In this he did not seem to be successful, for the charging bull kept straight on, and came up against the trunk of Sandy's refuge with a thump that staggered him not a little. "You see what you get!" called the boy, tauntingly, hovering behind the tree, and ready to glide around it at the first sign of pursuit. "Take care, he's going to chase after you! Keep close to the tree, and be sure you don't slip!" called Bob; who, his hands trembling with excitement, was trying to get a charge of powder into the barrel of his musket, no easy task while he sat perched on a limb. Meanwhile there was a scene of action close by. Sandy showed a clean pair of heels to the enemy, slipping adroitly around the beech as fast as the buffalo could chase after him. If he kept his footing all would be well; but, should he ever trip on one of the roots that cropped out of the ground, perhaps the ugly horns of the beast would gore him before he could roll out of reach. So, while he continued to load his gun, Bob kept up a succession of outcries, intended to encourage his brother, and at the same time disconcert the stubborn bison. "Keep moving, Sandy! Don't let him get a swipe at you, boy! Oh! I came near dropping that bullet then. Will I ever get this gun loaded? Be careful, lad! That time you were nearly down. He is tiring, Sandy; but unless I make haste something dreadful may happen. I must finish this job. Look out again, he's meaning to turn on you suddenly. There! just what I feared; but you were too quick for him!" By this time the boy who was spinning around the tree so rapidly had begun to realize that it was not so much fun, after all, this being pursued by a monster with wicked horns, and the power of a tornado in his thick-set neck. At times he could almost feel the hot breath of the animal upon his neck, which showed how very close the buffalo must be. Had Sandy chanced to be alone his condition must have been doubly desperate. As it was, his only hope seemed to lie in the ability of his brother to get his gun loaded in time to put an end to the crazy bison. "Keep it up just ten seconds longer, Sandy, and I'll be ready! The priming, boy, that's all! Now look out, here goes!" As Bob said this he discharged his musket, after securing a fair aim, as the animal's flank came around in full view. "Hurrah! he's down again!" gasped poor Sandy with almost his last breath, for he seemed on the verge of exhaustion from the whirl around that tree. "Climb up out of reach, quick!" shouted Bob, jumping down so as to attract the attention of the bull toward himself should the animal manage to stagger to his legs again, for he saw his brother was exhausted and would now prove an easy victim. But Sandy was on the ground, and he saw something that his brother did not. The last bullet had reached a vital spot, and already the big animal was quivering in the last expiring throes.