They proceeded at a trot, keeping it up for two hours or more. Lambert knew it was about ten o'clock when he stopped to investigate the man in the road. There was a feel in the air now that told him it was far past the turn of night. He knew about where they were in relation to the ranch by this time, for a man who lives in the open places develops his sense of direction until it serves him as a mole's in its underground tunneling. There was no talking among his conductors, no sound but the tramp of the horses in unceasing trot, the scraping of the bushes on the stirrups as they passed. Lambert's legs were drawn close to his horse's belly, his feet not in the stirrups, and tied so tightly that he rode in painful rigidity. The brush caught the loose stirrups and flung them against Whetstone's sides, treatment that he resented with all the indignation of a genuine range horse. The twisting and jumping made Lambert's situation doubly uncomfortable. He longed for the end of the journey, no matter what awaited him at its conclusion. For some time Lambert had noticed a glow as of a fire directly ahead of them. It grew and sank as if being fed irregularly, or as if smoke blew before it from time to time. Presently they rounded the base of a hill and came suddenly upon the fire, burning in a gulch, as it seemed, covering a large area, sending up a vast volume of smoke. Lambert had seen smoke in this direction many times while riding fence, but could not account for it then any more than he could now for a little while as he stood facing its origin. Then he understood that this was a burning vein of lignite, such as he had seen traces of in the gorgeously colored soil in other parts of the Bad Lands where the fires had died out and cooled long ago. These fires are peculiar to the Bad Lands, and not uncommon there, owing their origin to forest or prairie blazes which spread to the exposed veins of coal. As these broad, deep deposits of lignite lie near the surface, the fire can be seen through crevasses and fallen sections of crust. Sometimes they burn for years. At the foot of the steep bank on which Lambert and his captors stood the crust had caved, giving the fire air to hasten its ravages. The mass of slow-moving fire glowed red and intense, covered in places by its own ashes, now sending up sudden clouds of smoke as an indraft of air livened the combustion, now smoldering in sullen dullness, throwing off a heat that made the horses draw back. Kerr drew aside on arriving at the fire, and sat his horse looking at it, the light on his face. Sim Hargus pointed to the glowing pit. "That's our little private hell. What do you think of it, kid?" he said, with his grunting, insulting sneer.