Swithin, in the room overhead, had suspended his calculations, for the duologue interested him.

在头顶房间里，斯维辛暂停了算，因为二重奏引起了兴。

The hollow spiral, as he knew from old experience, would bring down to his ears the slightest sound from above; and it now revealed to him the words of a duologue in progress at the summit of the tower.

从过去经验，空心螺旋线会把上面最轻微声音传到耳朵里；现在，它向揭示了塔顶正在进行对白话。