Ancient Egyptians Used Wet Sand to Transport Pyramid Stones

Posted on May 1, 2014

Wall painting of a sledge being pulled at the tomb of Djehutihotep

Ancient Egyptians used wet sand to transport pyramid stones and sculptures. The objects were first placed on a sledge. A wall painting found in the tomb of Djehutihotep shows a person standing on the front of a pulled sledge pouring water on the sand in front of it. Physicists from the University of Amsterdam, led by professor Daniel Bonn, conducted experiments that found dampening the sand in front of the sledge could half the force required to pull it.

The physicists placed a laboratory version of the Egyptian sledge in a tray of sand. They determined both the required pulling force and the stiffness of the sand as a function of the quantity of water in the sand. To determine the stiffness they used a rheometer, which shows how much force is needed to deform a certain volume of sand. Experiments revealed that the required pulling force decreased proportional to the stiffness of the sand. The sledge glides more easily over firm desert sand because the sand does not pile up in front of the sled like it does with dry sand.

Sledge movement over dry and wet sand

A research paper, "Sliding Friction on Wet and Dry Sand," was published here in the journal, Physical Review Letters.

Top Photo: Al-Ahram Weekly, 5-11 August 2004, issue 702

Second Photo: University of Amsterdam

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