This is an article about canals in the age before the railways and roads took a large share in heavy goods carrying. But because these waterways are still an important part of the scheme of things, the story has been brought down to our own times. Again, it is mainly about the short and brilliant canal age in the British Isles, but it says something about matching periods elsewhere.
The Natural River
If it runs quickly enough and is sufficiently deep, cargo-carrying craft can sail or be poled along rivers. If a towing path has been built alongside, horses can tow barges. Nowadays self-propelled diesel craft can navigate it, as on the Meuse, or tugs pushing their barges in front, as on the Mississippi. But most rivers vary greatly in their depth and speed of current at different times of the year: after the wet season they will, run fast; in dry periods there may be only a few inches of water. This was the case with our own Severn and Trent in the eighteenth century and earlier. So for ease of navigation, weirs were built across the rivers, and locks inserted in them for the barges to pass through. A weir holds back the water in a stretch of river, and so slows the current. Instead of the water level falling gradually, the fall is concentrated at the points where it foams over the weir. Boats, however, must now be deliberately lowered from one level to the next.
Weirs & Flash Locks
In the old days – in this country the eighteenth century and earlier – weirs were often built not to help navigation, but to hold back water to provide power for corn, cloth or other mills on the river banks. Those were days when industry depended much more upon water than on steam power. Locks were primitive then. One sort was the flash-lock. A movable section was built into the weir so that by first removing vertical planks or paddles, and then the horizontal beams that held them in place, an opening was made. When this was done, water poured through the gap, lowering the river level above and raising it below.
Barges would shoot down through the gap, while those going upstream would be winched through the opening with a pulley and line from the bank, or would have to wait until the level had equalised. Some flash-locks remained on the upper Thames until this century. Other ways of doing the same thing were the vertically rising gate or staunch, many of which used to exist on Fenland waterways such as the River Lark, and the single pair of sideways-moving gates, that could be hauled open by a capstan and rope against the pull of the current. These were called water gates or half-locks. Two of them, three hundred years old, were removed a few years ago when the Lower Avon was restored between Evesham and Tewkesbury.
Such contraptions had a life Span of over two thousand years, for they are known on Chinese waterways in the last half of the century before Christ, especially in the form of staunches with vertically rising gates. They were so wasteful of water, however, that Chinese engineers then built slipways up which boats could be dragged from one level to the other. But dragging caused damage, and damage was an incentive to theft of the cargoes. China, therefore, moved another step, by building a chamber in the weir, with sets of gates at each end. A boat going upstream then entered the empty chamber. After the lower gates had been shut, water could be admitted through openings in the upper gates or the sides of the chamber until it was level with the section of river above the weir. Then the upper gates could be opened for the boat to proceed. So the weir itself could be undisturbed, and the only water used would be that which passed through the chamber.
Invention of the Pound-Lock
As far as we know, the invention of the ordinary or pound-lock is to be attributed to Chhiao Wei-Yo, assistant commissioner for transport on a section of the Grand Canal of China in the year AD 983, who created it as a solution to slipway problems, and the first, 250 ft long, was built on the West River near Huai—yin. It had vertically rising gates of a type seen in Britain on the River Nene, and on the Continent all the Upper Rhine locks, the Amsterdam—Rhine canal and elsewhere.
On the Continent of Europe, staunches or flash-locks are known to have existed in Holland in 1065, in Flanders in 1116, and in Italy in 1198. The first pound-lock known dates from 1373, at Vreeswijk in Holland on the River Lek, still an important boating town. This was, however, more of a basin connecting river and canal where boats could wait, than a true lock, such as that known in 1396 at Damme near Bruges. All these, and later examples, had vertically-rising gates. It was Leonardo da Vinci, painter and much else, who in his capacity as engineer to the Duke of Milan invented and built examples of locks with swinging or mitre-gates, of the kind that can be seen on any British waterway today.
Another step in improving a river for navigation was to straighten it by building artificial cuts or canals across the bends. This process, which could also include deepening and providing locks, might result in more new cuts than remaining portions of the old river. Such drastically reconstructed river navigations in England were, or are, the Wey, Kennet, Itchen and Welland. An Ordnance map will show what was done.
From river straightening it was an easy step to building a true canal to by-pass a section of difficult river.
This was taken for the first time in Britain between 1564 and 1566, when Exeter Corporation, with John Trew as engineer, built the first Exeter Canal, 1 3/4 miles long and 16 ft wide, from Exeter to below Countess Wear. On it were Britain’s first pound-locks, still with vertically-rising gates. A few years later the first mitre-gate look was probably built at Waltham Abbey on the River Lee.
This lock contains two double door of wood, Within the same a cesterne all of Plancke, Which only fills when boats come there to pass By opening of these mighty doors.
The Manchester Ship & Droitwich
Another remarkable early example is the 8-mile long waterway, with 12 locks, built before 1670 to by-pass the section of the River Welland between Market Deeping and Stamford. The biggest canal in Britain, and one of the biggest in the world, the Manchester Ship, is an artificial by-pass to the navigable rivers Mersey and Irwell, leading to Manchester. The St Lawrence Seaway, mainly in Canada, is a series of such by-passes.
An early step was to build a canal extension to, or branch from, a river, such as the Droitwich Canal from the Severn, on which salt could be shipped out from and coal brought into the town. A more difficult one was to connect two water heads by an artificial out between them. For the first of these we have to go back again to China to the ‘Magic Canal’, built over a saddle in the hills of north-east Kuangsi province in Shih Lu in 219 BC.
On the Continent
The Canal du Midi is a remarkable watershed out. It was built in the reign of Louis XIV between 1666 and 1681 to link the Atlantic with the Mediterranean by a heavily-locked waterway from the River Garonne near Toulouse to the Etang de Thau near Séte, 150 miles long, 64 ft wide, with three important aqueducts. The engineer John Smeaton called it ‘the noblest work of the kind that has ever been executed’.
Another was the Ludwigs Kanal, 112 miles long and with 100 locks, built between 1836 and 1845 by King Ludwig of Bavaria from Bamberg on the River Main to Dietfurt on the Altmiihl to connect the Rhine and Danube.
Trent & Mersey Canal
In England, the first was Brindley’s Trent & Mersey Canal, 93 miles long and with 74. locks, from the River Trent above Nottingham to Preston Brook, where it joined the Duke of Bridgewater’s Canal to the Mersey at Runcorn. The most notable we have are perhaps the Leeds & Liverpool between the Mersey and the Aire over the Pennines; the Kennet & Avon, linking the Thames, by way of the Kennet, with the Bristol Avon, and the Forth & Clyde across the waist of Scotland.
There are some magnificent examples across the Atlantic – the New York State Barge, formerly the Erie Canal, from the Hudson river at Albany to Lake Erie at Bufialo; the Rideau Canal in Canada from the river at Ottawa to Kingston on Lake Ontario; and the longest canal ever built, the former Wabash & Erie, from Evansville on the Ohio river to Toledo on Lake Erie. In Ireland the Grand Canal from the sea at Dublin to the Shannon is of this type.
There is a kind of waterway built primarily to drain the land, but which may be useful also for navigation. The Romans built our own Fossdyke from Lincoln to the Trent as a drainage canal, but they used it, as we do, for navigation; Vermuyden cut the Dutch river to divert the River Don, and the New Bedford river to supplement the Ouse, to lessen flooding, but made both navigable.
Finally, there are canals that owe little or nothing to rivers – such as the Gota, running from lake to lake across Sweden from Gothenburg to Soderkoping south of Stockholm, the Mittelland Canal that sweeps west to east across Germany, or our own Grand Union from London to Birmingham. These lead one to the sea-to-sea waterways, the greatest products of the waterway builders’ art: our own Caledonian, the Kiel, Corinth, Suez and Panama.
The canal age in the world, which contributed greatly to building its industry and trade, and made possible the kind of industrial revolution we had in Britain, perhaps began when Ptolemy II (285-246 DC) of Egypt finished a waterway between the Nile and the Red Sea that the Pharaoh Necho had begun about 600 BC, and Darius, King of Persia, had continued. In Holland, Flanders, Germany and Italy it began in the Middle Ages; in France perhaps with the Canal de Briare, completed in 1642; in the United States not until the Santee in South Carolina was finished in 1800. But in the British Isles we may date it from March 1742, when the Newry navigation in the north of Ireland was opened by the Lough Neagh colliers Boulter and Cape, laden with Tyrone coal for Dublin.