swing of pendulum

Like magic out of a Harry Potter novel, such a metal could contract on command, or swing back and forth like a pendulum.

像这种仿佛出自《哈利·波特》小说中的魔法一般的金属可以按照指令收缩，或者像钟摆那样前后摇摆。

On this same tack, you could take the barometer to the top of the building, attach a long rope to it, lower it to just above the street, and then swing it as a pendulum.

根据同样方法，将气压计带到屋顶，拴上一个长绳，直垂地面，像钟摆一样摆动。

Will no longer feel that life is too monotonous and old-fashioned as if the old house back and forth of that only know how to swing the pendulum clock units.

不会再觉得生活古板单调得犹如老房子里的那台只知来回摇摆的摆钟。