《明史·志·卷七》
现在推算二十六分六十秒，是虚暗的空间大于月亮，如果月食时离交点较速，月体就不能完全进入虚暗空间，只能从月体来说它的分数。
今推二十六分六十六十秒者，盖暗虚体大于月，若食时去交稍远，即月体不能全入暗虚，止从月体论其分数。
At present, the calculations yield twenty-six minutes and sixty seconds. This shows that the shadow is larger than the moon. If, during a lunar eclipse, the speed of the moon's approach to the intersection point is measured, then the moon will not be able to completely enter the shadow. The amount of eclipse can only be determined according to the moon's position.