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

...planets, and the constellations, with their respective distances. Below, it featured the Mysterious Pivot and Jade Balance, moved by a horizontal tube to observe the phenomena and examine the instrument—this is the utility of the instrument. The method of calculation and verification is based on the ecliptic. The equator is what spans the middle of the heavens, with the distance to the poles in the north and south being fixed and unchanging. The ecliptic is what observes where the sun shines, with the light of the gnomon's shadow expanding and contracting irregularly. Book of Tang, Treatise on Astronomy: In the 9th year of the Kaiyuan era, Yi Xing received an imperial order to revise the new calendar. He wanted to know the movement of the ecliptic, but the Grand Historian had no ecliptic instrument. Liang Lingzan made a travel instrument of wood. Yi Xing approved of it and requested to recast it in copper. In the 13th year, the instrument was completed. Using the ancient rule of four 'fen' per degree, it was what the ancients called the 'Jade Pivot'. Its equator spans the middle of the heavens to divide the degrees of the constellations; the ecliptic runs obliquely to clarify the sun, moon, and five planets, and even the eight seasonal divisions and nine limits, comparing the difference between the two paths and recording it in the calendar classic. An order was also given for Yi Xing and Lingzan to recast the 'All-Encompassing Heaven' copper instrument, modeling the round heavens, complete with constellations, the equator, and the degrees of the celestial circumference. Water was poured to drive a wheel, causing it to rotate by itself, completing one revolution day and night. Two separate wheels were placed to wrap around the outside of the heavens, with the sun and moon attached to move against the rotation of the heavens, their speed and slowness perfectly synchronized. A wooden cabinet was placed in the ground to keep half the instrument underground. Two wooden figures were also set up to strike a drum every 'ke' quarter-hour and a bell every double-hour; the machinery was all hidden in the cabinet. Song Huiyao: In the 4th year of the Taiping Xingguo era, Zhang Sixun of the Bureau of Astronomy constructed an armillary instrument. His own preface states: "In the Kaiyuan era of the Tang, an imperial order was given to the monk Yi Xing, Liang Lingzan, and various technical experts to build an 'All-Encompassing Heaven' instrument, casting copper into a model of the sun, moon, and round heavens, complete with constellations, the equator, and the celestial path, using fine water to drive a wheel to rotate it by itself. Later, the copper and iron became rusty and could not rotate by itself, and it was no longer used. Now, the one constructed by Sixun is built in the shape of a pavilion with three stories, over ten feet high. Inside, there are wheels, axles, and gears driving water to operate the wheels. Wooden puppets were used as the seven deities, with the left hand shaking a bell, the right hitting a chime, and the middle striking a drum to determine the time. Also, twelve deities were created, each in charge of one hour, each holding a time placard, cycling and appearing. Moreover, the images of the sun, moon, and stars were all such that they had to be looked up at, and the mechanical rotation was all hidden within the pavilion. When the water froze in winter, mercury was used as a substitute." In the 3rd year of the Dazhong Xiangfu era, the Bureau of Astronomy...