《宋书·志·卷十一》
这种情况的发生可以在冬至、夏至前后五天中增进减退，具有八种能力的人各以观察到的情况汇报上来，由太史令密封上报。
进退于先后五日之中，八能各以候状闻。太史令封上。
This tends to rise and fall within five days before and after winter solstice and summer solstice. The eight capable men all report their observations, which the official historian will seal and present.