On the Function of the Warring States Chu “Royal” Bronze Beams, as Well as “Establishing it with Things” in Lu Jiuci Asked Chen Qi about Numbers (鲁久次问数于陈起)

The National Museum of China houses two bronze balance beams inscribed with the character “wang (王, king or royal)” reportedly unearthed in Shou County, Anhui Province. These artifacts are undoubtedly from the Warring States period state of Chu. Given the presence of scales on the beams, scholars generally believe these items represent an intermediate stage in the development from balance scales to steelyards, making them a transitional type of weighing instrument. However, the exact function of these bronze beams remains somewhat unclear. This article attempts to propose a new hypothesis by integrating mathematical data from texts on excavated bamboo slips. It suggests that the “royal” bronze beams were not used for the accumulation of standard weights but rather for the division of unit weights, corresponding to the terms “destroy” (hui 毁) or “break” (po 破) mentioned in unearthed arithmetic books. This function might have two specific applications: first, to establish or verify standard weights, and second, to achieve more precise measurements when the smallest standard weight was still not accurate enough. Based on this, the article will also reconsider the phrase “yi wu qi zhi” (以物起之, establishing it with things) from the Peking University Qin manuscript Lu Jiuci Asked Chen Qi about Numbers (Lu Jiuci wenshu yu Chen Qi 鲁久次问数于陈起), suggesting that it discusses the relationship between measurements and fractions.