《明史·志·卷十三》
求食甚定时：即食甚定分。根据某日日月合朔的时间，太阳的运行度数在数据表经纬时差加减数据表。左面七宫时，时差黑字减，白字加，在右面七宫时，白字减，黑字加，都加减从午夜到合朔的时间，得数按漠历时间从午夜算起的规定减去十二，得到某时的初步整时。
求食甚定时视其日合朔时，太阳度在立成左七宫，其时差，黑字减，白字加，在右七宫，白字减，黑字加，皆加减於子正至合朔时，得数命起正减之，得某时初正。
Time of Total Eclipse: Specifying the exact time of a total eclipse. Based on the time of conjunction of sun and moon of a certain day, the difference in the data table of the longitude of sun is then, according to the data table, added or subtracted from or to the longitude of the sun. If it is during the time of the seven palaces on the left, the time difference should be subtracted for black characters and added for white characters. If it is during the time of the seven palaces on the right, the time difference should be subtracted for white characters and added for black characters. The time from midnight to conjunction is added or subtracted. The resulting number, according to the rule of Mo calendar is subtracted by twelve starting from midnight, to get the initial round hour of a certain time.