Spinning is an ancient textile art in which plant , animal or synthetic fibres are drawn out and twisted together to form yarn . For thousands of years, fibre was spun by hand using simple tools, the spindle and distaff . After the introduction of the spinning wheel in the 13th century, the output of individual spinners increased dramatically. Mass production later arose in the 18th century with the beginnings of the Industrial Revolution . Hand-spinning remains a popular handicraft .
153-528: Characteristics of spun yarn vary according to the material used, fibre length and alignment, quantity of fibre used, and degree of twist. The origins of spinning fibre to make string or yarn are lost in time, but archaeological evidence in the form of representation of string skirts has been dated to the Upper Paleolithic era some 20,000 years ago. There has also been recent discovery of plied cord spun by Neanderthals and dating back 41,000-52,000 years. In
306-483: A centre-pull ball , where one end feeds from within a ball of yarn while the other end feeds from the outside. "Andean plying", in which the single is first wound around one hand in a specific manner that allows unwinding both ends at once without tangling, is another way to ply smaller amounts of yarn. The name comes from a method used by Andean spinners to manage and splice unevenly matched singles being plied from multiple spindles. "Navajo plying", a.k.a. "chain-plying"
459-552: A social science and a branch of the humanities . It is usually considered an independent academic discipline , but may also be classified as part of anthropology (in North America – the four-field approach ), history or geography . Archaeologists study human prehistory and history, from the development of the first stone tools at Lomekwi in East Africa 3.3 million years ago up until recent decades. Archaeology
612-490: A Southern Europe hydropower race. In Italy's Po Valley , the main 20th-century transition was not the creation of hydropower but the transition from mechanical to electrical hydropower. 12,000 watermills churned in the Po watershed in the 1890s, but the first commercial hydroelectric plant, completed in 1898, signaled the end of the mechanical reign. These new large plants moved power away from rural mountainous areas to urban centers in
765-404: A Spinning Certificate and a Master Spinning Certificate. These programs feature in-depth examinations of handspinning topics, as well as extensive assignments and skill evaluations. A tightly spun wool yarn made from fibre with a long staple length in it is called worsted . It is hand spun from combed top , and the fibres all lie in the same direction as the yarn. A woollen yarn, in contrast,
918-464: A basic level of analysis, artifacts found are cleaned, catalogued and compared to published collections. This comparison process often involves classifying them typologically and identifying other sites with similar artifact assemblages. However, a much more comprehensive range of analytical techniques are available through archaeological science , meaning that artifacts can be dated and their compositions examined. Bones, plants, and pollen collected from
1071-546: A big impact throughout Europe. However, prior to the development of modern techniques, excavations tended to be haphazard; the importance of concepts such as stratification and context were overlooked. In the mid-18th century, the German Johann Joachim Winckelmann lived in Rome and devoted himself to the study of Roman antiquities, gradually acquiring an unrivalled knowledge of ancient art. Then, he visited
1224-443: A billion tonnes of CO2 greenhouse gas a year. This occurs when organic matters accumulate at the bottom of the reservoir because of the deoxygenation of water which triggers anaerobic digestion . People who live near a hydro plant site are displaced during construction or when reservoir banks become unstable. Another potential disadvantage is cultural or religious sites may block construction. A watermill or water mill
1377-557: A castle wheel) is invaluable when spinning flax to make linen. The ends of flax fibres tend to stick out from the thread unless wetted while being spun, so the spinner usually keeps a bowl of water handy when spinning flax. On these types of wheels both hands are free as the wheel is turned with a treadle rather than by hand, so the spinner can use one hand to draft the fibres and the other to wet them. These wheels can also be used to spin wool or cotton. Powered spinning, originally done by water or steam power but now done by electricity ,
1530-401: A clear objective as to what the archaeologists are looking to achieve must be agreed upon. This done, a site is surveyed to find out as much as possible about it and the surrounding area. Second, an excavation may take place to uncover any archaeological features buried under the ground. And, third, the information collected during the excavation is studied and evaluated in an attempt to achieve
1683-405: A combination of both techniques and thus make a semi-worsted yarn. Short draw spinning is used to create worsted yarns. It is spun from combed roving , sliver or wool top . The spinner keeps his/her hands very close to each other. The fibres are held, fanned out, in one hand, and the other hand pulls a small number from the mass. The twist is kept between the second hand and the wheel. There
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#17330934373611836-433: A device to serve wine, and five devices to lift water from rivers or pools, where three of them are animal-powered and one can be powered by animal or water. Moreover, they included an endless belt with jugs attached, a cow-powered shadoof (a crane-like irrigation tool), and a reciprocating device with hinged valves. In the 19th century, French engineer Benoît Fourneyron developed the first hydropower turbine. This device
1989-451: A field survey. Regional survey is the attempt to systematically locate previously unknown sites in a region. Site survey is the attempt to systematically locate features of interest, such as houses and middens , within a site. Each of these two goals may be accomplished with largely the same methods. Survey was not widely practised in the early days of archaeology. Cultural historians and prior researchers were usually content with discovering
2142-422: A hook of bone was added to the upper end. The bunch of wool or plant fibres is held in the left hand. With the right hand the fibres are drawn out several inches and the end fastened securely in the slit or hook on the top of the spindle. A whirling motion is given to the spindle on the thigh or any convenient part of the body. The twisted yarn is then wound on to the upper part of the spindle. Another bunch of fibres
2295-477: A lack of public interest, and opposition to the excavation of human remains. In Ancient Mesopotamia , a foundation deposit of the Akkadian Empire ruler Naram-Sin (ruled c. 2200 BC ) was discovered and analysed by king Nabonidus , c. 550 BC , who is thus known as the first archaeologist. Not only did he lead the first excavations which were to find the foundation deposits of
2448-528: A large region or site can be expensive, so archaeologists often employ sampling methods.) As with other forms of non-destructive archaeology, survey avoids ethical issues (of particular concern to descendant peoples) associated with destroying a site through excavation. It is the only way to gather some forms of information, such as settlement patterns and settlement structure. Survey data are commonly assembled into maps , which may show surface features and/or artifact distribution. The simplest survey technique
2601-460: A microturbine in a cylindrical housing. Electricity generated by that turbine is used to charge 12-volt batteries." The term rain power has also been applied to hydropower systems which include the process of capturing the rain. Evidence suggests that the fundamentals of hydropower date to ancient Greek civilization . Other evidence indicates that the waterwheel independently emerged in China around
2754-490: A mutual need for hydropower could lead to cooperation between otherwise adversarial nations. Hydropower technology and attitude began to shift in the second half of the 20th century. While countries had largely abandoned their small hydropower systems by the 1930s, the smaller hydropower plants began to make a comeback in the 1970s, boosted by government subsidies and a push for more independent energy producers. Some politicians who once advocated for large hydropower projects in
2907-495: A relatively consistent source of power. Nonetheless, it has economic, sociological, and environmental downsides and requires a sufficiently energetic source of water, such as a river or elevated lake . International institutions such as the World Bank view hydropower as a low-carbon means for economic development . Since ancient times, hydropower from watermills has been used as a renewable energy source for irrigation and
3060-525: A remote sensor." Villazon suggested a better application would be to collect the water from fallen rain and use it to drive a turbine, with an estimated energy generation of 3 kWh of energy per year for a 185 m roof. A microturbine-based system created by three students from the Technological University of Mexico has been used to generate electricity. The Pluvia system "uses the stream of rainwater runoff from houses' rooftop rain gutters to spin
3213-526: A sense of accomplishment, or a sense of connection to history and the land. In addition, they may take up spinning for its meditative qualities. Within the recent past, many new spinners have joined into this ancient process, innovating the craft and creating new techniques. From using new dyeing methods before spinning, to mixing in novelty elements (Christmas Garland, eccentric beads, money, etc.) that would not normally be found in traditional yarns, to creating and employing new techniques like coiling, this craft
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#17330934373613366-400: A site can all be analyzed using the methods of zooarchaeology , paleoethnobotany , palynology and stable isotopes while any texts can usually be deciphered . Hydropower Hydropower (from Ancient Greek ὑδρο -, "water"), also known as water power , is the use of falling or fast-running water to produce electricity or to power machines. This is achieved by converting
3519-504: A site excavated depends greatly on the country and "method statement" issued. Sampling is even more important in excavation than in survey. Sometimes large mechanical equipment, such as backhoes ( JCBs ), is used in excavation, especially to remove the topsoil ( overburden ), though this method is increasingly used with great caution. Following this rather dramatic step, the exposed area is usually hand-cleaned with trowels or hoes to ensure that all features are apparent. The next task
3672-414: A site reveals its stratigraphy; if a site was occupied by a succession of distinct cultures, artifacts from more recent cultures will lie above those from more ancient cultures. Excavation is the most expensive phase of archaeological research, in relative terms. Also, as a destructive process, it carries ethical concerns. As a result, very few sites are excavated in their entirety. Again the percentage of
3825-408: A sole source. The material record may be closer to a fair representation of society, though it is subject to its own biases, such as sampling bias and differential preservation. Often, archaeology provides the only means to learn of the existence and behaviors of people of the past. Across the millennia many thousands of cultures and societies and billions of people have come and gone of which there
3978-527: A stone wall, will develop more slowly, while those above other types of features (such as middens ) may develop more rapidly. Photographs of ripening grain , which changes colour rapidly at maturation, have revealed buried structures with great precision. Aerial photographs taken at different times of day will help show the outlines of structures by changes in shadows. Aerial survey also employs ultraviolet , infrared , ground-penetrating radar wavelengths, Lidar and thermography . Geophysical survey can be
4131-446: A stream can vary widely from season to season. The development of a hydropower site requires analysis of flow records , sometimes spanning decades, to assess the reliable annual energy supply. Dams and reservoirs provide a more dependable source of power by smoothing seasonal changes in water flow. However, reservoirs have a significant environmental impact , as does alteration of naturally occurring streamflow. Dam design must account for
4284-482: A systematic guide to the ruins and topography of ancient Rome in the early 15th century, for which he has been called an early founder of archaeology. Antiquarians of the 16th century, including John Leland and William Camden , conducted surveys of the English countryside, drawing, describing and interpreting the monuments that they encountered. The OED first cites "archaeologist" from 1824; this soon took over as
4437-580: A thicker yarn. Generally, handspun single plies are spun with a Z-twist, and plying is done with an S-twist. This is a cultural preference differing in some areas but surprisingly common. It is important, however, to spin the single plies in one direction and then spin them together in the opposite direction—in this way, the opposite-direction plying keeps the spun yarn from untwisting itself. Yarns can be made of two, three, four, or more plies, or may be used as singles without plying. Two-ply yarn can also be plied from both ends of one long strand of singles using
4590-660: A tool to interfere in the economic development of African countries, such as the World Bank with the Kariba and Akosombo Dams , and the Soviet Union with the Aswan Dam . The Nile River especially has borne the consequences of countries both along the Nile and distant foreign actors using the river to expand their economic power or national force. After the British occupation of Egypt in 1882,
4743-479: A turbine with 90% efficiency. He applied scientific principles and testing methods to the problem of turbine design. His mathematical and graphical calculation methods allowed the confident design of high-efficiency turbines to exactly match a site's specific flow conditions. The Francis reaction turbine is still in use. In the 1870s, deriving from uses in the California mining industry, Lester Allan Pelton developed
Hand spinning - Misplaced Pages Continue
4896-495: A wide range of influences, including systems theory , neo-evolutionary thought , [35] phenomenology , postmodernism , agency theory , cognitive science , structural functionalism , Marxism , gender-based and feminist archaeology , queer theory , postcolonial thoughts , materiality , and posthumanism . An archaeological investigation usually involves several distinct phases, each of which employs its own variety of methods. Before any practical work can begin, however,
5049-481: A wide variety of materials, including natural fibres such as animal , plant , and mineral fibres, and synthetic fibres . The direction in which the yarn is spun is called twist . Yarns are characterized as S-twist or Z-twist according to the direction of spinning (see diagram). Tightness of twist is measured in TPI (twists per inch or turns per inch) . Two or more spun yarns may be twisted together or plied to form
5202-535: 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 , and wire drawing mills. One major way to classify watermills
5355-404: Is another method of producing a three-ply yarn, in which one strand of singles is looped around itself in a manner similar to crochet and the resulting three parallel strands twisted together. This method is often used to keep colours together on singles dyed in sequential colours. Cabled yarns are usually four-ply yarns made by plying two strands of two-ply yarn together in the direction opposite to
5508-501: Is available on demand to be used to generate electricity by passing through channels that connect the dam to the reservoir. The water spins a turbine, which is connected to the generator that produces electricity. The other type is called a run-of-river plant. In this case, a barrage is built to control the flow of water, absent a reservoir . The run-of river power plant needs continuous water flow and therefore has less ability to provide power on demand. The kinetic energy of flowing water
5661-400: Is by an essential trait about their location: tide mills use the movement of the tide; ship mills are water mills onboard (and constituting) a ship. A plentiful head of water can be made to generate compressed air directly without moving parts. In these designs, a falling column of water is deliberately mixed with air bubbles generated through turbulence or a venturi pressure reducer at
5814-445: Is by using hybrid solar panels called "all-weather solar panels" that can generate electricity from both the sun and the rain. According to zoologist and science and technology educator, Luis Villazon, "A 2008 French study estimated that you could use piezoelectric devices, which generate power when they move, to extract 12 milliwatts from a raindrop. Over a year, this would amount to less than 0.001kWh per square metre – enough to power
5967-420: Is by wheel orientation (vertical or horizontal), one powered by a vertical waterwheel through a gear mechanism, and the other equipped with a horizontal waterwheel without such a mechanism. The former type can be further subdivided, depending on where the water hits the wheel paddles, into undershot, overshot, breastshot and pitchback (backshot or reverse shot) waterwheel mills. Another way to classify water mills
6120-412: Is constantly evolving and shifting. To make various yarns, besides adding novelty elements, spinners can vary all the same things as in a machined yarn, i.e., the fibre, the preparation, the colour, the spinning technique, the direction of the twist, etc. A common misconception is that yarn spun from rolags may not be as strong, but the strength of a yarn is actually based on the length of hair fibre and
6273-600: Is distinct from palaeontology , which is the study of fossil remains. Archaeology is particularly important for learning about prehistoric societies, for which, by definition, there are no written records. Prehistory includes over 99% of the human past, from the Paleolithic until the advent of literacy in societies around the world. Archaeology has various goals, which range from understanding culture history to reconstructing past lifeways to documenting and explaining changes in human societies through time. Derived from Greek,
Hand spinning - Misplaced Pages Continue
6426-516: Is done lock by lock in warm water with dish-soap. There are number of guilds and educational institutions which offer certificate programs in handspinning. The Handweavers Guild of America (HGA) offers a Certificate of Excellence in Handspinning. Olds College in Alberta, Canada offers a Master Spinner program both on campus and by distance education. The Ontario Handweavers & Spinners offer both
6579-413: Is drawn out, the spindle is given another twirl, the yarn is wound on the spindle, and so on. The distaff was used for holding the bunch of wool, flax , or other fibres. It was a short stick, on one end of which was loosely wound the raw material. The other end of the distaff was held in the hand, under the arm or thrust in the girdle of the spinner. When held thus, one hand was left free for drawing out
6732-401: Is hand spun from a rolag or other carded fibre (roving, batts), where the fibres are not as strictly aligned to the yarn created. The woollen yarn, thus, captures much more air, and makes for a softer and generally bulkier yarn. There are two main techniques to create these different yarns: short draw creates worsted yarns, and long draw creates woollen yarns. Often a spinner will spin using
6885-451: Is little or no written record or existing records are misrepresentative or incomplete. Writing as it is known today did not exist in human civilization until the 4th millennium BC, in a relatively small number of technologically advanced civilizations. In contrast, Homo sapiens has existed for at least 200,000 years, and other species of Homo for millions of years (see Human evolution ). These civilizations are, not coincidentally,
7038-439: Is lost from erosion. Furthermore, studies found that the construction of dams and reservoirs can result in habitat loss for some aquatic species. Large and deep dam and reservoir plants cover large areas of land which causes greenhouse gas emissions from underwater rotting vegetation. Furthermore, although at lower levels than other renewable energy sources, it was found that hydropower produces methane equivalent to almost
7191-419: Is never any twist between the two hands. Long draw is spun from a carded rolag . The rolag is spun without much stretching of the fibres from the cylindrical configuration. This is done by allowing twist into a short section of the rolag, and then pulling back, without letting the rolag change position in one's hands, until the yarn is the desired thickness. The twist will concentrate in the thinnest part of
7344-426: Is no one approach to archaeological theory that has been adhered to by all archaeologists. When archaeology developed in the late 19th century, the first approach to archaeological theory to be practised was that of cultural-historical archaeology , which held the goal of explaining why cultures changed and adapted rather than just highlighting the fact that they did, therefore emphasizing historical particularism . In
7497-443: Is reflected or emitted from the observed scene. Passive instruments sense only radiation emitted by the object being viewed or reflected by the object from a source other than the instrument. Active instruments emit energy and record what is reflected. Satellite imagery is an example of passive remote sensing. Here are two active remote sensing instruments: The archaeological project then continues (or alternatively, begins) with
7650-428: Is surface survey. It involves combing an area, usually on foot but sometimes with the use of mechanized transport, to search for features or artifacts visible on the surface. Surface survey cannot detect sites or features that are completely buried under earth, or overgrown with vegetation. Surface survey may also include mini-excavation techniques such as augers , corers, and shovel test pits. If no materials are found,
7803-403: Is the decreased efficiency of electricity generation because the process depends on the speed of the seasonal river flow. This means that the rainy season increases electricity generation compared to the dry season. The size of hydroelectric plants can vary from small plants called micro hydro , to large plants that supply power to a whole country. As of 2019, the five largest power stations in
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#17330934373617956-407: Is the energy per unit weight (or unit mass) of water. The static head is proportional to the difference in height through which the water falls. Dynamic head is related to the velocity of moving water. Each unit of water can do an amount of work equal to its weight times the head. The power available from falling water can be calculated from the flow rate and density of water, the height of fall, and
8109-423: Is the main source of energy. Both designs have limitations. For example, dam construction can result in discomfort to nearby residents. The dam and reservoirs occupy a relatively large amount of space that may be opposed by nearby communities. Moreover, reservoirs can potentially have major environmental consequences such as harming downstream habitats. On the other hand, the limitation of the run-of-river project
8262-592: Is through archaeology. Because archaeology is the study of past human activity, it stretches back to about 2.5 million years ago when the first stone tools are found – The Oldowan Industry . Many important developments in human history occurred during prehistory, such as the evolution of humanity during the Paleolithic period, when the hominins developed from the australopithecines in Africa and eventually into modern Homo sapiens . Archaeology also sheds light on many of humanity's technological advances, for instance
8415-431: Is to form a site plan and then use it to help decide the method of excavation. Features dug into the natural subsoil are normally excavated in portions to produce a visible archaeological section for recording. A feature, for example a pit or a ditch, consists of two parts: the cut and the fill . The cut describes the edge of the feature, where the feature meets the natural soil. It is the feature's boundary. The fill
8568-423: Is used to validate the manufacturer's efficiency guarantee. Detailed calculation of the efficiency of a hydropower turbine accounts for the head lost due to flow friction in the power canal or penstock, rise in tailwater level due to flow, the location of the station and effect of varying gravity, the air temperature and barometric pressure, the density of the water at ambient temperature, and the relative altitudes of
8721-419: Is vastly faster than hand-spinning. The spinning jenny , a multi- spool spinning wheel invented c. 1764 by James Hargreaves , dramatically reduced the amount of work needed to produce yarn of high consistency, with a single worker able to work eight or more spools at once. At roughly the same time, Richard Arkwright and a team of craftsmen developed the spinning frame , which produced a stronger thread than
8874-420: Is what the feature is filled with, and will often appear quite distinct from the natural soil. The cut and fill are given consecutive numbers for recording purposes. Scaled plans and sections of individual features are all drawn on site, black and white and colour photographs of them are taken, and recording sheets are filled in describing the context of each. All this information serves as a permanent record of
9027-891: The Columbia River and its tributaries. The Bureau of Reclamation built the Hoover Dam in 1931, symbolically linking the job creation and economic growth priorities of the New Deal . The federal government quickly followed Hoover with the Shasta Dam and Grand Coulee Dam . Power demand in Oregon did not justify damming the Columbia until WWI revealed the weaknesses of a coal-based energy economy. The federal government then began prioritizing interconnected power—and lots of it. Electricity from all three dams poured into war production during WWII . After
9180-639: The Democratic Republic of the Congo and Ghana , frequently sell excess power to neighboring countries. Foreign actors such as Chinese hydropower companies have proposed a significant amount of new hydropower projects in Africa, and already funded and consulted on many others in countries like Mozambique and Ghana. Small hydropower also played an important role in early 20th century electrification across Africa. In South Africa, small turbines powered gold mines and
9333-579: The Industrial Revolution would drive development as well. At the beginning of the Industrial Revolution in Britain, water was the main power source for new inventions such as Richard Arkwright 's water frame . Although water power gave way to steam power in many of the larger mills and factories, it was still used during the 18th and 19th centuries for many smaller operations, such as driving
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#17330934373619486-602: The Islamic world by 1030. It later spread to China by 1090, and then spread from the Islamic world to Europe and India by the 13th century. In medieval times, poor families had such a need for yarn to make their own cloth and clothes that practically all girls and unmarried women would keep busy spinning, and " spinster " became synonymous with an unmarried woman. Subsequent improvements with spinning wheels and then mechanical methods made hand-spinning increasingly uneconomic, but as late as
9639-670: The Mauryan , Gupta and Chola empires. Another example of the early use of hydropower is seen in hushing , a historic method of mining that uses flood or torrent of water to reveal mineral veins. The method was first used at the Dolaucothi Gold Mines in Wales from 75 AD onwards. This method was further developed in Spain in mines such as Las Médulas . Hushing was also widely used in Britain in
9792-853: The Medieval and later periods to extract lead and tin ores. It later evolved into hydraulic mining when used during the California Gold Rush in the 19th century. The Islamic Empire spanned a large region, mainly in Asia and Africa, along with other surrounding areas. During the Islamic Golden Age and the Arab Agricultural Revolution (8th–13th centuries), hydropower was widely used and developed. Early uses of tidal power emerged along with large hydraulic factory complexes. A wide range of water-powered industrial mills were used in
9945-474: The Neolithic era. They allowed the spinner to slowly lower, or drop, the spindle as it was spinning, thus allowing a greater quantity of yarn to be made before it had to be wound onto the spindle, hence the name "drop spindle," which is now most commonly used for the hand spindle with whorl attached. The Scottish drop spindle is called fairsaid , farsadh , or dealgan . The spinning wheel was possibly invented in
10098-481: The gravitational potential or kinetic energy of a water source to produce power. Hydropower is a method of sustainable energy production. Hydropower is now used principally for hydroelectric power generation , and is also applied as one half of an energy storage system known as pumped-storage hydroelectricity . Hydropower is an attractive alternative to fossil fuels as it does not directly produce carbon dioxide or other atmospheric pollutants and it provides
10251-567: The trench method , on several Native American burial mounds in Virginia . His excavations were prompted by the "Moundbuilders" question ; however, his careful methods led him to admit he saw no reason why ancestors of the Native Americans of his time could not have raised those mounds. One of the major achievements of 19th-century archaeology was the development of stratigraphy . The idea of overlapping strata tracing back to successive periods
10404-549: The 1870s. These scholars individuated nine different cities that had overlapped with one another, from prehistory to the Hellenistic period . Meanwhile, the work of Sir Arthur Evans at Knossos in Crete revealed the ancient existence of an equally advanced Minoan civilization . The next major figure in the development of archaeology was Sir Mortimer Wheeler , whose highly disciplined approach to excavation and systematic coverage in
10557-642: The 1920s and 1930s brought the science on swiftly. Wheeler developed the grid system of excavation , which was further improved by his student Kathleen Kenyon . Archaeology became a professional activity in the first half of the 20th century, and it became possible to study archaeology as a subject in universities and even schools. By the end of the 20th century nearly all professional archaeologists, at least in developed countries, were graduates. Further adaptation and innovation in archaeology continued in this period, when maritime archaeology and urban archaeology became more prevalent and rescue archaeology
10710-481: The 4th century BC refer to the term cakkavattaka (turning wheel), which commentaries explain as arahatta-ghati-yanta (machine with wheel-pots attached), however whether this is water or hand powered is disputed by scholars India received Roman water mills and baths in the early 4th century AD when a certain according to Greek sources. Dams, spillways, reservoirs, channels, and water balance would develop in India during
10863-807: The American West, organized opposition to hydroelectric dams sparked up in the 1950s and 60s based on environmental concerns. Environmental movements successfully shut down proposed hydropower dams in Dinosaur National Monument and the Grand Canyon , and gained more hydropower-fighting tools with 1970s environmental legislation. As nuclear and fossil fuels grew in the 70s and 80s and environmental activists push for river restoration, hydropower gradually faded in American importance. Foreign powers and IGOs have frequently used hydropower projects in Africa as
11016-656: The British worked with Egypt to construct the first Aswan Dam, which they heightened in 1912 and 1934 to try to hold back the Nile floods. Egyptian engineer Adriano Daninos developed a plan for the Aswan High Dam, inspired by the Tennessee Valley Authority's multipurpose dam. When Gamal Abdel Nasser took power in the 1950s, his government decided to undertake the High Dam project, publicizing it as an economic development project. After American refusal to help fund
11169-672: The Grand Coulee to build a nuclear site placed on the banks of the Columbia. The nuclear site leaked radioactive matter into the river, contaminating the entire area. Post-WWII Americans, especially engineers from the Tennessee Valley Authority , refocused from simply building domestic dams to promoting hydropower abroad. While domestic dam building continued well into the 1970s, with the Reclamation Bureau and Army Corps of Engineers building more than 150 new dams across
11322-596: The Hun waterwheel; some of the earliest ones are the Jijiupian dictionary of 40 BC, Yang Xiong 's text known as the Fangyan of 15 BC, as well as Xin Lun, written by Huan Tan about 20 AD. It was also during this time that the engineer Du Shi (c. AD 31) applied the power of waterwheels to piston - bellows in forging cast iron. Ancient Indian texts dating back to
11475-622: The Nile, hydroelectric projects cover the rivers and lakes of Africa. The Inga powerplant on the Congo River had been discussed since Belgian colonization in the late 19th century, and was successfully built after independence. Mobutu's government failed to regularly maintain the plants and their capacity declined until the 1995 formation of the Southern African Power Pool created a multi-national power grid and plant maintenance program. States with an abundance of hydropower, such as
11628-497: The Song period, were revived in the 17th century during the Qing dynasty , but were always considered a branch of Chinese historiography rather than a separate discipline of archaeology. In Renaissance Europe , philosophical interest in the remains of Greco - Roman civilization and the rediscovery of classical culture began in the late Middle Ages , with humanism . Cyriacus of Ancona
11781-652: The Spanish military engineer Roque Joaquín de Alcubierre in the ancient towns of Pompeii and Herculaneum , both of which had been covered by ash during the Eruption of Mount Vesuvius in AD 79 . These excavations began in 1748 in Pompeii, while in Herculaneum they began in 1738. The discovery of entire towns, complete with utensils and even human shapes, as well the unearthing of frescos , had
11934-753: The UK, metal detectorists have been solicited for involvement in the Portable Antiquities Scheme . Regional survey in underwater archaeology uses geophysical or remote sensing devices such as marine magnetometer, side-scan sonar , or sub-bottom sonar. Archaeological excavation existed even when the field was still the domain of amateurs, and it remains the source of the majority of data recovered in most field projects. It can reveal several types of information usually not accessible to survey, such as stratigraphy , three-dimensional structure, and verifiably primary context. Modern excavation techniques require that
12087-1235: The United States' hydroelectric plants in Niagara Falls and the Sierra Nevada inspired bigger and bolder creations across the globe. American and USSR financers and hydropower experts also spread the gospel of dams and hydroelectricity across the globe during the Cold War , contributing to projects such as the Three Gorges Dam and the Aswan High Dam . Feeding desire for large scale electrification with water inherently required large dams across powerful rivers, which impacted public and private interests downstream and in flood zones. Inevitably smaller communities and marginalized groups suffered. They were unable to successfully resist companies flooding them out of their homes or blocking traditional salmon passages. The stagnant water created by hydroelectric dams provides breeding ground for pests and pathogens , leading to local epidemics . However, in some cases,
12240-426: The ability to use fire, the development of stone tools , the discovery of metallurgy , the beginnings of religion and the creation of agriculture . Without archaeology, little or nothing would be known about the use of material culture by humanity that pre-dates writing. However, it is not only prehistoric, pre-literate cultures that can be studied using archaeology but historic, literate cultures as well, through
12393-408: The archaeological excavations being conducted at Pompeii and Herculaneum . He was one of the founders of scientific archaeology and first applied the categories of style on a large, systematic basis to the history of art He was one of the first to separate Greek art into periods and time classifications. Winckelmann has been called both "The prophet and founding hero of modern archaeology " and
12546-434: The area surveyed is deemed sterile . Aerial survey is conducted using cameras attached to airplanes , balloons , UAVs , or even Kites . A bird's-eye view is useful for quick mapping of large or complex sites. Aerial photographs are used to document the status of the archaeological dig. Aerial imaging can also detect many things not visible from the surface. Plants growing above a buried human-made structure, such as
12699-555: The artifacts they had found in chronological order. A major figure in the development of archaeology into a rigorous science was army officer and ethnologist Augustus Pitt Rivers , who began excavations on his land in England in the 1880s. Highly methodical by the standards of the time, he is widely regarded as the first scientific archaeologist. He arranged his artifacts by type or " Typology (archaeology) ", and within types chronologically. This style of arrangement, designed to highlight
12852-613: The bellows in small blast furnaces (e.g. the Dyfi Furnace ) and gristmills , such as those built at Saint Anthony Falls , which uses the 50-foot (15 m) drop in the Mississippi River . Technological advances moved the open water wheel into an enclosed turbine or water motor . In 1848, the British-American engineer James B. Francis , head engineer of Lowell's Locks and Canals company, improved on these designs to create
13005-563: The best-known; they are open to the inquiry of historians for centuries, while the study of pre-historic cultures has arisen only recently. Within a literate civilization many events and important human practices may not be officially recorded. Any knowledge of the early years of human civilization – the development of agriculture, cult practices of folk religion, the rise of the first cities – must come from archaeology. In addition to their scientific importance, archaeological remains sometimes have political or cultural significance to descendants of
13158-440: The cost of building new hydroelectric dams increased 4% annually between 1965 and 1990, due both to the increasing costs of construction and to the decrease in high quality building sites. In the 1990s, only 18% of the world's electricity came from hydropower. Tidal power production also emerged in the 1960s as a burgeoning alternative hydropower system, though still has not taken hold as a strong energy contender. Especially at
13311-651: The dam, and anti-British sentiment in Egypt and British interests in neighboring Sudan combined to make the United Kingdom pull out as well, the Soviet Union funded the Aswan High Dam. Between 1977 and 1990 the dam's turbines generated one third of Egypt's electricity. The building of the Aswan Dam triggered a dispute between Sudan and Egypt over the sharing of the Nile, especially since the dam flooded part of Sudan and decreased
13464-406: The degree of twist. When working with shorter hairs, such as from llama or angora rabbit , the spinner may choose to integrate longer fibres, such as mohair, to prevent yarn breakage. Yarns made of shorter fibres are also given more twist than yarns of longer fibres, and are generally spun with the short draw technique. The fibre can be dyed at any time, but is often dyed before carding or after
13617-417: The earliest type of spinning, tufts of animal hair or plant fibre are rolled down the thigh with the hand, and additional tufts are added as needed until the desired length of spun fibre is achieved. An advanced technique of thigh-spinning while simultaneously plying two singles is still used today in several cultures, such as with Chilkat weaving and Ravenstail weaving . In earlier practice of thigh-spinning,
13770-607: The early 20th century, two major factors motivated the expansion of hydropower in Europe: in the northern countries of Norway and Sweden , high rainfall and mountains proved exceptional resources for abundant hydropower, and in the south, coal shortages pushed governments and utility companies to seek alternative power sources. Early on, Switzerland dammed the Alpine rivers and the Swiss Rhine , creating, along with Italy and Scandinavia ,
13923-473: The early 20th century, many archaeologists who studied past societies with direct continuing links to existing ones (such as those of Native Americans , Siberians , Mesoamericans etc.) followed the direct historical approach , compared the continuity between the past and contemporary ethnic and cultural groups. In the 1960s, an archaeological movement largely led by American archaeologists like Lewis Binford and Kent Flannery arose that rebelled against
14076-628: The empirical evidence that existed for the understanding of the past, encapsulated in the motto of the 18th century antiquary, Sir Richard Colt Hoare : "We speak from facts, not theory". Tentative steps towards the systematization of archaeology as a science took place during the Enlightenment period in Europe in the 17th and 18th centuries. In Imperial China during the Song dynasty (960–1279), figures such as Ouyang Xiu and Zhao Mingcheng established
14229-589: The established cultural-history archaeology. They proposed a "New Archaeology", which would be more "scientific" and "anthropological", with hypothesis testing and the scientific method very important parts of what became known as processual archaeology . In the 1980s, a new postmodern movement arose led by the British archaeologists Michael Shanks , Christopher Tilley , Daniel Miller , and Ian Hodder , which has become known as post-processual archaeology . It questioned processualism's appeals to scientific positivism and impartiality, and emphasized
14382-572: The evolutionary trends in human artifacts, was of enormous significance for the accurate dating of the objects. His most important methodological innovation was his insistence that all artifacts, not just beautiful or unique ones, be collected and catalogued. William Flinders Petrie is another man who may legitimately be called the Father of Archaeology. His painstaking recording and study of artifacts, both in Egypt and later in Palestine , laid down many of
14535-555: The falls far enough away to actually reach enough people and justify installation. The project succeeded in large part due to Nikola Tesla's invention of the alternating current motor . On the other side of the country, San Francisco engineers, the Sierra Club , and the federal government fought over acceptable use of the Hetch Hetchy Valley . Despite ostensible protection within a national park, city engineers successfully won
14688-533: The father of the discipline of art history . The father of archaeological excavation was William Cunnington (1754–1810). He undertook excavations in Wiltshire from around 1798, funded by Sir Richard Colt Hoare. Cunnington made meticulous recordings of Neolithic and Bronze Age barrows , and the terms he used to categorize and describe them are still used by archaeologists today. Future U.S. President Thomas Jefferson also did his own excavations in 1784 using
14841-413: The fibre might be fastened to a stone which is twirled round until the yarn is sufficiently twisted, whereupon it is wound upon the stone and the process repeated over and over. The next method of spinning yarn is with the spindle , a straight stick eight to twelve inches long on which the yarn is wound after twisting. At first the stick had a cleft or split in the top in which the thread was fixed. Later,
14994-424: The fibres. A spindle containing a quantity of yarn rotates more easily, steadily, and continues longer than an empty one; hence, the next improvement was the addition of a weight called a spindle whorl at the bottom of the spindle. These whorls are discs of wood , stone , clay , or metal with a hole in the centre for the spindle, which keep the spindle steady and promote its rotation. Spindle whorls appeared in
15147-746: The fifteenth century, and the general accuracy of his records entitles him to be called the founding father of modern classical archeology." He traveled throughout Greece and all around the Eastern Mediterranean, to record his findings on ancient buildings, statues and inscriptions, including archaeological remains still unknown to his time: the Parthenon , Delphi , the Egyptian pyramids , the hieroglyphics . He noted down his archaeological discoveries in his diary, Commentaria (in six volumes). Flavio Biondo , an Italian Renaissance humanist historian, created
15300-584: The first century BC. The Barbegal mill , located in modern-day France, had 16 water wheels processing up to 28 tons of grain per day. Roman waterwheels were also used for sawing marble such as the Hierapolis sawmill of the late 3rd century AD. Such sawmills had a waterwheel that drove two crank-and-connecting rods to power two saws. It also appears in two 6th century Eastern Roman sawmills excavated at Ephesus and Gerasa respectively. The crank and connecting rod mechanism of these Roman watermills converted
15453-446: The first electric railway in the 1890s, and Zimbabwean farmers installed small hydropower stations in the 1930s. While interest faded as national grids improved in the second half of the century, 21st century national governments in countries including South Africa and Mozambique, as well as NGOs serving countries like Zimbabwe, have begun re-exploring small-scale hydropower to diversify power sources and improve rural electrification. In
15606-403: The first half of the 20th century began to speak out against them, and citizen groups organizing against dam projects increased. In the 1980s and 90s the international anti-dam movement had made finding government or private investors for new large hydropower projects incredibly difficult, and given rise to NGOs devoted to fighting dams. Additionally, while the cost of other energy sources fell,
15759-528: The first history books of India. One of the first sites to undergo archaeological excavation was Stonehenge and other megalithic monuments in England. John Aubrey (1626–1697) was a pioneer archaeologist who recorded numerous megalithic and other field monuments in southern England. He was also ahead of his time in the analysis of his findings. He attempted to chart the chronological stylistic evolution of handwriting, medieval architecture, costume, and shield-shapes. Excavations were also carried out by
15912-446: The forebay and tailbay. For precise calculations, errors due to rounding and the number of significant digits of constants must be considered. Some hydropower systems such as water wheels can draw power from the flow of a body of water without necessarily changing its height. In this case, the available power is the kinetic energy of the flowing water. Over-shot water wheels can efficiently capture both types of energy. The flow in
16065-432: The grease, as it is less work to wash the wool after it is in yarn form. Spinners who spin very fine yarn may also prefer to spin in the grease as it can allow them to spin finer yarns with more ease. Spinning in the grease covers the spinner's hands in lanolin and, thus, softens the spinner's hands. Spinning in the grease works best if the fleece is newly sheared. After several months, the lanolin becomes sticky, which makes
16218-460: The high-efficiency Pelton wheel impulse turbine , which used hydropower from the high head streams characteristic of the Sierra Nevada . The modern history of hydropower begins in the 1900s, with large dams built not simply to power neighboring mills or factories but provide extensive electricity for increasingly distant groups of people. Competition drove much of the global hydroelectric craze: Europe competed amongst itself to electrify first, and
16371-400: The high-level intake. This allows it to fall down a shaft into a subterranean, high-roofed chamber where the now-compressed air separates from the water and becomes trapped. The height of the falling water column maintains compression of the air in the top of the chamber, while an outlet, submerged below the water level in the chamber allows water to flow back to the surface at a lower level than
16524-401: The highest among all renewable energy technologies. Hydroelectricity generation starts with converting either the potential energy of water that is present due to the site's elevation or the kinetic energy of moving water into electrical energy. Hydroelectric power plants vary in terms of the way they harvest energy. One type involves a dam and a reservoir . The water in the reservoir
16677-468: The ideas behind modern archaeological recording; he remarked that "I believe the true line of research lies in the noting and comparison of the smallest details." Petrie developed the system of dating layers based on pottery and ceramic findings , which revolutionized the chronological basis of Egyptology . Petrie was the first to scientifically investigate the Great Pyramid in Egypt during the 1880s. He
16830-472: The importance of a more self-critical theoretical reflexivity . However, this approach has been criticized by processualists as lacking scientific rigor, and the validity of both processualism and post-processualism is still under debate. Meanwhile, another theory, known as historical processualism , has emerged seeking to incorporate a focus on process and post-processual archaeology's emphasis of reflexivity and history. Archaeological theory now borrows from
16983-591: The intake. A separate outlet in the roof of the chamber supplies the compressed air. A facility on this principle was built on the Montreal River at Ragged Shutes near Cobalt, Ontario , in 1910 and supplied 5,000 horsepower to nearby mines. Hydroelectricity is the biggest hydropower application. Hydroelectricity generates about 15% of global electricity and provides at least 50% of the total electricity supply for more than 35 countries. In 2021, global installed hydropower electrical capacity reached almost 1400 GW,
17136-497: The last unexploited energy sources in nature. When it rains, billions of litres of water can fall, which have an enormous electric potential if used in the right way." Research is being done into the different methods of generating power from rain, such as by using the energy in the impact of raindrops. This is in its very early stages with new and emerging technologies being tested, prototyped and created. Such power has been called rain power. One method in which this has been attempted
17289-444: The lives and interests of the populace. Writings that were produced by people more representative of the general population were unlikely to find their way into libraries and be preserved there for posterity. Thus, written records tend to reflect the biases, assumptions, cultural values and possibly deceptions of a limited range of individuals, usually a small fraction of the larger population. Hence, written records cannot be trusted as
17442-572: The local acceleration due to gravity: To illustrate, the power output of a turbine that is 85% efficient, with a flow rate of 80 cubic metres per second (2800 cubic feet per second) and a head of 145 metres (476 feet), is 97 megawatts: Operators of hydroelectric stations compare the total electrical energy produced with the theoretical potential energy of the water passing through the turbine to calculate efficiency. Procedures and definitions for calculation of efficiency are given in test codes such as ASME PTC 18 and IEC 60041. Field testing of turbines
17595-665: The locations of monumental sites from the local populace, and excavating only the plainly visible features there. Gordon Willey pioneered the technique of regional settlement pattern survey in 1949 in the Viru Valley of coastal Peru , and survey of all levels became prominent with the rise of processual archaeology some years later. Survey work has many benefits if performed as a preliminary exercise to, or even in place of, excavation. It requires relatively little time and expense, because it does not require processing large volumes of soil to search out artifacts. (Nevertheless, surveying
17748-720: The most effective way to see beneath the ground. Magnetometers detect minute deviations in the Earth's magnetic field caused by iron artifacts, kilns , some types of stone structures , and even ditches and middens. Devices that measure the electrical resistivity of the soil are also widely used. Archaeological features whose electrical resistivity contrasts with that of surrounding soils can be detected and mapped. Some archaeological features (such as those composed of stone or brick) have higher resistivity than typical soils, while others (such as organic deposits or unfired clay) tend to have lower resistivity. Although some archaeologists consider
17901-443: The now-destroyed archaeology and is used in describing and interpreting the site. Once artifacts and structures have been excavated, or collected from surface surveys, it is necessary to properly study them. This process is known as post-excavation analysis , and is usually the most time-consuming part of an archaeological investigation. It is not uncommon for final excavation reports for major sites to take years to be published. At
18054-423: The operation of mechanical devices, such as gristmills , sawmills , textile mills, trip hammers , dock cranes , domestic lifts , and ore mills . A trompe , which produces compressed air from falling water, is sometimes used to power other machinery at a distance. A hydropower resource can be evaluated by its available power . Power is a function of the hydraulic head and volumetric flow rate . The head
18207-529: The original research objectives of the archaeologists. It is then considered good practice for the information to be published so that it is available to other archaeologists and historians, although this is sometimes neglected. Before actually starting to dig in a location, remote sensing can be used to look where sites are located within a large area or provide more information about sites or regions. There are two types of remote sensing instruments—passive and active. Passive instruments detect natural energy that
18360-413: The past. Since its early development, various specific sub-disciplines of archaeology have developed, including maritime archaeology , feminist archaeology , and archaeoastronomy , and numerous different scientific techniques have been developed to aid archaeological investigation. Nonetheless, today, archaeologists face many problems, such as dealing with pseudoarchaeology , the looting of artifacts,
18513-693: The people who produced them, monetary value to collectors, or strong aesthetic appeal. Many people identify archaeology with the recovery of such aesthetic, religious, political, or economic treasures rather than with the reconstruction of past societies. This view is often espoused in works of popular fiction, such as Raiders of the Lost Ark, The Mummy, and King Solomon's Mines. When unrealistic subjects are treated more seriously, accusations of pseudoscience are invariably levelled at their proponents (see Pseudoarchaeology ) . However, these endeavours, real and fictional, are not representative of modern archaeology. There
18666-413: The plying direction for the two-ply yarns. Hand-spinning is still an important skill in many traditional societies. Hobby or small scale artisan spinners spin their own yarn to control specific yarn qualities and produce yarn that is not widely available commercially. Sometimes these yarns are made available to non-spinners online and in local yarn stores. Handspinners also may spin for self-sufficiency,
18819-550: The precise locations of objects and features, known as their provenance or provenience, be recorded. This always involves determining their horizontal locations, and sometimes vertical position as well (also see Primary Laws of Archaeology ). Likewise, their association , or relationship with nearby objects and features , needs to be recorded for later analysis. This allows the archaeologist to deduce which artifacts and features were likely used together and which may be from different phases of activity. For example, excavation of
18972-593: The region including fulling mills, gristmills , paper mills , hullers , sawmills , ship mills , stamp mills , steel mills , sugar mills , and tide mills . By the 11th century, every province throughout the Islamic Empire had these industrial mills in operation, from Al-Andalus and North Africa to the Middle East and Central Asia . Muslim engineers also used water turbines while employing gears in watermills and water-raising machines. They also pioneered
19125-468: The rights to both water and power in the Hetch Hetchy Valley in 1913. After their victory they delivered Hetch Hetchy hydropower and water to San Francisco a decade later and at twice the promised cost, selling power to PG&E which resold to San Francisco residents at a profit. The American West, with its mountain rivers and lack of coal, turned to hydropower early and often, especially along
19278-511: The rotary motion of the waterwheel into the linear movement of the saw blades. Water-powered trip hammers and bellows in China, during the Han dynasty (202 BC – 220 AD), were initially thought to be powered by water scoops . However, some historians suggested that they were powered by waterwheels. This is since it was theorized that water scoops would not have had the motive force to operate their blast furnace bellows. Many texts describe
19431-468: The roving; thus, when the yarn is pulled, the thicker sections with less twist will tend to thin out. Once the yarn is the desired thickness, enough twist is added to make the yarn strong. Then the yarn is wound onto the bobbin, and the process starts again. Handspinners are split, when spinning wool, as to whether it is better to spin it "in the grease" (with lanolin still in) or after it has been washed. More traditional spinners are more willing to spin in
19584-507: The same period. Evidence of water wheels and watermills date to the ancient Near East in the 4th century BC. Moreover, evidence indicates the use of hydropower using irrigation machines to ancient civilizations such as Sumer and Babylonia . Studies suggest that the water wheel was the initial form of water power and it was driven by either humans or animals. In the Roman Empire , water-powered mills were described by Vitruvius by
19737-575: The spinning jenny. Too large to be operated by hand, a spinning frame powered by a waterwheel became the water frame . In 1779, Samuel Crompton combined elements of the spinning jenny and water frame to create the spinning mule . This produced a stronger thread, and was suitable for mechanisation on a grand scale. A later development, from 1828/29, was Ring spinning . In the 20th century, new techniques including Open End spinning or rotor spinning were invented to produce yarns at rates in excess of 40 meters per second. Yarn can be, and is, spun from
19890-478: The start of the American hydropower experiment, engineers and politicians began major hydroelectricity projects to solve a problem of 'wasted potential' rather than to power a population that needed the electricity. When the Niagara Falls Power Company began looking into damming Niagara, the first major hydroelectric project in the United States, in the 1890s they struggled to transport electricity from
20043-475: The sub-discipline of historical archaeology . For many literate cultures, such as Ancient Greece and Mesopotamia , their surviving records are often incomplete and biased to some extent. In many societies, literacy was restricted to the elite classes, such as the clergy , or the bureaucracy of court or temple. The literacy of aristocrats has sometimes been restricted to deeds and contracts. The interests and world-view of elites are often quite different from
20196-511: The temples of Šamaš the sun god, the warrior goddess Anunitu (both located in Sippar ), and the sanctuary that Naram-Sin built to the moon god, located in Harran , but he also had them restored to their former glory. He was also the first to date an archaeological artifact in his attempt to date Naram-Sin's temple during his search for it. Even though his estimate was inaccurate by about 1,500 years, it
20349-476: The term archaeology means "the study of ancient history". The discipline involves surveying , excavation , and eventually analysis of data collected, to learn more about the past. In broad scope, archaeology relies on cross-disciplinary research. Archaeology developed out of antiquarianism in Europe during the 19th century, and has since become a discipline practiced around the world. Archaeology has been used by nation-states to create particular visions of
20502-555: The tradition of Chinese epigraphy by investigating, preserving, and analyzing ancient Chinese bronze inscriptions from the Shang and Zhou periods. In his book published in 1088, Shen Kuo criticized contemporary Chinese scholars for attributing ancient bronze vessels as creations of famous sages rather than artisan commoners, and for attempting to revive them for ritual use without discerning their original functionality and purpose of manufacture. Such antiquarian pursuits waned after
20655-482: The twentieth century hand-spinning remained widespread in poor countries: in conscious rejection of international industrialization, Gandhi was a notable practitioner. The hand spinning movement that he initiated as a part of the Indian freedom struggle has made the handwoven cloth known as "Khadi" made from handspun cotton yarn world-famous. Women spinners of cotton yarn still continue to work to produce handspun yarn for
20808-703: The use of dams as a source of water power, used to provide additional power to watermills and water-raising machines. Islamic irriguation techniques including Persian Wheels would be introduced to India, and would be combined with local methods, during the Delhi Sultanate and the Mughal Empire . Furthermore, in his book, The Book of Knowledge of Ingenious Mechanical Devices , the Muslim mechanical engineer, Al-Jazari (1136–1206) described designs for 50 devices. Many of these devices were water-powered, including clocks,
20961-576: The use of metal detectors to be tantamount to treasure hunting, others deem them an effective tool in archaeological surveying. Examples of formal archaeological use of metal detectors include musketball distribution analysis on English Civil War battlefields, metal distribution analysis prior to excavation of a 19th-century ship wreck, and service cable location during evaluation. Metal detectorists have also contributed to archaeology where they have made detailed records of their results and refrained from raising artifacts from their archaeological context. In
21114-472: The usual term for one major branch of antiquarian activity. "Archaeology", from 1607 onward, initially meant what we would call "ancient history" generally, with the narrower modern sense first seen in 1837. However, it was Jacob Spon who, in 1685, offered one of the earliest definitions of "archaeologia" to describe the study of antiquities in which he was engaged, in the preface of a collection of transcriptions of Roman inscriptions which he had gleaned over
21267-545: The volume of water available to them. Ethiopia , also located on the Nile, took advantage of the Cold War tensions to request assistance from the United States for their own irrigation and hydropower investments in the 1960s. While progress stalled due to the coup d'état of 1974 and following 17-year-long Ethiopian Civil War Ethiopia began construction on the Grand Ethiopian Renaissance Dam in 2011. Beyond
21420-473: The war, the Grand Coulee Dam and accompanying hydroelectric projects electrified almost all of the rural Columbia Basin , but failed to improve the lives of those living and farming there the way its boosters had promised and also damaged the river ecosystem and migrating salmon populations. In the 1940s as well, the federal government took advantage of the sheer amount of unused power and flowing water from
21573-548: The weaving of Khadi in Ponduru , a village in South India. A great wheel (also called a wool wheel, high wheel or walking wheel) is advantageous when using the long-draw technique to spin wool or cotton because the high ratio between the large wheel and the whorl (sheave) enables the spinner to turn the bobbin faster, thus significantly speeding up production. A Saxony wheel (also called a flax wheel) or an upright wheel (also called
21726-484: The wool harder to spin using the short-draw technique, and almost impossible to spin using the long-draw technique. In general, spinners who use the long-draw technique do not spin in the grease. Such spinners generally buy their fibres pre-washed and carded, in the form of roving , sliver, or batts. This means less work for the spinners, as they do not have to wash out the lanolin. Spinners then have available predyed fibre, or blends of fibres, which are hard to create when
21879-566: The wool is still in the grease. As machine carders cannot card wool in the grease, pre-carded yarn generally is not spun in the grease. Some spinners use spray-on lanolin-like products to get the same feel of spinning in the grease with carded fibre. Archaeology Archaeology or archeology is the study of human activity through the recovery and analysis of material culture . The archaeological record consists of artifacts , architecture , biofacts or ecofacts, sites , and cultural landscapes . Archaeology can be considered both
22032-618: The world are conventional hydroelectric power stations with dams. Hydroelectricity can also be used to store energy in the form of potential energy between two reservoirs at different heights with pumped-storage . Water is pumped uphill into reservoirs during periods of low demand to be released for generation when demand is high or system generation is low. Other forms of electricity generation with hydropower include tidal stream generators using energy from tidal power generated from oceans, rivers, and human-made canal systems to generating electricity. Rain has been referred to as "one of
22185-739: The worst-case, "probable maximum flood" that can be expected at the site; a spillway is often included to route flood flows around the dam. A computer model of the hydraulic basin and rainfall and snowfall records are used to predict the maximum flood. Some disadvantages of hydropower have been identified. Dam failures can have catastrophic effects, including loss of life, property and pollution of land. Dams and reservoirs can have major negative impacts on river ecosystems such as preventing some animals traveling upstream, cooling and de-oxygenating of water released downstream, and loss of nutrients due to settling of particulates. River sediment builds river deltas and dams prevent them from restoring what
22338-411: The yarn has been spun. Wool may be spun before or after washing, although excessive amounts of lanolin may make spinning difficult, especially when using a drop-spindle . Careless washing may cause felting . When done prior to spinning, this often leads to unusable wool fibre. In washing wool the key thing to avoid is too much agitation and fast temperature changes from hot to cold. Generally, washing
22491-412: The years of his travels, entitled Miscellanea eruditae antiquitatis. Twelfth-century Indian scholar Kalhana 's writings involved recording of local traditions, examining manuscripts, inscriptions, coins and architectures, which is described as one of the earliest traces of archaeology. One of his notable work is called Rajatarangini which was completed in c. 1150 and is described as one of
22644-516: Was a restlessly itinerant Italian humanist and antiquarian who came from a prominent family of merchants in Ancona , a maritime republic on the Adriatic . He was called by his contemporaries pater antiquitatis ('father of antiquity') and today "father of classical archaeology": "Cyriac of Ancona was the most enterprising and prolific recorder of Greek and Roman antiquities, particularly inscriptions, in
22797-421: Was also responsible for mentoring and training a whole generation of Egyptologists, including Howard Carter who went on to achieve fame with the discovery of the tomb of 14th-century BC pharaoh Tutankhamun . The first stratigraphic excavation to reach wide popularity with public was that of Hissarlik , on the site of ancient Troy , carried out by Heinrich Schliemann , Frank Calvert and Wilhelm Dörpfeld in
22950-423: Was borrowed from the new geological and paleontological work of scholars like William Smith , James Hutton and Charles Lyell . The systematic application of stratigraphy to archaeology first took place with the excavations of prehistorical and Bronze Age sites. In the third and fourth decades of the 19th century, archaeologists like Jacques Boucher de Perthes and Christian Jürgensen Thomsen began to put
23103-421: Was developed as a result of increasing commercial development. The purpose of archaeology is to learn more about past societies and the development of the human race . Over 99% of the development of humanity has occurred within prehistoric cultures, who did not make use of writing , thereby no written records exist for study purposes. Without such written sources, the only way to understand prehistoric societies
23256-652: Was implemented in the commercial plant of Niagara Falls in 1895 and it is still operating. In the early 20th century, English engineer William Armstrong built and operated the first private electrical power station which was located in his house in Cragside in Northumberland , England. In 1753, the French engineer Bernard Forest de Bélidor published his book, Architecture Hydraulique , which described vertical-axis and horizontal-axis hydraulic machines. The growing demand for
23409-464: Was still a very good one considering the lack of accurate dating technology at the time. The science of archaeology (from Greek ἀρχαιολογία , archaiologia from ἀρχαῖος , arkhaios , "ancient" and -λογία , -logia , " -logy ") grew out of the older multi-disciplinary study known as antiquarianism . Antiquarians studied history with particular attention to ancient artifacts and manuscripts, as well as historical sites. Antiquarianism focused on
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