"How do you know they are varmints?" laughed Walt Phelps. "Don't see what business they'd hev here otherwise, and----" began Pete, but a perfect tempest of laughter at his expense drowned the rest of his speech. "Well, now that we seem to have pretty well explored the habitation part of the mesa, let us make our way to the summit," suggested the professor. With a whoop and yell, the excited boys followed the suggestion at once, and a dash up the narrow causeway followed at imminent risk of one of another losing his footing. "Hey, hold on thar!" yelled Pete, as they dashed upward, "we don't want no funerals here, an' it's er drop of more'n a hundred feet to ther ground." This rather checked the boys' enthusiasm, and they went more slowly thereafter. The summit of the mesa was found to consist of a small plateau, about a quarter of an acre in extent, perfectly bare, and shaped like a saucer. Near the center was the hole which gave illumination to the council hall below them, while in a spot almost exactly in the middle of the queer elevation, was a rough, square erection of sun-baked brick. This was about twelve feet in length, five feet in height, and six feet or so through. Apparently it had once been a kind of an altar. The professor thought this assumption tenable, as it was known that the aborigines who had once inhabited the mesa had been sun-worshipers. "Ugh!" shuddered Jack, as he gazed at the altar. "And they used to offer human sacrifices here." "I think it altogether likely," said the professor calmly; "probably that altar has witnessed the immolation of more than a hundred victims at a single tribal ceremony." Ralph Stetson was clambering up on the altar as the professor spoke, but at hearing these words he hastily descended again. "I guess I'll defer examining it till some other time," he said decidedly. From the summit of the mesa a wonderful view could be obtained. At that altitude the rocky, desolate range of sierras to the south could be seen clearly, although a mile or so distant. "Thar's the border yonder," said Pete, pointing. "And over across there is father, I guess," said Jack. "I hope he found everything at the Esmeralda all right." "Sure he did," said Pete confidently. "I tell you, these greaser uprisings don't amount to a busted gourd. Mister Diaz's tin soldiers come along, and 'pop-bang! Adios!' It's all over." "But I have heard that in this case the insurrectionists of Northern Chihuahua are exceptionally well provided with arms and ammunition," objected the professor. "The American government can't make out from whence they are supplied with guns and munitions of war." "Huh, where'd they git 'em from, I'd like to know?" snorted Pete. "The border is well guarded at any point where they would be likely to ship 'em across, and----" "How about the _unlikely_ points?" inquired the professor amiably.