ay through the tunnel had been uphill all the way, as it must needs be
to allow the water to run down to the reservoir in Flume Valley. But,
so far, they had seen nothing to indicate any side channel for the
stream--any place that might drain off the water, and return it in such
a sudden volume as to cause a flood.

"I can't understand it," Bud remarked as he swung the lantern to and
fro. "It sure is a puzzle. Where does the water disappear?"

His cousins could offer no solution. All the way along they had
carefully scanned the underground stream, but there appeared no break
in its uneven, rocky bank in the middle of the tunnel.

"Well, let's keep on," suggested Nort. "We aren't at the end yet, and
it may be close to the intake--I mean the mysterious influence--that
shuts off our water supply and turns it on again, may be there.
Forward, march!" he cried gaily.

Together they started off, having come to a momentary halt to inspect a
place wider and deeper than usual, when Bud suddenly came to a stop and
exclaimed:

"Some one is coming!"

CHAPTER XIV

A NIGHT ATTACK

Instantly the boy ranchers came to a halt, standing there in the
tunnel, beside the running water. They had nearly reached the other
end of the flume, and could dimly see, ahead of them, a faint glow,
which told of daylight to come. Bud, who was carrying the lantern,
made shift to hide it behind the bodies of himself and his cousins, so
that the unknown, approaching, might not have them at a disadvantage,
he being in the dark.

"Who you reckon it is?" asked Nort. He and his brother were rapidly
falling into the custom of using the picturesque if not always elegant
talk of the west. Nort spoke in a whisper, and Bud answered in the
same tone.

"Can't imagine who it may be," spoke the western lad, "but if it's
Hank, Del Pinzo, or any of their gang----"

He did not finish, but a slight movement told that he was freeing his
.45 in its holster, an example quickly followed by Nort and Dick.

Meanwhile the steps continued to approach, echoing loudly in the
vaulted tunnel, as if the maker of them had no design to conceal his
movements. In another few seconds the boys saw, looming in front of
them, as displayed by the gleam of their half-hidden lantern, a bulky
figure. At the same moment the figure seemed to become aware of the
presence in the tunnel of others besides himself.

"Who's there?" came in sharp challenge.

And what a rel