Mrs. Halford sat in Paul's arm-chair, and he made a bench of the tally-board for Miss Nellie. The two boys were content to sit on the railway track, and each ate out of his or her own lunch-pail. All at once Paul said, "'Sh! There they are! See!" At this the visitors looked in the direction indicated, and both screamed. "Oh, you've frightened them away!" said Paul, regretfully. "Why, I do believe they were rats!" cried Mrs. Halford, in a tone of great surprise. "Of course they were," answered Paul--"my rat Socrates and Mrs. Socrates and a whole lot of little Soc rats. I meant to tell you, Derrick; he brought them out this morning, his wife and a family of such cunning little fellows." When the ladies had heard the whole story of Socrates the rat, and how wise he was, they became greatly interested, and wished he would appear again. "He will," said Paul, "if we only keep quiet. He's too wise to stay away at lunch-time, but he don't like loud talking." So they all kept very quiet, and sure enough the rat did come back after a little while, and sitting upon his hind-legs, gravely surveyed the party. In the gloom behind him could be seen the shining beady eyes of some members of his family, who made comical attempts to sit up as he did. Being duly fed, they all scampered away with squeaks of thanks, and soon afterwards Harry Mule broke up the picnic by coming jingling back from his stable, to which he had been sent for dinner. "I think he is just the very dearest old mule I ever saw," said Miss Nellie, when they were once more seated in the car, and Harry, was taking them towards a distant heading. "Yes, indeed, he is," answered Derrick, proud to hear his mule thus praised; "and I love him as much as--as he loves me," he finished, with a laugh. They spent several hours in visiting different parts of the mine, and becoming acquainted with all the details of its many operations. At the end of one heading they found the miners who had just finished drilling a hole deep in the wall of coal beyond them, and were about to fire a blast. The visitors were intensely interested in watching their operations. First a cartridge of stiff brown paper and powder was made. The paper was rolled into the shape of a long cylinder, about as big round as a broom-handle, the end of a fuse was inserted in the powder with which it was filled, and the cartridge was thrust into the hole just prepared for it. Then it was tamped with clay, the fuse was lighted, the miners uttered loud cries of "Blast ho!" and everybody ran away to a safe distance. In less than a minute came a dull roar that echoed and re-echoed through the long galleries. It was followed by a great upheaval of coal, a dense cloud of smoke, and the blast was safely over.