the Pocut stream, delivering it to the tunnel.

"But here's a queer part of it," went on Dick, as they joined the other
cowboys who were preparing to follow Slim in, and search for the
Diamond X lads. "No such body of water, as so nearly overwhelmed us,
ever came through this pipe," and he pointed to the one that tapped the
dammed-up water of the river.

"That's right!" agreed Bud. "This thing gets worse and worse! We'll
never get to the bottom of this mystery!"

"You're right!" declared one of the cowboys. "When you're dealing with
them underground water-courses you never know what you're up against.
The old Indians and Spaniards who lived here hundreds of years ago had
their own troubles, and maybe they wished them same troubles on to you."

"What you mean?" asked Slim. "That's all bosh!"

"Bosh nothin'!" declared another. "You read history an' you'll get
lots of cases where streams showed up, and then vanished under
mountains, more than once."

"A heap sight you know about _hist'ry_!" laughed Slim in good-natured
raillery.

"Well, this is sure queer, anyhow!" declared Bud. "Is there any
history of the stream that waters our valley?" he asked the cowboy who
had made the assertion.

"Not your particular one," was the answer, "but there's lots of just
such cases mentioned--hidden water-courses and all that."

"Well, there's something wrong," agreed Bud, "and I believe there must
be some place along the tunnel where our water shunts itself off at
times, and turns itself on again. We were looking for just such a
place."

"And you didn't find it?" asked Slim.

"Nary a find!" asserted Bud.

"But we aren't going to give up, just on that account!" said Nort.

"Bet you not!" added his brother. "We'll try it again, and take a
canoe with us, so if the dry water-course suddenly turns wet, we can
paddle along it."

"Well, it seems to be all right now," spoke Slim. "And you'd better
'phone your father that you're all right, Bud. He'll be anxious to
hear."

And after Mr. Merkel had been assured, over the wire, of the safe
transit of his son and nephews through the tunnel, the boys' camp was
called up, to let Old Billee and the others know that no accident had
happened.

"Gosh! I'm glad to hear that!" said the veteran cowboy over the wire.
"When we see that there water come gushin' out, we thought sure you was
goners, Bud!"

"Then the water is running again?" Bud asked.

"Absolutely!" declared Bil