《明史·志·卷九》
月亮运行快慢平立定三差的来源月亮运行一周焉二十七日五十五刻四六，测量分焉四象，每象各分七段，四象二十八段，每段十二限，每象八十四限，共三百三十六限，而四象合为一周。
太阴转周二十七日五十五刻四六。测分四象，象各七段，四象二十八段，每段十二限，每象八十四限，凡三百三十六限，而四象一周。
The moon runs a week for twenty-seven days, fifty-five moments and forty-six, measuring the difference in four directions, each direction is divided into seven sections, twenty-eight sections in four directions, each section is twelve limits, each direction is eighty-four limits, and a total of three hundred thirty-six limits, and four The elephant represents a week.