Journeying along, we came suddenly upon a place where the ground was covered with horses' tracks, which had been made since the rain, and indicated the immediate presence of Indians in our neighborhood. The buffalo, too, which the day before had been so numerous were nowhere in sight--another sure indication that there were people near. Riding on, we discovered the carcass of a buffalo recently killed--perhaps the day before. We scanned the horizon carefully with the glass, but no living object was to be seen. For the next mile or two, the ground was dotted with buffalo carcasses, which showed that the Indians had made a surround here, and were in considerable force. We went on quickly and cautiously, keeping the river bottom, and carefully avoiding the hills; but we met with no interruption, and began to grow careless again. We had already lost one of our horses, and here Basil's mule showed symptoms of giving out, and finally refused to advance, being what the Canadians call _reste_. He therefore dismounted, and drove her along before him; but this was a very slow way of traveling. We had inadvertently got about half a mile in advance, but our Cheyennes, who were generally a mile or two in the rear, remained with him. There were some dark-looking objects among the hills, about two miles to the left, here low and undulating, which we had seen for a little time, and supposed to be buffalo coming in to water; but, happening to look behind, Maxwell saw the Cheyennes whipping up furiously, and another glance at the dark objects showed them at once to be Indians coming up at speed. Had we been well mounted and disencumbered of instruments, we might have set them at defiance; but as it was, we were fairly caught. It was too late to rejoin our friends, and we endeavored to gain a clump of timber about half a mile ahead; but the instruments and tired state of our horses did not allow us to go faster than a steady canter, and they were gaining on us fast. At first, they did not appear to be more than fifteen or twenty in number, but group after group darted into view at the top of the hills, until all the little eminences seemed in motion; and, in a few minutes from the time they were first discovered, two or three hundred, naked to the breechcloth, were sweeping across the prairie. In a few hundred yards we discovered that the timber we were endeavoring to make was on the opposite side of the river; and before we reach the bank, down came the Indians upon us.