The front end of this cylindrical shield is provided with a diaphragm or bulkhead in which are apertures which may be opened or closed at will. 佚名.神奇的知识之书.
In this the spindles, arranged vertically in the frame, are driven by bands from a central cylinder, and project through apertures in a horizontal bar. 威廉·亨利·杜利特.世纪发明.
He found that fire-damp explodes only at high temperature, and that the flame of this explosive mi xture will not pass through small apertures. 李贝.西洋科学史.
The mixture flows through the apertures in the partition, and occupies the lower part of the generator. 弗雷德里克·科利尔·贝克维尔.伟大的事实.
And as these parts are used on separate occasions, the respective apertures are opened or closed by a sliding bottom and by a single movement of the hand. 威廉·亨利·杜利特.世纪发明.