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 fly-wheel 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
