Tom quickly took her up to about two thousand feet, and there, finding
the conditions to his liking, he began a few evolutions designed to
severely test the craft's stability, and to learn whether the engine was
working properly.

"How about it?" asked Mr. Damon anxiously.

"All right!" shouted Tom in his ear, for the motor was making a great
racket. "I guess we'll make the trial next time we come around. Get
ready to drop the signal ball."

Tom slowly brought the aeroplane around in a graceful curve. He sighted
down, and saw the first tall white pole that marked the beginning of the
course.

"Drop!" he called to Mr. Damon.

The white rubber ball went to the earth like a shot. Mr. Jackson and Mr.
Swift saw it, and started their timing-watches. Tom opened the throttle
and advanced the spark. The great test was on!

The Humming-Bird trembled and throbbed with the awful speed of the
motor, like a thing alive. She seemed to rush forward as an eagle
dropping down from a dizzy height upon some hapless prey.

"Faster yet!" murmured Tom. "We must go faster yet!"

The motor was warming up. Streaks of fire came from it. The exhaust of
the explosions was a continuous roar. Faster and faster flew the frail