To Sid’s naturalist soul all this arboreal desert was weird and beautiful and interesting. The tree choya, a clubby specimen with stiff branches of thorn bristles at the ends of crooked branches, began to appear; then the ocatilla, the “Devil’s Chair,” as Big John called it, a tree with no trunk but with more arms than an octopus and each branch covered with thorns and small green leaves bunched along a green stem as hard as iron. Towards evening, across the gray-green miles, a small brown _visita_ or mission outpost came to view. It was merely a large hut of adobe, but the bell in its upper tower told its purpose instantly. The boys thrilled as they looked at it, for they were now nearing the Papago Reservation and it was quite possible that Vasquez had forestalled them by train from Tucson. Big John reined in the white mustang. “Nobody to home, thar, these days,” quoth he. “The Injuns is all away at the cornfields. We gotto ride in thar though, an’ help ourselves to water afore these hosses kin go further.” Sid would have preferred to keep away, but there was no choice. Water was king in this country! They _had_ to get it, if it meant encountering a thousand malignant school-teachers. Vasquez’s subtle Spanish mind had no doubt led him to reason that they _must_ come here. But what redskin reinforcements he might have picked up in that lonely mission station imagination could not conjecture. Slowly the miles lessened; the building loomed up brown and enigmatical in the setting sun before them. ’Dobe houses, each with a mesquite pole veranda in front, appeared like magic among the green stakes of saguarros on the hillsides; then a round stone oven out in the valley near the schoolhouse became plain to sight. They were perhaps yet a mile away when around the corner of the building appeared a man on horseback. A cape or serapé of some sort hung over his shoulders, but it was too far away to get any sense of color from it. Niltci squinted his keen eyes and gazed at him long and fixedly while the others reined up. “Mexicano!” he ejaculated. “Sho’ is!” agreed Big John. “I’ll bet my hoss it’s that bird who tried to steal your tablet, boys!” Sid and Scotty fumbled for their hunting binoculars. A moment later they had trained them on the man. “It’s _him_, John, all right!” cried Sid. “_Now_ what do we do?” The rider in the serapé answered that question himself, for, wheeling his horse, he galloped off at full speed. “Ride, fellers! Burn it up!” roared Big John. “We got about _no_ time to git in thar an’ water our hosses. He’ll be back, right sudden, with the hull b’ilin’ of drunken Injuns!” CHAPTER IV PINACATE