After Polly had laughed herself weak over Nigger's clever performances, she called to John. "No use! You'll have to give Nig his freedom! He'll land Snowball in kingdom come if you keep him tied." So wise little Nigger was freed once more, and thereafter he walked as circumspectly as any good burro should. But the going was better, too, with the trail running through miles and miles of dark green forests, patterned here and there with golden stretches of mesa and parks. "Are you sure you know the trail, Polly?" asked John, as he gazed about at the unfamiliar path. "Oh, yes, I've gone this way lots of times when Mr. Montresor lived in the cabin where Carew's men are now camping." "Well, if it is much farther, then I say we'd best halt for something to eat." "I will second that motion whether it is far or near. We had best have a bite, as we will have to wait for the crew's dinner-time when we arrive in camp," added Tom Latimer. So the riders dismounted and hastily prepared a luncheon. When they were ready to proceed on the way, Nigger found his pack much lighter than before, so he, too, was delighted to have had the humans stop for lunch. It was past noon before the visitors reached Carew's Camp, but once there, they were given a hearty welcome by every one. Cookee had been mixing and stirring viands ever since the breakfast had been cleared away, and now he was ready to smile satisfactorily at results, for he was going to give these guests a rare meal that day. Mrs. Carew was a Chicago lady and, for once, Barbara was happy, as she found her hostess knew several people that the Maynards felt were exalted enough to be classed "in their set." As soon as their section master gave them the afternoon's vacation, Jim Latimer and Kenneth appropriated Polly and Eleanor, and the four started off on fresh horses from the corral, for an excursion. Jim wanted to ride to one of the peaks where they had surveyed that week, and show the girls the far-off desert that stretched for miles and miles between Buffalo Park and the Lincoln Memorial Highway. The trail was well defined, as the crew had traveled it twice a day that week, and had worn down cactus and sage-brush. The four finally reached the pinnacle where the gray expanse of sand could be seen stretching out to meet the blue sky on the horizon, and Jim laughingly remarked: "Ken and I came near finding a sandy grave there the other day." "How?" eagerly asked the girls. "Why, we were sent with our superior, to tie up a line at the edge of the desert down there, and having done so, one of the crew saw a fine little bit of water and a few trees growing about it, not more than half-a-mile from where we were working. "We concluded it would make an admirable place to rest and have lunch, and give the horses a good drink, too, at the same time. So we all started over the sand to enjoy the unusual oasis.