Watermill: A gradually receding landscape

Author: Chen Weishan
Publisher:
Publish Date: 2006-07-01
Features: "Two mountains hanging in the air, with a dragon under them flipping the Bagua. A stone mountain moves, and snow falls." This is a riddle about watermills that I was familiar with as a child. "The mill draws the stream, and the water pushes it." Watermills in the Tao River Basin are known for their exquisite craftsmanship, efficiency, and labor-saving features, playing a unique and important role in people's lives. According to their structure, Tao River watermills are classified into flat-wheel mills, vertical-wheel mills, and boat mills; by rotation season, they are divided into winter-turning mills and spring-water mills; by the number of grinding discs, they are categorized into four-disc, three-disc, two-disc, and one-disc mills. A vertical wheel driving two mills is called a "vertical wheel with two mills." The most common type is a vertical wheel driving two gears, with each gear driving one large mill. The large mills then drive two small mills each, totaling four mills per wheel, which is called a "water-driven connected mill." The grinding stones of winter-turning mills are primarily used to break ice drifting from upstream channels with long-handled hammers, preventing ice from forming and damaging the waterwheels to ensure normal operation during winter. Spring-level flat-wheel mills start turning after the water is released on the day of Jingze (the first solar term) and stop when the water recedes before Xiaoxue (the 20th solar term). Vertical-wheel mills are often built in mountainous areas with narrow and shallow rivers to provide greater power, allowing the water flow to drive the vertical wheel. The vertical wheel then drives the gears, which in turn drive the pillars to rotate the grinding stones. Boat mills are commonly found in the lower reaches of the Tao River, where the water flow is strong and steady. Their design resembles a boat covered with a house, with the hull slightly higher than a regular boat, divided into front, middle, rear, and stern cabins, separated by wooden boards. Three beams run through the boat interior, with the central beam as the main beam, used to tie steel cables and fix the boat mill. The two side beams are rectangular wooden frames to support the impeller shafts. Two impellers extend outside the cabin to harness water power. An additional vertical wheel is fixed on the rear cabin impeller shaft, surrounded by wooden gears that mesh with flat-wheel gears fixed on the grinding stone faces. The impellers drive the vertical wheel, which drives the flat wheel, which in turn drives the grinding stones. The rear of the boat also has a tail rod to support and stabilize the rear wing. On the riverbank side of the boat mill, wooden boards are placed for people to walk on and transport grinding materials. The boat mill moves to the river center or the riverbank with the ebb and flow of the river. The boat mill's construction is highly unique and exquisite, with the clever integration of the boat and the mill. Unfortunately, after enduring the hardships of life, it is now rare to find, having disappeared for over three or four decades. During the Jiajing era of the Ming Dynasty (1522–1566 AD), Prince Xiao Zhaowang wrote a poem titled "Watching the Boat Mill," which provides a detailed description and praise of the boat mill's intricate design. The poem goes:
"One board separates the deep,
Two wheels embrace the small boat.
Long momentum rushes through the grind,
Water ties the lonely side.
Waves rise and fall with the tide,
Mechanisms turn on their own.
The fragrance of the wind lifts the spirit,
The night rain disturbs the sleep.
Human ingenuity is exhausted,
Yet the heart remains restless."
A watermill mainly consists of three parts: the millhouse, the grinding discs, and the grinding wheels. The primary condition for building a watermill house is to have a "mill pool" on the river or canal, which means a high water source with a significant drop and a way for the water to recede. Then, based on the local water resources and water flow, a decision is made to build either a flat-wheel mill or a vertical-wheel mill. The number of grinding discs is determined by the width of the water surface and the amount of water power. Once the mill pool is selected, a dike is built upstream to raise the water level. On the ground connected to the main road, a side room, also called a dry room, is constructed for carriers or mill owners to tie animals. The area of each watermill house is approximately 10 to 30 square meters.