Roly and his father found it no easy matter to do rear-guard duty. There was a speckled horse called "Pinto" who made it his especial care to keep them busy. He had started in the van of the train, but, being a confirmed shirk, had gradually fallen back until there remained only a meek little white horse between him and the hindmost riders. Having gained this position, he dropped into a walk at every opportunity and was soon far behind the other horses, all efforts on the part of the amateur drivers to reach him with a switch or strap being futile. No sooner did he see them spurring up than he would jump ahead just out of reach, while the punishment intended for him--the clever rogue--fell upon the poor little white horse, whom he would not allow to pass him on the narrow trail. At the first wide clearing, however, Pinto got what he deserved, and, being thoroughly convinced that his new masters would have no trifling, he was as well behaved for the rest of the day as could be desired. Now let us follow the fortunes of Uncle Will and David. While the horses were being rounded up and loaded, the two pedestrians had obtained a good lead, walking as rapidly as the nature of the ground permitted, and pausing only to drink at a sparkling brook or to admire for a moment some scene of unusual beauty. They had covered several miles, and were ascending a wooded slope on the other side of which lay a deep and narrow ravine, when David broke a shoe-string and stopped to tie the ends, his uncle continuing over the crest and into the hollow beyond. A moment later, hurrying to catch up, David also mounted the slope, and had almost reached the top when a gleam of light caught his eye, coming from the opposite edge of the ravine and a little to the right. Looking there to discover the cause, he halted abruptly. The sun had glinted on the barrel of a rifle in the hands of a man who, at that moment crouched beside a large rock, was facing away from him and motioning to some one in the woods beyond. The stranger wore fringed buckskin breeches and a red flannel shirt, and his broad-brimmed felt hat lay on the ground beside him. There was something in the appearance and stealthy movements of this man which at once aroused David's suspicions. Instinctively he threw himself flat on the ground behind a young spruce which grew on the top of the bank, at the same time unslinging his rifle and laying it beside him. As he did so, he watched the gaudy stranger intently through the branches of the tree and tried to recall the description of the men who were suspected of robbing Dalton's Post. With every detail which he could remember, this man tallied exactly. He glanced also to the bottom of the ravine, where he was amazed to see his uncle bending over what seemed to be a man's lifeless body. Startled and wondering, David dared not long avert his eyes from the opposite bank.