Saturday, March 7, 2009

Pont de fer, 1



It seems like a French habit to start off in the abstract. A guest on a cooking program might first be asked, What is your idea of cooking? before How do you make REAL couscous? Me, I've got this bridge outside my kitchen window that seems more and more beautiful, more and more laden with meaning.

First there's the physics of it. A couple of towers at either end, a couple of cables hung between them, a plank suspended from the cables. The tower acting in compression, getting squished down, bringing the weight of the bridge itself and the vehicles back from the middle to the two ends. The cable, an upsidedown arch, acting in tension, getting pulled toward each end, a mammoth tug of war trying to win the middle point. At either end, a set of tensioning bolts anchoring the cable and keeping the two cables in balance. Every week a big man comes to adjust the bolts with just a tuning fork and a wrench. (Not true) Finally, the plank is supported by iron rods, also acting in tension.

Legend has it that an older version of this bridge, freshly built, was going to be dedicated. They had set the maximum design weight on the center and the newly-hired bridge guardian strode out to stand there too. Just then, the bridge collapsed and the guardian narrowly escaped being drowned. After the re-building, the guardian was never the same, always paranoid even about little boys playing near the tensioning bolts.

Legend has it that they used to decorate the bridge, covering it with flowers to celebrate some holiday in Spring.

There seem to be no legends about the architect of the bridge having to make a deal with the devil to give him the soul of the first to cross the bridge. The devil would lose when they sent across a cat first instead of a human. This is a legend that sticks to other ancient bridges including the Pont Valentré in Cahors.

There are pictures of an earlier version of this bridge with stone towers instead of the existing metal ones.



Someone told me this bridge was designed by Eiffel. I had done some research and doubt that Eiffel had anything to do with it. It's a shame since it probably means that my other favorite suspension bridge, the graceful one laner in Albas between Rue de la Cale and the D9, was also not built by Eiffel. I've been repeating that myth for seven years.





The genius behind the French suspension bridge craze of 1825 to 1850 was Seguin. Suspension bridges are of course an ancient invention dating from ropes and plank designs. There were also early suspension bridges in Pennsylvania that used chains instead of cables. There must have been some cross-fertilization between France and the US throughout the 19th century.



The present bridge outside my window bears a maker's plaque:



It's likely that by the time of this version of the bridge, the company was under the direction of another engineering genius, Imbault.