem to get it started.  I happened to hear your boat and I came here to hail you.  Bless my coat-pockets but I am in trouble!  Can you help me?  Bless my soul and gizzard!”

“Mr. Damon” exclaimed Tom, shutting off the power, for he was now near shore.  “Of course I’ll help you, Mr. Damon,” for the young inventor had recognized the eccentric man of whom he had purchased the motor-cycle and who had helped him in rounding up the thieves.