Earth, Water, Fire and Air: Playful Explorations in the Four Elements by Walter Kraul
This craft book for children shows how to make a waterwheel, paddle-steamer, propeller plane, parachute, windmill, simple pendulum clock, spinning tops, a little hot-air carousel or roundabout, a hot-air balloon, and lots more. Some suggestions are simple enough for six-year-olds, others challenging enough for a skilful twelve-year-old.