The Canal du Midi passes by the little village of Deyme near Toulouse and there are two engineering structures there that are listed as Historic Monuments: Deyme bridge and Joncasse aqueduct.
This bridge is typical of the engineering structures created by Pierre-Paul Riquet when the Canal du Midi was built in the late 17th century. Its half-barrel vault is a perfect semi-circle. It is characteristic of the engineering structures along the canal route. The way it was built, its size and the use of local building materials are all features that the structures along the canal have in common. Red brick is an iconic building material of the Toulouse area.
This bridge straddling the towns of Deyme and Pompertuzat has been listed as a Historic Monument since 1998.
Deyme bridge was partly destroyed in the battle of Toulouse on 12 April 1814 when Napoleon's troops led by Marshal Soult fought British-Portuguese and Spanish troops led by the Duke of Wellington. Marshal Soult destroyed the bridge and therefore saved his army by retreating to the south side of the Canal du Midi.
The bridge was restored as an exact copy in 1821. There is still a drinking trough visible alongside the upstream abutment on the left banks.
A little further on in the town of Deyme at kilometre marker 21, is the Joncasse siphon aqueduct.
It was built between 1734 and 1735 so that the waters of Rosiers and Joncasse streams (tributaries of the Hers) could flow under the canal.
Did you know?
The word Joncasse means land where rush grows, so wet, marshland. It is the name given to a farm nearby.
This aqueduct was built to allow the two streams to bypass the obstacle of the canal. It is a siphon aqueduct. There is an inlet sump upstream and a receiving reservoir lower down. They are connected by a brick tunnel. Water arrives by the force of gravity into the inlet sump and is then carried through the 3.90 metre opening of the brick tunnel. According to the principle of communicating vessels, water then flows into the lower stream.
Back then, the King's engineers and those working for the Province were competing with one another for the technological control of the public domain. This structure was built according to the highest level of quality, and it was one of the first structures to use hydraulic lime. This aqueduct was financed by the Province of Languedoc according to plans by engineer Jean de Clapiès, and it was classified as a Historic Monument in 1998.
A site managed by Voies navigables de France in collaboration with members of the “Entente du Canal du Midi” and their tourist operators.
