With it came the great mechanical improvement, the use of the two rollers.

One roller holds the long strip of film which is slowly wound over the second, the device familiar to every amateur photographer today.

With film photography was gained the possibility not only of securing a much larger number of pictures than Marey or Anschuetz made with their circular arrangements, but of having these pictures pass before the eye illumined by quickly succeeding flashlights for any length of time.
Moreover, instead of the quick illumination the passing pictures might be constantly lighted.

In that case slits must pass by in the opposite direction so that each picture is seen for a moment only, as if it were at rest.

This idea is perfectly realized in Edison's machine.
In Edison's kinetoscope a strip of celluloid film forty-five feet in length with a series of pictures each three-quarters of an inch long moved continuously over a series of rolls.