h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

No matter what the scale of the temple (dramatic, epic or even just plain, well, big), you'll notice how the capitals at the top of the columns never really leave a long stretch of lintel completely unsupported. About 2 metres is around the maximum.

Apparently it's all to do with masonry being weak in tension and the Greeks trying to do all they could to persuade it to stay in compression.

This was pointed out by J.E.Gordon, once Professor of Materials Science at Reading University. He had a singular gift of writing both technically erudite and at the same time enormously entertaining books, about the (at first sight) rather dry subject of the use of materials.

So, if you get the chance, look out these two modern day classics:

"The New Science of Strong Materials or Why You Don't Fall Through the Floor" Penguin Books, second edition, 1976 (ISBN 0140135979).

"Structures or Why Things Don't Fall Down" Penguin Books, 1978 (ISBN 0140136282).


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Just for the record, Dyvroeth has no affiliation with Penguin Books !

Fascinating, Dyvroeth!

That's the engineering side, yes, but you will also see that this causes that you can only look through the gaps between the collums when you are standing right in front of them. If you go to the side a bit they seem to be a massive wall. An interesting architectural aspect.

And compression is not the problem. The problem with stone is bending. Or the lack of it. Stone just breaks.



Did you read about all the corrections the Greeks made so the temples look correct? All the collumns are not exactly vertical. It's all a big optical illusion. And the ones in the middle are further apart than the ones at the rim (or was it the other way round? ).


Hmm... and you act like the orders were only about the collumns, which isn't exactly true. Pictures of the orders would also have benn nice.

Still, great entry.

Agree re: layout of columns. There is certainly a lot of Art that can be put back to solve a purely engineering problem in a most aesthetic and agreeable way, when real craftsmen are at work.

I seem to recall (but can't remember where I read it) that the great Moghul builders of India did a similar thing with the pillars at the 4 corners of the Taj Mahal. Here the column sides nearest the Taj are sloped outwards, but the sides away from it are vertical. The idea was that if the columns ever fell, they might be inclined (geddit ?) to fall away from the Taj, minimising the damage to the spectacular dome and the engraved and inlaid walls.

On bending: if a stone block is tending to bend downwards - sagging - the upper surface will be put into compression, whilst the lower surface will be extended or put under tension. If you are lucky, you have enough time and the weight isn't too great, the masonry might just flow in a smooth and managable fashion. If you are unlucky and one or more of these conditions is not met, then cracks will appear in the tensioned lower surface and at some critical juncture, will propagate (probably explosively - a la A.A. Griffith) and the slab will break.

If it is being forced upwards - hogging - the stress field is inverted but the results are as inevitable.

Did you ever see the bridge that Leonardo da Vinci designed to cross the Golden Horn in Istanbul? That's a great combination of engineering and art.