they have an astounding 3 or 4 layer one of these jobbies at the exploratorium. They have a what looks like a video projector above it so that they can
  • turn individual layers on and off
  • change layer colors
  • change motion, by means of adusting the phase and frequency of the light
  • blur
  • ajust each of these factors for each color channel
And there are two port holes in the side of the beast, so you can see the works.

While I was marveling the true identity of the Exploratorim occured to me.

From the greek words phenax-akos meaning "deceitful" and skopein which means "viewing", the phenakistoscope is an optical toy designed to give the illusion, via human retinal persistance, of movement. The contraption was created simultaneously by Belgian physicist Joseph Plateau (1801-1883) and Austrian professor Simon Von Stampfer (1792-1864). Inspired by the earlier works of Michael Faraday and using what Euclid and Newton called before them " the persistence of motion principle" , the two came up in 1830 with what became one of the first animation devices.

The workings of the phenakistocope are based on the idea that a sequence of images separated by tiny slits and set around the circumference of a disc can, if spun in the right manner and speed, reflect a motion. The trick is to place the spectator in front of a mirror, facing the blank back-side of the disc, and position his eyes so that they level with the slits. When turning the wheel, the see-through spaces allow the eyes to see the different frames in succession at very short intervals, making the image reflected on the mirror look animated.

The first images projected by Joseph Plateau and his sons when the phenakistoscope was introduced were drawings of jugglers and dancers in colorful dress. Like the different circular animation projects that followed, the succession of images had no start and no ending, hence preserving the continuity of the animation and its kinetic fluidity. What sets it apart from the zoetrope and the various inventions that came after is that the final result could only be viewed by one person at a time.

Different versions and refinements of the phenakistoscope were made, some used two discs, others were mounted on vertical metal rods and equipped with small mirrors. Its novelty as an invention soon worn off though, as more advanced widgets appeared in the field of animation, thanks to Plateau and Stampfer's work. Over the years, their stroboscopic device acquired different names, in Britain it was dubbed the phenakistiscope, in other parts of the world it became the fantoscope or (my favorite) the phantasmoscope.

Modern motion pictures still pretty much rely on the same principle. The process is only renewed, going around up to 30 times a second. The frame stops, light slips through the film, projection is shot, light is blocked again, it is passed to the next frame, which stops...etc... It's all just a subterfuge, a trick of the senses, that's the beauty of it.

Phen`a*kis"to*scope (?), n. [Gr. a deceiver + -scope.]

A revolving disk on which figures drawn in different relative attitudes are seen successively, so as to produce the appearance of an object in actual motion, as an animal leaping, etc., in consequence of the persistence of the successive visual impressions of the retina. It is often arranged so that the figures may be projected upon a screen.

 

© Webster 1913.

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