doesn't understand how to run it. I wonder if he'll offer to race now?"
But the red-haired owner of the auto boat evidently did not intend to offer Tom a race. The Red Streak went on down the lake, passing the Arrow about half a mile away. Then the young inventor saw that Andy had two other lads in the boat with him.
"Sam Snedecker and Pete Bailey, I guess," he murmured. "Well, they're a trio pretty much alike. The farther off they are the better I like it."
Tom once more gave his attention to his own boat. He was going at a fair speed, but not the limit, and he counted on reaching home in about a half hour. Suddenly, when he was just congratulating himself on the smooth-running qualities of his motor, which had not missed an explosion, the machinery stopped.
"Hello!" exclaimed the young inventor in some alarm. "What's up now?"
He quickly shut off the gasoline and went back to the motor. Now there are so many things that may happen to a gasoline engine that it would be difficult to name them all offhand, and Tom, who had not had very much experience, was at a loss to find what had stopped his machinery. He tried the spark and found that by touching the wire to the top of the cylinder, when the proper connec-
