初中语文课本对《李愬雪夜入蔡州》中的“四鼓”作了这样的注释:“旧时一夜分成五更,每更大约两小时,用鼓报更,一更为一鼓。四鼓,即四更天,相当于凌晨三四点钟”。这个注释是不够确切。我国以更、点计算夜里的时间始于明朝。那时候,用作报更的鸣具有鼓有钟。一更开始就打一下,二更开始就打两下,因此将“四 The junior high school language textbook made a commentary on “Four Drums” in Li Xue’s Snowy Night into Caizhou: “The old time was divided into Wuchuang overnight, and each time it was about two hours, it was reported with a tympanum and one more drum. Four drums, That is, four days, equivalent to three or four o’clock in the morning." This comment is not exact enough. In our country, the calculation of night time began with the Ming Dynasty. At that time, there was a bell for the bell. When you start playing it, you will start playing two more times.