For years researchers have been perplexed as to how the Egyptians were able to move large stones weighing several tons across desert sand without any advanced technology. After studying a wall painting from tomb Djehutihotep, Dutch physicist, Daniel Bonn noticed that in front of the sled that carried the “colossal statue,” one of the workers was pouring water onto the sand in front of the sled, as the other workers pulled the statue forward.
IFLScience.com released details Monday saying that Egyptologist previously interpreted the pouring as a purification ritual of some sort. Bonn says that based on the jar the worker uses in the painting, it appeared to be water pouring and not any other form of liquid lubricant.
When Bonn tested the theory in a lab he found that pouring water was able to greatly reduce the friction from the initial pull. This reduction in friction, and increase in gliding ability, was able to cut the number of workers by 50 percent. He also found that there was a science to the amount of water that could be placed in front of the sled. If too much water was added sliding friction increases again. He says that the ideal amount of water is “between 2 and 5 percent” of the sand’s volume.
Other researchers have responded to the water theory with some additional propositions. Mark Lehner, an ancient Egyptian researcher says that he believes desert clay was used as a lubricant to help the heavy objects glide across desert sand. Dr. Lehner worked with his own team putting together a mock process of sliding stones. They used sand and limestone debris and coated it with a thin layer of desert clay. They also used water on the clay to further assist the stones in gliding. Lehner says that desert clay “tafla” and “gypsum mortar” have both been seen under the rocks of the pyramids.