All at once, as they turned a corner, they received a sudden check.

Right ahead of them a man was driving some cows. Roy jammed down the emergency brake, causing them all to hold on for dear life to avoid being pitched out by the sudden change of speed.

"Wow! what a jolt!" exclaimed Jimsy; "it sure did----"

The sentence was never completed. The auto gave a pitch sideways and then plunged into a pit that had been dug across the road and covered with leaves and dust placed on a framework of branches. Down into this pit crashed the machine with a sickening jolt. The girls screamed aloud in fear. It appeared as if the machine would be a total wreck.

But that was not the worst of it. In the sudden fall into the pit Roy had been pitched out and now lay quite still at the roadside. Jimsy had saved himself from being thrown by clutching tight hold of the seat.

He stopped the engine and then clambering out of the car hastened to Roy's side. To his delight, just as he reached him, Roy sat up, and although his face was drawn with pain he declared that his injuries consisted of nothing more serious than a sprained ankle.

"But look at the machine!" cried Jimsy; "it's smashed, I'm sure of it."

The pit which had been dug across the road was about three feet deep and the front wheels of the auto rested in it. The hind wheels had not entered, as the excavation was not a wide one.

Both boys hastened to examine the car. To their satisfaction they found that not much damage had been done beyond a slight wrenching of the steering gear. This was due to the fact that they had been going at reduced speed.

"Gracious! Suppose we had been coming along at the same pace we'd been hitting up right along," exclaimed Jimsy.

"We wouldn't be here now," declared Roy; "we'd be in the next county or thereabouts."

"Yes, we'd have kept right on going," agreed Jimsy; "talk about flying!

But, say, who can have done this?"

"Not much doubt in my mind it's the work of that outfit of Kelly's. He told us to look out for trouble, and he appears to be making it for us."

"The precious rascal; he might have broken all our necks."

"That's true, if we'd been hitting up high speed."

"How are we going to get out of this?"

Peggy asked the question just as the man who had been driving the cattle came running up.

"What's the trouble?" he asked, gazing at the odd scene.

"You can see for yourself," rejoined Roy; "some rascals dug a trench across the road so as to wreck our machine if possible."

"Humph! So I see," was the rejoinder; "how be you goin' ter git out of thar?"

"That's a problem. If we could get a team of horses----" The man interrupted Roy, who was acting as spokesman.

"Tell you what, two of my cattle back thar are plow oxen. I'll go back to ther farm, git their yokes on 'em and yank you out of here. That is pervidin' you pay me, uv course."

"Don't worry about that. We're willing to pay anything in reason."

"All right, then, I'll hook up Jeb and Jewel."

The man walked back toward his cattle, which were contentedly browsing at the side of the road. Clucking in an odd manner, he drove two of them out of the herd and started back toward a farmhouse which was not far distant. In a wonderfully short time he was back with his oxen in harness.

"Gee, Jeb! Haw, Jewel!" he cried, as he came up. The oxen swung round and the heavy chain attached to their yoke was. .h.i.tched to the front axle of the car.

"Now for it!" cried Roy, when this had been done.

"Git ap!" shouted the man.

The slow but powerful oxen strained their muscular backs. The chain tightened and the next moment the car, from which Peggy and Jess and Bess had alighted, rose from the pit. Then the hind wheels dropped into it with a b.u.mp, but the shock absorbers prevented serious damage. With the oxen straining and pulling it was finally hauled into the road and they were ready to resume the trip.

Roy rewarded their helper with a substantial bill, and they were all warm in their thanks.

"'Twasn't nuthin'," declared the man, "an' now I guess I'll go to ther house and have my hired man fill in this road. Things is come to a fine pa.s.s when such things kin happen."

As the rescued party sped on toward the aviation field they fully agreed with the rustic's opinion. Had it not been for sheer luck they would have suffered extremely serious consequences as the result of a rascal's device. But as it was Kelly's plot against them appeared to have failed.

CHAPTER XX.

AN ATTACK IN THE AIR.

"B-o-o-m!"

The sound of a gun crashed out as the auto sped through the gates of the aviation field and rapidly skimmed across to where the aeroplanes had been parked.

"Just in time!" cried Peggy; "that's the five-minute warning gun."

By this time the grandstand was well filled and a band was playing lively airs. At the starting line three of the Kelly aeroplanes were gathered ready for the signal for the start of the alt.i.tude flight. The instant the car came to a standstill Jimsy was out and in a jiffy had the new spark plug adjusted. There was no time to test it, but he felt pretty confident that it would work all right.

"All ready!" shouted the official in charge of the starting arrangements.

"Ready!" rejoined Jimsy heartily, as he adjusted his leather helmet and Jake and Roy started the engine.

Kelly, whose back had been turned while he talked to some of his troup, faced round at the sound of the boy's voice.

"What, you here!" he choked out, his face purple.

"Yes; do you know any reason why I shouldn't be?" asked Jimsy, with meaning emphasis.

Under the lad's direct gaze Kelly's eyes fell. He couldn't face the lad, but turned away.

"There, if that isn't proof of his guilt I'd like to know what is,"

declared Jimsy to Roy.

"But the rascal covered up his tracks so cleverly that we can't prove anything on him," muttered Roy disgustedly.

At the same instant the starting bomb boomed out. The crowd yelled, and the drummer of the band pounded his instrument furiously. Above the uproar sounded the sharp, crackerlike report of the motors. As more power was applied they roared like batteries of Gatling guns.

Into the air shot one of them, a black biplane. It was followed by the others, two monoplanes and a triplane. Jimsy ascended last, but as this was not a race, but a cloud-climbing contest, he was in no hurry. He was anxious to see what the other air craft could do.