Inventors, rejoice! From the time Henry is a baby he loves to put things together -- wheels with rods, switches with levers, cranks with gears. By the age of six, he's built an Amazing Machine that fills his entire room. But Henry doesn't mind. He keeps on building. By the time he's ten, the machine has taken over the entire house --- and the yard. His parents are proud of Henry, but they're getting a little worried. They can't help wondering: What...