Sunday, November 22, 2015

The Phenakistoscope -- November 22, 2015

From The Story of the Motion Picture: 65 B.C. to 1920 A.D. By Ben Jehudah Lubschez.  Joseph Plateau was a Beligian mathematician. 

In the early thirties of the nineteenth century, following some optical experiments by Dr. Roget, Dr. Faraday and others, there was invented independently and almost simultaneously by Dr. Plateau of Ghent and Dr. Stampfer of Vienna, a disc contrivance showing the illusion of motion in pictures and depending on persistence of vision for effect. Plateau called his instrument the Phenakistoscope, and Stampfer called his, the Stroboscope. As Plateau carried his experiments much further than Stampfer, we shall ignore the Stroboscope. The Phenakistoscope consisted simply of two circular discs revolving on a common shaft. The front disc had several phases of a moving object drawn or painted on it, the different drawings being arranged radially near the outer edge. Behind this disc was a larger one with radial slots in it corresponding in number and position with the drawings on the front disc. The Phenakistoscope was held before a mirror and the discs rotated, the observer watching the reflected images of the front disc thru the slots of the back one, and seeing for the first time the illusion of motion in pictures!  Besides being pioneer in showing this illusion, the Phenakistoscope established in its crude form, the principal of the intermittent shutter, used to this day. As the slots in the disc passed before the eye, the space between the slots shut off the light and pictures while they were changing positions, the persistence of one image connecting it to the next. This is one of the fundamental principles upon which both the presentation and taking of modern photographic moving pictures depend. Plateau who was gradually growing blind kept up his experiments, under his direction when he himself was disabled, and in 1849 when totally blind produced with his Phenakistoscope, the "Diable Soufflant" (Devil Blowing up Fire). This instrument was somewhat larger than the original Phenakistoscope, the pictures of the different phases of motion were painted on a transparent disc, and artificial light was made to shine thru it. This disc revolved in front of a screen with an opening in it so that all the radially arranged pictures except the vertical one to be seen, were shut off. A number of people might sit in front of the slotted wheel and watch the pictures. The apparatus only needed the ordinary condensing and objective lenses of the magic lantern to present the pictures on a screen. But this far Plateau did not seem destined to go. His accomplishments, however, certainly entitle him to be always honored as one of the grandfathers of the moving picture.

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