The bracket set (dougong)
A Song bracket set of blocks (dou), arms (gong) and slanting levers (ang), proportioned in fen of the chosen grade of cai.
The rules it illustrates
Everything is measured in cai and fen. Take the section of the standard timber, the cai, as the module of the building: it is 15 fen high and 10 fen wide, and every member is dimensioned in fen.
Choose the grade of cai by the rank of the building. There are eight grades of cai, from 9 × 6 cun down to 4½ × 3 cun; use the first for great halls of nine or eleven bays and the smallest for pavilions and ceiling coffers.
A full timber is a cai and a zhi: 21 fen. Between two stacked arms leave a spacer of 6 fen, the zhi; a cai plus a zhi, 21 fen, is a “full timber” (zucai) and the vertical step of each tier of a bracket set.
The bracket set steps out 30 fen a tier. Build the bracket set (puzuo) of blocks (dou) and arms (gong) crossing at right angles, each tier projecting no more than 30 fen beyond the one below; a set of n projecting tiers is called an (n + 3)-puzuo, from four to eight.
The ang: reach further without climbing. Where the eaves must project far, replace the outer arms by slanting levers (ang) that run down and out beyond the bracket set and rise inward to be held down under an interior purlin.
Round off the ends: juansha. Shape the underside of every arm’s end in four or five facets, and reduce the upper third of a spindle column by the same method, so that no member ends in a hard corner.
Where it appears in the book
In the styles Chinese.
In the chapters China, Japan and Korea, Reading the Treatises.