"What's up now?" demanded Ned Rector and Tad in one breath.

Every member of the outfit had sprung to his feet.

"Sounds like a stampede," flung back the foreman, making a flying leap for his pony.

The other cowboys were up like a flash and into their saddles, uttering sharp "ki-yis" and driving in the spurs while they laid their quirts mercilessly over the rumps of the ponies.

Tad Butler, Ned Rector and Walter Perkins were not far behind the cowmen in reaching their own ponies and leaping into their saddles.

Not so with Chunky. He only paused in his eating long enough to look his surprise and to direct an inquiring look at the Chinaman, while the others went dashing across the plain toward the herd.

"Allee same likee this," announced Pong, making a succession of violent gestures that Stacy did not understand.

But the boy nodded his head wisely and went on with his eating.

Out where the grazing herd had been peacefully eating its noonday meal all was now excitement and action.

Revolvers were popping, cowboys were yelling and the herd was surging back and forth, bellowing and dashing in and out, a shifting, confused ma.s.s of color and noise.

The boys did not know what to make of it.

"Yes; they are stampeding," decided Ned, riding alongside of Tad Butler.

"I don't believe it," answered Tad. "It looks to me as if something else were the trouble."

"What?"

"I don't know. It's an awful mix-up, whatever they may call it."

"Yes; see! They are fighting."

Surely enough, large numbers of the cattle seemed to be arrayed against each other, sending up great clouds of dust as they ran toward each other, locked horns and engaged in desperate conflict. It was noticed, however, that the muleys kept well out of harm's way, standing aloof from the herd and looking on ready to run at the shake of a horn in their direction.

"Now, look there! What are they doing?" asked Walter.

"They seem to be cutting out a bunch of steers," answered Tad. "That's funny. I can't imagine what it is all about." Neither could Professor Zepplin, who had ridden up at a more leisurely pace, explain to the boys the meaning of the scene they were viewing.

"If we knew, we might turn in and help," suggested Walter.

"That's right," replied Tad. "Suppose we ride up there where the men are at work. We may find something to do. Anyway, we'll find out what the trouble is."

Starting up their ponies, the boys galloped up the line, keeping a safe distance from the herd as they did so, and halting only when they had reached the trail leaders, as the cattle at the head of the line are called.

"What's the trouble?" shouted Ned as they came within hailing distance of the perspiring foreman.

"Mixed herd," he called back, curtly, driving his pony into the thick of the fight and yelling out his orders to the men.

"I know almost as much about it as I did before," announced Ned, disgustedly. "Got any idea, Tad?"

"Yes; I have."

"For goodness sake, let's have it, then. If I don't find out what's going on here, pretty soon, I shall jump into the fight in sheer desperation."

"Mr. Stagings said it was a mixed herd. Don't you think that must mean that a lot of cattle who don't belong there have mixed up with ours?"

asked the freckle-faced boy.

"I guess that's the answer, Tad. But, if so, how can they tell one from the other?" wondered Walter.

"From the brands. I have learned that much about the business. Every one of our herd is branded with a capital D in the center of a diamond. That is the brand of Mr. Miller's ranch--the Diamond D Ranch. Evidently they are cutting out all that haven't that brand on."

"h.e.l.lo! There's Chunky. Now, what do you suppose he is up to!" exclaimed Ned.

Stacy Brown had finished his meal, mounted his pony and was now riding toward the herd at what was for him a reckless speed.

All at once they saw him pull his mount sharply to the left and drive straight at a bunch of cattle that the cowboys had separated from the herd a few moments before.

The boy was too far away, the racket too loud, for their voices to reach him in a warning shout.

Stacy, having observed the cattle straying away, and having in mind Tad Butler's achievement in driving back a bunch of stray steers, thought he would do something on his own account.

"I'll show them I can drive steers as well as anybody," he told himself, bringing down the quirt about the pony's legs.

The strong-limbed little beast sprang to his work with a will. He understood perfectly what was wanted of him. A few moments more, and he had headed off the rapidly moving bunch, effectually turning the leaders, sending them on a gallop back toward the vast herd fighting and bellowing in the cloud of dust they had stirred up.

The cowboys were so fully occupied with their task that they had failed to observe Stacy Brown's action, nor would they have known anything about it had not Tad, yelling himself hoa.r.s.e, managed to attract the attention of the foreman.

Tad pointed off to where Chunky was jumping his pony at the fleeing cattle, forcing them on with horse and quirt.

They had almost reached the main herd before Tad succeeded in informing the foreman.

One look was enough for Stallings.

Before he could act, however, the stray herd had once more mingled and merged with his own. The work of the cowboys had gone for naught.

Stallings fired three shots into the air as a signal to his men to stop their cutting out.

"Will you young men do me a favor?" he asked.

"Certainly, Mr. Stallings," answered Tad.

"Then ride around the herd and tell the boys not to try any more cutting out until the herd has quieted down. The dust is so thick that we can't do anything with the cows, anyway. You have some sense, but that's more than I can say for your friend, Brown. Of all the idiotic--oh, what's the use? Tell him to mind his own business and keep half a mile away from this herd for the rest of the afternoon."

"All right, sir. Where did those cattle come from?"

"I don't know, Tad. They have broken away from some nearby ranch.

Probably somebody has cut a wire fence and let them out. That's the worst of the wire fence in the modern cow business. They can get through wire without being seen. But they can't get by a cowpuncher without his seeing them."

"How many cattle do you think have got mixed with ours?"