《宋史·志·卷一》
现在应当斜着放置稍微偏一点，让周天的度数露出北际之外，自然就不居高遮蔽。
今当侧置少偏，使天度出北际之外，自不凌蔽。
It should now be placed at a slight slant, with the degree of the sphere protruding beyond the northern frontier, so that it would not be so high as to obstruct the view.