What those early craftsmen had found by trial and error was that under pressure a pagoda's loose stack of floors could be made to slither to and fro independent of one another.
"那些早期的工匠通过反复试验发现:在压力作用下,宝塔松散堆叠的楼层可以彼此独立地来回滑动。
2
The ray quivered to and fro, making her figure dim or distinct- now like a real child, now like a child's spirit- as the splendor went and came again.