The Use of Volume in the Measurement of Grain in Early Imperial China

Abstract

Officials managing grain in early imperial China used both capacity and volume units to quantify the spatial extension of grain. This chapter aims to explain why for the same thing, practitioners used two types of units that appear to us as equivalent. To begin with, we establish that volumes were magnitudes expressed with measurement units wholly different from capacities. In fact, there were no specific units devoted to the expression of volume, but simply a specific way of using measurement units for length. Of all types of magnitudes, for which ancient texts contain expressions of quantities, volume stands out for this reason. It also stands out because, as a rule, there is no standard with which volume can be measured. Expressions of volume derive from computation, in which geometric shape plays a crucial part. By contrast, amounts of capacity were expressed using the decimal system of dan (later on, named hu), dou and sheng, and they could be measured with vessels. Officially promulgated vessels included Shang Yang’s cuboidal sheng and Wang Mang’s cylindrical hu. We, then, examine the uses of volume in relation to grain. First, amounts of volume were used to define a second meaning of dan (later on, hu), that is, dan and hu as measurement units of value. Inscriptions on official vessels also used volume amounts to refer to the space they contained. This shows that these vessels did not only define units of capacity, but also units of value for a “standard” state of grain. Hence, these vessels also attest to a practice that connected extension and value through the use of volume. The third use of volume for grain likewise brought geometric shape into play and its primary goal was to assess an amount in value units. In conclusion, we suggest that using volume for grain occurred primarily in relation to the assessment of the value of an amount of grain, and geometric shape was systematically introduced to carry out the operation. This suggests some hypotheses about the management of granaries.