Period: Eastern Han (25-220)
Measurements: W.1.6 cm, L. 16.1 cm
Provenance: Unearthed at Pingle village of Mengjin district, Luoyang, 1959

Made of the white jade, the ruler has one round hole at either end, and was engraved with a vertical line at intervals of 2.3 centimeter as the mark of cun(unit of length). Be damaged when unearthed, it measures 23 cm in length after restoration, each cun roughly equals 2.3 cm, slightly shorter than the modern unit on the Chinese ruler.

The archaeologically discovered rulers from the Eastern Han dynasty were made of various materials, mostly the bronze, there were also other variations such as bone, ivory, jade, bamboo, and wood. Particularly, the length measurement of “five-units” which was comprised of “fen, cun, chi, zhang, yin” was well developed in the Eastern Han period, the actual length of one chi roughly equaled 23 cm, one cun was some 2.3 cm. The rational, unit-stable length measurement continually affected the development of the measuring standards in the later generations.