Development of the Midi Canal
Development of the Midi Canal
Civilizations depend on water supply, and since ancient times people have sought ways of building channels to hold water that would circumvent natural barriers both to the supply of water and to navigation. The Romans and Charlemagne dreamed of a way to transport merchandise that would avoid having to detour around the coast of Spain or risking attack by Barbary pirates. The solution appeared in the seventeenth century in the form of the Midi Canal.
The Briare Canal in France, constructed by Adam de Crappone (1526-1576), was the first important watershed canal in the West. A watershed is a ridge of high land that divides areas drained by different river systems. On his return to France in 1516, Francis I (1494-1547) discussed with Leonardo da Vinci (1452-1519) a watershed canal between the Mediterranean Sea and the Atlantic Ocean. The idea was to join the Garonne and Aude Rivers—the latter leading south to the sea—via a canal that was later called the Languedoc or Midi Canal. Francis died in 1547, and it was not until 1598 that Henri IV (1553-1610) resuscitated the plans for the canal. But at the time, he had several more pressing canal projects, and his first matter of business was to build the Briare Canal. Henri died before he could return to the Midi Canal, and it was Louis the XIV (1638-1715) under whose aegis the Midi Canal was realized.
The person hired to carry out the project was a French public official and self-made engineer named Pierre-Paul Riquet (1604-1680). Riquet had himself become interested in how to construct a shortcut from the Bay of Biscay to the Mediterranean Sea. In 1662, already past middle age, he wrote a canny letter to the controller-general of finances outlining his plans for a canal that would help to cut in on the King of Spain's profits from the Straits of Gibraltar. The letter was brought to the attention of the king, who appointed a royal commission to approve Riquet's project. Because the canal would have to cross a watershed, the royal commission immediately pointed out the difficulty of supplying water to the canal's summit. Riquet proposed to solve the problem using two feeders, one 26 miles (42 km) long. It would be one of the canal's most notable technical achievements. Work began on the water supply in 1665, and construction began on the canal soon after. Ultimately, 8,000 workers were put to work on building the canal, including several hundred women. It took 14 years to complete, and opened in 1681. Riquet did not live to see it finished.
The Midi Canal stretched 150 miles (240 km) between the City of Toulouse and the Mediterranean Sea, and had 101 locks—devices that allow a vessel to negotiate changes in altitude by raising or lowering the water level. Until the early 1800s, most locks used in river canalizations were flash locks. The flash lock was a barrier that acted as a dam. Water would build up behind the dam, and when the reach behind the dam was full, a line of waiting boats would be let in through narrow lift gates in the dam. The process circumvented some of the problems of natural rivers, but it was slow, wasteful of water, and expensive.
For the Midi Canal, Riquet used pound locks, which are enclosed chambers about the same size as the boats using them, with gates at both ends. These locks first appeared in the Netherlands and northern Italy during the fourteenth and fifteenth centuries. Although he did not invent them, Leondardo da Vinci is credited with having brought the idea to France in 1515. But for the next 200-odd years, they were used chiefly in building watershed canals. Riquet constructed his system of locks arranged like a staircase to negotiate the 206-foot (63-m) rise to the summit, and 620 feet (189 m) down.
Near the southern French town of Beziers, he encountered a rocky rise. The problem with the rise was that it was made of alluvial stone, liable to collapse, and permeable to water. In the face of considerable opposition, Riquet used black powder to blast a 515-foot (157-m) tunnel through the rise, afterward leading an astounded commission through it by candlelight. Riquet's was the first canal tunnel built in this way, and he was the first to use explosives in underground construction. He also constructed three large aqueducts to carry the canal over rivers. In one of these aqueducts, the Repudre aqueduct, the bed of the canal served as a single-arch bridge across the river.
Without sufficient water, a canal is no more reliable than the natural waterways it seeks to improve. The Midi Canal is most renowned for its water supply system, which included the world's first known artificial reservoir for canal water supply. The reservoir was an earth-filled dam with masonry walls across the Laudot River, and it took four years to build. As a gravity dam, it relied on its weight for stability, and it was the first in Europe of its size. Water could be let out from the reservoir by means of two underground vaults. Riquet and the military engineer Sebastien Vauban (1633-1707) built feeder channels to supplement the reservoir. Additional dams were built in the eighteenth century to supply still more water to the canal.
French canal builders of what is called the old regime focused their technical abilities on specific problems of artificial waterways. For ages, people had developed ways of moving water for drainage, irrigation, and water supply. But for all their remarkable achievement, these efforts at improving or creating navigable waterways represented a minor effort in the ancient world.
The Midi Canal has been called Europe's finest seventeenth-century engineering work. Apart from its architectural interest, it served as a model of technical ambition and excellence. For many years, leaders had sought an all-water link between the two seas as a triumph of military strategy over Spain. Landowners and merchants in the region saw the canal as a means to commercial development that bypassed bad roads.
But the Midi Canal also illustrates the contradictions between high and low technological systems that existed in France prior to the eighteenth century. Until the time of the French Revolution (1787-1799), France lacked a coherent transport policy. What this meant in practical terms was that no one had ever thought through a way of transporting goods and people that would maximize the benefits and minimize the inefficiencies of both roads and rivers. The result was confusion, and a disproportionate emphasis—for military and political reasons—on a system of highways linking Paris to other parts of the country, even though water was clearly preferable for shipping heavy, low-value goods. Another reason roads were preferred was that they were cheap because they were built and maintained largely by unpaid labor.
Until 1750, therefore, when the government began to take a greater interest in them, waterways were largely funded by private means. But the state did not abdicate control over them. The state chose the engineers to build the canals, approved the building specifications, and provided a portion of funding. A disadvantage to this hands-on, hands-off system was that it was political: the entire process from conception through construction was vulnerable to the fortunes and caprices of a particular government. An advantage for the Midi Canal was that the 14 years it took to build it fell within a peaceful and prosperous era in French history. By contrast, during the building of the Briare Canal, the king was assassinated, the treasurer was forced to resign, and a commission of inquiry was appointed.
By suggesting that the commercial success of the canal would enhance the king's revenues, Riquet was able to obtain construction subsidies from Louis XIV. Moreover, owing to the administration's affection for Riquet, royal support continued even after Riquet had spent the last penny of his personal funds. Asked why he had sunk all the money set aside for his daughters' dowries into the canal, Riquet answered, "The canal is my dearest child."
Economically speaking, Riquet's technological prowess was ahead of its time. Despite the improvements made to the waterways, including a handful of canals, of which the Midi Canal was one, navigation conditions progressed very little up to the time of the Revolution. Towpaths for hauling barges along canals were not well maintained, and in other places, farmers and millers encroached on them. Boatmen's corporations rose up that sought to establish their members' monopolies over carrying goods along a waterway. These monopolies were vigorously defended, using political, economic, and sometimes physical means. Moreover, tolls, heavy to begin with and often arbitrary from river to river, contributed to the high cost of water transport, which limited its appeal.
For all that the achievements of a few canal builders failed to fulfill the promises of canal enthusiasts, France was still the world leader in artificial waterways almost up to the end of the 1700s. Despite impressive waterway networks, some countries, like Holland, did not have to cope with the same technical problems posed by the French countryside. In other countries such as the United States and Germany, programs of waterway improvement had hardly begun.
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Payne, Robert. The Canal Builders: The Story of Canal Engineers through the Ages. New York: Macmillan, 1959.
"History of the Canal des Deux Mers." http://www.canaldu-midi.org/history.htm