Sunday, December 11, 2011

Arch Chronology



I always thought that the Romans invented the arch. I was wrong. 

Some time before the Romans,  the first true arch was discovered, or should we say invented. The arch proved to be a huge quantum leap over the earlier post and lintel approach to spanning openings. The corbel vault with a similar arc shape and principle, but quite different from the proper fanned arch, was perhaps an intermediate step. The challenges of corbelling over wider and wider openings may have led to the discovery of the arch. No matter how it happened who ever came up with the first arch changed the course of architectural history.

Contrary to what people think however, it wasn't the Romans who discovered it. Examples and evidence of arch structures have been found in earlier civilizations, beginning with the Mesopotamians. The Egyptians also constructed arch vaults to roof the tombs they built.  Then there were the Greeks who utilized the arch idea now and then but only in very simple structural applications.

It was not until the Etruscans came along that the arch became a practical element in some of their early 'monumental' architecture. One example is the Porta Augusta, where the idea of the arch was refined and merged with Greek elements. 

The Romans took this knowledge and developed it further and did some amazing things with it. They invented the idea of setting an arch on top of columns or abutments to span wide walkways and decorative entrance openings. They showed off and used it brilliantly in a number of their buildings. The Romans developed the arch also to be used for the very practical purpose of building bridges and aqueducts.

Pont du Gard in France built by the Romans

10 comments:

  1. John, The invention of the arch must have amazed its inventor because it continues to fascinate people today including myself.
    Stone is limited because it is weak in tension. Even the largest stone lintel can hardly span as far as you can spit.
    Then some person, somewhere, came up with the incredible concept of using relatively small stones (voussoirs)to span huge distances, eliminating tension and playing to the natural strength of most stones, compression.
    The arch was born, a thing of functional beauty. Pat McAfee

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  2. Pat, just so you know... while the average spit is approximately six feet, there are a variety of spitting records. The world record for spitting a watermelon seed is just under 69 feet. The record for the furthest ping pong ball spit is 48.1 feet while the furthest cherry pit was spat a whopping 93.5 feet. A grape was airborne just 28.5 feet before landing and a champagne cork was orally jettison 22 feet. Perhaps most pertinent to lintel calculation is the spitting of a dead cricket just over 30 feet in 1998. Thankfully, the human mouth produces one litre of spit per day, and 25,000 quarts in a lifetime.. about two swimming pools, so I’m sure there are more records to come. Finally, when I was in college I dated a girl who was writing a thesis on distances that fish would spit to knock food off a platform. We only had two dates because I had more in common with the fish!

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  3. Perhaps they found inspiration from natural arches. In a number a of places around the world natural arches of stone, some spanning quite large distances, have been formed over time by weathering and erosion.The largest known example of this is the Fairy Bridge in China spanning an impressive 400 feet - another beautiful example is Landscape Arch in Utah spanning 280 feet. Gavin.

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  4. I wouldn't have mentioned spitting if I'd known a world expert was lurking out there and one who had a girlfriend that done a thesis on the subject. You just never know whats next in the world of stone.

    With some trepidation I'd like to mention that we love to corbel here in Ireland and had done so for about 6,000 years when eventually we began to shape the underside of lintels to look like arches. We were happy enough with this until one day quite unexpectedly we were struck by the arrival of the real arch. Although this magically worked only in compression it was a bit too far for us because we were hung up on creating tension. It took many years for us to succumb to the show-off easy ways of compression. But every so often, quite unexpectedly, there is an outbreak of corbelling, I've done it myself, even on your continent. I cant help it, it's a neolithic gene thing.
    Pat McAfee

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  5. Ha! I had my eight year old look it up in her Guiness Book of Records! Instant genius!! Pat, I recall you explaining how falsework can be made with woven alder sticks and lime plaster... have you ever tried this technique with dry stone arches? I smell an experiment coming...

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  6. Next time I see you I'll challenge you to a spitting contest. Given the right wind I reckon I can spit from Inis Oirr to Inismaan.

    I haven't used wickerwork falsework for dry stone arches. It is normally only associated with lime mortared arches and vaults. The wickerwork was curved in to the necessary shape and supported. Lime mortar was then spread on top of it and then the voussoirs of the arch were laid on this. Afterwards the wickerwork was left in place and not removed. There are many examples of this throughout Ireland on castles and other buildings including the arch barrels of bridges. I always thought that this phenomena represented 15th or 16th century work but lately I came across an article that said it could be much earlier.
    Spitting didnt come in to this but strangely enough the curve that a spit follows is that of the catenary arch, the strongest arch of all, at times not too far off the shape of some gothic arches.
    Pat McAfee

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  7. I accept the challenge, prehaps after a pint or two? I hope it's not of the duel sort where we have to turn and face each other. Pat, It's a lesser known fact, given that I'm about to make it up, that the partial canterary arches of flying buttresses were inspired by the shape demonstrated when spitting off a short cliff. The rose window arch was invented the same day, when an updraft returned the spit to the sender. js

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  8. This explains the term. The large, round window looks nothing like the flower from the rosa family of plants. In fact, its designer, von Lewgey (pronounced Loo-Guh-Hee) returned from the cliff with a sizeable and quite colourful hork in his eye, seemingly lost in bewilderment. When asked what happened, he looked at the church plans through his contaminated eye and simply said, "it rose". js

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  9. Next time JS, the spitting contest. Could JSR photo the trajectory of the winner and design an arch barrel for a bridge based on its curve?

    I'd like to add a lesser known fact (probably only of interest to myself) to do with corbelling. It is to be found on some medieval (say 15th century)stone bridges here. They are arched, (pointed or slightly pointed is common) but from the springing stone up say a quarter to one third the rise of the arch the voussoirs are corbelled and not radiated towards centre points. Above that they are are radiated. I have not come across a good reason for it yet but it's common enough and must have had a purpose. PMcA

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