canal

1. An artificial waterway or artificially improved river used for travel, shipping, or irrigation.
2. Anatomy. A tube, duct, or passageway.
3. Astronomy. One of the faint, hazy markings resembling straight lines on early telescopic images of the surface of Mars.

1. To dig an artificial waterway through: canal an isthmus.
2. To provide with an artificial waterway or waterways.

[Partly French, channel, and partly Middle English, tube (from Medieval Latin canāle), both from Latin canālis, tube, channel, probably from canna, small reed. See cane.]

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Canal with a basic lock arrangement. Boats traveling upstream pass from the lower to the upper pool … (credit: © Merriam-Webster Inc.)

Artificial waterway built for transportation, irrigation, water supply, or drainage. The early Middle Eastern civilizations probably first built canals to supply drinking and irrigation water. The most ambitious navigation canal was a 200-mi (320-km) construction in what is now Iraq. Roman canal systems for military transport extended throughout northern Europe and Britain. The most significant canal innovation was the pound lock, developed by the Dutch c. 1373. The closed chamber, or pound, of a lock is flooded or drained of water so that a vessel within it is raised or lowered in order to pass between bodies of water at different elevations. Canals were extremely important before the coming of the railroad in the mid-19th century. Among the significant waterways in the U.S. were the Erie Canal, several canals linking the Great Lakes, and one connecting the Great Lakes to the Mississippi River. Modern waterway engineering enables larger vessels to travel faster by reducing delays at locks. See also Grand Canal, Panama Canal, Suez Canal.

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An artificial open channel usually used to convey water or vessels from one point to another. Canals are generally classified according to use as irrigation, power, flood-control, drainage, or navigation canals or channels. All but the last type are regarded as water conveyance canals.

Canals may be lined or unlined. Linings may consist of plain or reinforced concrete, cement mortar, asphalt, brick, stone, buried synthetic membranes, or compacted earth materials. Linings serve to reduce water losses by seepage or percolation through pervious foundations or embankments and to lessen the cost of weed control. Concrete and other hard-surface linings also permit higher water velocities and, therefore, steeper gradients and smaller cross sections, which may reduce costs and the amount of right-of-way required.

Navigation canals are artificial inland waterways for boats, barges, or ships. A canalized river is one that has been made navigable by construction of one or more weirs or overflow dams to impound river flow, thereby providing navigable depths. Locks may be built in navigation canals and canalized rivers to enable vessels to move to higher or lower water levels. A lock is a chamber equipped with gates at both upstream and downstream ends. Water impounded in the chamber is used to raise or lower a vessel from one elevation to another. The lock chamber is filled and emptied by means of filling and emptying valves and a culvert system usually located in the walls and bottom of the lock. See also Irrigation (agriculture); Transportation engineering; Water supply engineering.

The portion of the root that contains the pulp tissue and is bounded by dentin.

An artificial watercourse cut for inland navigation. Canals came into prominence in England in the late eighteenth century because of the poor state of the roads and the cheapness of water transport. As all-weather roads and railways developed, the canal became outmoded in Britain, but canalized rivers are an important mode of transport in larger countries, especially for non-perishable goods, mainly because of their low line-haul costs.

1. Channel, gutter, or pipe to convey any liquid, usually water.

2. Long, narrow, artificially created water-course for the ornamentation of a park, or for inland navigation.

3. Flute in the shaft of a column or pilaster.

4. Spiral channel (canalis) flanked by small convex mouldings from the eye following the revolutions of the volute, and carrying over to the other volute between the abacus and echinus of the Ionic capital.

Even before the Revolutionary War gave New impetus to American expansionism, the colonial political and economic elites were deeply interested in the improvement of inland transportation. Vessels that plied offshore waters, small boats and rafts on the streams down to tidewater, and local roads and turnpikes served the immediate commercial needs of farmers and townspeople in the Atlantic coastal area. But the loftier dreams of planters, merchants, and political leaders—as well as of the common farmers who constituted by far most of the free population in British America—looked beyond the "fall line" that separated the rivers flowing to the coast from those that ran to the Ohio-Mississippi basin. A vast area for settlement and productivity—and riches—lay in the interior, and by the early 1790s demands for diffusion of New transport technologies and for investment in internal improvements were voiced frequently in both state and national political forums.

It was widely recognized that unless bulk agricultural commodities, which were the staples of a commercialized and expanding farm economy, could be carried cheaply and over long distances, settlement and economic growth would be badly hampered in the region beyond the Appalachian Mountains. Then, too, there were opportunities for construction of short lines on the Atlantic seaboard to link already developed areas (coal mines, farming and lumber regions, and rising industrial sites), with the promise of immediate traffic and revenues. The latter were "exploitative" projects, tapping existing trade routes and resources; but the major east-west projects were "developmental," promoted with the goal of opening Newly or sparsely settled areas to economic opportunities. There was also a nationalistic or patriotic goal of canal promotion: to bind together far-flung sections of the young nation and to prove the efficacy of republican government.

And yet total canal construction in the United States up to 1816 totaled only 100 miles—the longest canal project being the Middlesex, which linked Boston's harbor with the farm region to the north. Other lines of some importance linked Norfolk, Virginia, to Albemarle Sound and connected the Santee River area to Charleston, South Carolina. Although many other canal projects were proposed up and down the Atlantic coast, progress was difficult because of shortages of capital and skepticism with regard to engineering feasibility projects. Moreover, regional or local jealousies notoriously worked against successful mobilization of governmental support in both the U.S. Congress and the state legislatures.

In the period from the mid-1820s to the Civil War, however, the United States underwent a vast expansion of canal construction, becoming the world's leading nation in both mileage of canals and the volume of tonnage carried on them. The canal lines were of crucial importance in the integration of a national economy, and they played a key role in the so-called "Transportation Revolution" that expedited both westward expansion and a robust industrialization process in the North and West.

Advantages, Disadvantages, and Construction Challenges

Canal technology proved especially attractive for several reasons. Since the 1760s, successful large-scale canal projects had been built in both Great Britain and France, and these canals had brought enormous economic advantages to the regions they served. The engineering advances pioneered in Europe gave American promoters confidence that they could build canals with equal success.

There was a downside to canal technology, too, though it was not always fully recognized in America. Difficult topography or uncertain water supply meant complex and highly expensive construction design. Canal building before the 1850s was mainly done with hand tools, augmented only by some primitive animal-powered machinery. A canal line had to be furnished with locks, permitting boats to pass through from one water level to another. The segments of line between the locks were of very gradual grade to permit controlled flow. At each lock, a gate at its higher level would be opened while the gate on the lower end was kept closed; once a boat entered the lock's chamber from the higher level, the upper gate was closed (holding the water flow back) while the lower gate was opened. As water ran out, the boat was carried down to the lower level, then passed through the open gate. For "upstream" movement, from the lower level to the higher, the process was reversed. The lock would be drained to the lower level, the boat would enter through the bottom gate, which was then closed, and water would then be admitted from the upper gate, lifting the boat up to the higher level. In steep areas, "flights" of locks, closely spaced, were necessary and often involved complex engineering; for transit of the boats, these series of locks meant a slow stretch and usually long waiting periods.

Locks varied in size. Lifts ranged from two to thirty feet, and there were great differences in the distances between gates as well as in the construction materials used. Masonry locks and metal or metal-trimmed gates were far more expensive—and more durable—than wooden gates and timber-supported rubble for the walls as found on some of the lines. The total rise and fall over an entire line was measured as "lockage," and served as an index of the difficulty of construction. For example, New York's Erie Canal route measured lockage of 655 feet, by contrast with Pennsylvania's lockage of 3,358 feet between Philadelphia and the Ohio River.

The size of the boats that could be accommodated, as well as the volume of water needed, were functions of the dimensions of the canal bed, or its "prism," as well as of the size of lock chambers. Prisms on American canals varied greatly, most of them ranging from forty to sixty feet in width at the top, with sloping sidewalls leading to a bottom of twenty-five to forty-five feet across. The Pennsylvania system was the most complex in engineering using inclined planes and steam-powered winches to drag boats out of the water and over some of the steepest hills.

To supply the line with flowing water, engineering plans had to include river connections, dams and reservoirs with feeder lines to the canals, and often massive culverts and aqueducts. Building the sidewalls to minimize loss of water through seepage was another challenging and expensive aspect of design. On many of the larger canals, such as the Ohio lines, engineers took advantage of fast-flowing feeder streams to design water-mill sites into the line.

Once a canal was in operation, moreover, maintaining navigation was a continuous challenge. Winter ice, droughts, floods, and breaches in the water-supply system would frequently cause navigational closings. Even in the best of circumstances, it was difficult to maintain regular schedules on the lines because of traffic bottlenecks at the locks and the continuous maintenance needed to keep water flowing.

Although steam-powered propeller craft were used on a few canal lines, this form of transport placed dangerous pressure on the canal walls. Hence, the use of horses or mules to haul canal boats was nearly universal, with the animals walking along the "towpath" alongside the line. Freight boats typically of 50-to 125-ton capacity operated at speeds of one to three miles per hour. On most lines they were owned by individuals or private companies, the line being a common carrier under the law.

In the short run, all the disadvantages of canal technology were more than offset by the cost savings for long-distance hauling, especially of bulk goods and produce. In the long run, however, innovations in steam technology and railroad engineering were destined to render many canals the losers in a New competitive age in transport that took shape in the late 1840s and the 1850s.

The Erie Canal

The great breakthrough came in 1817 with New York State's commitment to building the Erie Canal to connect the Hudson River at Albany with Buffalo on Lake Erie, a project far greater than any previously attempted in America. The Erie was important to subsequent canal development in several ways, most notably because it provided a model of public enterprise through its financing, administration, and implementation. The state raised capital through bond issues both in New York and in Europe, and supplemented these funds with tax revenues. Actual construction was overseen by a board of commissioners, some of whom were personally involved in the fieldwork, but the project became a celebrated "school for engineers," with most of the junior personnel learning their skills on the job under the tutelage of Benjamin Wright and James Geddes, two of less than twenty men who then constituted the profession in America. Many of the Erie engineers went on to direct canal surveys in other states.

The canal was divided into sections for purpose of construction, with private contractors taking on the work under the state engineers' supervision—a scheme that was emulated by nearly all the major canals subsequently built. It was an immediate commercial success once opened to its full length in 1825, leading the New York legislature to authorize a series of additional canals as well as the improvement and enlargement of the original line.

No nonmilitary enterprise in the United States had ever involved such expenditures as did the Erie, whose initial construction cost $6 million. The number of laborers employed was also unprecedented in any economic enterprise of the day. The state's construction expenditures energized local economies, giving part-time employment to farmers and creating sudden demand for stone, timber, mules, and oxen, and provisions for workers. Like canals and other public works throughout the country, moreover, the Erie attracted immigrant workers (mainly Irish and German) who were employed to do much of the most dangerous work.

The Erie's commercial impact on the rural countryside and on New York City's role as a center for trade with the interior and for exports to Europe—together with the rich stream of revenues from the tolls—heightened expectations everywhere in the country that other canals could produce equally spectacular fiscal and developmental results.

The Post-1825 Boom in Canal Building

Emulation of New York followed quickly. In 1825 Pennsylvania authorized a $10 million project, combining canal technology with the use of inclined planes. It was completed in 1834, tapping the Ohio Valley's farm country at Pittsburgh and giving Philadelphia trade advantages similar to those that its rival New York City had obtained from the Erie. The first of the western states to build a major line was Ohio, which authorized construction in 1825. Although still small in population and financial resources, Ohio, too, resorted to creation of a state enterprise and borrowed heavily both in the East and in Europe. Erie Canal engineers were brought in at first, but Alfred Kelley of Cleveland and Micajah Williams of Cincinnati, local entrepreneurs with no prior engineering experience, took principal charge of overseeing construction once the technical plans were adopted. Although administrative incompetence and corruption plagued the Pennsylvania project, Ohio's record was widely admired for its efficiency and strength of design. One line, the Ohio Canal, was completed in 1834 and extended from Cleveland on Lake Erie to Portsmouth on the Ohio River—the first water link between the Great Lakes and the great Mississippi-Ohio basin. A second line, completed in the mid-1840s, linked Cincinnati with Toledo to the north.

Other important lines begun or fully built prior to 1840 included the Delaware and Hudson Canal, a successful private line in the Pennsylvania coal country; the Delaware and Raritan Canal, also private, linking Philadelphia and New York; and the Chesapeake and Delaware Ohio Canal, which with substantial state support built a line, surveyed by the engineer William Strickland, through Maryland to link Baltimore with the Philadelphia port.

In the period 1815–1834, $60 million was invested in 2,088 miles of canals, with 70 percent of the funds coming from governmental sources, mainly the states. Most of the funds were borrowed at home and abroad. Also, Congress authorized the Army Engineers to conduct surveys for the states and federal companies; made some direct federal investments; and gave several million acres of public lands to Ohio, Indiana, and Illinois to subsidize their canal projects during this period.

In the decade following, 1834–1844, the "canal enthusiasm" continued to animate state governments and private promoters. Rivalries among states and competition among cities were intense, feeding the spirit of optimism. A new wave of canal construction followed, with the projects again heavily financed by loans from Europe and the eastern cities. Almost 1,300 miles of canal were built during this ten-year period. They cost $72 million, of which 79 percent represented public funds. In addition to major New state canal systems begun in Illinois and in Indiana (where the Wabash and Erie line would open another link for direct trade between the Ohio River and Lake Erie), and in Illinois, three of the pioneering state projects—the Erie, Ohio's two main canals, and the Pennsylvania system—were further expanded to satisfy sections of their states that had been left out of the original system designs. As the New canals were generally of larger dimensions than the first ones to be built, the carrying capacity for canal traffic doubled between 1834 and 1844. Until 1839, conditions of prosperity and expansion sustained the canal-building movement, and expenditures for the New canals stimulated overall economic growth.

Financial Problems and Railroad Competition

The 1837 financial panic and the 1839–1843 depression created enormous fiscal problems for many canal states, leading to defaults on state debts in Pennsylvania and Indiana. Because many of the expansion projects and new lines produced toll revenues far below expectations, moreover, there was widespread disillusionment with state enterprise; and this became a factor favoring railroads as an alternative to canals, especially given the much greater reliability of rail transport. In the Ohio-Indiana-Illinois area, by 1848 the proliferation of canal lines also produced intensified competition between the various Great Lakes and Mississippi River routes, now also served by steamboat lines on these connecting waters. The east-west and local railroads of the 1850s made matters worse. The result was heavy downward pressure on canal rates, consequently reduced revenues, and, soon, a scenario of operating deficits that placed an unwelcome burden on taxpayers.

Transport competition drove down rates so much that the period from the mid-1840s to the Civil War formed a distinctive "second phase" of the Transportation Revolution. By 1850–1852, for example, western canal tolls were less than a third the level of the 1830s, creating still further fiscal problems for the canal states and companies. Where private investment had been invited on a matching basis for "mixed" canal enterprises, the costs fell hard on the capitalists as well. But while revenues fell, ton-miles of canal transportation continued to expand on all the major lines throughout the 1850s.

During the period 1844–1860, a last major cycle of canal construction produced 894 miles of line at a cost of $57 million. Here again, governmental activism was crucial, with public funds accounting for two-thirds of the total expended. Much of this increase constituted the completion or improvement of lines built earlier; in addition, the still-successful Erie system in New York was further enlarged and upgraded. A large expenditure was made, too, on the Sault Ste. Marie Ship Canal, a short but massive deepwater project that connected Lake Huron with Lake Superior.

Although much of the canal system experienced operating deficits in the 1850s, the impetus these New facilities had given the economy had clearly warranted most of the capital invested. Commercialization of agriculture in the western states and other interior had been made possible, while eastern manufacturers and importers were afforded economical access to interior markets. Coal-mining and iron centers were linked, and consumer prices fell where the transport facilities had proliferated. In sum, the areas served by canals were enabled to build on comparative economic advantage; and, at least in the northern states, processing of primary products carried by the canals served as the origin of manufacturing growth that augmented urban commercial activity.

Railroad competition led to many closings of once-important canals; indeed, more than 300 miles of line were abandoned by 1860. A few of the canals did continue to carry heavy traffic after the Civil War. The most important to commerce in the twentieth century was the Atlantic intra-coastal waterway, which permitted vessels to transit offshore waters safely from New England to Florida. The Erie retained importance as a barge canal, as did some of the shorter coal-carrying lines. Some of the old canal lines became rights-of-way for railroads or modern roads; others were absorbed into the changing landscape as development went forward. In scattered locations, a few segments of the great canal lines are today preserved or restored for enjoyment of citizens seeking a glimpse of the once-glorious era of canal transport in America.

Bibliography

Fishlow, Albert. "Internal Transportation in the Nineteenth and Early Twentieth Centuries." In The Cambridge Economic History of the United States. Edited by Stanley L. Engerman and Robert E. Gallman. Volume 2. New York: Cambridge University Press, 2000.

Goodrich, Carter. Government Promotion of American Canals and Railroads, 1800–1890. New York: Columbia University Press, 1960. Reprint, Westport, Conn.: Greenwood Press, 1974.

Goodrich, Carter, ed. Canals and American Economic Development. New York: Columbia University Press, 1961.

Gray, Ralph D. The National Waterway: A History of the Chesapeake and Delaware Canal, 1769–1965. 2d ed. Urbana: University of Illinois Press, 1989. The original edition was published in 1967.

Larson, John Lauritz. Internal Improvement: National Public Works and the Promise of Popular Government in the Early United States. Chapel Hill: University of North Carolina Press, 2001.

Scheiber, Harry N. Ohio Canal Era: A Case Study of Government and the Economy, 1820–1861. 2d ed. Athens: Ohio University Press, 1987. The original edition was published in 1969.

Shaw, Ronald E. Canals for a Nation: The Canal Era in the United States, 1790–1860. Lexington: University of Kentucky Press, 1990.

Taylor, George Rogers. The Transportation Revolution, 1815– 1860. New York: Rinehart, 1951. Reprint, Armonk, N.Y.: M. E. Sharpe, 1989.

—Harry N. Scheiber

A relatively narrow tubular passage or channel.

• accessory c. — see lateral canal (below).
• alar c. — in the body of the basisphenoid bone, transmits the maxillary artery.
• alimentary c. — the digestive tube from mouth to anus. See also alimentary canal.
• anal c. — the terminal portion of the alimentary canal, from the rectum to the anus.
• atrioventricular c. — the common canal connecting the primitive atrium and ventricle; it sometimes persists as a congenital anomaly.
• birth c. — the canal through which the fetus passes in birth.
• carotid c. — one in the pars petrosa of the temporal bone, transmitting the internal carotid artery to the cranial cavity.
• carpal c. — on the palmar surface of the equine carpus where the carpal groove is converted into a canal by the flexor retinaculum which stretches from the accessory carpal bone to the medial side of the carpus. It houses the flexor tendons.
• central brain c. — lumen of the neural tube of the embryo within the brain.
• cervical c. — the part of the uterine cavity lying within the cervix.
• condyloid c. — in the occipital bone; transmits a vein.
• c. of Corti — a space between the outer and inner rods of Corti.
• external ear c. — the canal from the external auditory meatus to the eardrum.
• facial c. — osseous tube in the temporal bone that transmits the facial nerve.
• femoral c. — in the groin on the medial aspect of the thigh; contains the femoral artery and vein.
• c's of Gartner — in the ventral wall of the vagina; they are remnants of the mesonephric ducts and very variable in their occurrence. Called also ductus epoophori longitudinales.
• haversian c. — see haversian canal.
• c's of Hering — openings between the bile canaliculi and the cholangioles, the terminal ducts of the biliary duct system. Called also cholangiole.
• hyaloid c. — central canal of the vitreous humor running from the lens to the optic disk.
• hypoglossal c. — an opening in the occipital bone, transmitting the hypoglossal nerve and a branch of the posterior meningeal artery; called also anterior condyloid foramen.
• infraorbital c. — a canal running obliquely from the front of the orbit to the side of the muzzle, transmitting the infraorbital vessels and nerve. In the horse it passes through the maxillary sinus.
• inguinal c. — the oblique passage in the caudal abdominal wall on either side, through which passes the round ligament of the uterus in some females such as the bitch and the spermatic cord in the males.
• intestinal c. — small and large intestines.
• lacrimal c. — the nasolacrimal canal.
• lateral c. — a small canal in the root of a tooth which emerges on the side, rather than the apex. Called also accessory canal.
• mandibular c. — a passageway within the mandible for conduction of the inferior alveolar vessels and nerve; the inferior alveolar nerve enters the mandibular canal through the mandibular foramen and exits at the mental foramen supplying nerves to the lower cheek teeth in passing.
• medullary c. — 1. vertebral canal.
— 2. the cavity, containing marrow, in the diaphysis of a long bone; called also marrow or medullary cavity.
• metatarsal c. — formed by the metatarsal fascia on the plantar aspect of the chief metatarsal bone of the horse; transmits the tendons of the digital flexor muscles.
• modiolar c. — in the cochlea of the internal ear; it transmits blood vessels and nerves to the cochlea.
• nasolacrimal c. — in the maxilla it transmits the nasolacrimal duct.
• nutrient c's — large vascular canals through the cortex of bones. See also haversian canal.
• omasal c. — the direct passage through the omasum from the reticulum to the abomasum.
• optic c. — a passage for the optic nerve through the cranium into the orbit.
• palatine c. — formed by the maxilla and the palatine bone; transmits the palatine artery and nerve.
• pterygoid c. — in the basisphenoid bone; contains the pterygoid nerve.
• root c. — see root canal.
• sacral c. — the part of the vertebral canal through the sacrum.
• Schlemm's c. — the venous sinus of the sclera, a circular canal at the junction of the sclera and cornea that receives the aqueous humour. Called also scleral venous sinus.
• semicircular c's — the canals (anterior, lateral and posterior) of the bony labyrinth of the ear. See also semicircular canals.
• spinal c., vertebral c. — the canal formed by the series of vertebral foramina together, enclosing the spinal cord and meninges.
• supraorbital c. — in the frontal bone; transmits the frontal vein, passing through the zygomatic process to the orbital cavity.
• tarsal c. — formed by the plantar annular ligament of the tarsus which roofs over the tarsal groove; transmits the deep digital flexor tendon and plantar vessels.
• triosseus c. — the foramen at the junction of the coracoid, clavicle and scapula which transmits the tendon of a flight muscle, the supracoracoideus, in the avian skeleton.
• vertebral c. — spinal canal.
• Volkmann's c's — canals communicating with the haversian canals, for passage of blood vessels through bone from the periosteum.

From earliest civilized times people built canals for irrigation. Anyone who has ever portaged even a small canoe from one stream or lake to another has envisioned a canal replacing his or her trail, so the canal idea was extended from providing water for crops to providing a highway for boats. The technology of a short, level canal between two bodies of water at the same height is as simple as can be -- all you need is enough people to dig. In China, where finding enough people has never been a problem, transportation canals became important as early as the third century bce. In the West, early transportation canals were developed primarily to shorten sea routes, but Chinese canals connected river systems and bound the people together. Terrain was one of the reasons Chinese canals got a head start on European ones. Many of the obvious places that needed connecting in Europe were separated by rocky hills or even mountains. Where it was clear that a canal could help shipping, as across a narrow peninsula or between nearby bodies of water, Westerners built or at least planned to build canals.

Intervening changes in land height and different water levels posed problems. Canals could be and were built in sections; boats were hauled up artificial rapids from one level section to another or even on land around barriers. In the tenth century in China, the canal lock, or pound lock, was developed to permit better connections. Such locks enabled the Chinese Grand Canal to rise from sea level to 42 m (138 ft) above. Several hundred years later the idea of the lock was taken up by the West at a time when many Chinese influences began to be felt in Europe (paper and gunpowder are the best known), although by that time locks and canals had passed their greatest days in China.

With the coming of locks, certainly known in Italy in the 15th century, European canal building began to enter its great period of expansion. Canal building spread in much the same pattern as the Black Death had earlier, although more slowly and, of course, with more positive results. France began to build major canals in the 17th century, while England and northern Europe became more active in the 18th. In France, the grand project of connecting the two French coasts (Atlantic and Mediterranean) was active intermittently for more than 150 years before becoming reality in 1681. Other major French canals were built around this time as well. The French canals, like most canals that were to follow, were too narrow for much sailing. Instead, ships were towed through the canals by animals, such as mules, that walked on paths along the banks.

The French canals inspired the English. Notably, the Duke of Bridgewater, Francis Egerton, having seen French canals while on the Grand Tour, hired surveyor James Brindley, who had previous planned a canal but never built one, to construct a canal between coal mines on his estate at Worsley and the booming industrial center at Manchester. The Bridgewater (Worsley) Canal opened for traffic in 1761 and for some historians this date marks the beginning of the Industrial Revolution, for the cheap coal, available year-round, fueled all the factories of Manchester. Brindley became much sought after as a canal designer by various commercial enterprises.

By 1792 there were no less than 30 different canal schemes competing for capital financing in England. The craze spread back from England to the Continent, inspiring canal projects in Scandinavia, Russia, the Low Countries, Germany, and even back to the country of England's inspiration, France. Not only were new canals built, but also existing rivers were converted into canals by building walls and leveling river bottoms.

By the end of the 18th century or the beginning of the 19th, canal building had spread far beyond Europe. Canals were a feature of life in the United States and Canada in the early 19th century. Egypt, with an early history of canal building that had lapsed two millennia earlier, linked Alexandria with the navigable Nile using a canal built by 350,000 peasants, working largely with their bare hands.

Although the railroad was to replace the canal for inland commercial hauling in the 19th century, there were still two great ship canals needed, projects to carry goods beyond the capacity of rails. Ships carrying goods or passengers between Europe and the East Coast of North America, the two main commercial centers of the world of the 19th century, had to pass around either Africa or South America to reach the lucrative and populous Asian continent. Fairly short canals, albeit through difficult terrain, could shorten such journeys by thousands of kilometers. This solution was reached for Africa by the Suez Canal, between the Mediterranean and Red seas, which opened in 1869, although it was not commercially viable until the British deepened and widened it late in the 19th century. The Panama Canal connected the Atlantic and Pacific oceans in 1914. Both great canals were among the most colossal engineering enterprises of the time. A glance at the map of the world shows that these two canals finish off the only available opportunities to improve linkages so dramatically with relatively short waterways.

Although canals will continue to be built for special purposes, the great age of canal building is over. Although the age is past, canals delight people still. Devoid of serious shipping, remaining inland canals boast pleasure boats and even special canal excursions. A few canals -- Panama, Suez, St. Lawrence Seaway -- continue to have great economic presence, but for the most part canals reflect a more gracious period for shipping that passed well over a hundred years ago.

As a waterway that must be constructed (in contrast to a stream or a river), dreaming about a canal might be about channeling or directing our feelings. It could also be emblematic of our goals.

For other uses, see Canal (disambiguation).

The Alter Strom, in the sea resort of Warnemünde, Germany.

The Royal Canal in Ireland.

Canals are man-made channels for water. There are two types of canal:

1. Aqueduct (or water conveyance) canals that are used for the conveyance and delivery of fresh water, for human consumption, agriculture, etc.
2. Waterway canals that are navigable transportation canals used for carrying ships and boats loaded with goods and people, often connected to existing lakes, rivers, or oceans. Included here are inter-ocean canals such as the Suez Canal and the Panama Canal.

Many decades ago, it was thought by some astronomers, such as the American Percival Lowell (1855 - 1916), that there were thousands-of-miles-long canals on the planet Mars that had been constructed by intelligent beings there. They were thought to be used by the Martians to carry water from the ice caps to martian farmland closer to the equator. However, this notion has been completely overthrown, especially with pictures taken by spacecraft that were sent to Mars. It has been found that the appearance of martian canals through telescopes was merely an optical illusion formed in the minds of dozens of astronomers such as Lowell.

The word "canal" is also used for a city-canal (gracht) in Dutch cities.

Contents 1 Types of artificial waterways 2 Features 3 History 3.1 Ancient canals 3.2 Canals in the Middle Ages 3.3 Industrial revolution 3.4 The 19th century 3.5 Modern uses 4 Cities on water 5 Boats 6 Lists of canals 7 See also 8 References 8.1 Notes 8.2 Bibliography 9 External links

Types of artificial waterways

The Danube-Black Sea Canal in Romania

Some canals are part of an existing waterway. This is usually where a river has been canalised: making it navigable by widening and deepening some parts (by dredging, weirs or both), and providing locks with "cuts" around the weirs or other difficult sections. In France, these waterways are called lateral canals and in the UK they are generally called navigations, and the length of the artificial waterway often exceeds the natural. The individual cuts that make up such a canal system may each be called a reach.^[1]

Smaller transportation canals can carry barges or narrowboats, while ship canals allow seagoing ships to travel to an inland port (e.g.: Manchester Ship Canal), or from one sea or ocean to another (e.g.: Caledonian Canal, Panama Canal).

Features

The flight of 16 consecutive locks at Caen Hill on the Kennet and Avon Canal, Wiltshire, England

A canal boat traverses the longest and highest aqueduct in the UK, at Pontcysyllte in Denbighshire, Wales

At their simplest, canals consist of a trench filled with water. Depending on the stratum the canal passes through, it may be necessary to line the cut with some form of watertight material such as clay or concrete. When this is done with clay this is known as puddling.

Canals need to be level, and while small irregularities in the lie of the land can be dealt with through cuttings and embankments, for larger deviations, other approaches have been adopted. The most common is the pound lock which consists of a chamber within which the water level can be raised or lowered connecting either two pieces of canal at a different level or the canal with a river or the sea. When there is a hill to be climbed, flights of many locks in short succession may be used.

Prior to the development of the pound lock in 984AD in China by Chhaio Wei-Yo^[2] and later in Europe in the 15th century, either flash locks consisting of a single gate were used or ramps, sometimes equipped with rollers, were used to change level. Flash locks were only practical where there was plenty of water available.

Locks use a lot of water, so builders have adopted other approaches. These include boat lifts, such as the Falkirk wheel, which use a caisson of water in which boats float while being moved between two levels; and inclined planes where a caisson is hauled up a steep railway.

To cross a stream or road, the solution is usually to bridge with an aqueduct. To cross a wide valley (where the journey delay caused by a flight of locks at either side would be unacceptable) the centre of the valley can be spanned by an aqueduct - a famous example in Wales is the Pontcysyllte aqueduct across the valley of the River Dee.

Another option for dealing with hills is to tunnel through them. An example of this approach is the Harecastle Tunnel on the Trent and Mersey Canal. Tunnels are only practical for smaller canals.

Some canals attempted to keep changes in level down to a minimum. These canals known as contour canals would take longer winding routes, along which the land was a uniform altitude. Other generally later canals took more direct routes requiring the use of various methods to deal with the change in level.

Canals have various features to tackle the problem of water supply. In some cases such as the Suez Canal the canal is simply open to the sea. Where the canal is not at sea level a number of approaches have been adopted. Taking water from existing rivers or springs was an option in some cases, sometimes supplemented by other methods to deal with seasonal variations in flow. Where such sources were unavailable, reservoirs, either separate from the canal, or built into its course, and back pumping were used to provide the required water. In other cases water pumped from mines was used to feed the canal.

Where large amounts of goods are loaded or unloaded such as at the end of a canal a canal basin may be built. This would normally be a section of water wider than the general canal. In some cases the canal basins contain wharfs and cranes to assist with movement of goods.

When a section of the canal needs to be sealed off so it can be drained for maintenance stop planks are frequently used. These consist of planks of wood placed across the canal to form a dam. They are generally placed in pre existing grooves in the canal bank.

History

Ancient canals

The Grand Canal of China at Suzhou

The oldest known canals were irrigation canals, built in Mesopotamia circa 4000 BC, in what is now modern day Iraq and Syria. The Indus Valley Civilization in Pakistan and North India (circa 2600 BC) had sophisticated irrigation and storage systems developed, including the reservoirs built at Girnar in 3000 BC.^[3] In Egypt, canals date back at least to the time of Pepi I Meryre (reigned 2332–2283 BC), who ordered a canal built to bypass the cataract on the Nile near Aswan.^[4]

In ancient China, large canals for river transport were established as far back as the Warring States (481-221 BC), the longest one of that period being the Hong Gou (Canal of the Wild Geese), which according to the ancient historian Sima Qian connected the old states of Song, Zhang, Chen, Cai, Cao, and Wei.^[5] By far the longest canal was the Grand Canal of China, still the longest canal in the world today. It is 1,794 kilometres (1,115 mi) long and was built to carry the Emperor Yang Guang between Beijing and Hangzhou. The project began in 605 and was completed in 609, although much of the work combined older canals, the oldest section of the canal existing since at least 486 BC. Even in its narrowest urban sections it is rarely less than 30 metres (98 ft) wide.

Canals in the Middle Ages

Thal Canal, Punjab, Pakistan.

During the Muslim Agricultural Revolution, artificial canals, which were previously limited to specific regions, were incorporated into the 'water management technological complex' used by Muslim engineers. They subsequently diffused the technology across the Caliphate and to the rest of the Old World. For each region they introduced them to, they integrated the canals "into a quite different social, cultural and economic system than that prevailing before, according to norms they brought with them." In this manner, artificial canals were introduced to Europe through Islamic Spain.^[6]

In the Middle Ages, water transport was cheaper and faster than transport overland. This was because roads were unpaved and in poor condition and greater amounts could be transported by ship. The first artificial canal in Christian Europe was the Fossa Carolina built at the end of the 8th Century under personal supervision of Charlemagne. More lasting and of more economic impact were canals like the Naviglio Grande built between 1127 and 1257, the most important of the lombard “navigli”,^[7] Later, canals were built in the Netherlands and Flanders to drain the polders and assist the transportation of goods.

Canal building was revived in this age because of commercial expansion from the 12th century AD. River navigations were improved progressively by the use of single, or flash locks. Taking boats through these used large amounts of water leading to conflicts with watermill owners and to correct this, the pound or chamber lock first appeared, in 10th century AD in China and in Europe in 1373 in Vreeswijk, Netherlands.^[8] Another important development was the mitre gate which was probably introduced in Italy by Bertola da Novate in the sixteenth century. This allowed wider gates and also removed the height restriction of guillotine locks.

To break out of the limitations caused by river valleys, the first summit level canals were developed with the Grand Canal of China in 581-617 AD whilst in Europe the first, also using single locks, was the Stecknitz Canal in Germany in 1398. The first to use pound locks was the Briare Canal connecting the Loire and Seine (1642), followed by the more ambitious Canal du Midi (1683) connecting the Atlantic to the Mediterranean. This included a staircase of 8 locks at Béziers, a 157 metres (520 ft) tunnel and three major aqueducts.

Canal building progressed steadily in Germany in the 17th and 18th centuries with three great rivers, the Elbe, Oder and Weser being linked by canals. In post-Roman Britain, the first canal built appears to have been the Exeter Canal, which opened in 1563. The oldest canal built for industrial purposes in North America is Mother Brook in Dedham, MA. It was constructed in 1639 to provide water power for mills. In Russia, the Volga-Baltic Waterway, a nationwide canal system connecting the Baltic and Caspian seas via the Neva and Volga rivers, was opened in 1718.

Industrial revolution

Lowell's power canal system

See also: History of the British canal system

Canals were important for the industrial development. That's why the greatest stimulus to canal systems came from the Industrial Revolution with its need for cheap transport of raw materials and manufactured items.

In Europe, particularly Britain and Ireland, and then in the young United States and the Canadian colonies, inland canals preceded the development of railroads during the earliest phase of the Industrial Revolution. The opening of the Sankey Canal in 1757, followed by the Bridgewater Canal in 1761, which halved the price of coal in Liverpool and Manchester, respectively, triggered a period of "canal mania" in Britain so that between 1760 and 1820 over one hundred canals were built.

The Blackstone Canal in Massachusetts and Rhode Island fulfilled a similar role in the early industrial revolution between 1828-1848. The Blackstone Valley was considered the 'birthplace' of the American Industrial Revolution where Samuel Slater built his first mill.

In addition to their transportation purposes, parts of the United States, particularly in the Northeast, had enough fast-flowing rivers that water power was the primary means of powering factories (usually textile mills) until after the American Civil War. For example, Lowell, Massachusetts, considered to be "The Cradle of the American Industrial Revolution," has 6 miles (9.7 km) of canals, built from around 1790 to 1850, that provided water power and a means of transportation for the city. The output of the system is estimated at 10,000 horsepower^[9]. Other cities with extensive power canal systems include Lawrence, Massachusetts, Holyoke, Massachusetts, Manchester, New Hampshire, and Augusta, Georgia.

The 19th century

US canals circa 1825

Competition from the railway network from the 1830s, and in the 20th century the roads, made the smaller canals obsolete for most commercial transportation, and many of the British canals fell into decay. Only the Manchester Ship Canal and the Aire and Calder Canal bucked this trend. Yet in other countries canals grew in size as construction techniques improved. During the 19th century in the US, the length of canals grew from 100 miles (161 km) to over 4,000, with a complex network making the Great Lakes navigable, in conjunction with Canada, although some canals were later drained and used as railroad rights-of-way.

In the United States, navigable canals reached into isolated areas and brought them in touch with the world beyond. By 1825 the Erie Canal, 363 miles (584 km) long with 82 locks, opened up a connection from the populated Northeast to the Great Lakes. Settlers flooded into regions serviced by such canals, since access to markets was available. The Erie Canal (as well as other canals) was instrumental in lowering the differences in commodity prices between these various markets across America. The canals caused price convergence between different regions because of their reduction in transportation costs, which allowed Americans to ship and buy goods from farther distances for much lower prices compared to before. Ohio built many miles of canal, Indiana had working canals for a few decades, and the Illinois and Michigan Canal connected the Great Lakes to the Mississippi River system until replaced by a channelized river waterway.

Three major canals with very different purposes were built in what is now Canada. The first Welland Canal, which opened in 1829 between Lake Ontario and Lake Erie, bypassing Niagara Falls and the Lachine Canal (1825) which allowed ships to skirt the nearly impassable rapids on the St. Lawrence River at Montreal were built for commerce. The Rideau Canal, completed in 1832, connects Ottawa, on the Ottawa River to Kingston, Ontario on Lake Ontario. The Rideau Canal was built as a result of the War of 1812 to provide military transportation between the British colonies of Lower Canada and Lower Canada as an alternative to part of the St. Lawrence River which was susceptible to blockade by the United States.

In France, a steady linking of all the river systems—Rhine, Rhône, Saône and Seine—and the North Sea was boosted in 1879 by the establishment of the Freycinet gauge which specified the minimum size of locks so that canal traffic doubled in the first decades of the 20th century.^[10]

Many notable sea canals were completed in this period, starting with the Suez Canal (1869), and the Kiel Canal (1897), which carries tonnage many times that of most other canals, though the Panama Canal was not opened until 1914.

In the 19th century, a number of canals were built in Japan including the Biwako canal and the Tone canal. These canals were partially built with the help of engineers from the Netherlands and other countries.^[11]

Modern uses

Canals can disrupt water circulation in marsh systems.

Large scale ship canals such as the Panama Canal and Suez Canal continue to operate for cargo transportation; as do European barge canals. Due to globalization, they are becoming increasingly important, resulting in expansion projects such as the Panama Canal expansion project.

The narrow early industrial canals however have ceased to carry significant amounts of trade and many have been abandoned to navigation, but may still be used as a system for transportation of untreated water. In some cases railways have been built along the canal route, an example being the Croydon Canal.

A movement that began in Britain and France to use the early industrial canals for pleasure boats, such as hotel barges, has spurred rehabilitation of stretches of historic canals. In some cases abandoned canals such as the Kennet and Avon Canal have been restored and are now used by pleasure boaters. In Britain canalside housing has also proven popular in recent years.

The Seine-Nord Europe Canal is being developed into a major transportation waterway, linking France with Belgium, Germany and the Netherlands.

Canals have found another use in the 21st century, as wayleaves along the towing paths for fibre optic telecommunications networks.

Cities on water

An intersection of two canals (Grachten) in Amsterdam, The Netherlands.

Canals are so deeply identified with Venice that many canal cities have been nicknamed "the Venice of..." The city is built on marshy islands, with wooden piles supporting the buildings, so that the land is man-made rather than the waterways. The islands have a long history of settlement; by the 12th century, Venice was a powerful city state.

Amsterdam was built in a similar way, with buildings on wooden piles. It became a city around 1300.

Other cities with extensive canal networks include: Delft, Haarlem and Leiden in the Netherlands, Brugge in Flanders, Birmingham in England which has 35 miles of canals to Venice's 26 miles, Saint Petersburg in Russia, Hamburg in Germany, Fort Lauderdale, Florida, and Cape Coral, Florida in the United States.

Liverpool Maritime Mercantile City is a UNESCO World Heritage Site near the centre of Liverpool, England, where a system of intertwining waterways and docks now being developed for mainly residential and leisure use.

Canal estates are a form of subdivision popular in cities like Miami, Florida and the Gold Coast, Queensland; the Gold Coast has over 700 km of residential canals. Wetlands are difficult areas upon which to build housing estates, so dredging part of the wetland down to a navigable channel provides fill to build up another part of the wetland above the flood level for houses. Land is built up in a finger pattern that provides a suburban street layout of waterfront housing blocks. This practice is not popular with environmentalists.^{[citation needed]}

Boats

Two Panamax ships in the Miraflores Locks on the Panama Canal, Panama.

Inland canals have often had boats specifically built for them. An example of this is the British narrowboat, which is up to 72 feet (21.95 m) long and 7 feet (2.13 m) wide and was primarily built for British Midland canals. In this case the limiting factor was the size of the locks. This is also the limiting factor on the Panama canal where Panamax ships are limited to a length of 294.1 m (965 ft) and a width of 32.3 m (106 ft). For the lockless Suez Canal the limiting factor for Suezmax ships is generally draft, which is limited to 16 m (52.5 ft). At the other end of the scale, tub-boat canals such as the Bude Canal were limited to boats of under 10 tons for much of their length due to the capacity of their inclined planes or boat lifts. Most canals have a limit on height imposed either by bridges or tunnels.

Lists of canals

Amsterdam gracht

• Europe
  • Canals of France
  • Canals of Germany
  • Canals of Ireland
  • Canals of the United Kingdom
• North America
  • Canals of Canada
  • Canals of the United States

See also

UK Waterways portal

Barge (includes canal boats) Canal tunnel Channel Ditch Horse-drawn boat Infrastructure Irrigation district

List of navigation authorities in the United Kingdom List of waterway societies in the United Kingdom List of waterways Lock Navigation authority Environment Agency

Volumetric flow rate Water bridge Waterway restoration Water transportation Weigh lock

References

Notes

1. ^ "Reach". Oxford English Dictionary (Second ed.). Oxford, England: Oxford University Press. 1989. "...the portion of a canal between two locks, having a uniform level" 
2. ^ Hadfield 1986, p. 22.
3. ^ Rodda 2004, p. 161.
4. ^ Hadfield 1986, p. 16.
5. ^ Needham 1971, p. 269.
6. ^ Edmund Burke (June 2009), "Islam at the Center: Technological Complexes and the Roots of Modernity", Journal of World History (University of Hawaii Press) 20 (2): 165-186 [173], doi:10.1353/jwh.0.0045 
7. ^ Calvert 1963, p. .
8. ^ (PDF) The International Canal Monuments List, http://www.icomos.org/studies/canals.pdf, retrieved 2008-10-08 
9. ^ Lowell National Historical Park - Lowell History Prologue, http://www.nps.gov/archive/lowe/loweweb/Lowell%20History/prologue.htm, retrieved 2008-10-08 
10. ^ Edwards 2002, p. .
11. ^ Hadfield 1986, p. 191.

Bibliography

• Calvert, Roger (1963), Inland Waterways of Europe, George Allen and Unwin 
• Edwards-May, David (2002), European Waterways - map and concise directory, Euromapping 
• Hadfield, Charles (1986), World Canals: Inland Navigation Past and Present, David and Charles, ISBN 0-7153-8555-0 
• Needham, J (1971), Science and Civilisation in China, C.U.P. Cambridge 
• Rodda, J. C. (2004), The Basis of Civilization - Water Science?, International Association of Hydrological Sciences 

External links

Wikimedia Commons has media related to: canals

• British Waterways' leisure website - Britain's official guide to canals, rivers and lakes
• Leeds Liverpool Canal Photographic Guide
• Information and Boater's Guide to the New York State Canal System
• "Canals and Navigable Rivers" by James S. Aber, Emporia State University
• National Canal Museum (USA)
• Canals in Amsterdam
• Canal du Midi
• Canal des Deux Mers
• Canal flow measurement using a sensor.

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Dansk (Danish)
n. - kanal
v. tr. - kanalisere

Nederlands (Dutch)
kanaal, gracht

Français (French)
n. - canal, (Anat) conduit (auditif)
v. tr. - canaliser, construire une/des voie(s) navigable(s)

Deutsch (German)
n. - Kanal
v. - kanalisieren, mit Kanälen versehen

Ελληνική (Greek)
n. - διώρυγα, κανάλι

Italiano (Italian)
canale

Português (Portuguese)
n. - canal (m)
v. - canalizar

Русский (Russian)
канал, проход

Español (Spanish)
n. - canal
v. tr. - canalizar

Svenska (Swedish)
n. - kanal

中文（简体）(Chinese (Simplified))
运河, 灌溉水渠, 河渠, 水道, 管, 道, 开运河

中文（繁體）(Chinese (Traditional))
n. - 運河, 灌溉水渠, 河渠, 水道, 管, 道
v. tr. - 開運河

한국어 (Korean)
n. - 운하, 도관, 화성의 운하
v. tr. - ~에 운하를 만들다

日本語 (Japanese)
n. - 運河, 管, 導管
v. - 運河を開く

العربيه (Arabic)
‏(الاسم) قناة‏

עברית (Hebrew)
n. - ‮תעלה, צינור‬
v. tr. - ‮חפר תעלה דרך‬

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