Both secured the effect by cutting fine slits in a black disk in the direction of the radius.

When the disk is revolved around its center, these slits pass the eye of the observer.

If he holds it before a mirror and on the rear side of the disk pictures are drawn corresponding to the various slits, the eye will see one picture after another in rapid succession at the same place.

If these little pictures give us the various stages of a movement, for instance a wheel with its spokes in different positions, the whole series of impressions will be combined into the perception of a revolving wheel.

Stampfer called them the stroboscopic disks, Plateau the phenakistoscope.