Illustrated Explanation of Chariot Construction: Volume I

Page Eleven

However, the theory proposed by Jia Gongyan A Tang dynasty scholar known for his commentaries on the Rites of Zhou—that the mortise hole encroaches toward the outside—is an error not worth debating. Recently, Master Jiang Shenxiu referring to the Qing dynasty scholar Jiang Yong (1681–1762), a renowned expert on ritual and mathematics stated: "If we examine the un-tapered original: 殺 (sha), to reduce or taper spokes of the present day and interpret Zheng Xuan’s meaning, it suggests that the mortise on the rim is not centered. Instead, because the spoke uses an offset claw original: 蚤 (zao), the tenon at the end of the spoke to enter a straight mortise directed inward, the spoke appears to protrude outward by two-thirds of an inch. Therefore, when calculating the wheel's track width, one must add the measurement of the geng original: 綆, the ridge of the spoke where it meets the rim."

I, Yuan The author, likely Yuan Yuan (1764–1849) or a contemporary technician, find that this statement by Mr. Zheng is incorrect. The Record the Kao Gong Ji or Artificers' Record states: "A geng of two-thirds of an inch is what makes a wheel firm." This means that if the geng is two-thirds of an inch, the rim must be two inches thick for the wheel to be solid. If it were any thinner, it would not be firm.

If the rim is two inches thick, let us try dividing it into three parts. Each part would measure six fen, six li, and six hao These are decimal subdivisions of a Chinese inch: 0.666 inches.

• The inner third aligns with the place where the spoke's "claw" curves and pierces.
• The middle third serves as the mortise for the "claw."
• The outer third corresponds to the area where the spoke's calf the tapered outer section of the spoke is reduced.

This outer third is what we call the geng. Its width is exactly six fen, six li, and six hao. Since the tapered calf of the spoke does not sit flush with the edge of the rim, it creates an appearance as if the rim is protruding outward, but in reality—