THE EGYPTIANS might have built the pyramids using kites. It seems like a ridiculous idea, but an aeronautics professor at the California Institute of Technology has proved that it could nonetheless be correct.
The pyramids were built more than three thousand years ago, and no one knows how. The conventional picture is that tens of thousands of slaves dragged stones on sledges. But there is no evidence to back this up. It was a Californian software consultant called Maureen Clemmons who first suggested that kites were involved. While perusing a book on the monuments of Egypt she noticed a hieroglyph that showed a row of men standing in odd postures (see Graphic). They were holding what looked like ropes that led, via some kind of mechanical system, to a giant bird in the sky. She wondered if perhaps the bird was actually a giant kite, and the men were using it to lift a heavy object.
Intrigued, Clemmons set out to investigate this possibility. At a park in Northridge, California, she and some friends tried to lift a 2.5-metre-long redwood log and a 180-kilogram cement obelisk with shop-bought kites. Eventually, they managed it, and Clemmons began contacting university aeronautics departments to get help with taking things further. After several refusals she struck lucky at Caltech: Morteza Gharib was fascinated. 鈥淐oming from Iran, I have a keen interest in Middle Eastern science,鈥� he says.
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He too was puzzled by the picture that had sparked Clemmons鈥檚 interest. The object in the sky apparently had wings far too short and wide for a bird. 鈥淭he possibility certainly existed that it was a kite,鈥� he says. And since he needed a summer project for his student Emilio Graff, investigating the possibility of using kites as heavy lifters seemed like a good idea.
Gharib and Graff set themselves the task of raising a 4.5-metre stone obelisk from horizontal to vertical, using nothing but the wind. Their initial calculations and scale-model wind-tunnel experiments convinced them they wouldn鈥檛 need a strong wind to lift the 3.5-tonne column. Even a modest force, if sustained over a long time, would do. The key is to use a pulley system that would magnify the applied force.
So they rigged up a tent-shaped scaffold directly above the tip of the prone obelisk (see Graphic), with pulleys suspended from the scaffold鈥檚 apex. The idea was that as the tip of the obelisk rose, the base would roll across the ground on a trolley.
Earlier this year, the team put Clemmons鈥檚 unlikely theory to the test using a 40-square-metre rectangular nylon 鈥減ara-foil鈥� sail. The kite lifted the obelisk clean off the ground. 鈥淲e were absolutely stunned,鈥� Gharib says. 鈥淭he instant the sail opened into the wind, a huge force was generated and the obelisk was raised to the vertical in a mere 40 seconds.鈥�
The wind was blowing at a gentle 16 to 20 kilometres per hour, little more than half what they thought would be needed. What they had failed to reckon with was what happened when the kite was opened. 鈥淭here was a huge initial force-five times larger than the steady-state force,鈥� Gharib says.
This jerk means that kites could lift huge weights, Gharib realised. 鈥淓ven a 300-tonne obelisk could have been lifted to the vertical with 40 or so men and four or five sails,鈥� he says. So Clemmons was right: the pyramid builders could have used kites to lift massive stones into place. 鈥淲hether they actually did is another matter,鈥� Gharib says.
There are no pictures showing the construction of the pyramids, so there is no way to tell what really happened. 鈥淭he evidence for using kites for moving large stones is no better or worse than the evidence for the brute-force method,鈥� Gharib says.
All the materials used for harnessing wind power-the ropes, the sails, the pulleys-would have rotted away centuries ago, and Gharib believes there are good reasons why priests in charge of the pyramid building might have wanted to keep the secrets of the kites to themselves. An ability to harness the natural elements was a sacred privilege. 鈥淚t was by means of secret, mysterious knowledge that they maintained their power over the masses,鈥� he says. Kites certainly have religious significance in other cultures. In Polynesia, they are associated with particular deities. Kite flying is a sacred ritual to the Maoris, used in divination and funerals.
Harnessing the wind would not have been a problem for accomplished sailors like the Egyptians. And they are known to have used wooden pulleys, which could have been made strong enough to bear the weight of massive blocks of stone. 鈥淢y materials scientist colleagues at Caltech believe that wood, if cut along the right fibre direction, can be stronger than metals,鈥� Gharib says.
He now plans to recreate Egyptian-style equipment using hemp ropes and wooden pulleys. And the wheeled trolley can go: the Egyptians used to put oil and water on the sand to liquefy it and reduce friction under their sledges. 鈥淲e might try this under the base of the obelisk,鈥� Gharib says. He also plans to use a sail made from flax, waxed in some way to make it wind-proof.
Clemmons believes the Egyptians might have wind-proofed their sails and kites with a shellac-like substance excreted by scarab beetles. She was even invited to present this idea to the Scarab Biocontrol Workshop held at the University of Arizona earlier this year. The reaction was enthusiastic, she says, and the entomologists gave her tips on trying out the idea. By teasing exudate from green beetles she found in her garden, and painting it onto linen sheets, she has proved its windproofing capabilities.
A number of sacred Egyptian symbols might have their roots in construction. The Egyptian cross, or ankh (shown at the sides of the 鈥渒ite鈥� in the hieroglyph below, left) is topped by a loop that provides a perfect way to wind and control a kite line, Clemmons suggests. She points out that many of our familiar sacred symbols-the menorah and the cross, for example-have their origins in everyday life.
Such elaborate speculation based on so few hard facts has not gone down well with Egyptologists. 鈥淭he evidence for kite lifting is non-existent,鈥� says Willeke Wendrich, an associate professor of Egyptology at the University of California, Los Angeles. Colin Reader, an engineering geologist who has worked on the Giza Plateau Mapping Project is not quite so blunt: 鈥淭he biggest problem I have with the kite theory-and this isn鈥檛 very scientific, I鈥檓 afraid-is that there鈥檚 no reference to kites or any other sort of flying that I鈥檓 aware of in the ancient texts.鈥�
But as Reader acknowledges, there is some physical evidence that the Egyptians were interested in flight. A wooden artefact found on the step pyramid at Saqqara looks uncannily like a model glider, he says. Although it only dates from a few hundred years BC, its sophistication suggests that the Egyptians might have been developing ideas of flight for a long time. And other ancient civilisations certainly knew about kites: as early as 1250 BC, the Chinese were using them to deliver messages and to dump flaming debris on their foes.
Breeze blocks
Gharib thinks other ancient civilisations could have built their monuments using kites. 鈥淭he prerequisite is a windy location and a knowledge of sailing,鈥� he says. 鈥淪tonehenge fits the bill, as do the monuments of the Incas high up in the Andes.鈥�
The project鈥檚 success has certainly stirred imaginations, and National Geographic is considering giving the Caltech team a grant to raise a 30 to 50-tonne obelisk. Gharib is wary about accepting this, however. 鈥淚 don鈥檛 want to get caught up in a media circus,鈥� he says. 鈥淢y interest is in doing controlled experiments.鈥�
Those experiments might even have practical uses. There are plenty of places around the globe where people have no access to heavy machinery, but do know how to deal with wind, sailing and basic mechanical principles. Gharib has already been contacted by a civil engineer in Nicaragua who wants to put up buildings with adobe roofs supported by concrete arches on a site that heavy equipment can鈥檛 reach. His idea is to build the arches horizontally, then lift them into place using kites. 鈥淲e鈥檝e given him some design hints,鈥� says Gharib. 鈥淲e鈥檙e just waiting for him to report back.鈥�
Clemmons is delighted by this unexpected spin-off. When she first suggested that pyramid stones were flown into place, an Egyptian government minister scoffed at the idea and dubbed her a 鈥減yramidiot鈥�. But it seems that kites really can make sensible construction tools. 鈥淭his could prove very useful in many developing countries,鈥� Clemmons says. It might also prove she鈥檚 not so pyramidiotic after all.