When Qian ruled Zhejiang, a wooden tower was built in Brahma Temple in Hangzhou. Only two or three floors have been built, and Qian Chu climbed the wooden tower and felt shaking. The craftsman said, "there is no cover tile yet, but there is light on it, so it will be like this." So I covered it with tiles, but the wooden tower shook as before. There was no other way out, so the craftsman secretly asked his wife to see Yu Hao's wife, and gave her a gold hairpin, begging her to ask the reason why the wooden tower in Yu Hao was shaking. Yu Hao smiled and said, "It's easy. As long as you lay the boards layer by layer and nail them firmly, they won't shake. " The craftsman did as he said, and the tower was stable. Because after nailing the board, the upper and lower floors are more closely connected, and the upper, lower, left and right sides are connected with each other, just like an open box. People step on it and support each other up and down, left and right, of course, they won't shake. People admire Yu Hao's skill and good at it.