Its weight and smoothness, along with the slight concavity of the mirror, means it can spin for a long time.

它很轻，又很光滑再加上镜子上轻微角度，说明这个欧拉盘应该能转。

Swithin beheld around and above him, in place of the concavity of the dome, the open heaven, with its racing clouds, remote horizon, and intermittent gleam of stars.

斯威辛注视他四周和上方， 代替圆顶， 是开阔天空， 有飞驰云彩、遥远地平线和断断续续星星。

Overhead the groins and concavities of the arches curved in all directions, dropping low towards the walls, where the height was no more than sufficient to enable a person to stand upright.

头顶上拱门腹股沟和向各个方向弯曲，向墙壁低垂，高度仅足以使人直立。