21一支柱高十八肘，圓環十二肘，厚四指，中央空殼。Chi̍t-ki thiāu koâiⁿ cha̍p-poeh tiú, îⁿ-khoân cha̍p-jī tiú, kāu sì-cháiⁿ, tiong-ng khang-khak.