Monday, 3 November 2014

Egyptian rock and roll

The latest edition of PhysicsWorld includes an item entitled Egyptian rock and roll:
The pyramids at Giza are one of the seven wonders of the ancient world. But we still do not know for sure how the ancient Egyptians built the giant structures in the first place, or how they moved millions of huge limestone blocks each weighing about 2500 kg. Joseph West from Indiana State University and colleagues have now put their own pet theory to the test. They attached three wooden dowels to each side of a 30 kg concrete block – in effect turning it into a 12-sided polygon that could be rolled instead of dragged. “On the surfaces we tested the block on, we could roll the block with about the same amount of work as would be used in dragging the block over moistened sand,” West reveals. The researchers now plans to scale up their work to test the idea with a 900 kg block and to use fence posts as the rods. But was it likely that the ancient Egyptians used their method? West thinks it “could have been used”, but cautions that “the archeological evidence does not strongly support the idea”. The mystery deepens.
Personally, I think the "mystery" was resolved a long time ago. For example, see Building the pyramids from quarried stone blocks:
Dr R H G Parry[3] has suggested a method for rolling the stones, using a cradle-like machine that had been excavated in various new kingdom temples. Four of those objects could be fitted around a block so it could be rolled easily. Experiments done by the Obayashi Corporation, with concrete blocks 0.8 m square by 1.6 m long and weighing 2.5 tons, showed how 18 men could drag the block over a 1-in-4 incline ramp, at a rate of 18 meters per minute. This idea was previously described by John Bush in 1977 [4], and is mentioned in the "Closing Remarks" section of Parry's book. 
About 20 years ago I attended a seminar by Dick Parry at the University of Western Australia on exactly this topic. His book Engineering the Pyramids includes the material presented in his seminar and describes a simple and elegant solution involving four re-usable cradles. Even earlier, in 1977, the same idea was outlined by John Bush in his delightful one page engineering analysis entitled The Rolling Stones, where he explains how four cradles could used to parbuckle the blocks.

No comments:

Post a Comment