the engine trouble,
and soon decided that it was in the gasolene supply, since, though the
tank was nearly full, none of the fluid seemed to go into the
carburetor.

"There's a stoppage somewhere," the aviator said. The fluid was drawn
off into a reserve tank and then the cause of the mischief was easily
located.

A small piece of cotton waste had gotten into the supply pipe, and
completely stopped the flow of gasolene.

"There it is!" cried the aviator, as he took it out, holding it up for
all to see.

"I wonder if anyone could have done that on purpose?" asked Dick,
looking at his chums, reflectively.

"You mean--Larson?" inquired Jack Butt. "He's capable of anything like
that."

"But he wasn't near the machine," said Paul.

"Not unless he sneaked in the barn some night," went on the machinist,
who seemed to have little regard for the former lieutenant.

"Well, there's no way of telling for certain, so we had better say
nothing about it," decided Dick. "Then, too, any of us might have
accidentally dropped the waste in the tank while we were working around
the ship. I guess we'll call it an accident."

"But it must have been in the tank for some time," argued Larry Dexter,
"and yet it only stopped up the pipe a little while ago."

"It was probably floating around in the tank, doing no damage in
particular," explained Mr. Vardon. "Then, when we made the ship tilt
that way, to test the stabilizer, the gasolene shifted, and the waste
was flushed into the pipe. But we're all right now."

This was proved a little later when the motor was started with no
trouble whatever. There was not a very good place to make a start,
along the edge of the stream, but Dick and his chums realized that they
could not always have perfect conditions, so they must learn to do
under adverse ones.

"Look out of the way!" warned the young millionaire to the assembled
crowd. They scattered from in front of the craft. The motor throbbed
and thundered up to high speed, and then the propellers were thrown
into gear. The big blades beat on the air, the ship moved slowly
forward. It acquired speed, and then, amid the wondering comments and
excited shouts of the crowd, it soared aloft, and glided through the
air to a great height.

"Off again!" cried Dick, who was at the wheel.

The trip back to Hamilton Corners was made safely, and without incident
worthy of mention. The four young men took turns in working the
various con