or we'll abandon Flume Valley!"

"I'd hate to see you give it up," said the ranchman. "It is an ideal
place to raise cattle, with the water here. But without it, of course,
there's no use thinking of it. Well, good luck to you," he called, as
he turned to go back to Diamond X proper.

As he had said, there had been no further outbreak of the epidemic
among the cattle of the boy ranchers. The steers which Pocut Pete had
cut, injecting into them the pus and germs, died, however. And there
were more of these than Bud and his cousins had counted on.

But if they lost no more than this half-score, and could get the water
back, all might yet be well.

The water in the reservoir had gone down several feet when the
expedition started into the tunnel. Much of the fluid had to be drawn
off to water the thirsty cattle, for it was the height of summer now,
and the heat, in the middle of the day, was terrific.

But there was still enough of the supply to last for several days.
Then, if Bud and his companions could not discover the secret of the
stoppage, and get the water to running again. Flume Valley would have
to be abandoned.

"Well, I can't see that we can do any more," spoke Bud.

"No; you've got things as well fixed as possible," agreed Old Billee.

"Can't tell when you'll see us again," said Dick to the remaining
cowboys gathered about the reservoir end of the tunnel to see the
expedition start in.

"Well, good luck, anyhow!" came the answer.

A number of punchers had been sent over to Flume Valley from Diamond X
and Triangle B to replace Yellin' Kid, Billee and Snake Purdee who were
to accompany the boy ranchers.

Suddenly Yellin' Kid broke into song:

"Leave me alone with a rope an' a saddle,
Fold my spurs under my haid!
Give me a can of them sweet, yaller peaches,
'Cause why? My true-love is daid!"

"Oh, give us something cheerful!" laughed Bud, as the cowboy seemed
about to start on another verse.

"That's cheerful enough for this occasion," retorted Yellin' Kid.
"Wait 'till you hear me howl in that tunnel."

"Don't!" begged Dick with a laugh. "It echoes so you'll bring the roof
down!"

There was a hurried inspection of their weapons and supplies, for each
was equally needed. The inner tubes of several auto tires had been
provided and tested, and there was a small air pump with which to
inflate them.

"All ready?" asked Bud, at length.

"All ready," answered Old Billee. "But