It involved mechanical complications that seemed to be insurmountable, and up to the time Edison invented his perforating machine no really good method was available. 弗兰克·刘易斯·戴尔.爱迪生的生平和发明.
In practice, there was employed such a number of perforating machines as the exigencies of business demanded. 弗兰克·刘易斯·戴尔.爱迪生的生平和发明.
This was accomplished by making a chain of articulated cards, like a slatted belt, and perforating these cards with varying arrangements of holes. Edward W. Byrn.十九世纪发明进展.