格致鏡原 (Gezhi Jingyuan: Mirror of Scientific Origins) 100 Volumes

...started with the Yellow Emperor, and later it was used to appoint officials. In the Rites of Zhou, the 'Water-Clock Keeper' was the office. Luo's "Origins of Things": Xuanyuan the Yellow Emperor first created the water clock. The Duke of Zhou first divided it into 'geng' night watches and 'dian' points of time. Book of Sui, Treatise on Astronomy: The water clock is the fundamental instrument for measuring heaven and earth and correcting the models of the heavens. Book of Later Han, Treatise on Calendar and Rituals: They made a hollow pot to act as a leakage vessel and a floating arrow to mark the scale. As water leaks out, the scale marks indicate the center of the stars, and the darkness or brightness of the day and night are born from this. Shuowen Dictionary: A leakage vessel made of copper to hold water, marked with divisions for the hundred segments of day and night. Zhengyi Commentary: An arrow is placed inside the pot, marked to indicate the segments, and it floats on the water. As the water leaks, the scale descends to record the number of segments of day and night, dusk and dawn. In the Rites of Zhou, the 'Water-Clock Keeper' says: For all military matters, hang the pot to arrange the assembly, and use water and fire to guard it. Divide it by day and night. In winter, use fire to heat the tripod water until it boils, and then pour it [into the vessel]. Zheng Xuan's Annotation: Use water to equalize the number of gnomon shadow segments. Use fire to observe the changes in the water clock. Using water to guard the pot is called 'pouring into the leakage'. Using fire to guard the pot is for seeing the scale marks at night. 'Divide by day and night' refers to day and night leakage. Also, because the water freezes in winter and will not leak, fire is used to make the water boil to pour into it. Book of Sui, Treatise: In the Rites of Zhou, the 'Water-Clock Keeper's method totalizes one hundred segments divided into day and night. At the winter solstice, the day leakage is forty segments, and the night leakage is sixty. At the summer solstice, the day leakage is sixty segments, and the night leakage is forty. At the two equinoxes, the day and night are each fifty segments. There are 48 arrows in total. The day has morning, peak, middle, afternoon, and evening; the night has 'jia', 'yi', 'bing', 'ding', and 'wu'. Dusk and dawn determine the central stars. Each arrow has its number, which is used to divide the duty of the generations. Qunshu Kaosuo: The Han dynasty followed the ancient system. During the reign of Emperor Wu, the method used was to increase or decrease one segment every nine days after the two solstices. Sima Biao's "Continuation of the Book of Han": During the reign of Emperor He, Huo Rong submitted a memorial saying: "The rate of increasing or decreasing the water clock by one grade every nine days does not correspond to the heavens. It is not as good as the Xia Calendar's forty-eight arrows, as the gnomon shadow is rarely at odds with the segments." Zhang Heng's "All-Encompassing Heaven Water Clock": Made of copper vessels, layered and placed, filled with clean water. Below, each has a hole where a jade dragon spits out the leaking water into two pots; the right for night, the left for day. A cast bronze immortal is placed on the left pot, acting as the gold...