|
ALTHOUGH many of the arts in which
Edison has been a pioneer have been enriched by
his numerous inventions and patents, which were
subsequent to those of a fundamental nature, the
(so-called) motion-picture art is an
exception, as the following, together with
three other additional patents[30] comprise
all that he has taken out on this subject:
United States Patent No. 589,168,
issued August 31, 1897, reissued in two
parts--namely, No. 12,037, under date
of September 30,1902, and No.
12,192, under date of January 12,
1904. Application filed August 24,
1891.
There is nothing surprising in this, however,
as the possibility of photographing and
reproducing actual scenes of animate life are so
thoroughly exemplified and rendered practicable
by the apparatus and methods disclosed in the
patents above cited, that these basic inventions
in themselves practically constitute the
art--its development proceeding mainly along
the line of manufacturing details. That such a
view of his work is correct, the highest
criterion-- commercial expediency--bears
witness; for in spite of the fact that the
courts have somewhat narrowed the broad claims of
Edison's patents by reason of the
investigations of earlier experimenters,
practically all the immense amount of commercial
work that is done in the motion-picture field
to-day is accomplished through the use of
apparatus and methods licensed under the Edison
patents.
The philosophy of this invention having already
been described in Chapter XXI, it will be
unnecessary to repeat it here. Suffice it to
say by way of reminder that it is founded upon
the physiological phenomenon known as the
persistence of vision, through which a series of
sequential photographic pictures of animate
motion projected upon a screen in rapid
succession will reproduce to the eye all the
appearance of the original movements.
Edison's work in this direction comprised the
invention not only of a special form of camera
for making original photographic exposures from a
single point of view with very great rapidity,
and of a machine adapted to effect the
reproduction of such pictures in somewhat similar
manner but also of the conception and invention
of a continuous uniform, and evenly spaced
tape-like film, so absolutely essential for
both the above objects.
The mechanism of such a camera, as now used,
consists of many parts assembled in such
contiguous proximity to each other that an
illustration from an actual machine would not
help to clearness of explanation to the general
reader. Hence a diagram showing a sectional
view of a simple form of such a camera is
presented below.
In this diagram, A represents an outer
light-tight box containing a lens, C, and the
other necessary mechanism for making the
photographic exposures, H and H being cases
for holding reels of film before and after
exposure, F the long, tape-like film, G a
sprocket whose teeth engage in perforations on
the edges of the film, such sprocket being
adapted to be revolved with an intermittent or
step-by-step movement by hand or by motor, and
B a revolving shutter having an opening and
connected by gears with G, and arranged to
expose the film during the periods of rest. A
full view of this shutter is also represented,
with its opening, D, in the small illustration
to the right.
In practice, the operation would be somewhat as
follows, generally speaking: The lens would
first be focussed on the animate scene to be
photographed. On turning the main shaft of the
camera the sprocket, G, is moved
intermittently, and its teeth, catching in the
holes in the sensitized film, draws it
downward, bringing a new portion of its length
in front of the lens, the film then remaining
stationary for an instant. In the mean time,
through gearing connecting the main shaft with
the shutter, the latter is rotated, bringing
its opening, D, coincident with the lens, and
therefore exposing the film while it is
stationary, after which the film again moves
forward. So long as the action is continued
these movements are repeated, resulting in a
succession of enormously rapid exposures upon the
film during its progress from reel H to its
automatic rewinding on reel H. While the film
is passing through the various parts of the
machine it is guided and kept straight by various
sets of rollers between which it runs, as
indicated in the diagram.
By an ingenious arrangement of the mechanism,
the film moves intermittently so that it may have
a much longer period of rest than of motion. As
in practice the pictures are taken at a rate of
twenty or more per second, it will be quite
obvious that each period of rest is
infinitesimally brief, being generally
one-thirtieth of a second or less. Still it is
sufficient to bring the film to a momentary
condition of complete rest, and to allow for a
maximum time of exposure, comparatively
speaking, thus providing means for taking
clearly defined pictures. The negatives so
obtained are developed in the regular way, and
the positive prints subsequently made from them
are used for reproduction.
The reproducing machine, or, as it is called
in practice, the Projecting Kinetoscope, is
quite similar so far as its general operations in
handling the film are concerned. In appearance
it is somewhat different; indeed, it is in two
parts, the one containing the lighting
arrangements and condensing lens, and the other
embracing the mechanism and objective lens. The
"taking" camera must have its parts enclosed in
a light-tight box, because of the undeveloped,
sensitized film, but the projecting
kinetoscope, using only a fully developed
positive film, may, and, for purposes of
convenient operation, must be accessibly open.
The illustration (Fig. 2) will show the
projecting apparatus as used in practice.
The philosophy of reproduction is very simple,
and is illustrated diagrammatically in Fig.
3, reference letters being the same as in
Fig. 1. As to the additional reference
letters, I is a condenser J the source of
light, and K a reflector.
The positive film is moved intermittently but
swiftly throughout its length between the
objective lens and a beam of light coming through
the condenser, being exposed by the shutter
during the periods of rest. This results in a
pro- jection of the photographs upon a screen in
such rapid succession as to present an apparently
continuous photograph of the successive positions
of the moving objects, which, therefore,
appear to the human eye to be in motion.
The first claim of Reissue Patent No.
12,192 describes the film. It reads as
follows:
"An unbroken transparent or translucent
tape-like photographic film having thereon
uniform, sharply defined, equidistant
photographs of successive positions of an object
in motion as observed from a single point of view
at rapidly recurring intervals of time, such
photographs being arranged in a continuous
straight-line sequence, unlimited in number
save by the length of the film, and sufficient
in number to represent the movements of the
object throughout an extended period of time."
|
|
