There had been at some time or other a little stream in this ravine, and it was in the stony bed of it that Nelly was walking. She looked very carefully at the stones. They were all light gray or reddish colored: not a black one among them. She had in her pocket the little piece Mr. Kleesman had given her: she took it out, and looked at it again. It was totally unlike all the stones she saw about her. "Oh, dear!" sighed Nelly: "I expect I won't find it to-day. I'll come again to-morrow. At any rate, I'll go to that nice, shady place to eat my lunch." It was further than she thought. In Colorado, every thing looks a great deal nearer to you than it really is: the air is so thin and light that mountains twenty miles away look as if they were not more than three or four; and there are a great many funny stories of the mistakes into which travellers are led by this peculiarity of the air. They set off before breakfast, perhaps, to walk to a hill which looks only a little way off; and, after they have walked an hour or two, there stands the hill, still seeming just as far off as ever. One of the funniest stories is of a man who had been cheated in this way so often that at last he didn't believe his eyes any longer as to whether a distance were long or short; and one day he was found taking off his shoes and stockings to wade through a little ditch that anybody could easily step over. "Why, man alive!" said the people who stood by, "what are you about? You don't need to wade a little ditch like that! Step across it." "Ha!" said he, "you needn't try to fool me any more. I expect that ditch is ten feet wide." Nelly walked on and on in the narrow stony bed of the dried-up stream. The stones hurt her feet, but it was easier walking than on the rolling gravel of the steep sides above. She stopped thinking about the black stones. She was so hot and tired and hungry, all she thought of was getting to the trees to sit down. At last she reached the place just below them. They were much higher up on the hillside than she had supposed. She stood looking up at them. "I expect I'll tumble before I get up there," she thought. It looked about as steep as the side of the roof to a house. But the shade was so cool and inviting that Nelly thought it worth trying for. Half-way up her feet slipped, and down she came on her knees. She scrambled up; and, as she looked down, what should she see, in the place where her knees pressed into the gravel, but a bit of the black stone! At first she thought it was the very piece she had had in her pocket; but she felt in her pocket, and there was her own piece all safe. She took it out, held the two together, looked at them, turned them over and over: yes! the stones were really, exactly the same color! Now she was so excited that she forgot all about the heat, and all about her hunger.