Later on, in Circle City, Buck has yet another opportunity to demonstrate his devotion to John Thornton. An evil-tempered and malicious man named "Black" Burton is bullying a young "tenderfoot" in a bar (a tenderfoot is an inexperienced person in the frontier). When John Thornton tries to prevent a nasty fight, Burton strikes Thornton solidly and sends him sprawling. Immediately, Buck attacks the man, and even though Burton is able to protect himself from two different lunges by the dog, Buck is finally able to tear open the man's throat. A meeting is immediately called, and it is decided that Buck had sufficient provocation for defending his master against violence. Later on that year, Buck again proves his worth by again saving Thornton's life. While attempting to maneuver some dangerous rapids, Thornton's boat overturns, flinging him into the cold, swirling water, which, in turn, sweeps him into the midst of such wild rapids that not even a strong swimmer could survive. Buck does not hesitate to act; he swims out to Thornton, who knows that they are not strong enough to conquer the turbulent rapids. Thus he orders Buck back to the shore, and even though Buck hates to desert his master, he nevertheless obeys Thornton's commands. Once on shore, Hans and Pete tie a long rope to Buck's collar and send him back into the water with it. Buck launches boldly out into the stream, but finds that he cannot travel straight enough, and he misses Thornton by only a few yards. Again, he returns to shore, where the rope is once again attached to him. "He had miscalculated once, but he would not be guilty of it a second time." This time, he reaches Thornton, who is able to grab the rope, and almost "strangling and suffocating," the man and the dog, both bruised and battered, are dragged back to the shore. There, they discover that Buck has two broken ribs, and Thornton announces that they will not break camp until Buck's ribs are fully healed.
A third episode concerning Buck's extraordinary character occurs sometime later, and it is such a feat that Buck's fame spreads throughout all Alaska. It begins in a saloon, where some men are boasting of the exploits of their dogs. Thornton is intrigued and is driven to maintain that Buck can pull a sled with a thousand pounds on it. Furthermore, he says, Buck can break the sled loose — even if it is frozen fast — and, furthermore, that he can pull it a hundred yards. A man named Matthewson bets Thornton that Buck cannot do such an incredible feat; in fact, he is willing to bet a thousand dollars that Buck cannot do it. Thornton, at this point, momentarily becomes unsure whether or not Buck can actually perform such an enormous and appalling task, and he is confused as to what to do, since neither he, nor Hans, nor Pete has a thousand dollars. At that moment, however, an old friend of Thornton's, Jim O'Brien, walks into the saloon and offers to lend Thornton a thousand dollars. The bet is on, and all of the occupants of the town pour into the streets, the men all placing great odds that Buck cannot budge the sled. When it is discovered that the sled's runners are, in fact, frozen to the ice, and Thornton is not able to break the sled loose, the odds soar tremendously. Matthewson, however, offers to increase his wager by another thousand — at three to one odds — but Thornton, Hans and Pete are able to raise only two hundred dollars, which they bet against Matthewson's six hundred.
