an impression as if the picture remained at the same spot, only moving.
The bird flaps its wings and the horse trots. It was really a perfect
kinetoscopic instrument. Yet its limitations were evident. No movements
could be presented but simple rhythmical ones, inasmuch as after one
revolution of the wheel the old pictures returned. The marching men
appeared very lifelike; yet they could not do anything but march on and
on, the circumference of the wheel not allowing more room than was
needed for about forty stages of the moving legs from the beginning to
the end of the step.

If the picture of a motion was to go beyond these simplest rhythmical
movements, if persons in action were really to be shown, it would be
necessary to have a much larger number of pictures in instantaneous
illumination. The wheel principle would have to be given up and a long
strip with pictures would be needed. That presupposed a correspondingly
long set of exposures and this demand could not be realized as long as
the pictures were taken on glass plates. But in that period experiments
were undertaken on many sides to substitute a more flexible transparent
material for the glass. Translucent papers, gelatine, celluloid, and
other substances were tried. It is well known that the invention which
was decisive was the film which Eastman in Rochester produced. 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 Anschütz 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