On cloudy days or at night it was impossible to tell the time with a sun clock or a sundial.

在阴天或晚上，无法用太阳钟或日晷看出时间。

youdao

The main parts of a sundial are an erect stylus and a calibrated disk. As the sun moves in the sky, the shadow of the stylus moves like a clock hand around the disk indicating the hours.

日晷的主要部件是由一根晷针和刻有刻线的晷面组成，随着太阳在天空运行，晷针的投影像钟表指针一样在晷面上移动，就可以指示时辰。

youdao

Other important timekeeping tools include the sundial, the hourglass, the clock and the marine chronometer.

FORBES: No. 11 The Watch