By this time the grandstand was well filled and a band was playing lively airs. At the starting line three of the Kelly aëroplanes were gathered ready for the signal for the start of the altitude flight. The instant the car came to a standstill Jimsy was out and in a jiffy had the new spark plug adjusted. There was no time to test it, but he felt pretty confident that it would work all right.
"All ready!" shouted the official in charge of the starting arrangements.
"Ready!" rejoined Jimsy heartily, as he adjusted his leather helmet and Jake and Roy started the engine.
Kelly, whose back had been turned while he talked to some of his troup, faced round at the sound of the boy's voice.
"What, you here!" he choked out, his face purple.
"Yes; do you know any reason why I shouldn't be?" asked Jimsy, with meaning emphasis.
Under the lad's direct gaze Kelly's eyes fell. He couldn't face the lad, but turned away.
"There, if that isn't proof of his guilt I'd like to know what is," declared Jimsy to Roy.
"But the rascal covered up his tracks so cleverly that we can't prove anything on him," muttered Roy disgustedly.
At the same instant the starting bomb boomed out. The crowd yelled, and the drummer of the band pounded his instrument furiously. Above the uproar sounded the sharp, crackerlike report of the motors. As more power was applied they roared like batteries of Gatling guns.