When I had convinced myself that everything was in order, I called my party's attention to the fact that strict obedience to my regulations was indispensably necessary for our common safety. Tiger was entrusted with the guidance, and always rode about a hundred yards ahead, while one of us formed the rear-guard by the mules. I had with Tiger a long consultation as to the route we should follow, and while I proposed to keep more to the north-west, he insisted on a due north direction. I was of opinion that the lowest passage to the north would be found at the spot where the Rio Grande mountains sloped down to the east and joined the San Saba mountains; while, on the other hand, Tiger asserted that the mountain chain could be passed most easily due north, near the sources of the Rio Colorado. It is remarkable with what certainty the Indians know the nature and course of mountains and rivers, as well as the climatic circumstances of the country, and judge distances. The sense of locality is marvellously developed among the savages. Without being able to explain why it is so, the savage will indicate in an instant--without any examination of trees, rocks, &c.--the exact direction of the point he wishes to reach. Animals, and especially horses and mules, obey the same instinct. Frequently, when I have been hunting buffaloes in all directions over the prairie, and evening warned me about returning home, I have been in doubt as to the direction in which the Fort lay. I certainly knew that, for instance, I was on the north side of the Leone, and hence must ride southwards; but I could not determine whether I ought to proceed farther east or west, and an incorrect course might easily bring me to the river miles above or below the Fort. The horizon was bounded by the sky, as if I were at sea, and not a hill or forest reminded me of any familiar point. In such cases I laid the bridle on my horse's neck, let him graze for awhile, and then told him to go on, though without touching the bridle. The horse, missing the usual guidance, looked around him for a few minutes with upraised head, and then went in a straight line homewards. Remembering this, I followed Tiger's advice and went due north.