That night they filled with water the skin bags they had by degrees provided for the purpose. A spring that gurgled close by the camp gave them an unlimited supply of the necessary fluid; and they were warned by the guide that it would be the last waterhole they would expect to come across for many days. In the morning the start was made, not without misgivings. No one could say what terrible things lay before them, and the men cast wistful glances back toward that cooling spring, as though they disliked to say good-by to it. That day was one which served to give them a new experience, for, up to then, few of the explorers had ever known what it was to travel over a sandy waste where the sun beat down with blistering effect, and the air seemed fairly to quiver with the heat. No living thing had they seen all day long, save perhaps a skulking small animal, which the men at first thought to be a dog, though it must have been a coyote; a few sage hens; and some gophers, that burrowed in holes in the ground, from the entrances of which they timidly watched the horses file slowly past. In every direction lay cacti of various species and heights, while thorny plants belonging to the same family, and bearing a small pear-like fruit which the Indian told them was edible, lay upon the ground. They were glad when night came with its refreshing air. The camp was made in the open desert, for there was not a tree of any size in sight. And it seemed to the boys that, when the sun went down that evening, it was several times as large as usual, as well as fiery red. It beckoned them on just as before, since they knew well that _somewhere_, beyond the desert, the sun must be setting behind the vast ocean which they all aspired to see. Another like day followed, and all of them began to suffer more or less on account of the heat, and the sand glare, which affected their eyes. On account of this, it was suggested that hereafter they rest during the hottest part of each day, and continue their journey as far into the night as the horses could stand it. They seemed to be thirsty most of the time, and the horses, too, needed many a refreshing drink in order to continue their labors. More than one uneasy glance was cast toward the supply of the precious fluid. If the skin sacks should spring a leak the wanderers must face a desperate condition, indeed. So they settled down for the second night upon the open desert. Each day would be very much like another, unless they were unfortunate enough to experience one of those dreaded sand storms they had heard about, the terrors of which they could now easily imagine. The guide, however, had spoken cheering words in his own tongue, and, by holding up two fingers of his hand, gave them to understand they were by this time half-way across the desert. If they could stand this for two more days there was hope that the worst would be over.