Accordingly they started to climb upward, just as many other tourists had been doing for years. There were even places, "aisles of safety," Bob called them, where one who was ascending, upon happening to meet a descending investigator, could squeeze into a hole in the rock until the other had slipped by. Of course it was a risky climb, and no lightheaded person could ever dream of taking it. But the two saddle boys were possessed of good nerves and able to look downward toward the bottom of the canyon, even when several hundred feet up in the air. Then they entered the first hole. It seemed to be a fair-sized apartment, and was connected with a string of others, all running along the face of the cliff; so that those who occupied them in the long ago might have air and light. The boys observed everything with the ordinary curiosity expected of newcomers. Frank even investigated to see if there were any signs to indicate that those old dwellers in the canyon knew about the use of fire; and soon decided that it was so. "Well, what do you think about this?" Bob asked, after they had roamed from one room to another. "For my part I think I'd fancy living in one of those three story adobe houses of the Hopi Indians, we saw pictures of at the hotel; or even a Navajo hogan. But one thing sure, these people never had to worry about leaking roofs." "No," added Frank, laughing; "and floods couldn't bother them, because the Colorado never rose three hundred feet since it began cutting out this canyon." "And think of the grand view they had before their doors, with the canyon in places as much as thirteen miles across, and mountains in their dooryard, looking like anthills," Bob went on impressively. "Makes a fellow feel mighty small; doesn't it?" Frank remarked, as he stepped to a window to look out again. "Makes me feel that I want to get down again to the trail," admitted Bob. "I'm wondering whether it's going to be much harder getting back than it was coming up." "That's always the case," Frank declared, "as I've found out myself when climbing up a steep cliff. But the guide is ready for you, Bob, if you show signs of getting dizzy. You have seen that he carries a rope along, just like the Swiss guides do." "Oh! come, Frank! Go easy with me; can't you?" the other exclaimed. "I hope I'm not quite so bad as that." "All the same, Bob, don't take any chances; and if you feel the least bit giddy, let me know. This is a case where an ounce of prevention is better than a pound of cure. And a stout rope is a mighty good thing to feel when your foot slips." It turned out, however, that the Kentucky lad was as sure-footed as a mountain goat. He descended the trail, with its several ladders, placed there of course by modern investigators, without the least show of timidity.