Illustrated Explanation of the Chariot System in the Artificers' Record

The text only mentions the number of spoke ridges original: 綆 (geng); the protruding ridge where the spoke meets the rim and does not specify the rim thickness original: 牙厚 (ya hou) because the examples provided in the section on the Cartwright the Cheren official allow these details to be cross-referenced. Furthermore, the author used this method of description because, at the time, everyone was familiar with the construction; it was a way to keep the text concise. The author never anticipated that later generations would misunderstand it so completely. Therefore, if one does not explain in detail the meaning of the rim ridges for the Cartwright and the system of tapering the spoke body original: 輻骸外殺 (fuhai waisha) used by the Wheelwright, then the theory of the wheel’s ridge remains obscure, and there is no way to calculate the thickness of the rim.

Zheng Sinong Zheng Zhong (d. 83 AD), a Han dynasty scholar read the character for ridge as the word for "pancake" in the dialect of the regions east of the pass, which he equated with "calculation" original: 筭 (suan). It seems that Han dynasty people pronounced the word for "ridge" similarly to the word for "calculation," so Zheng Sinong used the character for "calculation" as a phonetic loan to establish the sound. However, the dictionary definition of "calculation" or "counting rods" is entirely unrelated to the meaning here.

The track of a chariot is called the gauge. original: 軌 (gui)

In ancient times, the main roads were nine gauges wide. A gauge was eight feet across; the Master Craftsman the Jiangren official used this as a standard of measurement. "Gauge" is itself a name for the tracks left by the wheels. The dictionary Explaining Graphs and Analyzing Characters the Shuowen Jiezi says: "A gauge is a chariot track; the character is formed from 'chariot' and the phonetic 'nine'." Although the status and height of riding chariots, war chariots, and hunting chariots differed, the width between their two wheels was consistently eight feet. It is not as if...