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80-668: The Glastonbury Canal ran for approximately 14 miles (23 km) through two locks from Glastonbury to Highbridge in Somerset , England , where it entered the River Parrett and from there the Bristol Channel . The canal was authorised by Parliament in 1827 and opened in 1834. It was operated by the Glastonbury Navigation and Canal Company. Most of it was abandoned as a navigation in 1854, when

160-740: A flash lock . Pound locks were first used in China during the Song dynasty (960–1279 CE), having been pioneered by the Song politician and naval engineer Qiao Weiyue in 984. They replaced earlier double slipways that had caused trouble and are mentioned by the Chinese polymath Shen Kuo (1031–1095) in his book Dream Pool Essays (published in 1088), and fully described in the Chinese historical text Song Shi (compiled in 1345): The distance between

240-404: A river more easily navigable, or to allow a canal to cross land that is not level. Later canals used more and larger locks to allow a more direct route to be taken. A pound lock is most commonly used on canals and rivers today. A pound lock has a chamber with gates at both ends that control the level of water in the pound. In contrast, an earlier design with a single gate was known as

320-528: A broad canal for more than one boat to be in a staircase at the same time, but managing this without waste of water requires expertise. On English canals, a staircase of more than two chambers is usually staffed: the lockkeepers at Bingley (looking after both the "5-rise" and the "3-rise") ensure that there are no untoward events and that boats are moved through as speedily and efficiently as possible. Such expertise permits miracles of boat balletics: boats travelling in opposite directions can pass each other halfway up

400-407: A detailed breakdown of the likely costs, revenue and profits of such a scheme, and the promoters prepared to obtain an act of Parliament . During this time, someone challenged the original survey and another local surveyor was asked to review it. John Beauchamp suggested that no locks would be required on the upper section, but that costs were likely to be £15,234. This was later raised to £18,000, and

480-426: A flight of locks is simply a series of locks in close-enough proximity to be identified as a single group. For many reasons, a flight of locks is preferable to the same number of locks spread more widely: crews are put ashore and picked up once, rather than multiple times; transition involves a concentrated burst of effort, rather than a continually interrupted journey; a lock keeper may be stationed to help crews through

560-576: A lock constructed on the old course of the River Brue, which had been bypassed by a new cut in 1801 and filled in. It then followed the course of the Brue to Cripps Bridge, after which it followed the Cripps River to Gold Corner. The first part of the Cripps River was originally part of a loop on the River Brue, which was bypassed by a new cut made under the 1801 act. Gold Corner is at the point where

640-480: A lock is simple. For instance, if a boat travelling downstream finds the lock already full of water: If the lock were empty, the boat would have had to wait 5 to 10 minutes while the lock was filled. For a boat travelling upstream, the process is reversed; the boat enters the empty lock, and then the chamber is filled by opening a valve that allows water to enter the chamber from the upper level. The whole operation will usually take between 10 and 20 minutes, depending on

720-537: A lock, and the position of the forward edge of the cill is usually marked on the lock side by a white line. The edge of the cill is usually curved, protruding less in the center than at the edges. In some locks, there is a piece of oak about 9 in (23 cm) thick which protects the solid part of the lock cill. On the Oxford Canal it is called a babbie; on the Grand Union Canal it is referred to as

800-426: A major part in the creation of the canal, disappeared, leaving a financial shortfall of over £40,000. It appears that they had put up most of the extra costs of construction, and may have borrowed some money from client's funds. They were declared bankrupt and Richard Prat was removed from office as town clerk and a Commissioner of Sewers, but the firm's collapse had a serious effect on the prosperity of Glastonbury. On

880-400: A prospectus to raise funds for the building of the canal. Construction commenced in the 1820s; however it was more expensive than envisaged and further funds had to be raised. It finally opened in 1833 but was only prosperous for a short period. The shortfall in income and engineering problems with water supply and waterlogged peat causing the clay puddling to fracture meant that it was sold to

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960-608: A railway was built along the towpath. An earlier canal had been built in the Middle Ages to supply Glastonbury Abbey and the town with stone and produce. In the early 19th century a new canal was proposed to improve commerce in Glastonbury and help with drainage of the surrounding area of the Somerset Levels . Several alternative routes were considered and costed before obtaining an Act of Parliament and issuing

1040-480: A staircase lock can be used as an emergency dry dock). To avoid these mishaps, it is usual to have the whole staircase empty before starting to descend, or full before starting to ascend, apart from the initial chamber. One striking difference in using a staircase of either type (compared with a single lock, or a flight) is the best sequence for letting boats through. In a single lock (or a flight with room for boats to pass) boats should ideally alternate in direction. In

1120-404: A staircase, however, it is quicker for a boat to follow a previous one going in the same direction. Partly for this reason staircase locks such as Grindley Brook, Foxton, Watford and Bratch are supervised by lockkeepers, at least during the main cruising season, they normally try to alternate as many boats up, followed by down as there are chambers in the flight. As with a flight, it is possible on

1200-530: A survey of the route in 1826. Hammett had experience of building a manure canal through peat heathland . He considered two main routes; the first followed the course of the River Brue , but was rejected on the grounds of engineering costs, and the interference with its drainage function. The second route followed the South Drain , which had been newly constructed following floods in 1794, to connect with

1280-400: A tunnel, which when descending does not become visible until the chamber is nearly empty. A pound is the level stretch of water between two locks (also known as a reach ). The cill , also spelled sill , is a narrow horizontal ledge protruding a short way into the chamber from below the upper gates. Allowing the rear of the boat to "hang" on the cill is the main danger when descending

1360-607: A wharf for the railway company, which was used until 1936, when it passed to the Commissioners of Sewers and was filled in. The Central Somerset Railway merged with the Dorset Central Railway to become the Somerset and Dorset Railway . The main line to Glastonbury closed in 1966, while the branches to the dairy at Bason Bridge and the Highbridge Wharf lasted until 1972. The canal started at

1440-426: Is a normal top gate, and the intermediate gates are all as tall as the bottom gate). As there is no intermediate pound, a chamber can only be filled by emptying the one above, or emptied by filling the one below: thus the whole staircase has to be full of water (except for the bottom chamber) before a boat starts to ascend, or empty (except for the top chamber) before a boat starts to descend. In an "apparent" staircase

1520-443: Is only a staircase if successive lock chambers share a gate (i.e. do not have separate top and bottom gates with a pound between them). Most flights are not staircases, because each chamber is a separate lock (with its own upper and lower gates), there is a navigable pound (however short) between each pair of locks, and the locks are operated in the conventional way. However, some flights include (or consist entirely of) staircases. On

1600-575: Is the change in water-level in the lock. The two deepest locks on the English canal system are Bath deep lock on the Kennet and Avon Canal and Tuel Lane Lock on the Rochdale Canal , which both have a rise of nearly 20 feet (6.1 m). Both locks are amalgamations of two separate locks, which were combined when the canals were restored to accommodate changes in road crossings. By comparison,

1680-582: The Glastonbury Navigation and Canal Act 1827 ( 7 & 8 Geo. 4 . c. xli), which authorised the construction of a canal that followed Hammett's plans, was obtained on 28 May 1827. The proprietors were empowered to raise £18,000 by the issue of 360 shares of £50 each, with powers to raise another £5,000 by mortgage, or to borrow any part of the £18,000 from the Exchequer Bills Commissioners. Construction began once

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1760-881: The Bollène lock on the River Rhône has a fall of at least 23 m (75 ft), the Leerstetten, Eckersmühlen and Hilpoltstein locks on the Rhine–Main–Danube Canal have a fall of 24.67 m (80.9 ft), each and the Oskemen Lock on the Irtysh River in Kazakhstan has a drop of 42 m (138 ft). The natural extension of the flash lock , or staunch, was to provide an upper gate (or pair of gates) to form an intermediate "pound" which

1840-458: The Bristol and Exeter Railway . They used the canal to transport materials for the construction of the new Somerset Central Railway which opened in 1854. Glastonbury is situated in an area of low-lying land, known as the Somerset Levels , through which rivers and drainage ditches (locally called " rhynes ") run. There is evidence that the town was served by a medieval canal connecting it to

1920-476: The Grand Union . Operation of a staircase is more involved than a flight. Inexperienced boaters may find operating staircase locks difficult. The key worries (apart from simply being paralysed with indecision) are either sending down more water than the lower chambers can cope with (flooding the towpath, or sending a wave along the canal) or completely emptying an intermediate chamber (although this shows that

2000-597: The Huntspill River , the Cripps River and the South Drain meet. Following the course of the enlarged South Drain, a lock raised the level of the canal at Shapwick , while the Drain turned off to run parallel to the canal but to its north. The railway ran between the two waterways, crossing to the south side of the canal immediately after the single arched aqueduct and syphon over the South Drain. The remains of

2080-604: The Kennet and Avon Canal . South Drain (river) The South Drain flows in a generally north-westerly direction from Actis Tunnel to Gold Corner, where it moves on to the Huntspill River , in Somerset , England. It flows through the Shapwick Heath Nature Reserve . It was constructed between 1802 and 1806 as a result of the Somerset Drainage Act 1801 ( 41 Geo. 3. (U.K.) c. lxxii). This Somerset location article

2160-613: The Milan canal system sponsored by Francesco Sforza ) between 1452 and 1458. In Ancient Egypt, the river-locks was probably part of the Canal of the Pharaohs : Ptolemy II is credited by some for being the first to solve the problem of keeping the Nile free of salt water when his engineers invented the lock around 274/273 BC. All pound locks have three elements: The principle of operating

2240-598: The Song dynasty (960–1279 CE). The Songshi or History of the Song Dynasty, volume 307, biography 66, records how Qiao Weiyue, a high-ranking tax administrator, was frustrated at the frequent losses incurred when his grain barges were wrecked on the West River near Huai'an in Jiangsu . The soldiers at one double slipway, he discovered, had plotted with bandits to wreck heavy imperial barges so that they could steal

2320-463: The peat moorlands and channelled it into the lower River Brue. Under the terms of the act, two small canals, called Galton's Canal and Brown's Canal, were built near the North Drain to serve peat extraction workings. The drainage works were not wholly successful in preventing flooding, and the Commissioners often failed to obtain the levies they required to finance their operations. One of

2400-689: The Carrapatelo and Valeira locks on the Douro river in Portugal, which are 279 feet (85 m) long and 39 feet (12 m) wide, have maximum lifts of 115 and 108 feet (35 and 33 m) respectively. The two Ardnacrusha locks near Limerick on the Shannon navigation in Ireland have a rise of 100 feet (30 m). The upper chamber rises 60 feet (18 m) and is connected to the lower chamber by

2480-466: The Chesapeake and Ohio Canal, the lockkeepers were required to remove the windlasses from all lock paddles at night, to prevent unauthorized use. A swell was caused by opening suddenly the paddle valves in the lock gates, or when emptying a lock. To help boats traveling downstream exit a lock, the locksman would sometimes open the paddles to create a swell, which would help "flush" the boat out of

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2560-547: The Commissioners which was required to cover any costs they might have as a result of the construction of the canal, and they sued for the money in 1831. Even Rennie threatened to sue, as much of his fee remained unpaid. The cost of construction was about £30,000, but it appears that some debts were never paid. On 16 December 1831 the proprietors borrowed £5,000 from the Exchequer at a 5% rate of interest. The canal finally opened on 15 August 1833, amid celebrations at both ends of

2640-507: The Glastonbury end, the canal was required to cross the South Drain and the River Brue. Rennie suggested inverted syphons , rather than locking down into the river and up again, and a cast iron aqueduct for the River Brue crossing was obtained for nearly £3,000 from a Glastonbury blacksmith called John Wright. At the Highbridge end, the plans for a floating harbour to accommodate vessels of up to 250 long tons (250 t) were dropped, and

2720-567: The Grand Union (Leicester) Canal, the Watford flight consists of a four-chamber staircase and three separate locks; and the Foxton flight consists entirely of two adjacent 5-chamber staircases. Where a very steep gradient has to be climbed, a lock staircase is used. There are two types of staircase, "real" and "apparent". A "real" staircase can be thought of as a "compressed" flight, where

2800-409: The River Brue near Cripps Bridge, and to re-use the old course of that River at Highbridge to create a basin. Hammett estimated that the main work required on the section from Highbridge to the South Drain would be the provision of a towpath. After this, the South Drain would need to be made wider and deeper, but this would aid its drainage function, and would reduce the levy on the local landowners, as

2880-475: The advent of canals in Britain. The sides of the turf-lock are sloping so, when full, the lock is quite wide. Consequently, this type of lock needs more water to operate than vertical-sided brick- or stone-walled locks. On British canals and waterways most turf-sided locks have been subsequently rebuilt in brick or stone, and so only a few good examples survive, such as at Garston Lock , and Monkey Marsh Lock , on

2960-587: The boat entered the lock. Pulling on the rope slowed the boat, due to the friction of the rope against the post. A rope 2 + 1 ⁄ 2 inches (6.4 cm) in diameter and about 60 feet (18 meters) long was typically used on the Erie Canal to snub a boat in a lock. One incident, which took place in June 1873 on the Chesapeake and Ohio Canal, involved the boat the Henry C. Flagg and its drunk captain. That boat

3040-471: The bottom cill at all but the higher tides – the new bottom chamber rises just far enough to get the boat over the original lock cill. In China, the recently completed Three Gorges Dam includes a double five-step staircase for large ships, and a ship lift for vessels of less than 3000 metric tons. Examples of "apparent" staircases are Foxton Locks and Watford Locks on the Leicester Branch of

3120-526: The canal and a cavalcade to and from Highbridge to Glastonbury. A second celebration for the "respectable trading classes" was held nine days later. The first cargo of wood from Canada arrived in July 1835. The canal appears to have been successful initially, but the revenues generated were inadequate, and there were problems with water levels on the upper section. In 1840, the Prat brothers, whose legal firm had played

3200-490: The canal company was dissolved in 1851. There was friction between the new owners and the Commissioners of Sewers. The railway company proposed the creation of a railway between Highbridge and Glastonbury in 1850, and the Somerset Central Railway was authorised by Parliament on 17 June 1852. The canal was transferred to the new company, and was used to speed the construction of the railway, earning £312 in

3280-414: The canal company would then be responsible for its maintenance. Two locks would be required on this upper section, with a total rise of just 7 feet (2.1 m). He did not believe that cutting a canal through peat would present serious engineering problems as a result of his previous experience with the manure canal, but he seriously underestimated the cost at £9,000. A prospectus was issued which contained

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3360-506: The canal was probably only carrying about 4,000 long tons (4,100 t) per annum. Railways arrived in the area in 1841, with the opening of part of the Bristol and Exeter Railway on 14 June, which eventually reached Exeter in 1844. In late 1846, the railway company attempted to buy the canal to prevent its use by rival railway companies. The sale was agreed in principle in June 1847, and was authorised by an act of Parliament passed on 30 June 1848. The shareholders received £7,372 in 1850, and

3440-641: The canal would cause frequent interruptions of the heavy road traffic. It can be emptied by pumping – but as this uses a lot of electricity the method used when water supplies are adequate is to drain the lock to a nearby burn . In 2016 the Kieldrecht Lock in the Port of Antwerp in Belgium took over the title of the world's largest lock from the Berendrecht Lock in the same port and still has

3520-544: The chambers so that some water from the emptying chamber helps to fill the other. This facility has long been withdrawn on the English canals, although the disused paddle gear can sometimes be seen, as at Hillmorton on the Oxford Canal . Elsewhere they are still in use; a pair of twinned locks was opened in 2014 on the Dortmund–Ems Canal near Münster , Germany. The once-famous staircase at Lockport, New York ,

3600-631: The chambers still have common gates, but the water does not pass directly from one chamber to the next, going instead via side ponds. This means it is not necessary to ensure that the flight is full or empty before starting. Examples of famous "real" staircases in England are Bingley and Grindley Brook . Two-rise staircases are more common: Snakeholme Lock and Struncheon Hill Lock on the Driffield Navigation were converted to staircase locks after low water levels hindered navigation over

3680-404: The chance of a boat finding a lock set in its favour. There can also be water savings: the locks may be of different sizes, so that a small boat does not need to empty a large lock; or each lock may be able to act as a side pond (water-saving basin) for the other. In this latter case, the word used is usually "twinned": here indicating the possibility of saving water by synchronising the operation of

3760-559: The cill bumper. Some canal operation authorities, primarily in the United States and Canada, call the ledge a miter sill (mitre sill in Canada). Gates are the watertight doors which seal off the chamber from the upper and lower pounds. Each end of the chamber is equipped with a gate, or pair of half-gates, traditionally made of oak or elm but now usually made of steel ). The most common arrangement, usually called miter gates ,

3840-523: The concept has been suggested in a number of cases, the only example in the world of a drop lock that has actually been constructed is at Dalmuir on the Forth and Clyde Canal in Scotland. This lock, of the single-chamber type, was incorporated during the restoration of the canal, to allow the replacement of a swing bridge (on a busy A road) by a fixed bridge, and so answer criticisms that the restoration of

3920-492: The entrance lock was moved further along the original course of the River Brue. This saved money, but meant that ships did not have to pay lockage charges to reach Highbridge. The proprietors failed to raise all of the capital promised, and there were financial difficulties. The Commissioners of Sewers were unhappy with some of the work at Highbridge in 1830, and reported that the contractor "had run away", and work had stopped in 1831. The company had also failed to lodge £1,000 with

4000-425: The flight quickly; and where water is in short supply, a single pump can recycle water to the top of the whole flight. The need for a flight may be determined purely by the lie of the land, but it is possible to group locks purposely into flights by using cuttings or embankments to "postpone" the height change. Examples: Caen Hill locks, Devizes . "Flight" is not synonymous with "Staircase" (see below). A set of locks

4080-518: The form of the now-disused Écluse des Lorraines , connecting the Canal latéral à la Loire with the River Allier . A drop lock can consist of two conventional lock chambers leading to a sump pound, or a single long chamber incorporating the sump – although the term properly applies only to the second case. As the pounds at either end of the structure are at the same height, the lock can only be emptied either by allowing water to run to waste from

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4160-414: The intermediate pounds have disappeared, and the upper gate of one lock is also the lower gate of the one above it. However, it is incorrect to use the terms staircase and flight interchangeably: because of the absence of intermediate pounds, operating a staircase is very different from operating a flight. It can be more useful to think of a staircase as a single lock with intermediate levels (the top gate

4240-458: The key promoters for a canal was Richard Prat, who was a lawyer in Glastonbury, had been the town clerk since 1813, and held several important offices in the town. He saw the canal as a way to halt the economic downturn in the town and its drainage problems, and called a meeting in August 1825, at which a firm plan was formulated. Richard Hammett, a local man from Street , was commissioned to conduct

4320-403: The lock gates could be replaced and the boat removed from the lock. To economise, especially where good stone would be prohibitively expensive or difficult to obtain, composite locks were made, i.e. they were constructed using rubble or inferior stone, dressing the inside walls of the lock with wood, so as not to abrade the boats. This was done, for instance, on the Chesapeake and Ohio Canal with

4400-403: The lock. A boatsman might ask for a back swell, that is, to open and shut the paddles a few times to create some waves, to help him get off the bank where he was stuck. If boats ran aground (from being overloaded) they sometimes asked passing crews to tell the upstream lock to give them an extra heavy swell, which consisted of opening all the paddles on the lock gate, creating a surge that affected

4480-757: The locks near the Paw Paw Tunnel . and also the Chenango Canal On large modern canals, especially very large ones such as ship canals , the gates and paddles are too large to be hand operated, and are operated by hydraulic or electrical equipment. On the Caledonian Canal the lock gates were operated by man-powered capstans , one connected by chains to open the gate and another to draw it closed. By 1968 these had been replaced by hydraulic power acting through steel rams. The construction of locks (or weirs and dams) on rivers obstructs

4560-479: The mills of the north of England took the trade. The area was hit by severe floods in 1794, as a result of which the Commissioners of Sewers obtained the Somerset Drainage Act 1801 ( 41 Geo. 3. (U.K.) c. lxxii), which allowed them to improve the course of the River Brue by the straightening of major loops at Highbridge and East Huntspill , and to construct the North and South Drains , which collected water from

4640-402: The necessary land had been purchased, but it soon became apparent that the original surveys were inadequate. The canal engineer John Rennie was asked to advise the proprietors, and proposed three options, for boats of 120 to 140 long tons (120–140 t), for boats of 40 to 60 long tons (41–61 t), and for barges which were 5 feet (1.5 m) wide. The first was ruled out on cost,

4720-688: The new canal was low. This resulted in a sequential pair of locks, with gates pointing in opposite directions: one example was at Hall Green near Kidsgrove , where the southern terminus of the Macclesfield Canal joined the Hall Green Branch of the earlier Trent and Mersey Canal . The four gate stop lock near Kings Norton Junction, between the Stratford-upon-Avon Canal and the Worcester and Birmingham Canal

4800-528: The passage of fish. Some fish such as lampreys, trout and salmon go upstream to spawn. Measures such as a fish ladder are often taken to counteract this. Navigation locks have also potential to be operated as fishways to provide increased access for a range of biota. Locks can be built side by side on the same waterway. This is variously called doubling , pairing , or twinning . The Panama Canal has three sets of double locks. Doubling gives advantages in speed, avoiding hold-ups at busy times and increasing

4880-519: The river system in the Saxon period, and the waterways were later used by the monks who were located at Glastonbury Abbey , both for draining the land and for transport of produce. In the 1750s, the town became a spa town , when the waters of the Chalice Well spring were thought to have medicinal properties, but this did not last for long, while the predominant wool and cloth industries declined as

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4960-469: The size of the lock and whether the water in the lock was originally set at the boat's level. Boaters approaching a lock are usually pleased to meet another boat coming towards them, because this boat will have just exited the lock on their level and therefore set the lock in their favour – saving about 5 to 10 minutes. However, this is not true for staircase locks, where it is quicker for boats to go through in convoy, and it also uses less water. The rise

5040-407: The spilled grain. In 984 Qiao installed a pair of sluice-gates two hundred and fifty feet apart, the entire structure roofed over like a building. By siting two staunch gates so close to one another, Qiao had created a short stretch of canal, effectively a pound-lock, filled from the canal above by raising individual wooden baulks in the top gate and emptied into the canal below by lowering baulks in

5120-411: The staircase by moving sideways around each other; or at peak times, one can have all the chambers full simultaneously with boats travelling in the same direction. When variable conditions meant that a higher water level in the new canal could not be guaranteed, then the older company would also build a stop lock (under its own control, with gates pointing towards its own canal) which could be closed when

5200-413: The sump to a lower stream or drain, or (less wastefully) by pumping water back up to the canal. Particularly in the two-chamber type, there would be a need for a bypass culvert, to allow water to move along the interrupted pound and so supply locks further down the canal. In the case of the single-chamber type, this can be achieved by keeping the lock full and leaving the gates open while not in use. While

5280-430: The third because of the need to transship all goods at Highbridge, and the second was adopted because it allowed the coasters that worked the Bristol Channel to use the canal. This option required locks of 64 feet (20 m) by 18 feet (5.5 m), and was costed at £28,720. The route would be as authorised, but a single lock was required on the upper section to simplify the water supply. Work resumed in July 1828. At

5360-494: The three-arched aqueduct and syphon over the River Brue are still visible, near the old railway bridge, and from there the canal headed towards Glastonbury , passing the Ham Wall and Street Heath nature reserves and making a sharp right-hand turn just before its terminal basin, which was located near the old Glastonbury and Street railway station . Download coordinates as: Canal lock Locks are used to make

5440-493: The title for largest volume. In 2022 the IJmuiden sea lock serving the Port of Amsterdam became the world's largest lock by surface area. The lock is 500 m (1,600 ft) long, 70 m (230 ft) wide and has sliding lock gates creating a usable depth of 18 m (59 ft). The size of locks cannot be compared without considering the difference in water level that they are designed to operate under. For example,

5520-400: The top gate and raising ones in the lower. A turf-sided lock is an early form of canal lock design that uses earth banks to form the lock chamber, subsequently attracting grasses and other vegetation, instead of the now more familiar and widespread brick, stone, or concrete lock wall constructions. This early lock design was most often used on river navigations in the early 18th century before

5600-462: The two locks was rather more than 50 paces, and the whole space was covered with a great roof like a shed. The gates were 'hanging gates'; when they were closed the water accumulated like a tide until the required level was reached, and then when the time came it was allowed to flow out. The water level could differ by 4 or 5 feet (1.2 or 1.5 m) at each lock and in the Grand Canal the level

5680-437: The upper section, the final pond prevented the proper drainage of the surrounding land, which being composed of peat, started to swell. This caused the canal itself to rise and the clay puddling to fracture, resulting in further loss of water, and a reduced depth for navigation. Traffic had to be transhipped to smaller boats at Highbridge, which added to the costs of delivery. Receipts for 1848 were £300, which would indicate that

5760-416: The water on the pound above sometimes causing boats to run aground. In addition, it raised the water level on the pound below, causing some boats to strike bridges or get stuck. On horse-drawn and mule-drawn canals, snubbing posts were used to slow or stop a boat in the lock. A 200-ton boat moving at a few miles an hour could destroy the lock gate. To prevent this, a rope was wound around the snubbing post as

5840-453: The whole pound below. On the Erie Canal, some loaded boats needed a swell to get out of the lock. Particularly lumber boats, being top heavy, would list to one side and get stuck in the lock, and needed a swell to get them out. Some lockkeepers would give a swell to anyone to help them on the way, but some would ask for money for the swell. The Erie Canal management did not like swelling for two reasons. First, it used too much water lowering

5920-408: The year ending September 1853. The line followed the route of the canal closely, with much of it built on the towpath. The canal was closed on 1 July 1854, and the lock and aqueducts on the upper section were dismantled. The railway opened on 17 August 1854. The lower sections of the canal were given to the Commissioners for Sewers, for use as a drainage ditch. The final section was retained to provide

6000-463: Was all that need be emptied when a boat passed through. This type of lock, called a pound lock was known in Imperial China and ancient Europe and was used by Greek engineers in the Canal of the Pharaohs under Ptolemy II (284 to 246 BC), when engineers solved the problem of overcoming the difference in height through canal locks . Pound locks were first used in medieval China during

6080-422: Was already leaking; the crew, having partially pumped the water out, entered Lock 74, moving in front of another boat. Because they failed to snub the boat, it crashed into and knocked out the downstream gates. The outrush of water from the lock caused the upstream gates to slam shut, breaking them also, and sending a cascade of water over the boat, sinking it. This suspended navigation on the canal for 48 hours until

6160-416: Was also a doubled set of locks. Five twinned locks allowed east- and west-bound boats to climb or descend the 60 feet (18 m) Niagara Escarpment , a considerable engineering feat in the nineteenth century. While Lockport today has two large steel locks, half of the old twin stair acts as an emergency spillway and can still be seen, with the original lock gates having been restored in early 2016. Loosely,

6240-412: Was invented by Leonardo da Vinci sometime around the late 15th century. On the old Erie Canal , there was a danger of injury when operating the paddles: water, on reaching a certain position, would push the paddles with a force which could tear the windlass (or handle) out of one's hands, or if one was standing in the wrong place, could knock one into the canal, leading to injuries and drownings. On

6320-456: Was raised in this way by 138 feet (42 m). In medieval Europe a sort of pound lock was built in 1373 at Vreeswijk , Netherlands. This pound lock serviced many ships at once in a large basin . Yet the first true pound lock was built in 1396 at Damme near Bruges , Belgium. The Italian Bertola da Novate (c. 1410–1475) constructed 18 pound locks on the Naviglio di Bereguardo (part of

6400-606: Was replaced in 1914 by a pair of guillotine lock gates which stopped the water flow regardless of which canal was higher. These gates have been permanently open since nationalisation. The best known example of a round lock is the Agde Round Lock on the Canal du Midi in France. This serves as a lock on the main line of the canal and allows access to the Hérault River . A second French round lock can be found in

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