the history of the moving pictures by the
following dates and achievements. In the year 1825 a Doctor Roget
described in the "Philosophical Transactions" an interesting optical
illusion of movement, resulting, for instance, when a wheel is moving
along behind a fence of upright bars. The discussion was carried much
further when it was taken up a few years later by a master of the craft,
by Faraday. In the _Journal of the Royal Institute of Great Britain_ he
writes in 1831 "on a peculiar class of optical deceptions." He describes
there a large number of subtle experiments in which cogwheels of
different forms and sizes were revolving with different degrees of
rapidity and in different directions. The eye saw the cogs of the moving
rear wheel through the passing cogs of the front wheel. The result is
the appearance of movement effects which do not correspond to an
objective motion. The impression of backward movement can arise from
forward motions, quick movement from slow, complete rest from
combinations of movements. For the first time the impression of movement
was synthetically produced from different elements. For those who fancy
that the "new psychology" with its experimental analysis of
psychological experiences began only in the second half of the
nineteenth century or perhaps even with the foundation of the
psychological laboratories, it might be enlightening to study those
discussions of the early thirties.

The next step leads us much further. In the fall of 1832 Stampfer in
Germany and Plateau in France, independent of each other, at the same
time designed a device by which pictures of objects in various phases of
movement give the impression of continued motion. 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. The smaller the slits, the sharper the pictures.
Uchatius in Vienna constructed an ap