ncle, "one that you'll have to
solve."

"We went over it all before," spoke Bud, "and we couldn't see even a
branch passage."

"Well, some of the men are going with you this time," his father said.
"They're more used to looking for signs than you fellows are, though I
must say you've done fine, so far!"

As Mr. Merkel had stated, it was decided to send several of the cowboys
with Bud and his cousins on this expedition into the dark tunnel. Old
Billee, Yellin' Kid and Snake Purdee would be of the party, which would
thus consist of six.

In this way, there being safety in numbers, it was hoped that accidents
might be avoided, or, if they happened, there would be at hand help for
the unfortunates.

"If we could only take a boat," said Dick, when the preparations were
almost completed, "it would be great!"

"What could we do with a boat in that stream, which is hardly three
feet wide in places?" asked his brother. A boat had been mentioned in
the first excitement, however, but the idea was abandoned as
impracticable.

"Well, if the flood came, as suddenly as it did when we had to take
refuge on the ledge, we could float out," answered Dick.

"A boat to hold six men would be too big to carry," spoke Bud. "Even a
folding canvas one wouldn't answer. But I know what we can do."

"What?" asked Nort.

"We can each take an inner automobile tire. Blown up, they are as good
as life preservers, and with them fastened to us we can float and be
carried along by the current, if a flood happens again."

It was decided that this was a wise precaution to take, and from
Diamond X some inner tubes were sent over--old ones that had outlived
their usefulness on the car, but which still held air, and would, as
Bud said, make excellent life preservers.

In order to make a thorough examination it was decided to take food and
water enough to last the expedition at least two days. It was easy to
traverse the tunnel in one day, as the boys had proved. But Old Billee
counseled a slower trip.

"I wish I could go with you," said Mr. Merkel to the boys, when the
time came for the start, "but I have a shipment of steers to get off,
and I want to keep watch of this epidemic. It begins to look as if we
had gotten the best of it, but I'm taking no chances."

"Oh, we'll make out all right, Dad," spoke Bud. "Though we would like
to have you with us. And when we come back we'll either settle, for
good and all, this fight for water,