Chinese Spurned Wheels for Sledge to Build Forbidden City

Chinese workers appear to have used a sledge, not wheels, to lug stones heavier than a Jumbo Jet to build Beijing’s Forbidden City palace six centuries ago.

Ice sledges were safer and more reliable for loads that weighed more than 300 tons, even though they were slower and more labor-intensive than wheeled alternatives, researchers in the U.S. and China found after studying records and experimenting with ancient haulage systems.

Wells were dug every half kilometer (third of a mile), providing water to slosh on roads that would freeze in winter, creating an artificial path of ice that lubricated the sledge, the scientists said. The research, by scientists from Princeton University and Beijing’s University of Science and Technology and Tsinghua University, was published yesterday in the Proceedings of the National Academy of Sciences.

Construction of the Forbidden City, the seat of imperial power during the Ming and Qing dynasties, started in 1417 after the Ming emperor Yongle moved his capital from Nanjing to Beijing, according to the Palace Museum’s website.

Wheeled vehicles were capable of hauling as much as 95 tons by 1596, which wasn’t sufficient, the authors said. The palace’s heaviest stone feature, the “Large Stone Carving,” weighed more than 300 tons when it was being transported. In comparison, Boeing’s 747 aircraft, nicknamed the Jumbo Jet, weighs about 220 tons when empty.

The translation of one 500-year-old text detailed how, in 1557, workers transported a stone weighing about 123 tons from a quarry to the palace in central Beijing, according to the study. The 70-kilometer journey took 28 days.

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— With assistance by Daryl Loo

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