A rhythmic spring (also: ebb and flow spring , periodic spring , intermittent spring ) is a cold water spring from which the flow of water either varies or starts and stops entirely, over a fairly regular time-scale of minutes or hours. Compared to continuously-flowing springs, rhythmic springs are uncommon, with the number worldwide estimated in 1991 to be around one hundred.
155-410: Although the cause of the periodicity in flow is not known for certain, the most accepted theory (first postulated in the early 18th century) is that as groundwater flows continuously into a cavern, it fills a narrow tube that leads upwards from near the base of the cavern, then downwards to the spring. As the water level reaches the high point of the tube, it creates a siphon effect, sucking water out of
310-639: A ceramic glaze known as faience , which was used well into the Roman Period to decorate cups, amulets, and figurines. During the last predynastic phase, the Naqada culture began using written symbols that eventually were developed into a full system of hieroglyphs for writing the ancient Egyptian language. The Early Dynastic Period was approximately contemporary to the early Sumerian - Akkadian civilization of Mesopotamia and of ancient Elam . The third-century BC Egyptian priest Manetho grouped
465-469: A corvée system. Artists and craftsmen were of higher status than farmers, but they were also under state control, working in the shops attached to the temples and paid directly from the state treasury. Scribes and officials formed the upper class in ancient Egypt, known as the "white kilt class" in reference to the bleached linen garments that served as a mark of their rank. The upper class prominently displayed their social status in art and literature. Below
620-417: A nomarch , who was accountable to the vizier for his jurisdiction. The temples formed the backbone of the economy. Not only were they places of worship , but were also responsible for collecting and storing the kingdom's wealth in a system of granaries and treasuries administered by overseers , who redistributed grain and goods. Much of the economy was centrally organized and strictly controlled. Although
775-450: A partial vacuum ; for siphons in vacuum he concluded: "The gravitational force on the column of liquid in the downtake tube less the gravitational force in the uptake tube causes the liquid to move. The liquid is therefore in tension and sustains a longitudinal strain which, in the absence of disturbing factors, is insufficient to break the column of liquid". But for siphons of small uptake height working at atmospheric pressure, he wrote: "...
930-444: A balanced relationship between people and animals was an essential element of the cosmic order; thus humans, animals and plants were believed to be members of a single whole. Animals, both domesticated and wild , were therefore a critical source of spirituality, companionship, and sustenance to the ancient Egyptians. Cattle were the most important livestock; the administration collected taxes on livestock in regular censuses , and
1085-607: A brief but spirited resurgence in the economy and culture, but in 525 BC, the Persian Empire, led by Cambyses II , began its conquest of Egypt, eventually defeating the pharaoh Psamtik III at the Battle of Pelusium . Cambyses II then assumed the formal title of pharaoh, but ruled Egypt from Iran, leaving Egypt under the control of a satrap . A few revolts against the Persians marked the 5th century BC, but Egypt
1240-407: A chain hanging over a pulley, with one end of the chain piled on a higher surface than the other. Since the length of chain on the shorter side is lighter than the length of chain on the taller side, the heavier chain on the taller side will move down and pull up the chain on the lighter side. Similar to a siphon, the chain model is obviously just powered by gravity acting on the heavier side, and there
1395-426: A chain, which has significant tensile strength, liquids usually have little tensile strength under typical siphon conditions, and therefore the liquid on the rising side cannot be pulled up in the way the chain is pulled up on the rising side. An occasional misunderstanding of siphons is that they rely on the tensile strength of the liquid to pull the liquid up and over the rise. While water has been found to have
1550-710: A confident, eloquent style. The relief and portrait sculpture of the period captured subtle, individual details that reached new heights of technical sophistication. The last great ruler of the Middle Kingdom, Amenemhat III , allowed Semitic -speaking Canaanite settlers from the Near East into the Delta region to provide a sufficient labor force for his especially active mining and building campaigns. These ambitious building and mining activities, however, combined with severe Nile floods later in his reign, strained
1705-417: A constant trickle of clean water being fed to the cistern by a slightly open valve. While if both ends of a siphon are at atmospheric pressure, liquid flows from high to low, if the bottom end of a siphon is pressurized, liquid can flow from low to high. If pressure is removed from the bottom end, the liquid flow will reverse, illustrating that it is pressure driving the siphon. An everyday illustration of this
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#17327801470831860-542: A cornerstone in the history of human civilization. Nomadic modern human hunter-gatherers began living in the Nile valley through the end of the Middle Pleistocene some 120,000 years ago. By the late Paleolithic period, the arid climate of Northern Africa had become increasingly hot and dry, forcing the populations of the area to concentrate along the river region. In Predynastic and Early Dynastic times,
2015-496: A deeper place outside a connection is built, using a tube or some pipes. They are filled with water through an intake valve (at the highest end of the construction). When the ends are opened, the water flows through the pipe into the sewer or the river. Siphoning is common in irrigated fields to transfer a controlled amount of water from a ditch, over the ditch wall, into furrows. Large siphons may be used in municipal waterworks and industry. Their size requires control via valves at
2170-576: A large-scale building campaign to promote the god Amun , whose growing cult was based in Karnak . They also constructed monuments to glorify their own achievements, both real and imagined. The Karnak temple is the largest Egyptian temple ever built. Around 1350 BC, the stability of the New Kingdom was threatened when Amenhotep IV ascended the throne and instituted a series of radical and chaotic reforms. Changing his name to Akhenaten , he touted
2325-414: A long-term method to limit leakage hazard in the retaining wall. Siphon drainage is also used in draining unstable slopes, and siphon roof-water drainage systems have been in use since the 1960s. A siphon spillway in a dam is usually not technically a siphon, as it is generally used to drain elevated water levels. However, a siphon spillway operates as an actual siphon if it raises the flow higher than
2480-402: A more functional siphon that does not require constant re-priming and restarting. In this respect, where the requirement is to match a flow into a container with a flow out of said container (to maintain a constant level in a pond fed by a stream, for example) it would be preferable to utilize two or three smaller separate parallel pipes that can be started as required rather than attempting to use
2635-415: A much larger weight of liquid in it, and yet the lighter volume of liquid in the down tube can pull liquid up the fatter up tube, and the siphon can function normally. Another difference is that under most practical circumstances, dissolved gases, vapor pressure, and (sometimes) lack of adhesion with tube walls, conspire to render the tensile strength within the liquid ineffective for siphoning. Thus, unlike
2790-576: A period of economic and cultural renaissance known as the Middle Kingdom . The kings of the Middle Kingdom restored the country's stability and prosperity, thereby stimulating a resurgence of art, literature, and monumental building projects. Mentuhotep II and his Eleventh Dynasty successors ruled from Thebes, but the vizier Amenemhat I , upon assuming the kingship at the beginning of the Twelfth Dynasty around 1985 BC, shifted
2945-508: A piece of papyrus or an ostracon . A combination of favorable geographical features contributed to the success of ancient Egyptian culture, the most important of which was the rich fertile soil resulting from annual inundations of the Nile River. The ancient Egyptians were thus able to produce an abundance of food, allowing the population to devote more time and resources to cultural, technological, and artistic pursuits. Land management
3100-475: A pressure differential within the siphon tube and the tensile strength of the liquid are required for a siphon to operate. A researcher at Humboldt State University , A. McGuire, examined flow in siphons in 2012. Using the advanced general-purpose multiphysics simulation software package LS-DYNA he examined pressure initialisation, flow, and pressure propagation within a siphon. He concluded: "Pressure, gravity and molecular cohesion can all be driving forces in
3255-496: A pressure differential, writing: "As the fluid initially primed on the long leg of the siphon rushes down due to gravity, it leaves behind a partial vacuum that allows pressure on the entrance point of the higher container to push fluid up the leg on that side". The research team of Boatwright, Puttick, and Licence, all at the University of Nottingham , succeeded in running a siphon in high vacuum , also in 2011. They wrote: "It
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#17327801470833410-689: A queen who established herself as pharaoh, launched many building projects, including the restoration of temples damaged by the Hyksos, and sent trading expeditions to Punt and the Sinai. When Tuthmosis III died in 1425 BC, Egypt had an empire extending from Niya in north west Syria to the Fourth Cataract of the Nile in Nubia , cementing loyalties and opening access to critical imports such as bronze and wood . The New Kingdom pharaohs began
3565-608: A rival dynasty in the delta arose in Leontopolis , and Kushites threatened from the south. Around 727 BC the Kushite king Piye invaded northward, seizing control of Thebes and eventually the Delta, which established the 25th Dynasty . During the 25th Dynasty, Pharaoh Taharqa created an empire nearly as large as the New Kingdom 's. Twenty-fifth Dynasty pharaohs built, or restored, temples and monuments throughout
3720-662: A series of vassals who became known as the Saite kings of the Twenty-Sixth Dynasty . By 653 BC, the Saite king Psamtik I was able to oust the Assyrians with the help of Greek mercenaries, who were recruited to form Egypt's first navy . Greek influence expanded greatly as the city-state of Naucratis became the home of Greeks in the Nile Delta. The Saite kings based in the new capital of Sais witnessed
3875-442: A significant tensile strength in some experiments (such as with the z-tube ), and siphons in vacuum rely on such cohesion, common siphons can easily be demonstrated to need no liquid tensile strength at all to function. Furthermore, since common siphons operate at positive pressures throughout the siphon, there is no contribution from liquid tensile strength, because the molecules are actually repelling each other in order to resist
4030-404: A single large pipe and attempting to throttle it. Siphons are sometimes employed as automatic machines, in situations where it is desirable to turn a continuous trickling flow or an irregular small surge flow into a large surge volume. A common example of this is a public restroom with urinals regularly flushed by an automatic siphon in a small water tank overhead. When the container is filled, all
4185-422: A siphon. Their conclusion was: "It follows from the above analysis that there must be a direct cohesive connection between water molecules flowing in and out of a siphon. This is true at all atmospheric pressures in which the pressure in the apex of the siphon is above the vapour pressure of water, an exception being ionic liquids". A plain tube can be used as a siphon. An external pump has to be applied to start
4340-413: A vacuum"), which dates to Aristotle , and which Galileo restated as resintenza del vacuo , but this was subsequently disproved by later workers, notably Evangelista Torricelli and Blaise Pascal – see barometer: history . A practical siphon, operating at typical atmospheric pressures and tube heights, works because gravity pulling down on the taller column of liquid leaves reduced pressure at
4495-483: A way similar to the chain fountain . It need not be one theory or the other that is correct, but rather both theories may be correct in different circumstances of ambient pressure. The atmospheric pressure with gravity theory cannot explain siphons in vacuum, where there is no significant atmospheric pressure. But the cohesion tension with gravity theory cannot explain CO 2 gas siphons, siphons working despite bubbles, and
4650-408: Is any of a wide variety of devices that involve the flow of liquids through tubes. In a narrower sense, the word refers particularly to a tube in an inverted "U" shape, which causes a liquid to flow upward, above the surface of a reservoir , with no pump , but powered by the fall of the liquid as it flows down the tube under the pull of gravity , then discharging at a level lower than the surface of
4805-401: Is being lifted), while the pressure at the top of the tube from the bottom reservoir is lower (since more water is being lifted), and since liquids move from high pressure to low pressure, the liquid flows across the horizontal tube from the top basin to the bottom basin. The liquid is under positive pressure (compression) throughout the tube, not tension. Bernoulli's equation is considered in
Rhythmic spring - Misplaced Pages Continue
4960-424: Is clearly no violation of conservation of energy, because the chain is ultimately just moving from a higher to a lower location, as the liquid does in a siphon. There are a number of problems with the chain model of a siphon, and understanding these differences helps to explain the actual workings of siphons. First, unlike in the chain model of the siphon, it is not actually the weight on the taller side compared to
5115-406: Is different from the common demonstration self-starting siphons in that there are ways the siphon can fail to function which require manual intervention to return to normal surge flow operation. A video demonstration of a self-starting siphon can be found here , courtesy of The Curiosity Show . The most common failure is for the liquid to dribble out slowly, matching the rate that the container
5270-430: Is filling, and the siphon enters an undesired steady-state condition. Preventing dribbling typically involves pneumatic principles to trap one or more large air bubbles in various pipes, which are sealed by water traps. This method can fail if it cannot start working intermittently without water already present in parts of the mechanism, and which will not be filled if the mechanism starts from a dry state. A second problem
5425-399: Is lower because the tube is longer (there is more water pushing down), and requires that the lower reservoir is lower than the upper reservoir, or more generally that the discharge outlet simply be lower than the surface of the upper reservoir. Considering now the horizontal tube connecting them, one sees that the pressure at the top of the tube from the top reservoir is higher (since less water
5580-435: Is not much larger than necessary. Using piping of too great a diameter and then throttling the flow using valves or constrictive piping appears to increase the effect of previously cited concerns over gases or vapor collecting in the crest which serve to break the vacuum. If the vacuum is reduced too much, the siphon effect can be lost. Reducing the size of pipe used closer to requirements appears to reduce this effect and creates
5735-402: Is not required for the operation of a siphon, but: "The basic explanation of siphon action is that, once the tube is filled, the flow is initiated by the greater pull of gravity on the fluid on the longer side compared with that on the short side. This creates a pressure drop throughout the siphon tube, in the same sense that 'sucking' on a straw reduces the pressure along its length all the way to
5890-418: Is that the trapped air pockets will shrink over time if the siphon is not operating due to no inflow. The air in pockets is absorbed by the liquid, which pulls liquid up into the piping until the air pocket disappears, and can cause activation of water flow outside the normal range of operating when the storage tank is not full, leading to loss of the liquid seal in lower parts of the mechanism. A third problem
6045-557: Is the siphon coffee brewer, which works as follows (designs vary; this is a standard design, omitting coffee grounds): Ancient Egypt Ancient Egypt was a civilization of ancient Northeast Africa . It was concentrated along the lower reaches of the Nile River , situated within the contemporary territory of modern-day Egypt . Ancient Egyptian civilization followed prehistoric Egypt and coalesced around 3100 BC (according to conventional Egyptian chronology ) with
6200-404: Is used to automatically empty the gauge. It is often simply called a "siphon gauge" and is not to be confused with a siphon pressure gauge. A siphon drainage method is being implemented in several expressways as of 2022. Recent studies found that it can reduce groundwater level behind expressway retaining walls, and there was no indication of clogging. This new drainage system is being pioneered as
6355-693: Is what made possible the human settlement in ancient Jerusalem . Pliny the Younger – who is famous for his accurate description of the Vesuvius eruption of AD 79 – also accurately described a rhythmic spring in the last letter of Book IV. This rhythmic spring is still acting to the same time scale today ( Villa Pliniana spring in Como, Italy). In Serbia there are four intermittent springs: Siphon A siphon (from Ancient Greek σίφων ( síphōn ) 'pipe, tube'; also spelled syphon )
Rhythmic spring - Misplaced Pages Continue
6510-439: Is where the lower end of the liquid seal is simply a U-trap bend in an outflow pipe. During vigorous emptying, the kinetic motion of the liquid out the outflow can propel too much liquid out, causing a loss of the sealing volume in the outflow trap and loss of the trapped air bubble to maintain intermittent operation. A fourth problem involves seep holes in the mechanism, intended to slowly refill these various sealing chambers when
6665-517: Is widely believed that the siphon is principally driven by the force of atmospheric pressure. An experiment is described that shows that a siphon can function even under high-vacuum conditions. Molecular cohesion and gravity are shown to be contributing factors in the operation of a siphon; the presence of a positive atmospheric pressure is not required". Writing in Physics Today in 2011, J. Dooley from Millersville University stated that both
6820-583: The Amarna Period . Around 1279 BC, Ramesses II , also known as Ramesses the Great, ascended the throne, and went on to build more temples, erect more statues and obelisks, and sire more children than any other pharaoh in history. A bold military leader, Ramesses II led his army against the Hittites in the Battle of Kadesh (in modern Syria ) and, after fighting to a stalemate, finally agreed to
6975-508: The Egyptian climate was much less arid than it is today . Large regions of Egypt were covered in treed savanna and traversed by herds of grazing ungulates . Foliage and fauna were far more prolific in all environs, and the Nile region supported large populations of waterfowl . Hunting would have been common for Egyptians, and this is also the period when many animals were first domesticated . By about 5500 BC , small tribes living in
7130-501: The Great Kenbet , over which the vizier or pharaoh presided. Plaintiffs and defendants were expected to represent themselves and were required to swear an oath that they had told the truth. In some cases, the state took on both the role of prosecutor and judge, and it could torture the accused with beatings to obtain a confession and the names of any co-conspirators. Whether the charges were trivial or serious, court scribes documented
7285-613: The Macedonians under Alexander the Great . The Greek Ptolemaic Kingdom , formed in the aftermath of Alexander's death, ruled until 30 BC, when, under Cleopatra , it fell to the Roman Empire and became a Roman province . Egypt remained under Roman control until 642 AD, when it was conquered by the Rashidun Caliphate . The success of ancient Egyptian civilization came partly from its ability to adapt to
7440-971: The Mouseion . The Lighthouse of Alexandria lit the way for the many ships that kept trade flowing through the city—as the Ptolemies made commerce and revenue-generating enterprises, such as papyrus manufacturing, their top priority. Hellenistic culture did not supplant native Egyptian culture, as the Ptolemies supported time-honored traditions in an effort to secure the loyalty of the populace. They built new temples in Egyptian style, supported traditional cults, and portrayed themselves as pharaohs. Some traditions merged, as Greek and Egyptian gods were syncretized into composite deities, such as Serapis , and classical Greek forms of sculpture influenced traditional Egyptian motifs. Despite their efforts to appease
7595-496: The Near East . The New Kingdom pharaohs established a period of unprecedented prosperity by securing their borders and strengthening diplomatic ties with their neighbours, including the Mitanni Empire, Assyria , and Canaan . Military campaigns waged under Tuthmosis I and his grandson Tuthmosis III extended the influence of the pharaohs to the largest empire Egypt had ever seen. Between their reigns, Hatshepsut ,
7750-772: The New Kingdom of the Late Bronze Age . Ancient Egypt reached the pinnacle of its power during the New Kingdom, ruling much of Nubia and a sizable portion of the Levant . After this period, it entered an era of slow decline. During the course of its history, ancient Egypt was invaded or conquered by a number of foreign powers, including the Hyksos , the Nubians , the Assyrians , the Achaemenid Persians , and
7905-584: The Nile . They also traded with Nubia to the south, the oases of the western desert to the west, and the cultures of the eastern Mediterranean and Near East to the east. The Naqada culture manufactured a diverse selection of material goods, reflective of the increasing power and wealth of the elite, as well as societal personal-use items, which included combs, small statuary, painted pottery, high quality decorative stone vases , cosmetic palettes , and jewelry made of gold, lapis, and ivory. They also developed
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#17327801470838060-467: The Nubians to the south of Egypt, but failed to defeat the Hyksos. That task fell to Kamose's successor, Ahmose I , who successfully waged a series of campaigns that permanently eradicated the Hyksos' presence in Egypt. He established a new dynasty and, in the New Kingdom that followed, the military became a central priority for the kings, who sought to expand Egypt's borders and attempted to gain mastery of
8215-606: The Persians and was welcomed by the Egyptians as a deliverer. The administration established by Alexander's successors, the Macedonian Ptolemaic Kingdom , was based on an Egyptian model and based in the new capital city of Alexandria . The city showcased the power and prestige of Hellenistic rule, and became a centre of learning and culture, that included the famous Library of Alexandria as part of
8370-619: The Thirtieth , proved to be the last native royal house of ancient Egypt, ending with the kingship of Nectanebo II . A brief restoration of Persian rule, sometimes known as the Thirty-First Dynasty , began in 343 BC, but shortly after, in 332 BC, the Persian ruler Mazaces handed Egypt over to Alexander the Great without a fight. In 332 BC, Alexander the Great conquered Egypt with little resistance from
8525-549: The Wadi Natrun for mummification , which also provided the gypsum needed to make plaster. Ore-bearing rock formations were found in distant, inhospitable wadis in the Eastern Desert and the Sinai, requiring large, state-controlled expeditions to obtain natural resources found there. There were extensive gold mines in Nubia , and one of the first maps known is of a gold mine in this region. The Wadi Hammamat
8680-451: The chaff from the grain, and the grain was then ground into flour, brewed to make beer, or stored for later use. The ancient Egyptians cultivated emmer and barley , and several other cereal grains, all of which were used to make the two main food staples of bread and beer. Flax plants, uprooted before they started flowering, were grown for the fibers of their stems. These fibers were split along their length and spun into thread, which
8835-581: The composite bow and the horse-drawn chariot . After retreating south, the native Theban kings found themselves trapped between the Canaanite Hyksos ruling the north and the Hyksos' Nubian allies, the Kushites , to the south. After years of vassalage, Thebes gathered enough strength to challenge the Hyksos in a conflict that lasted more than 30 years, until 1555 BC. The kings Seqenenre Tao II and Kamose were ultimately able to defeat
8990-458: The earliest known peace treaty , made with the Hittites . Ancient Egypt has left a lasting legacy. Its art and architecture were widely copied, and its antiquities were carried off to be studied, admired or coveted in the far corners of the world. Its monumental ruins have inspired the imaginations of travelers and writers for millennia. A newfound respect for antiquities and excavations in
9145-414: The surface of the source reservoir, as sometimes is the case when used in irrigation. In operation, a siphon spillway is considered to be "pipe flow" or "closed-duct flow". A normal spillway flow is pressurized by the height of the reservoir above the spillway, whereas a siphon flow rate is governed by the difference in height of the inlet and outlet. Some designs make use of an automatic system that uses
9300-523: The vizier and his court for redress. Although slaves were mostly used as indentured servants, they were able to buy and sell their servitude, work their way to freedom or nobility, and were usually treated by doctors in the workplace. Both men and women had the right to own and sell property, make contracts, marry and divorce, receive inheritance, and pursue legal disputes in court. Married couples could own property jointly and protect themselves from divorce by agreeing to marriage contracts, which stipulated
9455-572: The Assyrians. The effects of external threats were exacerbated by internal problems such as corruption, tomb robbery, and civil unrest . After regaining their power, the high priests at the temple of Amun in Thebes accumulated vast tracts of land and wealth, and their expanded power splintered the country during the Third Intermediate Period. Following the death of Ramesses XI in 1078 BC, Smendes assumed authority over
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#17327801470839610-476: The Christian emperor Theodosius introduced legislation that banned pagan rites and closed temples. Alexandria became the scene of great anti-pagan riots with public and private religious imagery destroyed. As a consequence, Egypt's native religious culture was continually in decline. While the native population continued to speak their language , the ability to read hieroglyphic writing slowly disappeared as
9765-435: The Delta, seized control of Egypt and established their capital at Avaris , forcing the former central government to retreat to Thebes . The king was treated as a vassal and expected to pay tribute. The Hyksos ('foreign rulers') retained Egyptian models of government and identified as kings, thereby integrating Egyptian elements into their culture. They and other invaders introduced new tools of warfare into Egypt, most notably
9920-453: The Egyptians, the Ptolemies were challenged by native rebellion, bitter family rivalries, and the powerful mob of Alexandria that formed after the death of Ptolemy IV . In addition, as Rome relied more heavily on imports of grain from Egypt, the Romans took great interest in the political situation in the country. Continued Egyptian revolts, ambitious politicians, and powerful opponents from
10075-504: The Greeks towards the Egyptians, some traditions such as mummification and worship of the traditional gods continued. The art of mummy portraiture flourished, and some Roman emperors had themselves depicted as pharaohs, though not to the extent that the Ptolemies had. The former lived outside Egypt and did not perform the ceremonial functions of Egyptian kingship. Local administration became Roman in style and closed to native Egyptians. From
10230-545: The Late Period, the worship of the gods in their animal form was extremely popular, such as the cat goddess Bastet and the ibis god Thoth , and these animals were kept in large numbers for the purpose of ritual sacrifice. Egypt is rich in building and decorative stone, copper and lead ores, gold, and semiprecious stones. These natural resources allowed the ancient Egyptians to build monuments, sculpt statues, make tools, and fashion jewelry . Embalmers used salts from
10385-452: The Late Period. There is also evidence to suggest that elephants were briefly used in the Late Period but largely abandoned due to lack of grazing land. Cats , dogs, and monkeys were common family pets, while more exotic pets imported from the heart of Africa, such as Sub-Saharan African lions , were reserved for royalty. Herodotus observed that the Egyptians were the only people to keep their animals with them in their houses. During
10540-525: The Near East made this situation unstable, leading Rome to send forces to secure the country as a province of its empire. Egypt became a province of the Roman Empire in 30 BC, following the defeat of Mark Antony and Ptolemaic Queen Cleopatra VII by Octavian (later Emperor Augustus) in the Battle of Actium . The Romans relied heavily on grain shipments from Egypt, and the Roman army , under
10695-569: The Nile valley had developed into a series of cultures demonstrating firm control of agriculture and animal husbandry , and identifiable by their pottery and personal items, such as combs, bracelets, and beads. The largest of these early cultures in upper (Southern) Egypt was the Badarian culture , which probably originated in the Western Desert ; it was known for its high-quality ceramics, stone tools , and its use of copper. The Badari
10850-474: The Nile valley, including at Memphis, Karnak, Kawa, and Jebel Barkal. During this period, the Nile valley saw the first widespread construction of pyramids (many in modern Sudan) since the Middle Kingdom. Egypt's far-reaching prestige declined considerably toward the end of the Third Intermediate Period. Its foreign allies had fallen under the Assyrian sphere of influence, and by 700 BC war between
11005-582: The Old Kingdom, and provided both honey and wax. The ancient Egyptians used donkeys and oxen as beasts of burden , and they were responsible for plowing the fields and trampling seed into the soil. The slaughter of a fattened ox was also a central part of an offering ritual. Horses were introduced by the Hyksos in the Second Intermediate Period . Camels, although known from the New Kingdom, were not used as beasts of burden until
11160-405: The Old Kingdom. Under the direction of the vizier , state officials collected taxes, coordinated irrigation projects to improve crop yield , drafted peasants to work on construction projects, and established a justice system to maintain peace and order. With the rising importance of central administration in Egypt, a new class of educated scribes and officials arose who were granted estates by
11315-512: The Ruler ", to defend against foreign attack. With the kings having secured the country militarily and politically and with vast agricultural and mineral wealth at their disposal, the nation's population, arts, and religion flourished. In contrast to elitist Old Kingdom attitudes towards the gods, the Middle Kingdom displayed an increase in expressions of personal piety. Middle Kingdom literature featured sophisticated themes and characters written in
11470-459: The accidental swallowing of gasoline, or aspirating it into the lungs, which can cause death or lung damage. ) If the tube is flooded with liquid before part of the tube is raised over the intermediate high point and care is taken to keep the tube flooded while it is being raised, no pump is required. Devices sold as siphons often come with a siphon pump to start the siphon process. In some applications it can be helpful to use siphon tubing that
11625-499: The administration, aside from the royal high priestesses, apparently served only secondary roles in the temples (not much data for many dynasties), and were not so probably to be as educated as men. The head of the legal system was officially the pharaoh, who was responsible for enacting laws, delivering justice, and maintaining law and order, a concept the ancient Egyptians referred to as Ma'at . Although no legal codes from ancient Egypt survive, court documents show that Egyptian law
11780-418: The air bubble down and out of the tube. The apparatus will then continue to operate as a normal siphon. As there is no contact between the liquid on either side of the siphon at the beginning of this experiment, there can be no cohesion between the liquid molecules to pull the liquid over the rise. It has been suggested by advocates of the liquid tensile strength theory, that the air start siphon only demonstrates
11935-557: The ancient Egyptians did not use coinage until the Late period , they did use a type of money-barter system, with standard sacks of grain and the deben , a weight of roughly 91 grams (3 oz) of copper or silver, forming a common denominator. Workers were paid in grain; a simple laborer might earn 5 + 1 ⁄ 2 sacks (200 kg or 400 lb) of grain per month, while a foreman might earn 7 + 1 ⁄ 2 sacks (250 kg or 550 lb). Prices were fixed across
12090-407: The ancient Egyptians include the quarrying , surveying , and construction techniques that supported the building of monumental pyramids , temples , and obelisks ; a system of mathematics , a practical and effective system of medicine , irrigation systems, and agricultural production techniques, the first known planked boats, Egyptian faience and glass technology, new forms of literature , and
12245-896: The basic mechanism of a siphon does not depend upon atmospheric pressure." Gravity , pressure and molecular cohesion were the focus of work in 2010 by Hughes at the Queensland University of Technology . He used siphons at air pressure and his conclusion was: "The flow of water out of the bottom of a siphon depends on the difference in height between the inflow and outflow, and therefore cannot be dependent on atmospheric pressure…" Hughes did further work on siphons at air pressure in 2011 and concluded: "The experiments described above demonstrate that ordinary siphons at atmospheric pressure operate through gravity and not atmospheric pressure". The father and son researchers Ramette and Ramette successfully siphoned carbon dioxide under air pressure in 2011 and concluded that molecular cohesion
12400-407: The bottom ( dregs ) or the top ( foam and floaties) from being transferred out of one container into a new container. Siphoning is thus useful in the fermentation of wine and beer for this reason, since it can keep unwanted impurities out of the new container. Self-constructed siphons, made of pipes or tubes, can be used to evacuate water from cellars after floodings. Between the flooded cellar and
12555-403: The bubble out. Another common misconception about siphons is that because the atmospheric pressure is virtually identical at the entrance and exit, the atmospheric pressure cancels, and therefore atmospheric pressure cannot be pushing the liquid up the siphon. But equal and opposite forces may not completely cancel if there is an intervening force that counters some or all of one of the forces. In
12710-418: The bubbles to move against the liquid flow; though other designs call for a shallow slope in the outlet leg as well to allow the bubbles to be carried out of the siphon. At the crest the gas can be trapped in a chamber above the crest. The chamber needs to be occasionally primed again with liquid to remove the gas. A siphon rain gauge is a rain gauge that can record rainfall over an extended period. A siphon
12865-407: The chain model can be instructive. Further, in other settings water transport does occur due to tension, most significantly in transpirational pull in the xylem of vascular plants . Water and other liquids may seem to have no tensile strength because when a handful is scooped up and pulled on, the liquids narrow and pull apart effortlessly. But liquid tensile strength in a siphon is possible when
13020-754: The chamber. Eventually air rushes into the tube and breaks the siphon, stopping the flow if there is no other source feeding the spring, or reducing the flow if there is a continuous flow from another non-siphon source. In 2006 the University of Utah studied the Intermittent Spring in Swift Creek canyon in Star Valley , Wyoming , United States. Kip Solomon, a hydrologist at the University concluded that "The spring water's gas content has now been tested [...]. The data strongly suggests
13175-410: The complaint, testimony, and verdict of the case for future reference. Punishment for minor crimes involved either imposition of fines, beatings, facial mutilation, or exile, depending on the severity of the offense. Serious crimes such as murder and tomb robbery were punished by execution, carried out by decapitation, drowning, or impaling the criminal on a stake. Punishment could also be extended to
13330-419: The conditions of the Nile River valley for agriculture . The predictable flooding and controlled irrigation of the fertile valley produced surplus crops, which supported a more dense population, and social development and culture. With resources to spare, the administration sponsored mineral exploitation of the valley and surrounding desert regions, the early development of an independent writing system ,
13485-505: The control of a prefect appointed by the emperor, quelled rebellions, strictly enforced the collection of heavy taxes, and prevented attacks by bandits, which had become a notorious problem during the period. Alexandria became an increasingly important center on the trade route with the orient, as exotic luxuries were in high demand in Rome. Although the Romans had a more hostile attitude than
13640-401: The country and recorded in lists to facilitate trading; for example a shirt cost five copper deben, while a cow cost 140 deben. Grain could be traded for other goods, according to the fixed price list. During the fifth century BC coined money was introduced into Egypt from abroad. At first the coins were used as standardized pieces of precious metal rather than true money, but in
13795-403: The country's economy. Regional governors could not rely on the king for help in times of crisis, and the ensuing food shortages and political disputes escalated into famines and small-scale civil wars. Yet despite difficult problems, local leaders, owing no tribute to the king, used their new-found independence to establish a thriving culture in the provinces. Once in control of their own resources,
13950-399: The crest and if enough accumulates to break the flow of liquid, the siphon stops working. The siphon itself will exacerbate the problem because as the liquid is raised through the siphon, the pressure drops, causing dissolved gases within the liquid to come out of solution. Higher temperature accelerates the release of gas from liquids so maintaining a constant, low temperature helps. The longer
14105-447: The crest of the siphon to start the flow of water which then completely empties the contents of the cistern into the toilet bowl. The advantage of this system was that no water would leak from the cistern excepting when flushed. These were mandatory in the UK until 2011. Early urinals incorporated a siphon in the cistern which would flush automatically on a regular cycle because there was
14260-421: The criminal's family. Beginning in the New Kingdom, oracles played a major role in the legal system, dispensing justice in both civil and criminal cases. The procedure was to ask the god a "yes" or "no" question concerning the right or wrong of an issue. The god, carried by a number of priests, rendered judgement by choosing one or the other, moving forward or backward, or pointing to one of the answers written on
14415-408: The double-concentric siphon. Siphons were studied further in the 17th century, in the context of suction pumps (and the recently developed vacuum pumps ), particularly with an eye to understanding the maximum height of pumps (and siphons) and the apparent vacuum at the top of early barometers . This was initially explained by Galileo Galilei via the theory of horror vacui ("nature abhors
14570-411: The early modern period by Europeans and Egyptians has led to the scientific investigation of Egyptian civilization and a greater appreciation of its cultural legacy. The Nile has been the lifeline of its region for much of human history. The fertile floodplain of the Nile gave humans the opportunity to develop a settled agricultural economy and a more sophisticated, centralized society that became
14725-572: The economy and precipitated the slow decline into the Second Intermediate Period during the later Thirteenth and Fourteenth dynasties. During this decline, the Canaanite settlers began to assume greater control of the Delta region, eventually coming to power in Egypt as the Hyksos . Around 1785 BC, as the power of the Middle Kingdom kings weakened, a Western Asian people called the Hyksos , who had already settled in
14880-414: The effect as the siphon starts, but that the situation changes after the bubble is swept out and the siphon achieves steady flow. But a similar effect can be seen in the flying-droplet siphon (see above). The flying-droplet siphon works continuously without liquid tensile strength pulling the liquid up. The siphon in the video demonstration operated steadily for more than 28 minutes until the upper reservoir
15035-503: The example of two carts being pushed up opposite sides of a hill. As shown in the diagram, even though the person on the left seems to have his push canceled entirely by the equal and opposite push from the person on the right, the person on the left's seemingly canceled push is still the source of the force to push the left cart up. In some situations siphons do function in the absence of atmospheric pressure and due to tensile strength – see vacuum siphons – and in these situations
15190-424: The fertile delta region, as well as the lucrative and critical trade routes to the Levant . The increasing power and wealth of the kings during the early dynastic period was reflected in their elaborate mastaba tombs and mortuary cult structures at Abydos, which were used to celebrate the deified king after his death. The strong institution of kingship developed by the kings served to legitimize state control over
15345-524: The financial obligations of the husband to his wife and children should the marriage end. Compared with their counterparts in ancient Greece, Rome, and even more modern places around the world, ancient Egyptian women had a greater range of personal choices, legal rights, and opportunities for achievement. Women such as Hatshepsut and Cleopatra VII even became pharaohs, while others wielded power as Divine Wives of Amun . Despite these freedoms, ancient Egyptian women did not often take part in official roles in
15500-613: The first recorded peace treaty , around 1258 BC. Egypt's wealth, however, made it a tempting target for invasion, particularly by the Libyan Berbers to the west, and the Sea Peoples , a conjectured confederation of seafarers from the Aegean Sea . Initially, the military was able to repel these invasions, but Egypt eventually lost control of its remaining territories in southern Canaan , much of it falling to
15655-427: The floodwaters had receded, the growing season lasted from October to February. Farmers plowed and planted seeds in the fields, which were irrigated with ditches and canals. Egypt received little rainfall, so farmers relied on the Nile to water their crops. From March to May, farmers used sickles to harvest their crops, which were then threshed with a flail to separate the straw from the grain. Winnowing removed
15810-406: The flow of water in a spiral vortex to remove the air above to prime the siphon. Such a design includes the volute siphon. Flush toilets often have some siphon effect as the bowl empties. Some toilets also use the siphon principle to obtain the actual flush from the cistern . The flush is triggered by a lever or handle that operates a simple diaphragm-like piston pump that lifts enough water to
15965-421: The flying droplet siphon, where gases do not exert significant pulling forces, and liquids not in contact cannot exert a cohesive tension force. All known published theories in modern times recognize Bernoulli’s equation as a decent approximation to idealized, friction-free siphon operation. Egyptian reliefs from 1500 BC depict siphons used to extract liquids from large storage jars. Physical evidence for
16120-417: The following centuries international traders came to rely on coinage. Egyptian society was highly stratified, and social status was expressly displayed. Farmers made up the bulk of the population, but agricultural produce was owned directly by the state, temple, or noble family that owned the land. Farmers were also subject to a labor tax and were required to work on irrigation or construction projects in
16275-412: The government, who relied on a bureaucracy of officials to manage his affairs. In charge of the administration was his second in command, the vizier , who acted as the king's representative and coordinated land surveys, the treasury, building projects, the legal system, and the archives . At a regional level, the country was divided into as many as 42 administrative regions called nomes each governed by
16430-407: The intake point. The ambient atmospheric pressure at the intake point responds to the reduced pressure by forcing the fluid upwards, sustaining the flow, just as in a steadily sucked straw in a milkshake." Again in 2011, Richert and Binder (at the University of Hawaii ) examined the siphon and concluded that molecular cohesion is not required for the operation of a siphon but relies upon gravity and
16585-404: The intake, outlet and crest of the siphon. The siphon may be primed by closing the intake and outlets and filling the siphon at the crest. If intakes and outlets are submerged, a vacuum pump may be applied at the crest to prime the siphon. Alternatively the siphon may be primed by a pump at either the intake or outlet. Gas in the liquid is a concern in large siphons. The gas tends to accumulate at
16740-411: The king in payment for their services. Kings also made land grants to their mortuary cults and local temples , to ensure that these institutions had the resources to worship the king after his death. Scholars believe that five centuries of these practices slowly eroded the economic vitality of Egypt, and that the economy could no longer afford to support a large centralized administration. As the power of
16895-593: The kingdom's capital to the city of Itjtawy , located in Faiyum . From Itjtawy, the kings of the Twelfth Dynasty undertook a far-sighted land reclamation and irrigation scheme to increase agricultural output in the region. Moreover, the military reconquered territory in Nubia that was rich in quarries and gold mines, while laborers built a defensive structure in the Eastern Delta, called the " Walls of
17050-528: The kings diminished, regional governors called nomarchs began to challenge the supremacy of the office of king. This, coupled with severe droughts between 2200 and 2150 BC, is believed to have caused the country to enter the 140-year period of famine and strife known as the First Intermediate Period. After Egypt's central government collapsed at the end of the Old Kingdom, the administration could no longer support or stabilize
17205-566: The land, labor, and resources that were essential to the survival and growth of ancient Egyptian civilization. Major advances in architecture, art, and technology were made during the Old Kingdom , fueled by the increased agricultural productivity and resulting population growth, made possible by a well-developed central administration. Some of ancient Egypt's crowning achievements, the Giza pyramids and Great Sphinx , were constructed during
17360-402: The level falls below the intake, allowing air or other surrounding gas to break the siphon, or until the outlet of the siphon equals the level of the reservoir, whichever comes first. In addition to atmospheric pressure , the density of the liquid, and gravity , the maximal height of the crest in practical siphons is limited by the vapour pressure of the liquid. When the pressure within
17515-411: The liquid adheres to the tube walls and thereby resists narrowing. Any contamination on the tube walls, such as grease or air bubbles, or other minor influences such as turbulence or vibration, can cause the liquid to detach from the walls and lose all tensile strength. In more detail, one can look at how the hydrostatic pressure varies through a static siphon, considering in turn the vertical tube from
17670-453: The liquid drops to below the liquid's vapor pressure, tiny vapor bubbles can begin to form at the high point, and the siphon effect will end. This effect depends on how efficiently the liquid can nucleate bubbles; in the absence of impurities or rough surfaces to act as easy nucleation sites for bubbles, siphons can temporarily exceed their standard maximal height during the extended time it takes bubbles to nucleate. One siphon of degassed water
17825-409: The liquid flowing and prime the siphon (in home use this is often done by a person inhaling through the tube until enough of it has filled with liquid; this may pose danger to the user, depending on the liquid that is being siphoned). This is sometimes done with any leak-free hose to siphon gasoline from a motor vehicle's gasoline tank to an external tank. (Siphoning gasoline by mouth often results in
17980-413: The liquid is in the siphon, the more gas is released, so a shorter siphon overall helps. Local high points will trap gas so the intake and outlet legs should have continuous slopes without intermediate high points. The flow of the liquid moves bubbles thus the intake leg can have a shallow slope as the flow will push the gas bubbles to the crest. Conversely, the outlet leg needs to have a steep slope to allow
18135-497: The long line of kings from Menes to his own time into 30 dynasties, a system still used today. He began his official history with the king named "Meni" (or Menes in Greek), who was believed to have united the two kingdoms of Upper and Lower Egypt . The transition to a unified state happened more gradually than ancient Egyptian writers represented, and there is no contemporary record of Menes. Some scholars now believe, however, that
18290-436: The lower-pressure zone at the top of the siphon, over the top, and then, with the help of gravity and a taller column of liquid, down to the higher-pressure zone at the exit. The chain model is a useful but not completely accurate conceptual model of a siphon. The chain model helps to understand how a siphon can cause liquid to flow uphill, powered only by the downward force of gravity. A siphon can sometimes be thought of like
18445-464: The mid-first century AD, Christianity took root in Egypt and it was originally seen as another cult that could be accepted. However, it was an uncompromising religion that sought to win converts from the pagan Egyptian and Greco-Roman religions and threatened popular religious traditions. This led to the persecution of converts to Christianity, culminating in the great purges of Diocletian starting in 303, but eventually Christianity won out. In 391,
18600-528: The mythical Menes may have been the king Narmer , who is depicted wearing royal regalia on the ceremonial Narmer Palette, in a symbolic act of unification. In the Early Dynastic Period, which began about 3000 BC, the first of the Dynastic kings solidified control over lower Egypt by establishing a capital at Memphis , from which he could control the labor force and agriculture of
18755-405: The nobility were the priests, physicians, and engineers with specialized training in their field. It is unclear whether slavery as understood today existed in ancient Egypt; there is difference of opinions among authors. The ancient Egyptians viewed men and women, including people from all social classes, as essentially equal under the law, and even the lowliest peasant was entitled to petition
18910-682: The north, while a rival clan based in Thebes , the Intef family , took control of Upper Egypt in the south. As the Intefs grew in power and expanded their control northward, a clash between the two rival dynasties became inevitable. Around 2055 BC the northern Theban forces under Nebhepetre Mentuhotep II finally defeated the Herakleopolitan rulers, reuniting the Two Lands. They inaugurated
19065-676: The northern part of Egypt, ruling from the city of Tanis . The south was effectively controlled by the High Priests of Amun at Thebes , who recognized Smendes in name only. During this time, Libyans had been settling in the western delta, and chieftains of these settlers began increasing their autonomy. Libyan princes took control of the delta under Shoshenq I in 945 BC, founding the so-called Libyan or Bubastite dynasty that would rule for some 200 years. Shoshenq also gained control of southern Egypt by placing his family members in important priestly positions. Libyan control began to erode as
19220-611: The operation of siphons". In 2014, Hughes and Gurung (at the Queensland University of Technology) ran a water siphon under varying air pressures ranging from sea level to 11.9 km ( 39 000 ft ) altitude. They noted: "Flow remained more or less constant during ascension indicating that siphon flow is independent of ambient barometric pressure ". They used Bernoulli's equation and the Poiseuille equation to examine pressure differentials and fluid flow within
19375-462: The organization of collective construction and agricultural projects, trade with surrounding regions, and a military intended to assert Egyptian dominance. Motivating and organizing these activities was a bureaucracy of elite scribes , religious leaders, and administrators under the control of a pharaoh , who ensured the cooperation and unity of the Egyptian people in the context of an elaborate system of religious beliefs . The many achievements of
19530-557: The political unification of Upper and Lower Egypt under pharaoh or king Menes (often identified with Narmer ). The history of ancient Egypt unfolded as a series of stable kingdoms interspersed by periods of relative instability known as "Intermediate Periods". The various kingdoms fall into one of three categories: the Old Kingdom of the Early Bronze Age , the Middle Kingdom of the Middle Bronze Age , or
19685-423: The pressure, rather than pulling on each other. To demonstrate, the longer lower leg of a common siphon can be plugged at the bottom and filled almost to the crest with liquid as in the figure, leaving the top and the shorter upper leg completely dry and containing only air. When the plug is removed and the liquid in the longer lower leg is allowed to fall, the liquid in the upper reservoir will then typically sweep
19840-528: The previously obscure sun deity Aten as the supreme deity , suppressed the worship of most other deities, and moved the capital to the new city of Akhetaten (modern-day Amarna ). He was devoted to his new religion and artistic style . After his death, the cult of the Aten was quickly abandoned and the traditional religious order restored. The subsequent pharaohs, Tutankhamun , Ay , and Horemheb , worked to erase all mention of Akhenaten's heresy, now known as
19995-621: The provinces became economically richer—which was demonstrated by larger and better burials among all social classes. In bursts of creativity, provincial artisans adopted and adapted cultural motifs formerly restricted to the royalty of the Old Kingdom, and scribes developed literary styles that expressed the optimism and originality of the period. Free from their loyalties to the king, local rulers began competing with each other for territorial control and political power . By 2160 BC, rulers in Herakleopolis controlled Lower Egypt in
20150-406: The reservoir from which it came. There are two leading theories about how siphons cause liquid to flow uphill, against gravity, without being pumped, and powered only by gravity. The traditional theory for centuries was that gravity pulling the liquid down on the exit side of the siphon resulted in reduced pressure at the top of the siphon. Then atmospheric pressure was able to push the liquid from
20305-718: The role of the Egyptian temple priests and priestesses diminished. The temples themselves were sometimes converted to churches or abandoned to the desert. In the fourth century, as the Roman Empire divided, Egypt found itself in the Eastern Empire with its capital at Constantinople . In the waning years of the Empire, Egypt fell to the Sasanian Persian army in the Sasanian conquest of Egypt (618–628). It
20460-452: The same principle. The ratio of heights (about 13.6) equals the ratio of densities of water and mercury (at a given temperature), since the column of water (resp. mercury) is balancing with the column of air yielding atmospheric pressure, and indeed maximal height is (neglecting vapor pressure and velocity of liquid) inversely proportional to density of liquid. In 1948, Malcolm Nokes investigated siphons working in both air pressure and in
20615-408: The scientific literature to be a fair approximation to the operation of the siphon. In non-ideal fluids, compressibility, tensile strength and other characteristics of the working fluid (or multiple fluids) complicate Bernoulli's equation. Once started, a siphon requires no additional energy to keep the liquid flowing up and out of the reservoir. The siphon will draw liquid out of the reservoir until
20770-401: The shorter side that matters. Rather it is the difference in height from the reservoir surfaces to the top of the siphon, that determines the balance of pressure . For example, if the tube from the upper reservoir to the top of the siphon has a much larger diameter than the taller section of tube from the lower reservoir to the top of the siphon, the shorter upper section of the siphon may have
20925-500: The siphon is dry. The seep holes can be plugged by debris and corrosion, requiring manual cleaning and intervention. To prevent this, the siphon may be restricted to pure liquid sources, free of solids or precipitate. Many automatic siphons have been invented going back to at least the 1850s, for automatic siphon mechanisms that attempt to overcome these problems using various pneumatic and hydrodynamic principles. When certain liquids needs to be purified, siphoning can help prevent either
21080-421: The siphon pushing down (until one reaches the maximal height of a barometer/siphon, at which point the liquid cannot be pushed higher) – the hydrostatic pressure at the top of the tube is then lower than atmospheric pressure by an amount proportional to the height of the tube. Doing the same analysis on the tube rising from the lower reservoir yields the pressure at the top of that (vertical) tube; this pressure
21235-446: The siphon, the atmospheric pressure at the entrance and exit are both lessened by the force of gravity pulling down the liquid in each tube, but the pressure on the down side is lessened more by the taller column of liquid on the down side. In effect, the atmospheric pressure coming up the down side does not entirely "make it" to the top to cancel all of the atmospheric pressure pushing up the up side. This effect can be seen more easily in
21390-402: The size of a herd reflected the prestige and importance of the estate or temple that owned them. In addition to cattle, the ancient Egyptians kept sheep, goats, and pigs. Poultry , such as ducks, geese, and pigeons, were captured in nets and bred on farms, where they were force-fed with dough to fatten them. The Nile provided a plentiful source of fish . Bees were also domesticated from at least
21545-490: The stored liquid is released, emerging as a large surge volume that then resets and fills again. One way to do this intermittent action involves complex machinery such as floats, chains, levers, and valves, but these can corrode, wear out, or jam over time. An alternate method is with rigid pipes and chambers, using only the water itself in a siphon as the operating mechanism. A siphon used in an automatic unattended device needs to be able to function reliably without failure. This
21700-403: The tension of the liquid column is neutralized and reversed by the compressive effect of the atmosphere on the opposite ends of the liquid column." Potter and Barnes at the University of Edinburgh revisited siphons in 1971. They re-examined the theories of the siphon and ran experiments on siphons in air pressure. They concluded: "By now it should be clear that, despite a wealth of tradition,
21855-410: The top of the siphon (formally, hydrostatic pressure when the liquid is not moving). This reduced pressure at the top means gravity pulling down on the shorter column of liquid is not sufficient to keep the liquid stationary against the atmospheric pressure pushing it up into the reduced-pressure zone at the top of the siphon. So the liquid flows from the higher-pressure area of the upper reservoir up to
22010-417: The top reservoir, the vertical tube from the bottom reservoir, and the horizontal tube connecting them (assuming a U-shape). At liquid level in the top reservoir, the liquid is under atmospheric pressure, and as one goes up the siphon, the hydrostatic pressure decreases (under vertical pressure variation ), since the weight of atmospheric pressure pushing the water up is counterbalanced by the column of water in
22165-494: The two states became inevitable. Between 671 and 667 BC the Assyrians began the Assyrian conquest of Egypt . The reigns of both Taharqa and his successor, Tanutamun , were filled with constant conflict with the Assyrians, against whom Egypt enjoyed several victories. Ultimately, the Assyrians pushed the Kushites back into Nubia, occupied Memphis, and sacked the temples of Thebes . The Assyrians left control of Egypt to
22320-407: The upper reservoir, up into the reduced pressure at the top of the siphon, like in a barometer or drinking straw , and then over. However, it has been demonstrated that siphons can operate in a vacuum and to heights exceeding the barometric height of the liquid. Consequently, the cohesion tension theory of siphon operation has been advocated, where the liquid is pulled over the siphon in
22475-558: The use of siphons by Greeks are the Justice cup of Pythagoras in Samos in the 6th century BC and usage by Greek engineers in the 3rd century BC at Pergamon . Hero of Alexandria wrote extensively about siphons in the treatise Pneumatica . The Banu Musa brothers of 9th-century Baghdad invented a double-concentric siphon, which they described in their Book of Ingenious Devices . The edition edited by Hill includes an analysis of
22630-590: The water was exposed to air underground; strong support for the siphon theory." The Intermittent Spring in Wyoming, mentioned above, is the largest rhythmic spring in the world. The Gihon Spring in the City of David in Jerusalem used to be a rhythmic spring before modern-time overpumping affected the level of the underground water table. It was of great historical, archaeological, and cultural importance because it
22785-542: Was also the beginning of trade with Mesopotamia , which continued into the early dynastic period and beyond. Over a period of about 1,000 years, the Naqada culture developed from a few small farming communities into a powerful civilization whose leaders were in complete control of the people and resources of the Nile valley. Establishing a power center at Nekhen (in Greek, Hierakonpolis), and later at Abydos , Naqada III leaders expanded their control of Egypt northwards along
22940-423: Was based on a common-sense view of right and wrong that emphasized reaching agreements and resolving conflicts rather than strictly adhering to a complicated set of statutes. Local councils of elders, known as Kenbet in the New Kingdom, were responsible for ruling in court cases involving small claims and minor disputes. More serious cases involving murder, major land transactions, and tomb robbery were referred to
23095-421: Was crucial in ancient Egypt because taxes were assessed based on the amount of land a person owned. Farming in Egypt was dependent on the cycle of the Nile River. The Egyptians recognized three seasons: Akhet (flooding), Peret (planting), and Shemu (harvesting). The flooding season lasted from June to September, depositing on the river's banks a layer of mineral-rich silt ideal for growing crops. After
23250-411: Was demonstrated to 24 m (79 feet ) for an extended period of time and other controlled experiments to 10 m (33 feet ). For water at standard atmospheric pressure , the maximal siphon height is approximately 10 m (33 feet); for mercury it is 76 cm (30 inches ), which is the definition of standard pressure. This equals the maximal height of a suction pump , which operates by
23405-414: Was empty. Another simple demonstration that liquid tensile strength is not needed in the siphon is to simply introduce a bubble into the siphon during operation. The bubble can be large enough to entirely disconnect the liquids in the tube before and after the bubble, defeating any liquid tensile strength, and yet if the bubble is not too big, the siphon will continue to operate with little change as it sweeps
23560-541: Was followed by the Naqada culture : the Naqada I ( Amratian ), the Naqada II ( Gerzeh ), and Naqada III ( Semainean ). These brought a number of technological improvements. As early as the Naqada I Period, predynastic Egyptians imported obsidian from Ethiopia , used to shape blades and other objects from flakes . Mutual trade with the Levant was established during Naqada II ( c. 3600–3350 BC ); this period
23715-577: Was never able to overthrow the Persians until the end of the century. Following its annexation by Persia, Egypt was joined with Cyprus and Phoenicia in the sixth satrapy of the Achaemenid Persian Empire . This first period of Persian rule over Egypt, also known as the Twenty-Seventh Dynasty , ended in 402 BC, when Egypt regained independence under a series of native dynasties. The last of these dynasties,
23870-476: Was then recaptured by the Byzantine emperor Heraclius (629–639), and was finally captured by Muslim Rashidun army in 639–641, marking the end of both Byzantine rule and of the period typically considered Ancient Egypt. The pharaoh was the absolute monarch of the country and, at least in theory, wielded complete control of the land and its resources. The king was the supreme military commander and head of
24025-420: Was used to weave sheets of linen and to make clothing. Papyrus growing on the banks of the Nile River was used to make paper. Vegetables and fruits were grown in garden plots, close to habitations and on higher ground, and had to be watered by hand. Vegetables included leeks, garlic, melons, squashes, pulses, lettuce, and other crops, in addition to grapes that were made into wine. The Egyptians believed that
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