Watermill

A watermill uses moving water.

The water hits a big wheel. This makes the wheel turn. The turning wheel moves machines.

These machines can grind grain. They can also cut wood. Some mills make paper. Some mills make cloth. This helps people do hard work. It is a clever way to use nature.

A watermill is a machine that uses hydropower. Hydropower is power from moving water.

The water turns a wheel or a turbine. This wheel makes parts move. These parts can grind grain into flour. They can also saw wood or make paper.

There are two main kinds of wheels. Some wheels stand up straight. We call these vertical wheels. They use gears to move machines. Other wheels lie flat. These are horizontal wheels. They are simpler and do not need gears.

People have used watermills for a very long time. The Greeks helped invent the parts. In China, people used watermills by 30 AD. They used them to work with iron. In the Roman Empire, mills were very common. Some mills even worked with the tide. A tide mill uses the rising and falling sea.

In the Middle Ages, many mills were built. In 1086, England had over 5,000 mills. Some mills even sat on boats. These were called ship mills. They floated in fast rivers.

A watermill is a machine that uses hydropower. Hydropower is the energy we get from moving water.

These structures use a water wheel or a turbine to drive a mechanical process. This means the moving water makes parts of the machine work. Watermills help make many different goods. They can grind grain into flour for bread. They can also saw lumber or make paper and textiles.

Some mills even hammer metal products. This makes them very important for making things people need.

There are two main ways a watermill works. One way uses a vertical waterwheel. This wheel stands up straight and uses gears to move other parts.

Another way uses a horizontal waterwheel. These wheels lie flat and do not need gears to work. We can also group mills by where the water hits the wheel. Some are undershot, which means water hits the bottom. Others are overshot, where water hits the top. There are also breastshot wheels where water hits the middle.

Some mills even use the tide or float on ships.

People have used waterpower for a very long time. The Greeks invented the waterwheel and toothed gearing.

A Greek engineer named Philo of Byzantium wrote about water wheels around 280 BC. The Roman engineer Vitruvius wrote a technical description of a mill around 40 BC. He described a mill with an undershot wheel and gears. Later, the Romans built huge complexes like Barbegal in southern France. This complex had 16 overshot wheels. It could make 4.5 tons of flour every single day. This was enough bread for 12,500 people.

Watermills appeared in many different places around the world. In China, waterwheels were found from 30 AD onwards. People used them to power hammers or to work with iron. By 488 AD, an engineer named Zu Chongzhi had a watermill built. In Europe, mills became very common during the Middle Ages. The Domesday Book from 1086 recorded 5,624 watermills in England alone. By the year 1300, that number grew to between 10,000 and 15,000.

Many new types of mills appeared in France during this time too.

Watermills change how rivers work in the places they are built. They can cause sediment, which is dirt and sand, to build up in the water.

Over time, the river banks might become higher because of this. If a mill is removed, the river channel might actually get deeper. You can think of a watermill like a giant tool powered by nature. Just as a battery gives power to a toy, moving water gives power to the mill. It turns the energy of a flowing river into useful work for humans.

A watermill is a machine that uses hydropower to perform mechanical work. Hydropower is the energy generated by the movement of water.

These structures use a waterwheel or a water turbine to drive various processes. Common tasks include milling grain, sawing lumber, or making paper and textiles. Watermills can also be used for hammering metal or rolling materials. Because they provide reliable power, they are essential for producing many material goods.

There are two primary ways to classify watermills by their wheel orientation. The first type uses a vertical waterwheel. This design requires a gear mechanism to transfer power to the machinery. This is often called a "Roman Mill" because of its historical use. The second type uses a horizontal waterwheel. This design does not require a gear mechanism and is sometimes called a "Greek Mill."

Greek-style mills are simpler but only work well with high water velocities and small millstones.

Vertical waterwheels are further divided by how the water hits the paddles. In an undershot wheel, the water flows against the bottom of the wheel. An overshot wheel is powered by water falling onto the top. A breastshot wheel receives water at the middle section. There is also a pitchback, or reverse shot, wheel where the water hits the wheel from behind.

Additionally, mills can be classified by their location. Tide mills use the movement of the ocean tides. Ship mills are built directly onto boats to use fast-flowing river currents.

The history of waterpower begins in classical antiquity. The Greeks invented the two main components: the waterwheel and toothed gearing. The engineer Philo of Byzantium described waterwheels in his technical treatises around 280–220 BC.

By 240 BC, Ptolemaic Alexandria was using vertical-wheeled mills. The Roman engineer Vitruvius provided the first technical description of a watermill around 40/10 BC. He described a device using an undershot wheel and a gearing mechanism. In the 2nd century AD, the Barbegal complex in southern France featured 16 overshot wheels. This massive site could produce 4.5 tons of flour every day. This was enough to provide bread for 12,500 inhabitants.

Waterpower technology continued to evolve throughout the Roman Empire. The Hierapolis sawmill in the 3rd century AD was the first known machine to use a crank and connecting rod.

This allowed for more complex movements, such as sawing stone. By the late 3rd or early 4th century AD, the earliest turbine mills appeared in Roman North Africa. These mills, found in Chemtou and Testour, used tangential water inflow to turn a horizontal wheel. In East Asia, waterwheels were used in China from 30 AD onwards. These powered trip hammers and bellows for smelting iron. By 488 AD, the engineer Zu Chongzhi had a watermill installed for the Emperor of Southern Qi.

During the Middle Ages, the use of watermills expanded rapidly across Europe. In England, the Domesday Book of 1086 recorded 5,624 watermills. By the year 1300, this number had risen to between 10,000 and 15,000 mills.

Many new industrial types of mills appeared during this era. For example, malt mills appeared in France around 770 AD. Paper mills were recorded in Spain in 1282 AD. In the 6th century, ship mills were used by the general Belisarius. These floating mills were attached to boats moored in fast rivers. This allowed them to function even when land-based water supplies were cut off.

Watermills also impact the physical dynamics of the rivers where they are installed. When mills operate, the channels tend to undergo sedimentation, which is the buildup of dirt and sand. This often happens in backwater areas. Inundation events and the buildup of sediment on adjacent floodplains can also increase. However, these effects are often cancelled over time as the river banks grow higher. If mills are removed from a location, the river incision increases. This causes the river channels to become deeper.