Ji Chang's grand undertaking finally woke Chong Houhu from his sleep.
Chong Houhu had planned to sleep beneath the trees again that day. Taking an occasional nap out in the countryside, listening to birdsong and the chirping of insects while breathing in the fragrance of grass and flowers, felt rather pleasant.
But he discovered that sleep was no longer possible.
A huge object stood in the little river beside the shade of the trees. It appeared to be made of wood and shaped like a long dragon, with wooden planks forming a trough. Its tail dipped into the current, linking the low-lying river to the fields above.
Zhang San and Li Si were continuously treading wooden cranks on the frame behind the long dragon, driving a wooden chain around and around. Scrapers mounted on the chain drew water upward, carrying it into a hastily dug ditch beside the fields.
"What is this?"
Chong Houhu exclaimed in surprise.
Ji Chang smiled in satisfaction and extended a finger as gnarled as the bark of an old pine. "This device is called a waterwheel."
"Most of the land here is dry farmland. Eight households share a single well, so disputes are inevitable. Although a river lies nearby, the fields are too high for its water to irrigate them. This waterwheel can solve that difficulty."
"One need only set its body at an incline beside the water and join three planks into a long rectangular trough, with a sprocket wheel mounted at either end. A wooden chain passes through the trough, while the lower sprocket and part of the trough are submerged. The sprocket on the bank serves as the main wheel, with four wooden cranks attached to each end. Farmers need only tread the cranks to turn the sprockets. The scrapers draw water