history. Your air-ship has been stolen, hasn't it?"

"Stolen?" Brady gave another startled jump. "Not that anybody knows of. Why? What put that in your head?"

Matt was "stumped." He looked blankly at Carl and found that Carl had turned an equally blank look at him.

"Where is the Hawk now?" queried Matt.

"She went out on a trial spin with three men in the car. Expect her back any moment."

There was a shifty look in Brady's face, and he spoke in a fashion that aroused Matt's suspicions.

"Then the Hawk wasn't stolen and you didn't send two men with a horse and buggy to look for her?" queried Matt. "We saw the air-ship, but there were only a couple of men in the car and the machine was out of control. We tried to stop the craft by means of the drag-rope, but the rope broke loose and the Hawk got away. One of the men on board dropped a roll of papers out of his coat-pocket and we picked it up."

Brady looked at the other man. The glances they exchanged were significant, and both swore softly.

"Here's a purty kettle o' fish!" growled the fellow with the pipe. "What dy'ye s'pose has happened, Brady?"

Brady muttered something unintelligible, and whirled to Matt with a scowl.

"That roll of papers belongs to me," said he. "Just pass 'em over, King."

"I don't know whether I ought to give them to you, Mr. Brady, or to the police," answered Matt, making no move to take the roll from his pocket.

"Police!" exclaimed Brady. "What the blazes are you talking about? The fellow on that car was working for me, and the papers belong to me."

"Then you ought to be able to identify the roll," proceeded Matt, coolly. "What did it contain, Mr. Brady?"

"Just papers."

"Typewritten-papers?"

"Well, yes, some of them were typewritten."

"How were they tied up? In a piece of yellow paper?"

"That's it. Hand 'em over. It's queer they got lost out of the car in that way, but mighty lucky you picked 'em up."

"I guess you're thinking of the wrong roll," said Matt, coolly. "The one you've described isn't the one we found."

"Whether the description is right or wrong, the papers are mine, and I'll have 'em!"

Brady, in sudden temper, hurled himself at Matt. The other man, taking his cue from Brady, jumped for Carl and grabbed him by the arm.

"Hoop-e-la!" tuned up Carl. "Be jeerful, eferypody! Here's somet-ing vat ve ditn't oxbect!" And, with that, the Dutch boy began struggling and using his fists.

CHAPTER IV.

THE KETTLE CONTINUES TO BOIL.

Both Matt and Carl were well skilled in the art of self-defense. Matt, perhaps, was a shade more adept in the use of his fists. Neither of the lads, however, had been looking for violence, and the sudden attack of Brady and the other man had taken them by surprise.

The two men had plenty of muscle, and Brady was desperately determined to secure the roll of papers. The very fact that he was using force to accomplish his designs proved that he was not entitled to the papers. For that reason, Matt was determined to keep them away from him at all costs.

"Hold the Dutchman, Pete!" puffed Brady, hanging to the collar of Matt's leather coat and trying to get one hand into the inside pocket.

"Quiet, Dutchy," threatened Pete, as he and Carl swung back and forth across the big shed. "I'll strangle ye if ye ain't peaceable. Ye ain't got no sense, roughin' things up like—wow!"

At that instant, Carl landed a telling blow on the point of Pete's chin. A bushel of shooting-stars must have danced in front of Pete's eyes, for the jolt hurled him backward and caused him to claw the air in an attempt to keep his balance. He was not more than an instant getting the whip-hand of himself, and when he came out of his brief daze he was as mad as a hornet.

"I'll kill ye for that!" he yelled, and picked up a heavy hammer that lay on the floor.

Pete was between Carl and the open end of the shed; he was likewise between Carl and Matt and Brady. The struggle had carried Pete and the Dutch boy down toward the middle of the balloon house.

Matt, out of the tails of his eyes, saw the dangerous position in which Pete's temper was placing Carl. The young motorist had been successfully fending off the attempt of Brady to get into his coat pocket; now, thinking Carl might need him, he undertook more aggressive measures.

An empty box, which had evidently been used as a seat, stood just within the big door. With a sudden lurch, Matt heaved himself against Brady and knocked him backward over the box.

As Brady felt himself falling, the instinct to save himself caused him to let go of Matt. The instant the young motorist found himself with the free use of his fists, he let drive at Brady and still further helped him over the box.

With a roar of anger, Brady doubled up on the floor. Matt whirled and darted for Pete, reaching that scoundrel just in time to catch the arm that was whirling the heavy hammer.

The hammer was wrenched away, and Matt cast it against the wall of the balloon house.

"Cut for it, Carl!" cried Matt. "Run for the road!"

"You bed my life!" wheezed Carl. "Dis blace don'd vas gedding fery comfordable."

Brady was picking himself up from the floor as the boys rushed past with Pete in hot pursuit.

"Get those papers!" yelled Brady.

"I'll git that Dutch kid if it costs me my life!" whooped Pete.

Brady rushed after Pete, and there was a chase across the marshy meadow toward the road.

Carl was chunky of build and not nearly so good in a sprint as was Matt. Matt was in the lead on the rush from the balloon house, but, anticipating that Carl might have further trouble with Pete, he slackened his pace.

It was well that he did so. Pete was steadily gaining on Carl and would undoubtedly have overtaken him had Matt not executed a quick move with an empty salt barrel that lay in the line of flight.

At the right moment, Matt rolled the salt barrel in front of the enraged Pete. Pete's shins slammed against it, then he dropped on it and plowed up the mucky soil with the top of his head.

So far as the set-to was concerned, it was settled right there, Brady being so far in the rear that the boys were able to clear the fence and get into the automobile before he could come anywhere near them. As a matter of fact, Brady gave up the fight as soon as he had witnessed Pete's mishap with the barrel.

As the two chums glided away toward the more thickly settled part of South Chicago, they could look back and see Brady assisting the disgruntled Pete to an erect position. The barrel had been smashed, and Brady was scraping the mud off Pete with one of the staves.

"How you like dot, hey?" gloried Carl, standing up in the automobile and shaking his fist. "You vill know pedder der next time dan to make some foolishness mit Modor Matt und his bard. Yah, yah, yah!"

Carl wanted to be as tantalizing as he could, but the automobile was getting too far away. Sinking down in the seat beside Matt, the Dutch boy chuckled blithely.

"Dis has peen a pooty fine leedle trip, Matt," he observed, "und has peen full oop mit oxcidement oof a nofel kindt, yah, so helup me. Dot's vat I like. I'll bed my life dose fellers t'ink dey vas fell on mit a brick house. Vat's der madder mit Prady, anyvays?"

"There's something queer about that air-ship affair," answered Matt, thoughtfully. "The two men who rode past us in that buggy said the pair in the car were thieves, but Brady didn't know anything about the Hawk's being stolen. Brady said, too, that there ought to have been three men in the car instead of two. The one who was missing may have been the driver. That would account for the poor work the other two were making with the engine."

"Ve can make some