In truth, the herd was now bound straight for the hill on which the boy maintained his solitary watch. Swiftly running down to the gully in which the horses were tethered, Sandy got out his brother's gun and carefully examined the caps and the load. They had run some heavy slugs of lead in a rude mould which they had made, the slug being just the size of the barrel of the shot-gun. One barrel was loaded with a heavy charge of buckshot, and the other with a slug. The latter was an experiment, and a big slug like that could not be expected to carry very far; it might, however, do much damage at short range. Running up to the head of the gully, which was in the nature of a shallow ravine draining the hill above, Sandy emerged on the highest point of land, a few hundred feet to the right and north of his former post of observation. The herd was in full drive directly toward him. Suppose they should come driving down over the hills where he was! They would sweep down into the gully, stampede the horses, and trample all the camp stuff into bits! The boy fairly shook with excitement as the idea struck him. On they came, the solid ground shaking under their thundering tread. "I must try to head 'em off," said the boy to himself. "The least I can do is to scare them a good bit, and then they'll split in two and the herd will divide right here. But I must get a shot at one, or the other fellows will laugh at me." The rushing herd was headed right for the spot where Sandy stood, spreading out to the left and right, but with the centre of the phalanx steering in a bee-line for the lad. Thoroughly alarmed now, Sandy looked around, and perceiving a sharp outcropping of the underlying stratum of limestone at the head of the little ravine, he resolved to shelter himself behind that, in case the buffalo should continue to come that way. Notwithstanding his excitement, the lad did not fail to note two discharges, one after the other, in the distance, showing that his friends were still keeping up a fusillade against the flying herds. At the second shot, Sandy thought that the masses in the rear swung off more to the southward, as if panic-stricken by the firing, but the advance guard still maintained a straight line for him. There was no escape from it now, and Sandy looked down at the two horses tethered in the ravine below, peacefully grazing the short, thick grass, unconscious of the flood of buffalo undulating over the prairie above them, and soon to swoop down over the hill-side where they were. In another instant the lad could see the tossing, shaggy manes of the leaders of the herd, and could even distinguish the redness of their eyes as they swept up the incline, at the head of which he stood. He hastily dodged behind the crag of rock; it was a small affair, hardly higher than his head, but wide enough, he thought, to divide the herd when they came to it. So he ducked behind it and waited for coming events.