Jimsy spoke in a voice that fairly bubbled over with indignation.

“Don’t get sore, kid; I wouldn’t harm your old mowing machine.  There isn’t one of mine but could beat it the fastest day it ever flew.”

As he spoke Kelly slouched off.  They saw him go up to a group of his aviators and begin talking earnestly to them.  Once or twice he motioned with his head in their direction.

“So he does mean mischief, after all,” said Roy; “let’s take a good look at the Dragon’s engine.  He may have injured it, although I don’t think he’d have had time to hurt it seriously.”

They strolled over to the Dragon, with the girls trailing behind.

“Oh!” cried Peggy, as they came up, “look at that spark plug.”

“What’s the matter with it?” demanded Jimsy,

“Look, it’s all bent and twisted out of shape.”

“Jove, sis, so it is.  Your eyes are as sharp as they are pretty!” cried Roy.

“No compliments, please.  Oh, that horrid man!”

“Who is he?” asked Jess.  “You appeared to know him.”

“Yes, we had some conversation with him this morning,” laughed Roy; “but to return to the spark plug; it’s a good thing we carry extra ones.”

“But we don’t!” cried Jimsy, in a dismayed tone.

“What! you had a supply in a locker on your machine.”

Jimsy looked confused.

“I’ve got to make a confession,” he said.

“You didn’t bring them!” cried Peggy.

“No, the fact is I—­I forgot.”

Jimsy looked miserably from one to the other.  Here was a quandary indeed.  It might prove hard to get such a commodity as a spark plug in Millbrook.

CHAPTER XVIII.

IN SEARCH OF A NEW PLUG.

It was while they were still discussing the situation that the automobile with Jake at the wheel and Miss Prescott and The Wren in the tonneau, drove into the grounds.  What a difference there was in the child since her benefactors had fitted her out!  She looked like a dainty, ethereal little princess instead of the ragged little waif that had been rescued from the gipsy camp.

But the minds of our young friends were now intent on different matters.  Time pressed.  The altitude flight, in which Jimsy had planned to take part, was to be the first thing on the program.  If anything was to be done about reequipping the Dragon it must be done quickly.

“Tell you what,” said Roy suddenly, “we’ll get into the car and drive back to town.  It won’t take long and maybe we can dig up an extra one some place.”

“If we don’t I’m out of it for keeps,” groaned Jimsy; “oh, that Kelly.  I’d like to punch his head.”

He doubled up his fists aggressively; but, after all, what chance had he to prove that Kelly had actually damaged the plug.  If confronted the man would have probably denied all knowledge of it.  Nobody had actually seen him do it, so that positive proof was out of the question.  No, they must repair the damage as best they could.