Reverse overshot water-wheel
Encyclopedia
Frequently used in mines and probably elsewhere (such as agricultural drainage), the reverse overshot water wheel
was a Roman innovation to help remove water from the lowest levels of underground workings. It is described by Vitruvius
in his work De Architectura
published circa 25 BC. The remains of such systems found in Roman mines by later mining operations show that they were used in sequences so as to lift water a considerable height.
The Roman author Vitruvius
gives explicit instructions on the construction of dewatering devices, and describes three variants of the "tympanum" in Chapter X of De Architectura
. It is a large wheel fitted with boxes, which in the first design, encompass the whole diameter of the wheel. Holes are bored in the boxes to allow water into them, so that as a box dips into the water, it enters and is raised as the wheel turns. When it reaches to the top of the turn, the water runs out into a channel. He then describes a second variant where the boxes are only fitted to the ends of the wheel, so that although the volume of water carried is much smaller, it is carried to a greater height. The final variant is an endless chains of buckets, and much greater lifts can be achieved, although greater effort is needed.
is probably referring to such devices in a discussion of silver/lead mines in his Naturalis Historia
. Spain produced the most silver
in his time, many of the silver mines having been started by Hannibal. One of the largest had galleries running for between one and two miles into the mountain, "water-men" (in Latin "aquatini") draining the mine, and they
That they stood suggests that they operated the wheels by standing on the top to turn the cleats, and continuous working would produce a steady stream of water.
Fragments of such machines have been found in mines which were re-opened in the Victorian era
in Spain, especially at Rio Tinto, where one example used no less than 16 such wheels working in pairs, each pair of wheels lifting water about 3.5 m (12 feet), so giving a total lift of 30 m (96 feet). The system was carefully engineered, and was worked by individuals treading slats at the side of each wheel. It is not an isolated example, because Oliver Davies mentions examples from the Tharsis copper mine and Logroño
in Spain
, as well as from Dacia
. The gold deposits in Dacia, now modern Romania
were especially rich, and worked intensively after the successful Roman invasion under Trajan
. According to Oliver Davies, one such sequence discovered at Ruda
in Hunedoara County
in modern Romania
was 75 metres in depth, or over 200 feet. If worked like the Rio Tinto example, it would have needed at least 32 wheels.
One such wheel from Spain was rescued and part of it is now on display in the British Museum
. Some of the components are numbered, suggesting that it was prefabricated above ground before assembly in the underground passages. In the 1930s, a fragment of a wooden bucket from a drainage wheel was found in deep workings at the Dolaucothi gold mine in west Wales
, and is now preserved in the National Museum of Wales in Cardiff
. It has been carbon dated to about 90 AD. From the depth of 160 feet below known open workings, it can be inferred that the drainage wheel was part of a sequence just like that found in Spain
. The shape of the edge of one of the lifting buckets is almost identical with that from Spain, suggesting that a template was used to make the devices.
Another device which was used widely was the Archimedean screw, and examples of such drainage machines have also been found in many old mines. Depictions show the screws being powered by a human treading on the outer casing to turn the entire apparatus as one piece.
They were also used in series, so increasing the lift of water from the workings. However, they must have been more difficult to operate since the user had to stand on a slanting surface to turn the screw. The steeper the incline, the greater the risk of the user slipping from the top of the screw. No doubt the reverse water wheel was easier to use with a horizontal treading surface. On the other hand, the screw could be operated by a crank handle
fitted to the central axle
, but would be more tiring since the weight of the operator does not bear on the crank, as it does when trod from above.
Like the reverse water wheel, the cochlea was used for many other purposes apart from draining mines. Irrigation of farmland would have the most popular application, but any activity which involved lifting water would have employed the devices.
, such as the famous example at Barbegal
in southern France
. This system was also a stack of 16 wheels but worked like a normal overshot wheel, the wheels driving stone mills and used to grind corn. The water mills were worked from a masonry aqueduct
supplying the Roman town at Arles
, and the remains of the masonry mills are still visible on the ground today, unlike the underground drainage systems of the mines, which were destroyed by later mining operations. Other such sequences of mills existed on the Janiculum
in Rome
, but have been covered and changed by later buildings built on top of them.
Water wheel
A water wheel is a machine for converting the energy of free-flowing or falling water into useful forms of power. A water wheel consists of a large wooden or metal wheel, with a number of blades or buckets arranged on the outside rim forming the driving surface...
was a Roman innovation to help remove water from the lowest levels of underground workings. It is described by Vitruvius
Vitruvius
Marcus Vitruvius Pollio was a Roman writer, architect and engineer, active in the 1st century BC. He is best known as the author of the multi-volume work De Architectura ....
in his work De Architectura
De architectura
' is a treatise on architecture written by the Roman architect Vitruvius and dedicated to his patron, the emperor Caesar Augustus, as a guide for building projects...
published circa 25 BC. The remains of such systems found in Roman mines by later mining operations show that they were used in sequences so as to lift water a considerable height.
Vitruvius
Vitruvius
Marcus Vitruvius Pollio was a Roman writer, architect and engineer, active in the 1st century BC. He is best known as the author of the multi-volume work De Architectura ....
gives explicit instructions on the construction of dewatering devices, and describes three variants of the "tympanum" in Chapter X of De Architectura
De architectura
' is a treatise on architecture written by the Roman architect Vitruvius and dedicated to his patron, the emperor Caesar Augustus, as a guide for building projects...
. It is a large wheel fitted with boxes, which in the first design, encompass the whole diameter of the wheel. Holes are bored in the boxes to allow water into them, so that as a box dips into the water, it enters and is raised as the wheel turns. When it reaches to the top of the turn, the water runs out into a channel. He then describes a second variant where the boxes are only fitted to the ends of the wheel, so that although the volume of water carried is much smaller, it is carried to a greater height. The final variant is an endless chains of buckets, and much greater lifts can be achieved, although greater effort is needed.
Pliny the Elder
Pliny the ElderPliny the Elder
Gaius Plinius Secundus , better known as Pliny the Elder, was a Roman author, naturalist, and natural philosopher, as well as naval and army commander of the early Roman Empire, and personal friend of the emperor Vespasian...
is probably referring to such devices in a discussion of silver/lead mines in his Naturalis Historia
Naturalis Historia
The Natural History is an encyclopedia published circa AD 77–79 by Pliny the Elder. It is one of the largest single works to have survived from the Roman Empire to the modern day and purports to cover the entire field of ancient knowledge, based on the best authorities available to Pliny...
. Spain produced the most silver
Silver
Silver is a metallic chemical element with the chemical symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal...
in his time, many of the silver mines having been started by Hannibal. One of the largest had galleries running for between one and two miles into the mountain, "water-men" (in Latin "aquatini") draining the mine, and they
- stood night and day in shifts measured by lamps, bailing out water and making a stream.
That they stood suggests that they operated the wheels by standing on the top to turn the cleats, and continuous working would produce a steady stream of water.
Examples
Victorian era
The Victorian era of British history was the period of Queen Victoria's reign from 20 June 1837 until her death on 22 January 1901. It was a long period of peace, prosperity, refined sensibilities and national self-confidence...
in Spain, especially at Rio Tinto, where one example used no less than 16 such wheels working in pairs, each pair of wheels lifting water about 3.5 m (12 feet), so giving a total lift of 30 m (96 feet). The system was carefully engineered, and was worked by individuals treading slats at the side of each wheel. It is not an isolated example, because Oliver Davies mentions examples from the Tharsis copper mine and Logroño
Logroño
Logroño is a city in northern Spain, on the Ebro River. It is the capital of the autonomous community of La Rioja, formerly known as La Rioja Province.The population of Logroño in 2008 was 153,736 and a metropolitan population of nearly 197,000 inhabitants...
in Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
, as well as from Dacia
Dacia
In ancient geography, especially in Roman sources, Dacia was the land inhabited by the Dacians or Getae as they were known by the Greeks—the branch of the Thracians north of the Haemus range...
. The gold deposits in Dacia, now modern Romania
Romania
Romania is a country located at the crossroads of Central and Southeastern Europe, on the Lower Danube, within and outside the Carpathian arch, bordering on the Black Sea...
were especially rich, and worked intensively after the successful Roman invasion under Trajan
Trajan
Trajan , was Roman Emperor from 98 to 117 AD. Born into a non-patrician family in the province of Hispania Baetica, in Spain Trajan rose to prominence during the reign of emperor Domitian. Serving as a legatus legionis in Hispania Tarraconensis, in Spain, in 89 Trajan supported the emperor against...
. According to Oliver Davies, one such sequence discovered at Ruda
Ruda
Ruda may refer to:* Ruda, worshipped among the North Arabian tribes of pre-Islamic Arabia* Ruda, Sweden* Ruda, Italy* Ruda, a village in Ghelari Commune, Hunedoara County, Romania* Ruda, a village in Budeşti Commune, Vâlcea County, Romania...
in Hunedoara County
Hunedoara County
Hunedoara is a county of Romania, in Transylvania, with its capital city at Deva.-Demographics:In 2002, it had a population of 485,712 and the population density was 69/km².*Romanians - 92%*Hungarians - 5%*Romas - 2%*Germans under 1%....
in modern Romania
Romania
Romania is a country located at the crossroads of Central and Southeastern Europe, on the Lower Danube, within and outside the Carpathian arch, bordering on the Black Sea...
was 75 metres in depth, or over 200 feet. If worked like the Rio Tinto example, it would have needed at least 32 wheels.
One such wheel from Spain was rescued and part of it is now on display in the British Museum
British Museum
The British Museum is a museum of human history and culture in London. Its collections, which number more than seven million objects, are amongst the largest and most comprehensive in the world and originate from all continents, illustrating and documenting the story of human culture from its...
. Some of the components are numbered, suggesting that it was prefabricated above ground before assembly in the underground passages. In the 1930s, a fragment of a wooden bucket from a drainage wheel was found in deep workings at the Dolaucothi gold mine in west Wales
Wales
Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...
, and is now preserved in the National Museum of Wales in Cardiff
Cardiff
Cardiff is the capital, largest city and most populous county of Wales and the 10th largest city in the United Kingdom. The city is Wales' chief commercial centre, the base for most national cultural and sporting institutions, the Welsh national media, and the seat of the National Assembly for...
. It has been carbon dated to about 90 AD. From the depth of 160 feet below known open workings, it can be inferred that the drainage wheel was part of a sequence just like that found in Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
. The shape of the edge of one of the lifting buckets is almost identical with that from Spain, suggesting that a template was used to make the devices.
The Cochlea
They were also used in series, so increasing the lift of water from the workings. However, they must have been more difficult to operate since the user had to stand on a slanting surface to turn the screw. The steeper the incline, the greater the risk of the user slipping from the top of the screw. No doubt the reverse water wheel was easier to use with a horizontal treading surface. On the other hand, the screw could be operated by a crank handle
Crank (mechanism)
A crank is an arm attached at right angles to a rotating shaft by which reciprocating motion is imparted to or received from the shaft. It is used to change circular into reciprocating motion, or reciprocating into circular motion. The arm may be a bent portion of the shaft, or a separate arm...
fitted to the central axle
Axle
An axle is a central shaft for a rotating wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to its surroundings, with the wheels rotating around the axle. In the former case, bearings or bushings are provided at the mounting points where the axle...
, but would be more tiring since the weight of the operator does not bear on the crank, as it does when trod from above.
Like the reverse water wheel, the cochlea was used for many other purposes apart from draining mines. Irrigation of farmland would have the most popular application, but any activity which involved lifting water would have employed the devices.
Water wheels
The use of multiple sequences of water wheels was used elsewhere in the Roman EmpireRoman Empire
The Roman Empire was the post-Republican period of the ancient Roman civilization, characterised by an autocratic form of government and large territorial holdings in Europe and around the Mediterranean....
, such as the famous example at Barbegal
Barbegal aqueduct and mill
The Barbegal aqueduct and mill is a Roman watermill complex located on the territory of the commune of Fontvieille, near the town of Arles, in southern France. The complex has been referred to as "the greatest known concentration of mechanical power in the ancient world"...
in southern France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
. This system was also a stack of 16 wheels but worked like a normal overshot wheel, the wheels driving stone mills and used to grind corn. The water mills were worked from a masonry aqueduct
Aqueduct
An aqueduct is a water supply or navigable channel constructed to convey water. In modern engineering, the term is used for any system of pipes, ditches, canals, tunnels, and other structures used for this purpose....
supplying the Roman town at Arles
Arles
Arles is a city and commune in the south of France, in the Bouches-du-Rhône department, of which it is a subprefecture, in the former province of Provence....
, and the remains of the masonry mills are still visible on the ground today, unlike the underground drainage systems of the mines, which were destroyed by later mining operations. Other such sequences of mills existed on the Janiculum
Janiculum
The Janiculum is a hill in western Rome, Italy. Although the second-tallest hill in the contemporary city of Rome, the Janiculum does not figure among the proverbial Seven Hills of Rome, being west of the Tiber and outside the boundaries of the ancient city.-Sights:The Janiculum is one of the...
in Rome
Rome
Rome is the capital of Italy and the country's largest and most populated city and comune, with over 2.7 million residents in . The city is located in the central-western portion of the Italian Peninsula, on the Tiber River within the Lazio region of Italy.Rome's history spans two and a half...
, but have been covered and changed by later buildings built on top of them.
See also
- De ArchitecturaDe architectura' is a treatise on architecture written by the Roman architect Vitruvius and dedicated to his patron, the emperor Caesar Augustus, as a guide for building projects...
- Dolaucothi
- Frontinus
- List of ancient watermills
- Naturalis HistoriaNaturalis HistoriaThe Natural History is an encyclopedia published circa AD 77–79 by Pliny the Elder. It is one of the largest single works to have survived from the Roman Empire to the modern day and purports to cover the entire field of ancient knowledge, based on the best authorities available to Pliny...
- NoriaNoriaA noria is a machine for lifting water into a small aqueduct, either for the purpose of irrigation or, in at least one known instance, to feed seawater into a saltern....
- Pliny the ElderPliny the ElderGaius Plinius Secundus , better known as Pliny the Elder, was a Roman author, naturalist, and natural philosopher, as well as naval and army commander of the early Roman Empire, and personal friend of the emperor Vespasian...
- Roman engineeringRoman engineeringRomans are famous for their advanced engineering accomplishments, although some of their own inventions were improvements on older ideas, concepts and inventions. Technology for bringing running water into cities was developed in the east, but transformed by the Romans into a technology...
- Roman technologyRoman technologyRoman technology is the engineering practice which supported Roman civilization and made the expansion of Roman commerce and Roman military possible over nearly a thousand years....
- VitruviusVitruviusMarcus Vitruvius Pollio was a Roman writer, architect and engineer, active in the 1st century BC. He is best known as the author of the multi-volume work De Architectura ....
- watermillWatermillA watermill is a structure that uses a water wheel or turbine to drive a mechanical process such as flour, lumber or textile production, or metal shaping .- History :...
- water wheelWater wheelA water wheel is a machine for converting the energy of free-flowing or falling water into useful forms of power. A water wheel consists of a large wooden or metal wheel, with a number of blades or buckets arranged on the outside rim forming the driving surface...