"But," objected the other, "he may be miles away from here by now." "Very well, Roger; if we find that such is the case we can give the hunt up, and do the next best thing. But let's start out, and see where his tracks lead." "But how are we to know which are the tracks of the led animal, Dick?" queried Roger. "Horses' hoofs are pretty much the same, seems to me." "Well, yes, as a rule that is so," came the reply, with a confident smile; "but in this case it happens that old Peter had a chip knocked from the outside edge of his off hind hoof, which always left a mark I could tell. I've noticed it about a hundred times, and always thought that, if the old stray ever did get away, from us, with the stuff on his back, we could easily follow his trail." "It takes you to notice all those things, Dick; and yet I have a good pair of eyes, too," observed Roger, thoughtfully. "As good as mine, and perhaps better, Roger; but the trouble is you seldom use them as much as you might. But come, let us start out and see what there is to be found. And look for the track with the outer edge sheared off." The two boys had been in camp in a little depression on the bank of the river, which they had reached on the preceding afternoon. At the time, the day had not been so far advanced but that they could have gone a few miles farther; but as soon as Dick had seen this camping place he had surprised and partly dismayed the eager Roger by expressing a desire to put in the night there. The reason for this became manifest later on, when he showed his companion unmistakable signs to prove that the expedition they were following had, in fact, tied up there for the night. There were numerous indications to prove this--tracks of white men's shoes, and the moccasins of the guides and trappers accompanying the soldiers; as well as the hoof prints of the horses. Of course, when he learned this fact Roger was reconciled to wasting a little of their precious time. He knew that they could discover a variety of things while camping in the same place that those who preceded them had occupied. And, after a careful examination of the signs, with a remembrance of the fact that quite a heavy rain had fallen two weeks before, which would have washed away any tracks made before its coming, both boys were convinced that the expedition must have camped here after that storm. This was most important to the boys. It assured them that they had gained remarkably on Captain Lewis and his company, who had had such a long start of them. If the expedition had been here within two weeks, their chances of overtaking it were excellent. Perhaps in another week, or two at least, they might expect to come upon the boats. That anticipation had made Roger unusually cheerful all through the preceding night. Indeed, he even found difficulty in sleeping, and had been on his feet numerous times after they lay down in their blankets under the shelter of the tent.