The Abridged Armilla, an instrument made by Guo Shoujing of the Yuan Dynasty (1271-1368) for measuring the position of celestial bodies, is simpler than the Armillary Sphere in both structure and operation, hence its name "Jian Yi" (simple instrument). With it, the whole sky, except for the area around the North Star, can be taken in at one glance.

The instrument is composed of two mutually perpendicular rings, with one parallel to the equatorial plane named the "Equatorial Ring." The other is a double-ring structure -- the Equator-Longitude Double-Ring -- that crosses vertically across the center of the equator, and can rotate around the metal axis.

In celestial observation, an observatory tube is first directed towards the star to be observed, and the star's position can be read from the dial on the Equatorial Ring and the Equator-Longitude Double-Ring.

Two stands are employed to support the observatory device by holding the metal axis, which goes in the north-south direction to keep the device "higher in the north and lower in the south."

The Abridged Armilla was the first equatorial mount invented by ancient Chinese people, 500 earlier than the Europeans.

Author: Jessie