The Missouri River is the longest river in North America. Rising in the Rocky Mountains of western Montana, the Missouri flows east and south for 2,341 miles before entering the Mississippi River north of St. Louis, Missouri; the river takes drainage from a sparsely populated, semi-arid watershed of more than half a million square miles, which includes parts of ten U. S. states and two Canadian provinces. When combined with the lower Mississippi River, it forms the world's fourth longest river system. For over 12,000 years, people have depended on the Missouri River and its tributaries as a source of sustenance and transportation. More than ten major groups of Native Americans populated the watershed, most leading a nomadic lifestyle and dependent on enormous bison herds that roamed through the Great Plains; the first Europeans encountered the river in the late seventeenth century, the region passed through Spanish and French hands before becoming part of the United States through the Louisiana Purchase.
The Missouri River was one of the main routes for the westward expansion of the United States during the 19th century. The growth of the fur trade in the early 19th century laid much of the groundwork as trappers explored the region and blazed trails. Pioneers headed west en masse beginning in the 1830s, first by covered wagon by the growing numbers of steamboats that entered service on the river. Settlers took over former Native American lands in the watershed, leading to some of the most longstanding and violent wars against indigenous peoples in American history. During the 20th century, the Missouri River basin was extensively developed for irrigation, flood control and the generation of hydroelectric power. Fifteen dams impound the main stem of the river, with hundreds more on tributaries. Meanders have been cut and the river channelized to improve navigation, reducing its length by 200 miles from pre-development times. Although the lower Missouri valley is now a populous and productive agricultural and industrial region, heavy development has taken its toll on wildlife and fish populations as well as water quality.
From the Rocky Mountains of Montana and Wyoming, three streams rise to form the headwaters of the Missouri River: the longest begins near Brower's Spring, 9,100 feet above sea level on the southeastern slopes of Mount Jefferson in the Centennial Mountains. From there it flows west north, it passes through Canyon Ferry Lake, a reservoir west of the Big Belt Mountains. Issuing from the mountains near Cascade, the river flows northeast to the city of Great Falls, where it drops over the Great Falls of the Missouri, a series of five substantial waterfalls, it winds east through a scenic region of canyons and badlands known as the Missouri Breaks, receiving the Marias River from the west widening into the Fort Peck Lake reservoir a few miles above the confluence with the Musselshell River. Farther on, the river passes through the Fort Peck Dam, downstream, the Milk River joins from the north. Flowing eastward through the plains of eastern Montana, the Missouri receives the Poplar River from the north before crossing into North Dakota where the Yellowstone River, its greatest tributary by volume, joins from the southwest.
At the confluence, the Yellowstone is the larger river. The Missouri meanders east past Williston and into Lake Sakakawea, the reservoir formed by Garrison Dam. Below the dam the Missouri receives the Knife River from the west and flows south to Bismarck, the capital of North Dakota, where the Heart River joins from the west, it slows into the Lake Oahe reservoir just before the Cannonball River confluence. While it continues south reaching Oahe Dam in South Dakota, the Grand and Cheyenne Rivers all join the Missouri from the west; the Missouri makes a bend to the southeast as it winds through the Great Plains, receiving the Niobrara River and many smaller tributaries from the southwest. It proceeds to form the boundary of South Dakota and Nebraska after being joined by the James River from the north, forms the Iowa–Nebraska boundary. At Sioux City the Big Sioux River comes in from the north; the Missouri flows south to the city of Omaha where it receives its longest tributary, the Platte River, from the west.
Downstream, it begins to define the Nebraska–Missouri border flows between Missouri and Kansas. The Missouri swings east at Kansas City, where the Kansas River enters from the west, so on into north-central Missouri. To the east of Kansas City, the Missouri receives, on the left side, the Grand River, it passes south of Columbia and receives the Osage and Gasconade Rivers from the south downstream of Jefferson City. The river rounds the northern side of St. Louis to join the Mississippi River on the border between Missouri and Illinois. With a drainage basin spanning 529,350 square miles, the Missouri River's catchment encompasses nearly one-sixth of the area of the United States or just over five percent of the continent of North America. Comparable to the size of the Canadian province of Quebec, the watershed encompasses most of the central Great Plains, stretching from the Rocky Mountains in the
The Murray River is Australia's longest river, at 2,508 kilometres in length. The Murray rises in the Australian Alps, draining the western side of Australia's highest mountains, meanders across Australia's inland plains, forming the border between the states of New South Wales and Victoria as it flows to the northwest into South Australia, it turns south at Morgan for its final 315 kilometres. The water of the Murray flows through several terminal lakes that fluctuate in salinity including Lake Alexandrina and The Coorong before emptying through the Murray Mouth into the southeastern portion of the Indian Ocean referenced on Australian maps as the Southern Ocean, near Goolwa. Despite discharging considerable volumes of water at times before the advent of largescale river regulation, the mouth has always been comparatively small and shallow; as of 2010, the Murray River system receives 58 percent of its natural flow. It is Australia's most important irrigated region, it is known as the food bowl of the nation.
The Murray River forms part of the 3,750 km long combined Murray–Darling river system which drains most of inland Victoria, New South Wales, southern Queensland. Overall the catchment area is one seventh of Australia's total land mass; the Murray carries only a small fraction of the water of comparably-sized rivers in other parts of the world, with a great annual variability of its flow. In its natural state it has been known to dry up during extreme droughts, although, rare, with only two or three instances of this occurring since official record keeping began; the Murray River makes up most of the border between the Australian states of Victoria and New South Wales. Where it does, the border is the top of the bank of the Victorian side of the river; this was determined in a 1980 ruling by the High Court of Australia, which settled the question as to which state had jurisdiction in the unlawful death of a man, fishing by the river's edge on the Victorian side of the river. This boundary definition can be ambiguous, since the river changes its course over time, some of the river banks have been modified.
West of the line of longitude 141°E, the river continues as the border between Victoria and South Australia for 11 km, where this is the only stretch where a state border runs down the middle of the river. This was due to a miscalculation during the 1840s, when the border was surveyed. Past this point, the Murray River is within the state of South Australia; the following major settlements are located along the course of the river, with population figures from the 2011 Census: The Murray River support a variety of river life adapted to its vagaries. This includes a variety of native fish such as the famous Murray cod, trout cod, golden perch, Macquarie perch, silver perch, eel-tailed catfish, Australian smelt, western carp gudgeon, other aquatic species like the Murray short-necked turtle, Murray River crayfish, broad-clawed yabbies, the large clawed Macrobrachium shrimp, as well as aquatic species more distributed through southeastern Australia such as common longnecked turtles, common yabbies, the small claw-less paratya shrimp, water rats, platypus.
The Murray River supports fringing corridors and forests of the river red gum. The health of the Murray River has declined since European settlement due to river regulation, much of its aquatic life including native fish are now declining, rare or endangered. Recent extreme droughts have put significant stress on river red gum forests, with mounting concern over their long-term survival; the Murray has flooded on occasion, the most significant of, the flood of 1956, which inundated many towns on the lower Murray and which lasted for up to six months. Introduced fish species such as carp, weather loach, redfin perch, brown trout, rainbow trout have had serious negative effects on native fish, while carp have contributed to environmental degradation of the Murray River and tributaries by destroying aquatic plants and permanently raising turbidity. In some segments of the Murray River, carp have become the only species found. Between 2.5 and 0.5 million years ago the Murray River terminated in a vast freshwater lake called Lake Bungunnia.
Lake Bungunnia was formed by earth movements that blocked the Murray River near Swan Reach during this period. At its maximum extent Lake Bungunnia covered 33,000 km2, extending to near the Menindee Lakes in the north and to near Boundary Bend on the Murray in the south; the draining of Lake Bungunnia occurred 600,000 years ago. Deep clays deposited by the lake. Higher rainfall would have been required to keep such a lake full. A species of Neoceratodus lungfish existed in Lake Bungunnia; the noted Barmah Red Gum Forests owe their existence to the Cadell Fault. About 25,000 years ago, displacement occurred along the Cadell fault, raising the eastern edge of the fault, which runs north-south, 8 to 12 m above the floodplain; this created a complex series of events. A section of the original Murray River channel immediately
A dugout canoe or dugout is a boat made from a hollowed tree trunk. Other names for this type of boat are monoxylon. Monoxylon is Greek -- mono- + ξύλον xylon -- and is used in classic Greek texts. In German, they are called einbaum. Some, but not all, pirogues are constructed in this manner. Dugouts are the oldest boats archaeologists have found, dating back about 8,000 years to the Neolithic Stone Age; this is because they are made of massive pieces of wood, which tend to preserve better than, e.g. bark canoes. Along with bark canoe and hide kayak, dugout boats were used by indigenous peoples of the Americas. Construction of a dugout begins with the selection of a log of suitable dimensions. Sufficient wood needed to be removed to make the vessel light in weight and buoyant, yet still strong enough to support the crew and cargo. Specific types of wood were preferred based on their strength and density; the shape of the boat is fashioned to minimize drag, with sharp ends at the bow and stern. First the bark is removed from the exterior.
Before the appearance of metal tools, dugouts were hollowed out using controlled fires. The burnt wood was removed using an adze. Another method using tools is to chop out parallel notches across the interior span of the wood split out and remove the wood from between the notches. Once hollowed out, the interior was smoothed out with a knife or adze. More primitive designs keep the tree's original dimensions, with a round bottom. However, it is possible to steam the sides of the hollow log until they are pliable bend to create a more flat-bottomed "boat" shape with a wider beam in the centre. For travel in the rougher waters of the ocean, dugouts can be fitted with outriggers. One or two smaller logs are mounted parallel to the main hull by long poles. In the case of two outriggers, one is mounted on either side of the hull; the Dufuna canoe from Nigeria is an 8000-year-old dugout, the oldest boat discovered in Africa, the third-oldest worldwide. The well-watered tropical rainforest and woodland regions of sub-Saharan Africa provide both the waterways and the trees for dugout canoes, which are commonplace from the Limpopo River basin in the south through East and Central Africa and across to West Africa.
African Teak is the timber favoured for their construction, though this comprises a number of different species, is in short supply in some areas. Dugouts are paddled across deep lakes and rivers or punted through channels in swamps or in shallow areas, are used for transport and hunting, including, in the past, the dangerous hunting of hippopotamus. Dugouts are called pirogues in Francophone areas of Africa. An 8000-year-old dugout canoe was found by archaeologists in Kuahuqiao, Zhejiang Province, in east China; this is the earliest canoe found in Asia. The Moken, an ethnic group that lives in Myanmar's Mergui Archipelago and the north of Thailand as sea nomads, still builds and uses dugout canoes. According to the Moken's accounts of their people's origin, a mythical queen punished the forbidden love of their ancestral forefather for his sister-in-law by banishing him and his descendants to life on sea in dugout canoes with indentations fore and aft, symbolizing the unending cycle of ingestion and evacuation.
A centuries-old unfinished dugout boat, a big banca was accidentally retrieved on November, 2010 by Mayor Ricardo Revita at Barangay Casanicolasan, Pangasinan, Philippines, in Lagasit River, near Agno River. It is now on display in front of the Municipal Town Hall. In ancient many dugouts were made for several reasons. First, it was abundant in the Paleolithic after the melting of the Weichselian glaciation and available. Secondly it grew to be one of the tallest trees in the forests of the time, making it easier to build longer boats. Linden wood lends itself well to carving and doesn't split or crack easily, it is lighter and therefore boats made from it have a better cargo capacity and are easier to carry, than most other tree types from the European old-growth forests. The Pesse canoe, found in the Netherlands, is a dugout, believed to be the world's oldest boat, carbon dated to between 8040 BCE and 7510 BCE. Other dugouts discovered in the Netherlands include two in the province of North Holland: in 2003, near Uitgeest, dated at 617-600 BC.
Dugouts have been found in Germany. In German, the craft are known as einbaum. In the old Hanseatic town of Stralsund three log-boats were excavated in 2002. Two of the boats are the oldest boats found in the Baltic area; the third boat holds the record as the longest dugout in the region. The finds have deteriorated due to poor storage conditions. In 1991, remains of a linden wood log-boat of nearly 6 meters were found at Männedorf-Strandbad in Switzerland at Lake Zürich; the boat has since been dated to be 6,500 years old. In 1902 an oak log boat over 15m long and 1m wide, was found at Addergoole Bog, County Galway and delivered to the National Museum of Ireland; the Lurgan boat radiocarbon date was 3940 +/- 25 BP. The boat has holes suggesting that it was joined to another boat. In 2012, at Parc Glyndwr, Monmouthshire, Wales, UK, an excavation by Monmouth Archeological Society, revealed three ditches suggesting a Neolithic dugout trimaran of similar length to the Lurgan log boat, carbon dated 3700+/-35 BP.
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Japan is an island country in East Asia. Located in the Pacific Ocean, it lies off the eastern coast of the Asian continent and stretches from the Sea of Okhotsk in the north to the East China Sea and the Philippine Sea in the south; the kanji that make up Japan's name mean "sun origin", it is called the "Land of the Rising Sun". Japan is a stratovolcanic archipelago consisting of about 6,852 islands; the four largest are Honshu, Hokkaido and Shikoku, which make up about ninety-seven percent of Japan's land area and are referred to as home islands. The country is divided into 47 prefectures in eight regions, with Hokkaido being the northernmost prefecture and Okinawa being the southernmost one; the population of 127 million is the world's tenth largest. 90.7 % of people live in cities. About 13.8 million people live in the capital of Japan. The Greater Tokyo Area is the most populous metropolitan area in the world with over 38 million people. Archaeological research indicates; the first written mention of Japan is in Chinese history texts from the 1st century AD.
Influence from other regions China, followed by periods of isolation from Western Europe, has characterized Japan's history. From the 12th century until 1868, Japan was ruled by successive feudal military shōguns who ruled in the name of the Emperor. Japan entered into a long period of isolation in the early 17th century, ended in 1853 when a United States fleet pressured Japan to open to the West. After nearly two decades of internal conflict and insurrection, the Imperial Court regained its political power in 1868 through the help of several clans from Chōshū and Satsuma – and the Empire of Japan was established. In the late 19th and early 20th centuries, victories in the First Sino-Japanese War, the Russo-Japanese War and World War I allowed Japan to expand its empire during a period of increasing militarism; the Second Sino-Japanese War of 1937 expanded into part of World War II in 1941, which came to an end in 1945 following the Japanese surrender. Since adopting its revised constitution on May 3, 1947, during the occupation led by SCAP, the sovereign state of Japan has maintained a unitary parliamentary constitutional monarchy with an Emperor and an elected legislature called the National Diet.
Japan is a member of the ASEAN Plus mechanism, UN, the OECD, the G7, the G8, the G20, is considered a great power. Its economy is the world's third-largest by nominal GDP and the fourth-largest by purchasing power parity, it is the world's fourth-largest exporter and fourth-largest importer. Japan benefits from a skilled and educated workforce. Although it has renounced its right to declare war, Japan maintains a modern military with the world's eighth-largest military budget, used for self-defense and peacekeeping roles. Japan is a developed country with a high standard of living and Human Development Index, its population enjoys the highest life expectancy and third lowest infant mortality rate in the world, but is experiencing issues due to an aging population and low birthrate. Japan is renowned for its historical and extensive cinema, influential music industry, video gaming, rich cuisine and its major contributions to science and modern technology; the Japanese word for Japan is 日本, pronounced Nihon or Nippon and means "the origin of the sun".
The character nichi means "sun" or "day". The compound therefore means "origin of the sun" and is the source of the popular Western epithet "Land of the Rising Sun"; the earliest record of the name Nihon appears in the Chinese historical records of the Tang dynasty, the Old Book of Tang. At the end of the seventh century, a delegation from Japan requested that Nihon be used as the name of their country; this name may have its origin in a letter sent in 607 and recorded in the official history of the Sui dynasty. Prince Shōtoku, the Regent of Japan, sent a mission to China with a letter in which he called himself "the Emperor of the Land where the Sun rises"; the message said: "Here, I, the emperor of the country where the sun rises, send a letter to the emperor of the country where the sun sets. How are you". Prior to the adoption of Nihon, other terms such as Yamato and Wakoku were used; the term Wa is a homophone of Wo 倭, used by the Chinese as a designation for the Japanese as early as the third century Three Kingdoms period.
Another form of Wa, Wei in Chinese) was used for an early state in Japan called Nakoku during the Han dynasty. However, the Japanese disliked some connotation of Wa 倭, it was therefore replaced with the substitute character Wa, meaning "togetherness, harmony"; the English word Japan derives from the historical Chinese pronunciation of 日本. The Old Mandarin or early Wu Chinese pronunciation of Japan was recorded by Marco Polo as Cipangu. In modern Shanghainese, a Wu dialect, the pronunciation of characters 日本; the old Malay word for Japan, Japun or Japang, was borrowed from a southern coastal Chinese dialect Fukienese or Ningpo – and this Malay word was encountered by Portuguese traders in Southeast Asia in the 16th century. These Early Portuguese traders brought the word
A river is a natural flowing watercourse freshwater, flowing towards an ocean, lake or another river. In some cases a river flows into the ground and becomes dry at the end of its course without reaching another body of water. Small rivers can be referred to using names such as stream, brook and rill. There are no official definitions for the generic term river as applied to geographic features, although in some countries or communities a stream is defined by its size. Many names for small rivers are specific to geographic location. Sometimes a river is defined as being larger than a creek, but not always: the language is vague. Rivers are part of the hydrological cycle. Potamology is the scientific study of rivers, while limnology is the study of inland waters in general. Most of the major cities of the world are situated on the banks of rivers, as they are, or were, used as a source of water, for obtaining food, for transport, as borders, as a defensive measure, as a source of hydropower to drive machinery, for bathing, as a means of disposing of waste.
A river begins at a source, follows a path called a course, ends at a mouth or mouths. The water in a river is confined to a channel, made up of a stream bed between banks. In larger rivers there is also a wider floodplain shaped by flood-waters over-topping the channel. Floodplains may be wide in relation to the size of the river channel; this distinction between river channel and floodplain can be blurred in urban areas where the floodplain of a river channel can become developed by housing and industry. Rivers can flow down mountains, through valleys or along plains, can create canyons or gorges; the term upriver refers to the direction towards the source of the river, i.e. against the direction of flow. The term downriver describes the direction towards the mouth of the river, in which the current flows; the term left bank refers to the left bank in the direction of right bank to the right. The river channel contains a single stream of water, but some rivers flow as several interconnecting streams of water, producing a braided river.
Extensive braided rivers are now found in only a few regions worldwide, such as the South Island of New Zealand. They occur on peneplains and some of the larger river deltas. Anastamosing rivers are quite rare, they have multiple sinuous channels carrying large volumes of sediment. There are rare cases of river bifurcation in which a river divides and the resultant flows ending in different seas. An example is the bifurcation of Nerodime River in Kosovo. A river flowing in its channel is a source of energy which acts on the river channel to change its shape and form. In 1757, the German hydrologist Albert Brahms empirically observed that the submerged weight of objects that may be carried away by a river is proportional to the sixth power of the river flow speed; this formulation is sometimes called Airy's law. Thus, if the speed of flow is doubled, the flow would dislodge objects with 64 times as much submerged weight. In mountainous torrential zones this can be seen as erosion channels through hard rocks and the creation of sands and gravels from the destruction of larger rocks.
A river valley, created from a U-shaped glaciated valley, can easily be identified by the V-shaped channel that it has carved. In the middle reaches where a river flows over flatter land, meanders may form through erosion of the river banks and deposition on the inside of bends. Sometimes the river will cut off a loop, shortening the channel and forming an oxbow lake or billabong. Rivers that carry large amounts of sediment may develop conspicuous deltas at their mouths. Rivers whose mouths are in saline tidal waters may form estuaries. Throughout the course of the river, the total volume of water transported downstream will be a combination of the free water flow together with a substantial volume flowing through sub-surface rocks and gravels that underlie the river and its floodplain. For many rivers in large valleys, this unseen component of flow may exceed the visible flow. Most but not all rivers flow on the surface. Subterranean rivers flow underground in caverns; such rivers are found in regions with limestone geologic formations.
Subglacial streams are the braided rivers that flow at the beds of glaciers and ice sheets, permitting meltwater to be discharged at the front of the glacier. Because of the gradient in pressure due to the overlying weight of the glacier, such streams can flow uphill. An intermittent river only flows and can be dry for several years at a time; these rivers are found in regions with limited or variable rainfall, or can occur because of geologic conditions such as a permeable river bed. Some ephemeral rivers flow during the summer months but not in the winter; such rivers are fed from chalk aquifers which recharge from winter rainfall. In England these rivers are called bournes and give their name to places such as Bournemouth and Eastbourne. In humid regions, the location where flow begins in the smallest tributary streams moves upstream in response to precipitation and downstream in its absence or when active summer vegetation diverts water for evapotrans
A sail is a tensile structure—made from fabric or other membrane materials—that uses wind power to propel sailing craft, including sailing ships, windsurfers, ice boats, sail-powered land vehicles. Sails may be made from a combination of woven materials—including canvas or polyester cloth, laminated membranes or bonded filaments—usually in a three- or four-sided shape. A sail provides propulsive force via a combination of lift and drag, depending on its angle of attack—its angle with respect to the apparent wind. Apparent wind is the air velocity experienced on the moving craft and is the combined effect of the true wind velocity with the velocity of the sailing craft. Angle of attack is constrained by the sailing craft's orientation to the wind or point of sail. On points of sail where it is possible to align the leading edge of the sail with the apparent wind, the sail may act as an airfoil, generating propulsive force as air passes along its surface—just as an airplane wing generates lift—which predominates over aerodynamic drag retarding forward motion.
The more that the angle of attack diverges from the apparent wind as a sailing craft turns downwind, the more drag increases and lift decreases as propulsive forces, until a sail going downwind is predominated by drag forces. Sails are unable to generate propulsive force if they are aligned too to the wind. Sails may be attached to a mast, boom or other spar or may be attached to a wire, suspended by a mast, they are raised by a line, called a halyard, their angle with respect to the wind is controlled by a line, called a sheet. In use, they may be designed to be curved in both directions along their surface as a result of their curved edges. Battens may be used to extend the trailing edge of a sail beyond the line of its attachment points. Other non-rotating airfoils that power sailing craft include wingsails, which are rigid wing-like structures, kites that power kite-rigged vessels, but do not employ a mast to support the airfoil and are beyond the scope of this article. Sailing craft employ two types of the square rig and the fore-and-aft rig.
The square rig carries the primary driving sails are carried on horizontal spars, which are perpendicular or square, to the keel of the vessel and to the masts. These spars are called yards and their tips, beyond the last stay, are called the yardarms. A ship so rigged is called a square-rigger; the square rig is aerodynamically most efficient. A fore-and-aft rig consists of sails that are set along the line of the keel rather than perpendicular to it. Vessels so rigged. Archaeological studies of the Cucuteni-Trypillian culture ceramics show use of sailing boats from the sixth millennium BCE onwards. Excavations of the Ubaid period in Mesopotamia provides direct evidence of sailing boats. Sails from ancient Egypt are depicted around 3200 BCE, where reed boats sailed upstream against the River Nile's current. Ancient Sumerians used square rigged sailing boats at about the same time, it is believed they established sea trading routes as far away as the Indus valley; the proto-Austronesian words for sail and other rigging parts date to about 3000 BCE when this group began their Pacific expansion.
Greeks and Phoenicians began trading by ship by around 1200 BCE. Triangular fore-and-aft rigs were invented in the Mediterranean as single-yarded lateen sails and independently in the Pacific as the more efficient bi-sparred crab claw sail, continue to be used throughout the world. During the 16th-19th centuries other fore-and-aft sails were developed in Europe, such as the spritsail, gaff rig, genoa and Bermuda rig mainsail, improving the upwind sailing ability of European vessels; the fore-and-aft rig began as a convention of southern Europe and the Mediterranean Sea: the gentle climate made its use practical, in Italy a few centuries before the Renaissance it began to replace the square rig which had dominated all of Europe since the dawn of sea travel. Northern Europeans were resistant to adopting the fore-and-aft rig, despite having seen its use in the course of trade and during the Crusades; the Renaissance changed this: beginning in 1475, their use increased and within a hundred years the fore-and-aft rig was in common use on rivers and in estuaries in Britain, northern France, the Low Countries, though the square rig remained standard for the harsher conditions of the open North Sea as well as for trans-Atlantic sailing.
The lateen sail proved to have better upwind performance for smaller vessels. Aerodynamic forces on sails depend on wind speed and direction and the speed and direction of the craft; the direction that the craft is traveling with respect to the true wind is called the "point of sail". The speed of the craft at a given point of sail contributes to the apparent wind —the wind speed and direction as measured on the moving craft; the apparent wind on the sail creates a total aerodynamic force, which may be resolved into drag—the force component in the direction of the apparent wind—and lift—the force component normal to the apparent wind. Depending on the alignment of the sail with the apparent wind, lift or drag may be the predominant propulsive component. Total aerodynamic force resolves into a forward, driving force—resisted by the medium through or over which the craft is passing —and a lateral force, resisted by the underwater foils, ice runners, or wheels of the sailing craft. For apparent wind angles aligned with the entry point of the sail, the sail acts as an airfoil and lift is the predominant component of propulsion.
The Rhine is one of the major European rivers, which has its sources in Switzerland and flows in an northerly direction through Germany and The Netherlands to the North Sea. The river begins in the Swiss canton of Graubünden in the southeastern Swiss Alps, forms part of the Swiss-Liechtenstein, Swiss-Austrian, Swiss-German and the Franco-German border flows through the German Rhineland and the Netherlands and empties into the North Sea; the largest city on the Rhine is Cologne, with a population of more than 1,050,000 people. It is the second-longest river in Central and Western Europe, at about 1,230 km, with an average discharge of about 2,900 m3/s; the Rhine and the Danube formed most of the northern inland frontier of the Roman Empire and, since those days, the Rhine has been a vital and navigable waterway carrying trade and goods deep inland. Its importance as a waterway in the Holy Roman Empire is supported by the many castles and fortifications built along it. In the modern era, it has become a symbol of German nationalism.
Among the biggest and most important cities on the Rhine are Cologne, Düsseldorf, Rotterdam and Basel. The variants of the name of the Rhine in modern languages are all derived from the Gaulish name Rēnos, adapted in Roman-era geography as Greek Ῥῆνος, Latin Rhenus; the spelling with Rh- in English Rhine as well as in German Rhein and French Rhin is due to the influence of Greek orthography, while the vocalisation -i- is due to the Proto-Germanic adoption of the Gaulish name as *Rīnaz, via Old Frankish giving Old English Rín,Old High German Rīn, early Middle Dutch Rijn. The diphthong in modern German Rhein is a Central German development of the early modern period, the Alemannic name Rī retaining the older vocalism, as does Ripuarian Rhing, while Palatine has diphthongized Rhei, Rhoi. Spanish is with French in adopting the Germanic vocalism Rin-, while Italian and Portuguese retain the Latin Ren-; the Gaulish name Rēnos belongs to a class of river names built from the PIE root *rei- "to move, run" found in other names such as the Reno in Italy.
The grammatical gender of the Celtic name is masculine, the name remains masculine in German and French. The Old English river name was variously inflected as feminine; the length of the Rhine is conventionally measured in "Rhine-kilometers", a scale introduced in 1939 which runs from the Old Rhine Bridge at Constance to Hoek van Holland. The river is shortened from its natural course due to a number of canalisation projects completed in the 19th and 20th century; the "total length of the Rhine", to the inclusion of Lake Constance and the Alpine Rhine is more difficult to measure objectively. Its course is conventionally divided as follows: The Rhine carries its name without distinctive accessories only from the confluence of the Rein Anteriur/Vorderrhein and Rein Posteriur/Hinterrhein next to Reichenau in Tamins. Above this point is the extensive catchment of the headwaters of the Rhine, it belongs exclusively to the Swiss canton of Graubünden, ranging from Saint-Gotthard Massif in the west via one valley lying in Ticino and Italy in the south to the Flüela Pass in the east.
Traditionally, Lake Toma near the Oberalp Pass in the Gotthard region is seen as the source of the Anterior Rhine and the Rhine as a whole. The Posterior Rhine rises in the Rheinwald below the Rheinwaldhorn; the source of the river is considered north of Lai da Tuma/Tomasee on Rein Anteriur/Vorderrhein, although its southern tributary Rein da Medel is longer before its confluence with the Anterior Rhine near Disentis. The Anterior Rhine springs from Lai da Tuma/Tomasee, near the Oberalp Pass and passes the impressive Ruinaulta formed by the largest visible rock slide in the alps, the Flims Rockslide; the Posterior Rhine starts near the Rheinwaldhorn. One of its tributaries, the Reno di Lei, drains the Valle di Lei on politically Italian territory. After three main valleys separated by the two gorges and Viamala, it reaches Reichenau in Tamins; the Anterior Rhine arises from numerous source streams in the upper Surselva and flows in an easterly direction. One source is Lai da Tuma with the Rein da Tuma, indicated as source of the Rhine, flowing through it.
Into it flow tributaries from the south, some longer, some equal in length, such as the Rein da Medel, the Rein da Maighels, the Rein da Curnera. The Cadlimo Valley in the canton of Ticino is drained by the Reno di Medel, which crosses the geomorphologic Alpine main ridge from the south. All streams in the source area are sometimes captured and sent to storage reservoirs for the local hydro-electric power plants; the culminating point of the Anterior Rhine's drainage basin is the Piz Russein of the Tödi massif of the Glarus Alps at 3,613 metres above sea level. It starts with the creek Aua da Russein. In its lower course the Anterior Rhine flows through a gorge named Ruinaulta; the whole stretch of the Anterior Rhine to the Alpine Rhine confluence next to Reichen