“That’s curious,” said Franklin.  “How do you account for it?”

“Kin savvy,” said Curly.  “I don’t try to account for it, me.  I only know it’s so.  You see if it ain’t.”

And so it was.  The wall of the sand hills was for a time apparently as endless and impervious as ever, and they still travelled on in silence, the Mexican making no further sign of interest.  Yet presently the procession of the sand dunes began to show gaps and open places.  The hills grew less tall and more regular of outline.  Finally they shrank and fell away, giving place again to the long roll of the prairie, across which, and near at hand to the edge of the sand hills, there cut the open and flat bed of a water way, now apparently quite dry.

“We’re all right for water now,” said Sam.  “See that little pile of rocks, ’bout as high as your head, off to the right down the creek?  That’s water there, sure.”

“Yep,” said Curly.  “She’s there, sure.  Or you could git it by diggin’ anywheres in here in the creek bed, inside of four or five feet at most.”

Franklin again felt constrained to ask somewhat of the means by which these two felt so confident of their knowledge.  “Well, now, Curly,” he said, “it isn’t instinct this time, surely, for Juan didn’t say anything about it to you.  I would like to know how you know there is water ahead.”

“Why,” said Curly, “that’s the sign for water on the plains.  If you ever see one of them little piles of stones standin’ up, you can depend you can git water there.  Sometimes it marks a place where you can git down through the breaks to the creek bed, and sometimes it means that if you dig in the bed there you can find water, ‘lowin’ the creek’s dry.”

“But who built up the rock piles to make these signs?” asked Franklin.

“O Lord! now you’ve got me,” said Curly.  “I don’t know no more about that than you do.  Injuns done it, maybe.  Some says the first wild-horse hunters put ’em up.  They was always there, all over the dry country, far back as ever I heard.  You ask Juan if there ain’t water not far off.  See what he says.—­Oye, Juan!  Tengo agua, poco tiempo?”

The giant did not even lift his head, but answered listlessly, “Agua?  Si,” as though that were a matter of which all present must have equal knowledge.

“That settles it,” said Curly.  “I never did know Juan to miss it on locatin’ water yet, not onct.  I kin fairly taste it now.  But you see, Juan, he don’t seem to go by no rock-pile signs.  He just seems to smell water, like a horse or a steer.”

They now rode on more rapidly, bearing off toward the cairn which made the water sign.  All at once Juan lifted his head, listened for a moment, and then said, with more show of animation than he had yet displayed and with positiveness in his voice:  “Vacas!” ("cows; cattle").

Curly straightened up in his saddle as though electrified. “Vacas?  Onde, Juan?—­where’s any cows?” He knew well enough that no hoof of domestic cattle had ever trod this country.  Yet trust as he did the dictum of the giant’s strange extra sense, he could not see, anywhere upon the wide country round about them, any signs of the buffalo to which he was sure the Mexican meant to call his attention.