‘I found Rome a city of bricks and left it a city of marble.’ That is supposed to have been the boast of Caesar Augustus, the first Roman emperor, just over two thousand years ago. If it was, he was exaggerating: ancient Rome is a city of brick, and no less glorious for that.
Augustus was also joining a long tradition of denigrating or overlooking one of the most ancient and versatile of building materials. The great Roman architectural writer Vitruvius mentions them only in passing. Denis Diderot’s great French Encyclopaedia ‘of the Sciences, Arts and Crafts’, published in 1751 and an inspiration for Adam Smith’s famous description of the pin factory – well, Diderot doesn’t trouble himself to include any images of brickmaking at all.
That’s because a brick is such an intuitive thing: people have been teaching themselves to build simple structures out of brick for many thousands of years – and grand ones too. The Hanging Gardens of Babylon were made of brick. So was the biblical tower of Babel: ‘Come, let’s make bricks and bake them thoroughly.’ That’s Genesis 11 verse 3. ‘They used brick instead of stone.’ By verse 5, The Lord is on the scene and things aren’t looking too good for the brick-loving citizens of Babel.
As James Campbell and Will Pryce point out in their magisterial history of bricks, the humble cuboid is everywhere. The biggest man-made structure on the planet, the Ming Dynasty Great Wall of China, is largely constructed of brick. The astonishing temples of Bagan in Myanmar; mighty Malbork Castle in Poland; Siena’s Palazzo and Florence’s Duomo; the bridges of Isfahan in Iran; Hampton Court Palace in West London. All brick. So is the best church in the world, Hagia Sophia in Istanbul, and the best skyscraper, the Chrysler Building in Manhattan, and even the Taj Mahal. Brick. Brick. Brick. The architect Frank Lloyd Wright once boasted that he could make a brick worth its weight in gold.
This all started a long time ago; bricks seem to have been with us since the very dawn of civilisation – the oldest were found in Jericho, in Jordan, by the archaeologist Kathleen Kenyon in 1952. They are something between 10,300 and 9,600 years old, and are simply loaves of mud, baked dry in the sun, then stacked up and glued together with more mud.
The next big step forward was the simple brick mould, also originating from Mesopotamia, at least 7,000 years old, and depicted with great clarity on a tomb painting in Thebes, Egypt. The brick mould is a wooden rectangle, with four sides but no top or bottom, into which clay and straw could be packed to make bricks faster and more precisely. These moulds can’t have been easy to make – they pre-date the use of metal itself – but once constructed they made mud bricks much cheaper and better.
Even in a dry climate, sun-dried mud bricks do not usually last. Fired bricks are much more durable – they’re stronger, and waterproof. Making such bricks, by heating clay and sand at a temperature of about 1,000° centigrade, has been possible for many thousands of years – but at a price. Accounts from the Third Dynasty of Ur, dating back just over 4,000 years, note that you could get 14,400 mud bricks for the price of a piece of silver; but only 504 fired clay bricks – an exchange rate of nearly 29 mud bricks for a single clay one. Some 1500 years later, by Babylonian times, kiln technologies had improved and the price of fired clay bricks had fallen to between 2 and 5 mud bricks.
That’s still too much for many people – cheap and easy mud bricks are still perhaps the most popular material in the world for building houses. But, as the Nobel prize-winning economists Abhijit Banerjee and Esther Duflo observe, fired bricks can be an effective way for a very poor household to save. If you have a little money, buy a brick or two. Slowly, slowly, slowly, you’ll have a better house.
The brick is one of those old technologies, like the wheel or paper, that seem to be basically unimprovable. ‘The shapes and sizes of bricks do not differ greatly wherever they are made,’ write Edward Dobson in the fourteenth edition of his Rudimentary Treatise on the Manufacture of Bricks and Tiles. There’s a simple reason for the size: it has to fit in a human hand. As for the shape, building is much more straightforward if the width is half the length.
That’s why, if you get your nose up close to some buildings that seem vibrantly distinctive to their culture – the Minaret of Kalan Mosque in Uzbekistan, Herstmonceux Castle in England, the Twin Pagodas of Suzhou in China – you’ll find the bricks are all much the same. It’s precisely the uniformity of the brick that makes it so versatile – a lesson freshly rediscovered by every generation of parents when their children start playing with Lego.
Lego, by the way, point out that their plastic bricks don’t need to be sent for recycling because they can be reused almost indefinitely. And what is true for toy bricks is truer yet for the real thing. Lego’s interlocking bricks demand a high level of precision – the fault rate is just 18 per million. But bricks jointed with mortar have a higher tolerance. Many medieval buildings, such as St Alban’s Cathedral in England, simply reused Roman bricks. Why not?
‘Bricks manage time beautifully.’ That’s Stewart Brand in his book and TV series, How Buildings Learn. ‘They can last nearly forever. Their rough surface takes a handsome patina that keeps improving for centuries.’ My own house, a brick building from the mid-nineteenth century, now has a large glass door in the back. To make the hole for the glass, we took away some bricks. Then we mixed them with similar reclaimed bricks, and used the brick salad to extend the house elsewhere.
Brick production still uses traditional methods in many parts of the world – for example in India, handmade bricks are often fired using a Bull’s Trench kiln – a long ditch lined with bricks that can burn almost any fuel and produce 30,000 bricks a day. It may be fuel-hungry and polluting, but it uses local labour and materials.
But automation is gradually nosing its way into most parts of brick production: hydraulic shovels dig the clay; slow conveyor belts carry bricks through long tunnel kilns; forklift trucks shift precision-stacked pallets of bricks. All this makes the brick itself cheaper.
Building sites have resisted automation: the weather and the unique demands of each site require well-trained workers. The bricklayer has long been celebrated as a symbol of the honest dignity of skilled manual labour, and bricklaying tools have barely changed since the seventeenth century. But, as in so many other professions, there are signs that the robots may be coming to bricklaying. A human bricklayer can lay 300–600 bricks a day; the designers of SAM, the Semi-Automated Mason, claim it can do 3,000.
What of the brick itself? Various designs of interlocking brick, much like Lego, are catching on across the developing world: the result tends to be less strong and waterproof than bricks and mortar, but they’re quicker and cheaper to lay. And if you have robot bricklayers, why not give them bigger hands so you can make bigger bricks? Hadrian X is a robot arm which lays gigantic bricks that no human bricklayer could wield.
Maybe we shouldn’t get too excited, though. SAM has a predecessor – the ‘Motor Mason’, for which similar claims were made back in 1967. Perhaps the bricklayer will last a little longer yet. The brick certainly will.
This essay is an extract from “The Next 50 Things That Made The Modern Economy” – the paperback is out this week in the UK.
“Endlessly insightful and full of surprises — exactly what you would expect from Tim Harford.”- Bill Bryson
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