side 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."

"Hello! There's Chunky. Now, what do you suppose he is up to!" exclaimed