"The Designers Go to the Fair: Norman Bel Geddes, the General Motors Futurama and the Visit-to-the-Factory Transformed" by Roland Marchand.
Design Issues, Volume VIII, Number 2,
Spring 1992, MIT Press Journals. ISSN 0747-9360
The Polyrhetor at the 1939 World's Fair Futurama
The General Motors Futurama at the 1939 New York World's Fair was one of the most elaborate dark rides in history. A chain of over three hundred seats snaked past gigantic animated tableaux of the city of the future == 1960, to be exact.
The ride was narrated, and the narration was in sync with the scenery. The people sitting behind you would soon hear what you were hearing; the people in front, what you were about to hear. How do you deliver sound to an individual car in a ride? You build a twenty ton gizmo called the Polyrhetor.
The cars travelled in pairs, which cuts the job down to delivering about 150 separate soundtracks at once. The soundtrack was broken up into 22 segments of about 39 seconds each, and recorded onto the audio track of motion picture film. Engineers looped each of these 22 segments, and rigged seven light beams and pickups to each loop.
Okay, let's deliver the sound to the cars. The track was divided into 22 segments, over which a pair of cars traveled in 39 seconds, and each track segment corresponded with a film loop. Under the track were seven smaller tracks, hooked to the sound pickups.
Under each pair of cars rode a miniature trolley, the wheels of which rode in these wee tracks and were electrically hooked to the speakers. As the first two cars entered the first segment of track, the trolley entered groove number one, and out came the sound from film loop number one, pickup number one.
The trolley under the second set of cars rode in groove two, and received the soundtrack from film loop number one, pickup number two, and so on.
By the time the first set of cars moved out into the second track segment == film loop number two, pickup one == the eighth set moved into its groove in the first track segment, and the narration from pickup one began again.
In the late 1960's, Disneyland designers faced similar problems with "Adventure Through Inner Space" and the "Haunted Mansion." I have yet to confirm it, but I feel confident a system similar to the Polyrhetor, probably substituting magnetic tape for film loops, was used in these rides. For years, the Haunted Mansion "Ghost Host" narration has been shut off, but every Halloween they fire it up and it still works == both technically and aesthetically.
The Futurama was a huge hit, far and away the most popular attraction at the fair. Designer Norman Bel Geddes did everything he could to extend the run of the ride beyond the Fair's 1940 finale. When GM decided against building a permanent public relations building to house it, he considered loading the whole shebang into 44 trucks and taking it on tour. Then he came up with a much more practical idea == the entire ride could be installed inside a Zeppelin and flown around the country.
Sadly, America had other things on its mind in 1940, and this lovely scheme came to nothing.
Daniel B. Howland (email@example.com)
Organization: Journal of Ride Theory