Now his school children were well and happy. Their cheeks were round and rosy, for they had a lunch at school and their mothers gave them good food at home. Their clothes were neat and clean, their eyes were bright and shining, and they were ready to study and play. But where should they play? There was no trouble about a place to study. They could study at school or at home, but when they wanted to play there was no place at all. Rio is one of the most beautiful cities in the world, and many of the people are very wealthy and live in beautiful homes, but Dr. Tucker's poor little children in the slums lived in houses that were built close together right on the street. There was a very beautiful park, with lovely green grass, but the superintendent of parks was very proud of his green grass and had a fence of iron rails around it with a sign, "Keep off the grass" wherever a child could get in. Every time Dr. Tucker saw that park, his eyes looked like the eyes of his school children when they were hungry. But one day as he went through the park, his eyes began to twinkle. He clapped his hands and said to himself, "I'll do it!" At once he walked up boldly to the mayor of Rio and the superintendent of parks. "The children have no place to play," he said. "Why don't you open up a part of the city park for a public playground?" The mayor and the superintendent of parks were so shocked they could scarcely say a word. They were so proud of their beautiful park, they had never let people even walk on the grass; and now this bold man actually dared to propose that they should put swings and teeter boards and tennis courts right where the grass was most beautiful! But they could not forget what he said about happy children being worth more than beautiful grass, and one day they drove to Dr. Tucker's door in a fine automobile and invited him to ride with them. They did not ask him where he wanted to go, but drove straight to the park. "We have decided to do what you ask and let you make your playground on one condition," announced the mayor. "Good!" said Dr. Tucker, "What's the condition?" "That you get all the equipment for a first-class playground," answered the superintendent of parks. Dr. Tucker was thinking very fast. "Equipment for a first-class playground" meant swings and bars and teeter boards and tennis nets and footballs and ever so many other things boys and girls love in a playground. With the same twinkle that was in his eyes when he looked at the park and said, "I'll do it," he said now, "All right, I'll take you up." He did not have a single cent in his pocket to buy all these things and he did not know where he was going to get so much money, but he said to himself: "I'll look around a bit and see what I can see." The first thing he saw was some men tearing up an old street-car track. He went to the manager of the street-car company. "What are you going to do with those old rails?" he asked. "May I have them?"