The armillary sphere (Fig. 117) stands at the east end of the court. It is an instrument of huge dimensions being described in early records somewhat as follows, in each reference there being allusion to its beautiful workmanship, and to its design as possessing remarkable excellence. The supporting base of the piece has a mythological significance. The four dragons, which play such a part in the Chinese geomancy, are here represented as chained to the earth, while upholding the spheres. Its substantial horizon circle, crossed at right angles by a double ring representing an azimuth circle, forms the outer supporting framework. The upper surface of the horizon circle is divided into twelve equal parts, marked by the several Chinese cyclical characters applied to the twelve hours into which the day and night was divided. Around the outside of this horizon circle these twelve characters appear again, with the Chinese names for the several points of the compass. On the inside of this circle one finds the names of the twelve States into which the ancient Empire was divided, each State being thought of as under the influence of a particular quarter of the heavens. [Illustration: Fig. 117. Ancient Mongolian Armillary Sphere, ca. 1274.] Inside this frame is placed an equatorial circle within which is a series of movable circles made to turn on polar pivots attached to the azimuth circle. These movable circles consist of an equatorial circle, a double ring ecliptic, an equinoctial colure, and a double ring solstitial colure. The equator is divided into twenty-eight unequal portions marked by the names of as many constellations of very ancient origin. The ecliptic is divided into twenty-four equal parts according with the divisions of the year. Within the circles just described there is a double revolving meridian with a double axis and within this a fixed tube for taking sights. All the circles of this armillary sphere are divided into 365-1/4 degrees corresponding to the days of the year and each degree is divided into hundreds. At the corners of the base outside the dragons are four miniature rocks in bronze, with the respective inscriptions “Keen Shan,” northwest or celestial mountain; “Kwan Shan,” southwest or terrestrial mountain; “Seuen-Shan,” or southeast mountain; “Kan Shan,” northeast mountain.