A Bridge, as Nature Intended It

"We speak well of the bridge that carries us over" goes a proverb. Obviously. Bridges are practical. Far more fascinating is the wonder that bridges often elicit: sights to see.

From processional Roman viaducts to minimalist flight paths of modern suspension and cable-stayed bridges, this metamorphosis persists: Mundane function turns into elated form.

There is something theatrical about bridges. They are like stages. The Japanese printmakers - Horishige, Hokusai, and company - knew this well, depicting people elegantly moving over bridges as if they were models on a catwalk.

Bridges over the Seine, the Arno, the Venetian canals are tourist meccas. Prague's Charles Bridge is now a milling promenade. According to David Brown (in "Bridges: 3,000 Years of Defying Nature," London: Mitchell Beazly, revised 1996) this sturdy 14th-century structure "marches with its 16 arches" across the longest continuous extent of water covered by any medieval bridge" - 1,692 feet.

Bridges can sometimes be bones of contention. "The old Turkish bridge" in Mostar, Bosnia, lasted from 1566 to 1993, when it was blown up. Its stones are now being salvaged. If rebuilt, it will become a far-from-facile symbol of a more stable future for that torn patch on the world. Burning bridges, that archetypal gesture of conflict, must finally have its corollary in mending them.

Pausing on a bridge is a kind of balm. I stopped the car in Dorset one recent Sunday morning and strolled onto a medieval bridge, now bypassed by traffic. A man was reading his paper in one of the bridge's recesses. I chose another (these recesses are at the upper end of the cutwaters that project from the stone piers of medieval bridges) and ate a homemade bun in the sun. A pair of swans, their necks up like periscopes, let the current carry them away under me.

Some people love old bridges but seem unmoved by more recent spans. Yet the breathtaking elegance that some 20th-century bridges achieve is daring and awesome. Bridges are still bridges, whatever their period. Eighteenth-century stone bridges, coolly rational, measure their way over chasm or stream. Cast-iron bridges, strong testimony to the inventiveness of the early Industrial Revolution, initiate structures seemingly supported by ever-thinner air.

Mr. Brown's book quotes the poet Robert Southey on one of Thomas Telford's iron bridges: "something like a spider's web in the air." I'd like to know what he might have said about some of today's weightless marvels.

Or, for that matter, about the far-from-weightless Tarr Steps.

Tarr Steps, a "clapper bridge," is more famous than I realized. I came across it in a book and was immediately determined to see it. It is in the English West Country, on Exmoor.

I imagined it would be miles across wild moorland. But in fact it (or they, since the bridge is named in the plural because it is made of piled and leaning stones, without mortar, held together by placement and weight) is on the map and well sign-posted.

I was not alone on my visit. Though thankfully not overcommercialized, Tarr Steps are apparently a favorite outing. As I walked down the steep path through banked meadows, wondering how soon I would see the bridge, I was aware of numbers of others bent on the same destination. And they, too, clearly had what I call a vivid sense of occasion. It was as if we were all about to witness some remarkable event.

Tarr Steps are a kind of event. They have the excitement of stepping stones, but are actually a continuous, real bridge, though not at all high above the water.

NOBODY seems able to argue convincingly about their age. They could be medieval. They might even be prehistoric. They have in this century been breached and flood-damaged more than once, anyway, and reconstructed.

What matters is that this structure is very primitive, a primeval bridge. Without arch or cantilever, it strides across the stony riverbed. Presumably it was made with rocks lifted from the river itself. Its enormous slabs are laid flat on piers piled up like dry-stone walling, and against these are leaned sloping stones graded by size - loose and basic cutwaters.

Brown's book shows a photograph of Tarr Steps at its outset. He obviously thinks of this bridge as being very near the beginning of his 3,000-year story. But while he rightly describes most of the bridges in that story as "defying nature," Tarr Steps is a natural work of art. It does defy the flow and wetness of the river it crosses, but it is composed of materials provided directly and locally by nature. These materials have been found and organized, that's all. If ever there was a bridge that looks as if nature intended it, Tarr Steps is, fascinatingly, the one.

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