《周礼·冬官考工记·磬氏&车人》
匠人建造都城，用立柱悬水法测量地平，用悬绳的方法设置垂直的木柱，用以观察日影辨别方向。以所树木柱为圆心画圆，记下日出时木柱在圆上的投影与日落时木柱在圆上的投影，这样来确定东西方向。白天参考正中午时的日影，夜里参考北极星，以确定正南北和正东西的方向。
匠人建国，水地以县，置槷以县，眡以景，为规，识日出之景与日入之景，昼参诸日中之景，夜考之极星，以正朝夕。
When craftsmen build a capital city, they use a water level to measure the horizon, and a plumb line to set up vertical wooden columns, which are used to observe the shadow of the sun to determine the direction. Draw a circle with the wooden column as the center, mark the projection of the wooden column on the circle at sunrise and the projection of the wooden column on the circle at sunset, so as to determine the east-west direction. During the day, refer to the noon shadow to determine the north-south and east-west directions at night, refer to the North Star to determine the north-south direction.