TAKE a cardboard disc and punch two holes in it, on either side of its centre.
取一张圆纸板，在其两侧的中心分别打两个孔，用多根线穿过每个孔。
2
A disc lit by a stroboscopic light rotates. The disc is covered with a series of pictures which move in a spiral from the outer edge to the centre.
一张由频闪观测仪旋转照亮的光盘，光盘本身被一系列图片覆盖，由外部边缘向中心螺旋式旋转。
3
The balancing machine of the gravitation type is an equipment for detecting the unbalance ofdisc-shaped parts by means of the moment caused by centre-of-gravity shift.