“All right.  Thanks.”

Kelly drove on.

“Do you know what happened to that plug, Carlos?” he asked, as they reached the open road and bowled forward at a good speed.

“I’ve got a pretty good guess.  It was not altogether an accident, eh?”

“An accident, well, it was, in a sense.  I happened to be near that machine with a monkey wrench and in some way was careless enough to let it put that plug out of business.”

Both men laughed heartily, as if Kelly’s rascally act had been the most amusing thing in the world.

“You are a genius,” declared Le Roy.

“Well, I reckon I know a thing or two,” was the modest response; “besides, I need that money.”

“But what is your plan?”

“I’ll tell you as we go along.  Drive fast, but don’t keep so close to that other car that they can get sight of us.”

“Not much fear of that.  They had a long start of us and are out of sight now.”

“So much the better.  It doesn’t interfere with my plans a bit, provided they take the same road back.”

“What do you mean to do?”

“Are you good with a shovel?” was the cryptic reply.

“I don’t understand you, I must say.”

“You will later on.  We’ll drive up to that farmhouse yonder.”

“Yes, and what then?”

“We’ll borrow two shovels.”

“Two shovels!”

“That’s what I said.”

“But what on earth have two shovels to do with stopping a bunch of kids from entering in an aeroplane race?”

“Carlos, your brain is dull to-day.”

“It would take a wizard to understand what you intend to do.”

“Well, you will see later on.  Drive in this gate.  That’s it, and now for the shovels.”

CHAPTER XIX.

THE TRAP.

For more than half an hour eager inquiries were made in Millbrook for a spark plug such as they wanted.  But all their search was to no avail.  But suddenly, just as they were about to give up in despair, a man, of whom they had made inquiries, recalled that not far out of town there was a small garage.

“We’ll try there,” determined Jimsy.

Finding out the road, they speeded to the place.  It did not look very promising, a small, badly fitted up auto station, run by an elderly man with red-rimmed, watery eyes, looking out from behind a pair of horn spectacles that somehow gave him the odd look of a frog.

“Got any spark plugs?” asked Jimsy, as the machine came to a halt.

“Yes, all kinds,” said the man, in a wheezy, asthmatic voice that sounded like the exhaust of a dying-down engine.

“Good!” cried Jimsy, hopping out of the car.

“That is, we will have all kinds next week,” went on the man; “I’ve ordered ’em.”

“Goodness, then you haven’t any right now?”

“I’ve got a few.  Possibly you might find what you want among them.”