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thought led to the undoing of many early experimenters in colour photography. They took their
images through successive screens of red, yellow, and blue, and when projecting used the
complementary coloured screens—orange, green, and violet. The results were startling. It was
not until Greene took his pictures through the red, green, and violet screens, and subsequently
projected them through screens of the same colours—that is to say, the picture taken through the
green glass was projected through the green glass, the red through the red, and the violet through
the violet—that any tangible progress was made.

When celluloid film came into vogue the experimenters lost no time in commercialising a
system of natural-colour cinematography. The idea was to take a picture through each succes-
sive screen. In other words, the first picture was taken through the red screen; the film was moved
forward, and the second picture was taken through the green screen; lastly, a fresh area of
sensitised surface was brought before the lens and third or violet screen. Thus three consecutive
pictures, taken through three different screens, were secured. The screens comprised sectors of
red, green, and violet respectively, each colour screen being succeeded by an opaque sector. Thus
the shutter was divided into six parts—three colour screens and three opaque sectors alternately.
After exposure through one screen, as the following opaque sector flitted across the lens, the film
was moved into position to bring a fresh surface of sensitised surface before the next screen in
the revolving shutter.

When the red screen is brought into position before the lens, the colours in the object are
filtered, as it were, only the red rays being permitted to pass through the screen to the film. The
picture on the film, therefore, is a photograph of the red tones in the subject. Similarly the
green screen absorbs all but the green rays, and photographs a record of the green tones in
the subject. The same is true of the violet server. The developed film possesses no tinge of
colour itself it is merely a black-and-white image. Close examination of three consecutive
pictures, however, reveals varying densities according to the filtering action of the respective
screens. In projecting, the picture taken through the red screen is thrown through a red screen,
the green image through a green screen, and the violet though a violet screen. Thus the lantern
reconstructs upon the sheet what the camera dissects when photographing the object. Experi-
menters anticipated that, in virtue of the law of visual persistence, if these pictures were projected
at a sufficient speed upon the sheet, the three images taken through the red, green, and violet
screens would be superimposed one on the next, thereby conveying to the eye a faithful colour
record of Nature. It sounds feasible and seems attractively simple to perform; but Nature has not
been caught yet.

At the very outset the investigators were baffled. The sensitised emulsion on the film was too
slow to render the application possible. Every photographer knows that the red light is non-
actinic—he uses it for the illumination of his dark-room while developing his plates. Obviously,
therefore, it was hopeless to endeavour to take a photograph through the red screen in 1/100th
part of a second. For this reason Greene’s process failed, as did also that of Lee and Turner.

18 REEL DEALS September 2017