sible to devise an
instrument which should do for the eye what the phonograph does for the
ear, and that by a combination of the two, all motion and sound could
be recorded and reproduced simultaneously. This idea, the germ of which
came from the little toy called the Zoetrope and the work of Muybridge,
Marey, and others, has now been accomplished, so that every change
of facial expression can be recorded and reproduced life-size. The
kinetoscope is only a small model illustrating the present stage of the
progress, but with each succeeding month new possibilities are brought
into view. I believe that in coming years, by my own work and that
of Dickson, Muybridge, Marey, and others who will doubtless enter the
field, grand opera can be given at the Metropolitan Opera House at New
York without any material change from the original, and with artists and
musicians long since dead."

In the earliest experiments attempts were made to secure the
photographs, reduced microscopically, arranged spirally on a cylinder
about the size of a phonograph record, and coated with a highly
sensitized surface, the cylinder being given an intermittent movement,
so as to be at rest during each exposure. Reproductions were obtained in
the same way, positive prints being observed through a magnifying glass.
Various forms of apparatus following this general type were made,
but they were all open to the serious objection that the very rapid
emulsions employed were relatively coarse-grained and prevented the
securing of sharp pictures of microscopic size. On the other hand, the
enlarging of the apparatus to permit larger pictures to be obtained
would present too much weight to be stopped and started with the
requisite rapidity. In these early experiments, however, it was
recognized that, to secure proper results, a single camera should be
used, so that the objects might move across its field just as they
move across the field of the human eye; and the important fact was
also observed that the rate at which persistence of vision took place
represented the minimum speed at which the pictures should be obtained.
If, for instance, five pictures per second were taken (half of the time
being occupied in exposure and the other half in moving the exposed
portion of the film out of the field of the lens and bringing a new
portion into its place), and the same ratio is observed in exhibiting
the pictures, the interval of time between successive pictures wou