Analysis of Doubts in the Artificers' Record

On the Construction of the Hub and Spoke Sockets

"Use one-third le: a technical ratio representing one-third of a measurement of the circumference to carve out the spoke sockets sou: the hollowed-out mortise or hole in the hub designed to receive the spoke tenon."

The standard annotations and commentaries discuss this in terms of the hub’s diameter to calculate the depth to which the spoke tenon zai: the carved end of a spoke that fits into the hub enters. However, the diameter of the middle-hub xian: the widest part of the hub is six inches and a fraction. If one subtracts the thickness of the metal bushing chuanmu zhī jin: a metal lining used to prevent the axle from wearing down the wooden interior of the hub inside the inner cavity hu: literally "the pot," referring to the hollow interior of the hub, the remaining thickness of the wood around the perimeter is only about two inches.

Yet, the commentaries claim the spoke tenon enters the hub to a depth of three and five-ninths inches. This logic is untenable The commentator points out a physical impossibility: the spoke cannot be deeper than the wood it is being inserted into.. By using one-third of the circumference to chisel fu: to hollow out or carve the spoke sockets, one is actually using the outer measurement of the hub to determine the width and spacing of the sockets.

"Chisel" means to carve. To carve wood to make a hole is the same principle as "carving a ditch" mentioned in the Records of Artisans original: 捎溝 (shao gou), which refers to excavating soil to create a channel. If the hub circumference is three feet and two inches, two parts are retained as the flesh original: 肉 (rou), referring to the solid wood left between the chiseled holes, and one part is chiseled out to receive the spoke tenons. In this way, the hub remains solid and sturdy, without the risk of splitting chelie: structural failure where the wood cracks under pressure. However, if one-third of the circumference is only one foot and a fraction, then each spoke tenon would be only three-tenths of an inch and a fraction wide. There is a fear that...