"Anything the matter?" asked Mr. Swift, as he followed his son.

"No, but when you mentioned that Andy was out here I thought he
might have been up to some of his tricks. He had a little trouble
with Eradicate this morning, and he threatened to get even with me
for it." And Tom told of the whitewashing incident.

"I just happened to see him as I was coming to dinner," went on the
aged inventor. "He hurried off--when he noticed me, but I thought he
might have been here to leave another letter."

"No," said Tom. "I must tell Eradicate to keep his weather eye open
for him, though. No telling what Andy'll do. Well, I must finish
eating, or Ned will be here before I'm through."

After dinner, Ned arrived, and helped Tom start the motor. With a
roar and a bang the swift little machine rapidly got up speed, the
propellers whizing so fast that they looked like blurs of light. The
sky racer was held back by a rope, as Tom wanted to note the "pull"
of the propellers, the force they exerted against the air being
registered on a spring balance.

"What does it say, Ned?" cried the young inventor as he adjusted the
carburettor.

"A shade over nine hundred pounds."

"Guess that'll do. Hop in, and I'll cast off from the seat."