by Andrew Boyd

Click here for audio of Episode 2870

Today, coast to coast. The University of Houston presents this program about the machines that make our civilization run, and the people whose ingenuity created them.

In the mid seventeenth century Pierre-Paul Riquet had an idea. It wasn't entirely new. The Romans had long considered it. Leonardo da Vinci had pondered it. But Riquet was a French engineer with friends in high places. He made a plan, secured financing, and began work on one of the great civil engineering projects in history: construction of the Canal du Midi.

Pierre-Paul Riquet, builder of the Canal du Midi

France has the luxury of coast on both the Atlantic Ocean and the Mediterranean Sea. But travel from one to the other requires sailing around Spain and Portugal. In Riquet's time that was both geographically and geopolitically dangerous. A canal just made sense.

The distance from one coast to the other was a lengthy 250 miles as the crow flies. But nature provided some help. Two great rivers flowed from the Pyrenees Mountains in the south of France. Upon reaching the country's relatively flat interior, one turned west to the Atlantic, the other east to the Mediterranean. If they could be connected — a distance of about 40 miles — a coast to coast transportation route would result.

But the task was harder than it might sound. The land between the two rivers was higher than either river and too high to dig a trench through. A system of locks was needed to traverse the higher land. The locks in turn needed a new, higher source of water to fill the canal.

Twelve miles from the summit of the canal — on higher ground — was a third river. It was small and ran seasonally, so Riquet had a massive dam built to hold water year round. At one point over twelve thousand people worked on it.

A group of swimmers gathering near the dam

While the dam was the canal's single largest undertaking, it was far from the only engineering challenge. Almost 100 locks were constructed along with many aqueducts and a tunnel, each requiring the attention of seasoned engineers. Final plans called for the canal to parallel but bypass the eastern river. As a result, the completed canal stretched 150 miles on its way to the Mediterranean.

A boat embarking on a pleasure cruise

And the canal was far more than a utilitarian enterprise. It spoke to the power and prestige of France, and to the French realization of a project the Romans only dreamt of. Neoclassical design elements and plaques bearing Latin inscriptions were placed along the length of the canal.

A boat on the Canal du Midi

The canal was a vibrant trade route for almost two centuries. But with the arrival of rail in the mid 1800s its use rapidly declined. The Canal du Midi is still in use, though mostly for recreation. But its place in history isn't lost. In 1996, it was deemed a world heritage site by UNESCO, the United Nations Educational, Scientific, and Cultural Organization. It's a fitting tribute to the many French engineers, laborers, and administrators who made the Roman dream a reality.

I'm Andy Boyd at the University of Houston, where we're interested in the way inventive minds work.

A map of the Canal du Midi and the Canal du Garonne

(Theme music)

Notes and References:

The Canal du Midi stretches from Toulouse, situated on the westward flowing Garonne River, to the east, where it meets the Aude River in Carcassonne before continuing on to the Mediterranean Sea. The Canal de Garonne, completed 150 years after the Canal du Midi, extended the canal system further down the Garonne River. Together, the two canals are known as the Canal des Deux Mers. Canals were used even when rivers were available because water levels and embankments could be controlled, greatly easing the movement of barges.

Canal de Garonne. From the Wikipedia website: Accessed March 19, 2013.

Canal du Midi. From the UNESCO World Heritage website: Accessed March 19, 2013.

Canal du Midi. From the Wikipedia website: Accessed March 19, 2013.

Locks on the Canal du Midi. From the Wikipedia website: Accessed March 19, 2013.

H. Samuel. Canal du Midi: History of the 17th Century Engineering Marvel. The Telegraph: July 26, 2011. See also: Accessed March 19, 2013.

All pictures are from Wikimedia Commons.