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. "_Vacas! muchas_," repeated Juan carelessly. "Lots of 'em, eh? Well, I'd like to know where they are, my lily of the valley," said Curly, for once almost incredulous. And then he stopped and listened.--"Hold on, boys, listen," he said. "Look out--look out! Here they come!" Every ear caught the faint distant pattering, which grew into a rapid and insistent rumble. "Cavalry, b'gad!" cried Battersleigh. Franklin's eyes shone. He spurred forward fast as he could go, jerking loose the thong which held his rifle fast in the scabbard under his leg.