Tide mill

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Tidal mill at Olhao, Portugal Olhao Tide Mill.jpg
Tidal mill at Olhão, Portugal

A tide mill is a water mill driven by tidal rise and fall. A dam with a sluice is created across a suitable tidal inlet, or a section of river estuary is made into a reservoir. As the tide comes in, it enters the mill pond through a one-way gate, and this gate closes automatically when the tide begins to fall. When the tide is low enough, the stored water can be released to turn a water wheel.

Watermill structure that uses a water wheel or turbine to drive a mechanical process

A watermill or water mill is a mill that uses hydropower. It is a structure that uses a water wheel or water turbine to drive a mechanical process such as milling (grinding), rolling, or hammering. Such processes are needed in the production of many material goods, including flour, lumber, paper, textiles, and many metal products. These watermills may comprise gristmills, sawmills, paper mills, textile mills, hammermills, trip hammering mills, rolling mills, wire drawing mills.

Tide The daily, twice daily or similar rise and fall of the sea.

Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun, and the rotation of the Earth.

Sluice A water channel controlled at its head by a gate

A sluice is a water channel controlled at its head by a gate. A mill race, leet, flume, penstock or lade is a sluice channelling water toward a water mill. The terms sluice, sluice gate, knife gate, and slide gate are used interchangeably in the water and wastewater control industry.


Tide mills are usually situated in river estuaries, away from the effects of waves but close enough to the sea to have a reasonable tidal range. Cultures that built such mills have existed since the Middle Ages, and some may date back to the Roman period.

Tidal range is the height difference between high tide and low tide. Tides are the rise and fall of sea levels caused by gravitational forces exerted by the Moon and Sun and the rotation of Earth. Tidal range is not constant but changes depending on the locations of the Moon and Sun.

Middle Ages Period of European history from the 5th to the 15th century

In the history of Europe, the Middle Ages lasted from the 5th to the 15th century. It began with the fall of the Western Roman Empire and merged into the Renaissance and the Age of Discovery. The Middle Ages is the middle period of the three traditional divisions of Western history: classical antiquity, the medieval period, and the modern period. The medieval period is itself subdivided into the Early, High, and Late Middle Ages.

A modern version of a tide mill is the electricity-generating tidal barrage.

Tidal barrage dam-like structure used to capture the energy from masses of water

A tidal barrage is a dam-like structure used to capture the energy from masses of water moving in and out of a bay or river due to tidal forces.

Early history

Possibly the earliest tide mill in the Roman world was located in London on the River Fleet, dating to Roman times. [1]

River Fleet subterranean river in London, England

The River Fleet is the largest of London's subterranean rivers. Its headwaters are two streams on Hampstead Heath, each of which was dammed into a series of ponds—the Hampstead Ponds and the Highgate Ponds—in the 18th century. At the southern edge of Hampstead Heath these descend underground as sewers and join in Camden Town. The waters flow 4 mi (6 km) from the ponds to the River Thames.

Ancient Rome History of Rome from the 8th-century BC to the 5th-century

In historiography, ancient Rome is Roman civilization from the founding of the Italian city of Rome in the 8th century BC to the collapse of the Western Roman Empire in the 5th century AD, encompassing the Roman Kingdom, Roman Republic and Roman Empire until the fall of the western empire. The civilization began as an Italic settlement in the Italian Peninsula, conventionally founded in 753 BC, that grew into the city of Rome and which subsequently gave its name to the empire over which it ruled and to the widespread civilisation the empire developed. The Roman Empire expanded to become one of the largest empires in the ancient world, though still ruled from the city, with an estimated 50 to 90 million inhabitants ) and covering 5.0 million square kilometres at its height in AD 117.

Three Mills, Stratford, one of the world's earliest recorded tide mills. Three Mills, Stratford.jpg
Three Mills, Stratford, one of the world's earliest recorded tide mills.

Since the late 20th century, a number of new archaeological finds have consecutively pushed back the date of the earliest tide mills, all of which were discovered on the Irish coast: A 6th-century vertical-wheeled tide mill was located at Killoteran near Waterford. [2] A twin-flume, horizontal-wheeled tide mill, dating to c. 630, was excavated on Little Island in Cork. [3] [4] Alongside it, another tide mill was found that was powered by a vertical undershot wheel. [3] [4] The Nendrum Monastery mill from 787 was situated on an island in Strangford Lough in Northern Ireland. Its millstones are 830mm in diameter and the horizontal wheel is estimated to have developed 7/8HP at its peak. Remains of an earlier mill dated at 619 were also found at the site. [5] [6]

Waterford City in Munster, Ireland

Waterford is a city in Ireland. It is in County Waterford in the south east of Ireland and is part of the province of Munster. The city is situated at the head of Waterford Harbour. It is the oldest and the fifth most populous city in the Republic of Ireland. It is the tenth most populous settlement on the island of Ireland. Waterford City and County Council is the local government authority for the city. According to the 2016 Census, 53,504 people live in the city, with a wider metropolitan population of 82,963.

Little Island, Cork Civil Parish in Munster, Ireland

Little Island, County Cork, is a civil parish and mainly industrial area to the east of Cork city in Ireland. It is no longer an island, since the northern channel separating it from the mainland has filled over. To the west and south is Lough Mahon, part of Cork Harbour; across a channel to the east is Fota Island.

The Nendrum Monastery mill was a tide mill on an Mahee Island in Strangford Lough now in Northern Ireland. It is the earliest excavated tide mill, dating from 787 AD. Its millstones are 830mm in diameter and the horizontal wheel is estimated to have developed 7/8HP at its peak. Remains of an earlier mill dated at 619 AD were also found.

Three Mills, House Mill and Miller's House at low tide House Mill 2009a.JPG
Three Mills, House Mill and Miller's House at low tide

The earliest recorded tide mills in England are listed in the Domesday Book (1086). Eight mills are recorded on the River Lea (the site at Three Mills remains, with Grade I listed buildings and a small museum), as well as a mill in Dover harbour. By the 18th century, there were about 76 tide mills in London, including two on London Bridge.

Domesday Book 11th-century survey of landholding in England as well as the surviving manuscripts of the survey

Domesday Book is a manuscript record of the "Great Survey" of much of England and parts of Wales completed in 1086 by order of King William the Conqueror. The Anglo-Saxon Chronicle states:

Then, at the midwinter [1085], was the king in Gloucester with his council .... After this had the king a large meeting, and very deep consultation with his council, about this land; how it was occupied, and by what sort of men. Then sent he his men over all England into each shire; commissioning them to find out "How many hundreds of hides were in the shire, what land the king himself had, and what stock upon the land; or, what dues he ought to have by the year from the shire."

River Lea River in southern England

The River Lea originates in the Chiltern Hills, England, and flows southeast through east London where it meets the River Thames, the last looping section being known as Bow Creek. It is one of the largest rivers in London and the easternmost major tributary of the Thames. Its valley creates a long chain of marshy ground along its lower length, much of which has been used for gravel and mineral extraction, reservoirs and industry. Much of the river has been canalised to provide a navigable route for boats into eastern Hertfordshire, known as the Lee Navigation. While the lower Lea remains somewhat polluted, its upper stretch and tributaries, classified as chalk streams, are a major source of drinking water for London. A diversion known as the New River, opened in 1613, abstracts clean water away from the lower stretch of the river for drinking. Its origins in the Chilterns contribute to the extreme hardness of London tap water.

Three Mills human settlement in United Kingdom

The Three Mills are former working mills and an island of the same name on the River Lea. It is one of London’s oldest extant industrial centres. The mills lie in the London Borough of Newham; and, despite lying on the Newham side of the Lea, access is principally from the western, London Borough of Tower Hamlets, side of the river.

Woodbridge Tide Mill, an excellent example, survives at Woodbridge, Suffolk, England. This mill, dating from 1170 and reconstructed in 1792, has been preserved and is open to the public. It was further restored in 2010 and re-opened in 2011 in full working order. It is the second working tide mill in the United Kingdom that is regularly producing flour. Carew Castle in Wales also has an intact tide mill, but it is not operating. The first tide mill to be restored to working order is Eling Tide Mill in Eling, Hampshire. Another example, now extant only in historic documents, is the mill in the hamlet of Tide Mills, East Sussex. Traces of a tide mill may be seen at Fife Ness, revealed through an archaeological survey. [7]

Tidal mill at l'ile de Brehat Moulin maree brehat.jpg
Tidal mill at l'île de Bréhat

A mediæval tide mill still operates at Rupelmonde near Antwerp, and there are several that have survived in the Netherlands.

At one time there were 750 tide mills operating along the shores of the Atlantic Ocean: approximately 300 in North America, [8] [9] including many in colonial Boston over a 150-year span. [10] In addition, 200 have been documented in the British Isles, and 100 in France. [11] The Rance estuary in France was also home to some of these mills.

By the mid-20th century, the use of water mills had declined dramatically. In 1938, an investigation by Rex Wailes discovered that of the 23 extant tidal mills in England, only 10 were still working by their own motive power. Of one at Beaulieu, H. J. Massingham wrote in the 1940s,

"Part of the mill is built on piles into the river and is weatherboarded, while the rest of the building is a warm red brick roofed with lozenge-shaped and rounded tiles which I believe are called fish-tiles. All the interior is of wood - ladders, bins for the meal, floor-boarding, square pillars, beams, narrow passages, fittings, shaft rising to the first floor and all. So ramshackle is the arrangement of the props and supports that it is a wonder that the whole edifice does not tumble about the miller's ears like a pack of cards. The point is that it has stood in this way for something like six centuries, and that gives the explorer into its dusky depths a more penetrating notion of how the old builders could build, more than does a Gothic church or even a cathedral. The pulse and swing of the great wheel sets the whole building in an ague, but it will still be standing when all the flimsy excrescences of development between Beaulieu and Poole have fallen down." [12]

Modern examples

Newer types of tidal power often propose construction of a dam across a large river estuary. Although hydroelectric power represents a source of renewable energy, each proposal tends to come under local opposition because of its likely adverse effect on coastal habitats. One proposal, which was developed in 1966, is the Rance barrage, which generates 250MW. Unlike historical tide mills, which could operate only on an ebb tide, the Rance barrage can generate electricity on both flows of the tide, or it can be used for pumped storage, depending on demand. A less intrusive design is a 1MW free-standing turbine, constructed in 2007 at Strangford Lough Narrows; this site is close to an historic tide mill.

Surviving tide mills in Britain

Fingringoe Tide Mill Mill on Roman River - geograph.org.uk - 37851.jpg
Fingringoe Tide Mill

See also

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  1. Spain, Rob: "A possible Roman Tide Mill", Paper submitted to the Kent Archaeological Society
  2. Murphy 2005
  3. 1 2 Wikander 1985 , pp. 155–157
  4. 1 2 Rynne 2000 , pp. 10, fig. 1.2; 17; 49
  5. McErlean & Crothers 2007
  6. Recently discovered Tide Mill from 787 AD at Nendrum Monastic Site
  7. Day of Archaeology
  8. Peveril Meigs, "Historical geography of tide mills on the Atlantic coast," American Philosophical Society Yearbook 1970 (Philadelphia, Pennsylvania: American Philosophical Society, 1971), pp. 462-464.
  9. Peveril Meigs, "Tide mills on the Atlantic," Old Mill News, no. 7, 1979
  10. http://thewestendmuseum.org/exhibitions/tide-power-in-colonial-boston/
  11. Minchinton, W. E. : "Early Tide Mills: Some Problems", Technology and Culture, Vol. 20, No. 4 (Oct. 1979), pp. 777-786
  12. Skelton, C.P. British Windmills and Watermills, Collins, 1947


Further reading