Illustrated Explanations for the Preface of the Record of Trades

The construction of chariots for land travel was a task established by the Sages. By the time of the Zhou peopleReferring to the Zhou Dynasty (c. 1046–256 BCE), the era during which the standards in the Record of Trades were supposedly set., they valued the carriage body above all else. Although it is a single vessel, it is the one craft that requires the greatest gathering of diverse artisans. The existing commentaries and explanations on the Record of TradesThe Kao Gong Ji (考工記). remain somewhat superficial. Scholars since the Tang dynasty618–907 CE; Ruan Yuan is criticizing the long-standing academic tradition of simply repeating old notes rather than investigating the physical engineering. have strictly adhered to these traditional annotations, yet they have rarely managed to fully synthesize and master the original text of the Classic itself.

I, Ruan Yuan, observe that while several gentlemen of our current age have already settled the various matters regarding the other crafts in the Record of Trades, there are still gaps concerning the specific craft of chariot making. Consequently, I have closely examined the measurements, ratios, and standards of the era. I have relied on the OdesThe Shijing (詩經) or Classic of Poetry, which contains many descriptions of contemporary chariots. to verify the terminology for the felloes, spokes, hub-covers, and naves; the wheel-cords and the "ears" of the carriage; and the axle-housing, the depth of the axle-mounting, the support timbers, the crossbar, the yoke, the pole, and the sideboards.

I have organized this work as follows:
First: Explanations on the construction of the wheel.
Second: Explanations on the carriage body.
Third: Explanations on the axle and undercarriage.
Fourth: Explanations on leatherwork.
Fifth: Explanations on metalwork.
Sixth: Explanations on the sequence and calculation of chariot dimensions.

My goal is to explain what was previously unclear and to make the obscured details manifest. To this end, I have created:
Diagram One: The Wheel.
Diagram Two: The Carriage Body.
Diagram Three: The Axle and Undercarriage.

Written by the student Ruan Yuan of Yizheng, in the 53rd year of the Qianlong reignThis corresponds to the year 1788..