According to the new study, published in the journal Physical Review Letters, ancient Egyptians used a simple trick to make the job of hauling heavy colossi easier – they moistened the sand before thousands of workers pulled the objects on a sledge.
“Liquid bridges start to form between the grains when water is added. Once there is enough water, these bridges act like glue, keeping the grains in place,” wrote the study authors.
To test their hypothesis, the team of researchers placed a lab version of the Egyptian sledge in a tray of sand and measured the level of friction in dry versus wet sand. The results showed that the required pulling force decreased proportional to the stiffness of the sand.
In support of the theory, a wall painting found within the tomb of Djehutihotep appears to depict a scene of slaves hauling a colossal statue of the Middle Kingdom ruler and in it, the scientists claim the person at the front of the sled is pouring liquid onto the sand.
Find all about this study here.