Misplaced Pages

#528471

71-519: The Goejanverwellesluis is a lock in Hekendorp , Netherlands . The 'Goejannen' - the men from the surrounding polders who went to sea - said their last farewells by this channel. According to the tradition, Wilhelmina of Prussia , wife of stadholder William V was captured here on 28 June 1787 by the Patriots from Gouda . In reality, her entourage were arrested at Bonrepas on the river Vlist , on

142-419: 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

213-555: 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 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

284-464: 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 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

355-500: 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 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

426-528: 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

497-411: A canal to it (for it would have been of no little advantage to them for the whole region to have become navigable; Sesostris is said to have been the first of the ancient kings to try), but he found that the sea was higher than the land. So he first, and Darius afterwards, stopped making the canal, lest the sea should mix with the river water and spoil it. Strabo also wrote that Sesostris started to build

568-509: A canal, as did Pliny the Elder (see quote further down). However, the canal was probably first cut or at least begun by Necho II (r. 610–595 BC), in the late 7th century BC, and it was either re-dug or possibly completed by Darius the Great (r. 550–486 BC). Classical sources disagree as to when it was finally completed. Darius the Great's Suez Inscriptions comprise five Egyptian monuments, including

639-426: 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

710-412: 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 , 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

781-421: 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 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

SECTION 10

#1732855170529

852-430: 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 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

923-480: 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

994-404: 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

1065-454: 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 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

1136-473: A trench 100 feet wide, 30 feet deep and about 35 miles long, as far as the Bitter Lakes. Although Herodotus (2.158) tells us Darius I continued work on the canal, Aristotle (Aristot. met. I 14 P 352b.), Strabo (Strab. XVII 1, 25 C 804. 805.), and Pliny the Elder (Plin. n. h. VI 165f.) all say that he failed to complete it, while Diodorus Siculus does not mention a completion of the canal by Necho II. After

1207-426: 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

1278-487: 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. The canal was reconstructed by Roman emperor Trajan , who moved its mouth on the Nile further south to what is now Old Cairo , and named it Amnis Traianus after himself. Remains of the massive stone walls that made up the entrance to Trajan's canal have been found under

1349-626: 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 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

1420-443: 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

1491-846: 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

SECTION 20

#1732855170529

1562-464: 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 the passage of fish. Some fish such as lampreys, trout and salmon go upstream to spawn. Measures such as

1633-617: The Caspian Sea and then to India . Following the discovery of a direct sea route to India through the Cape of Good Hope by Portugal, the Venetians and Mamluks negotiated with each other to fund the construction of a new canal in order to weaken Portuguese trade. However, the Ottoman conquest of Egypt by Selim I and its subsequent annexation ended any hopes for Venice to maintain their trade dominance in

1704-470: 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

1775-730: The Kennet and Avon Canal . Canal of the Pharaohs The Canal of the Pharaohs , also called the Ancient Suez Canal or Necho's Canal , is the forerunner of the Suez Canal , constructed in ancient times and kept in use, with intermissions, until being closed in 767 AD for strategic reasons during a rebellion. It followed a different course from its modern counterpart, by linking the Nile to

1846-609: The Red Sea via the Wadi Tumilat . Work began under the pharaohs . According to Darius the Great's Suez Inscriptions and Herodotus , the first opening of the canal was under Persian king Darius the Great , but later ancient authors like Aristotle , Strabo , and Pliny the Elder claim that he failed to complete the work. Another possibility is that it was finished in the Ptolemaic period under Ptolemy II , when engineers solved

1917-700: 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, 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

1988-581: 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

2059-628: The Chalouf Stele, that commemorate the construction and completion of the canal linking the Nile River with the Red Sea by Darius I of Persia . They were located along the Darius Canal through the valley of Wadi Tumilat and probably recorded sections of the canal as well. In the second half of the 19th century, French cartographers discovered the remnants of the north–south section of Darius Canal past

2130-510: 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 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

2201-552: 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

Goejanverwellesluis - Misplaced Pages Continue

2272-747: The Mediterranean. Sokollu Mehmed Pasha , the Grand Vizier of the Ottoman Empire from 1565 to 1579, also considered constructing a new canal to reduce Portuguese dominance in the Indian Ocean and connect the divided Ottoman navy in the Mediterranean Sea and the Indian Ocean, but it was deemed too expensive to construct and was cancelled. During the Egyptian expedition , Napoleon Bonaparte learnt about

2343-526: The Nile, known as the Khalij , continued to serve a local function as part of Cairo's water infrastructure up until the late 1890s, when it was completely filled in and converted into what is now Port Said Street. Thereafter, the land routes to tranship camel caravans' goods were from Alexandria to ports on the Red Sea or the northern Byzantine silk route through the Caucasus Mountains transhipping on

2414-512: 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 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

2485-470: 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

2556-463: 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

2627-525: The canal as the "River of Trajan". Diocletian's fortress enveloped the Nile entrance of the canal and protected it on either side. The canal passed between two massive round towers and then through the middle of the fortress. In later centuries, this entry was blocked with new wall constructed between the towers. The canal was difficult to maintain and by the time of the Muslim conquest in 641 AD, it had fallen out of use and into disrepair. Islamic texts discuss

2698-617: 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

2769-620: The canal, which they say had been silted up, but was reopened in 641 or 642 AD by 'Amr ibn al-'As , the commander of the Muslim army in Egypt. The new canal dug by Amr was excavated further north, joining the Nile close to what is now the Sayyida Zaynab neighbourhood of Cairo. Its connection to the Red Sea remained open until 767, when it was closed to stop supplies reaching Mecca and Medina , which were in rebellion . The canal's remaining section near

2840-588: 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 ,

2911-617: 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

Goejanverwellesluis - Misplaced Pages Continue

2982-404: 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

3053-514: 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

3124-406: The death of Alexander the Great , the general Ptolemy gained control of Egypt , declared himself Pharaoh and began the Ptolemaic dynasty . His son, the 2nd leader of that dynasty, Ptolemy II took up the canal work again, but also stopped because of the differences of water level. Diodorus, however, reports that it was completed by Ptolemy II after being fitted with a water lock . Ptolemy II

3195-708: The direction of Schoonhoven and turned back to her spouse stadholder William V at Nijmegen . This event formed the main reason for the Prussians' raid into Holland, with Frederick William II of Prussia coming to his sister Wilhelmina's aid and so making possible William's return to the Hague . This raid led to an exodus of the Patriots from the United Republic of the Seven Netherlands in 1787. A foot ferry at Goejanverwellesluis

3266-747: The east side of Lake Timsah and ending near the north end of the Great Bitter Lake . Pliny the Elder wrote: 165. Next comes the Tyro tribe and, on the Red Sea, the harbour of the Daneoi, from which Sesostris, king of Egypt, intended to carry a ship-canal to where the Nile flows into what is known as the Delta; this is a distance of over 60 miles. Later the Persian king Darius had the same idea, and yet again Ptolemy II, who made

3337-401: 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 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

3408-548: 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 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

3479-425: 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

3550-512: 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

3621-516: 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 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

SECTION 50

#1732855170529

3692-414: 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

3763-450: 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 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

3834-413: 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 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

3905-656: 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

3976-478: The present-day Coptic Church of Saint Sergius and the Coptic Church of Saint George. The walls are 6 metres (20 ft) thick and are set 40 metres (130 ft) apart. Where the canal joined the Nile, Trajan constructed a harbor and fortifications, which Diocletian expanded in the 3rd century AD along with the construction of the present Babylon Fortress . In the 2nd century AD, Claudius Ptolemy refers to

4047-399: The problem of overcoming the difference in height through canal locks . At least as far back as Aristotle there have been suggestions that perhaps as early as the 12th Dynasty , Pharaoh Senusret III (1878–1839 BC), called Sesostris by the Greeks, may have started a canal joining the River Nile with the Red Sea. In his Meteorology , Aristotle wrote: One of their kings tried to make

4118-408: 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 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

4189-404: 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 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

4260-407: 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

4331-411: 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

SECTION 60

#1732855170529

4402-413: 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

4473-438: 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,

4544-400: 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

4615-404: 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 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

4686-414: The way to Schoonhoven near Haastrecht . Wilhelmina was at a farm overhanging the Goejanverwellesluis, where Cornelis Johan de Lange , commander of the free corps of Gouda, had been billeted. Informed of her plans by the gentleman Martinus van Toulon, former bailiff of Gouda, the Commission of Defense stopped her from driving on to Gouda that night. The princess left the very same evening after 10pm in

4757-405: 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 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

4828-399: 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

4899-416: 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,

4970-405: Was replaced by the Wilhelmina van Pruisen Bridge in 1992. 52°00′50″N 4°48′40″E  /  52.014°N 4.811°E  / 52.014; 4.811 Lock (water transport) Locks are used to make 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

5041-427: 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

#528471