"This trip lets me out," said the young Texan to the brothers, "of walking up the trail and leading fagged-out saddle stock. A mount of six horses to the man may be all right on a ranch, but it won't do on the trail. Especially in a dry year, with delivery on the Platte. Actually, this afternoon is the first time I have felt a horse under me since we crossed Red River. Give me a sheet of paper, please. I want to give you a bill of sale for these six drag ponies that I'm sawing off on you. I carry written authority to give a bill of sale, and it will always protect your possession of the horses. They wouldn't bring a dollar a head in Ogalalla, but when they round into form again next summer, some brand ferret passing might want to claim them on you. Any cattle that I cull out here are abandoned, you understand, simply abandoned." The boys were left alone for the first time in several nights. The rush of the past few days had kept them in the saddle during their waking hours. The dead-line had been neglected, the drifting of cripples to the new tanks below was pressing, and order must be established. The water in the pools was the main concern, a thing beyond human control, and a matter of constant watchfulness. A remark dropped during the day, of water flowing at night, was not lost on the attentive ear of Joel Wells. "What did you mean?" he politely inquired of the Running W foreman, while the latter's herd was watering, "of a river only running at night?" "All over this arid country moisture rises at night and sinks by day," replied the trail boss. "Under drouth, these sandy rivers of the plain, including the Platte and for a thousand miles to the south, only flow at night. It's their protection against the sun's absorption. Mark these pools at sunset and see if they don't rise an inch to-night. Try it and see." Willow roots were notched on the water-line of each beaver dam. The extreme upper pool was still taking water from a sickly flow, a struggling rivulet, fed by the springs at its head. Doubt was indulged in and freely expressed. "If the water only holds a week longer," ventured Dell, sleepless in his blankets, "it'll double our holding of cattle." "It'll hold a month," said Joel, equally sleepless. "We've got to stand by these trail herds--there is no other water short of the Republican. I've figured it all out. When the Beaver ponds are gone, we'll round up the wintered cattle, drift them over to the south fork of the Republican, and get some one to hold them until frost falls. Then we'll ship the cripples up to Hackberry Grove, and that will free the new tanks--water enough for twenty trail herds. We have the horses, and these trail outfits will lend us any help we need. By shifting cattle around, I can see a month's supply. And there may be something in water rising at night. We'll know in the morning."