Chinas creations and progress in science and technology

　　《中国科技的创造与进步（英文）》：　　The traditional Chinese calendar is a lunisolar calendar, namely a calendar that takes the solar year as the basis of the length of a year and the synodic month as a month and adjusts the relation between seasons and months by setting leap months. In such a calendar, the correspondance between months and seasons has a certain range of disagreement, which can be nearly a month in maximum. In the beginning the 24 solar terms were determined in a year according to the position of the sun among the stars. This, in fact, is the part of solar calendar in traditional Chinese calendar. The 24 Solar Terms divide a tropical year into 24 equal intervals. Each term point is called a "JieQz" （pre-climate） or "ZhongQi" （mid-climate）. Pre-climate and mid-climate are arranged in an alternating manner. Among them, pre-climates are State of Spring, Awakening of Insects, Clear and Bright, Start of Summar, Grain in Ear, Minor Heat, State of Autumn, White Dew, Cold Dew, State of Winter, Major Snow and Minor Cold; however, mid-climates include Rain Water, Spring Equinox, Grain Rain, Grain Buds, Summer Solstic, Major Heat, Limit of Heat, Autum Equinox, Frost Descent, Minor Snow, Winter Solstice and Major Cold. During the Southern and Northern Dynasties, astronomers discovered that the sun did not move evenly in the celestial background, so they modified the calculation of the 24 solar terms according to the actual position of the sun rather than simply divided a year's time into equal intervals. The 24 Solar Terms were mainly used to provide informauon for farming and became an integral part of tradiuonal Chinese culture. Many ancient Chinese poems take them as literary themes.　　Ancient Chinese astronomers divided the celestial sky into three enclosures or "Yuan" and 28 mansions or "X/u." The Chinese word Yuan means city walls. Three enclosures are in fact three celestial areas enclosed with "walls" carved out in the sky. The 28 mansions are 28 constellations. Such division method became mature in the Periods of Spring and Autumn and of Warring States. The 28 mansions and the North Celestial Pole were combined together to form an equtorial coordinate system in ancinet China. The position of any celestial body can be determined with "mansion-approaching degree" and "pole-departing degree." The 28 mansions were also grouped into four symbols, corresponding to four totems of the remote ancient Chinese peoples, respectively the Azure Dragon in the east, the White Tiger in the west, the Vermilion Bird in the south, and the Black Turtle in the north. For example, the Azure Dragon in the east includes seven mansions of Horn, Neck, Root, Room, Heart, Tail and Winnowing Basket. The term Three Enclosures appeared at the latest in the Sui （581-618） and Tang dynasties. These three enclosures were respectively Purple Forbidden, Supreme Palace and Heavenly Market. Due to the influence of the idea of the "unity between heaven and man," the arrangement and nomination of the celestial bodies in the sky corresponded with the human WOfld. For example, the enclosure of Purple Forbidden was a celestial area with the North CelesUal Pole as its center. It was regarded as the "imperial palace" in the heaven. In this enclosure, the "Emperor Star" corresponded to the emperor in the human world, "Empress Palace" to the empress in the human world and "Eight Grains" to the granary in the human world. The enclosure of the Supreme Palace was where the heavenly emperor and his ministers handled adminstrative matters.　　……