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A Study Finds Ancient Egyptians Transported Big Objects over Wet Sand

The new study, published in the journal of Physical Review Letters, has demonstrated that ancient Egyptians applied a simple approach to moistening the sand and then transporting heavy colossi and pyramid stones by sledge in a much easier way.

Ancient Egyptians

Drawing of a wall painting from the tomb of Djehutihotep, a semi-feudal ruler of an Ancient Egyptian province, 1880 BC. A person standing at the front of the sled is pouring water onto the sand.

In order to construct pyramids, ancient Egyptians were forced to transport heavy blocks of stone and large statues across the desert. By doing so, they would put the heavy and large objects on a sledge which would be pulled by the workers over the sand.

Based on hypothesis by Prof Daniel Bonn from the University of Amsterdam and his multinational research team, ancient Egyptians were more likely to wet the desert sand in front of the sledge before transportation.

To examine such hypothesis was true or not, the team set up a miniature Egyptian sledge put in a tray of sand in their lab. In the test, the team determined both the necessary pulling force and the stiffness of the sand as a function of the quantity of water in the sand. As for identifying the stiffness it resorted to a rheometer, which would show how strongly the force was required in deforming a certain volume of sand.

According to the research results, the required pulling force decreased in proportion to the stiffness of the sand. When the sand was wetted by water, the capillary bridges came into being, because small water droplets could allow the sand grains to be bond together.

With the right amount of water, wet desert sand would become twice as stiff as dry sand so as to keep a sledge move quiet easily over firm desert sand. The reason was simple that the sand would not accumulate in front of the sledge as it did in regard to the dry sand.

The ancient Egyptians might know such simple approach well, which could be clearly illustrated by a wall painting in the tomb of Djehutihotep. The painting pictured a person standing ahead of the pulled sledge while pouring water over the sand in front of him.

Apart from showing something related with the ancient Egyptians, the research would shed light to more wide applications today. As scientists have to know more about the properties of granular material such as sand, they should work harder to find out how granular materials like asphalt, coal and concrete and could be better utilized in terms of optimizing the transport and processing of such granular materials for useful energy consumption all over the world.

Journal reference: 

A.Fall et al. 2014. Sliding Friction on Wet and Dry Sand. Phys. Rev. Lett. 112, 175502; doi: 10.1103/PhysRevLett.112.175502