Derrick did as he was directed, and quickly found himself intensely interested in the strange and busy scene before him. The travelling-road entered the mine in a large chamber close beside the foot of the slope that led upward to the new breaker. From this chamber branched several galleries, or "gangways," in which were laid railway-tracks. Over these, trains of loaded and empty coal-cars drawn by mules were constantly coming and going. By the side of the track in each gangway was a ditch containing a stream of ink-black water, flowing towards a central well in one corner of the chamber, from which it was pumped to the surface. Opposite to where he stood, Derrick saw the black, yawning mouth of another slope, which, as he afterwards learned, led down into still lower depths of the mine. The men around him were handling long bars of railroad iron, which they were loading with a great racket on cars, and despatching to distant gangways in which new tracks were needed. Two large reflector lamps in addition to the miners' lamps made the chamber quite bright, and with all its noise and bustle it seemed to Derrick the most interesting place he had ever been in. He was sorry when the mine boss called and told him to bring along his mule and follow him. They entered one of the gangways, leading from the central chamber, which the mine boss said was known as Gangway No. 1. He also told Derrick something about his mule, and said that by its last driver, Bill Tooley, the poor animal had been so cruelly abused that he had sent it to the surface for a few days to recover from the effects. "I guess he has recovered," said Derrick, "judging from the way he brought me into the mine." They had not gone very far before they came to a closed door on one side of the gangway beyond which the mule absolutely refused to go, in spite of all Derrick's coaxings and commands. "It is the door of his stable," said the mine boss, who stood quietly looking on, without offering any assistance or advice, waiting to see what the boy would do. Tying the end of the halter to one of the rails of the track on which they were walking, Derrick started into the stable, where he quickly found what he wanted. Coming out with a handful of oats, he let the mule have a little taste of them; and then, loosening the halter, tried to tempt him forward with them. This plan failed, for Harry declined to yield to temptation, and remained immovable. Then Derrick turned a questioning glance upon the mine boss, who said, "Never again hitch an animal to a track along which cars are liable to come at any moment. Now, why don't you beat the mule?" "Oh no, sir!" exclaimed Derrick, in distress. "I don't want to do that." "Neither do I want you to," laughed the other. "I only asked why you didn't?" "Because," said Derrick, "I want him to become fond of me, and my mother says the most stubborn animals can be conquered by kindness, while beatings only make them worse."