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,"