In the early 1900s, French engineer Leon Gaumont designed and patented audio playback systems. One issues with early motion pictures is that there was no easy or accurate way to store audio with the images, or even to sync audio and images together. That is why the motion picture industry started off with silent movies, which were occasionally accompanied by a live pianist for entertainment and scoring purposes.
In 1910, Gaumont unveiled his Chronophone system, which was designed to synchronize sound and film. By having a dual platter setup, he effectively doubled the amount of playtime for the audio associated with a film, without having to have any interruptions in the performance.
The platters are driven by an electric motor, and there is a curious air-pump that supposedly controlled the cross-fading between the dual platter system. Since the records used at the time ran at 78 RPM, having a two platter setup allowed the sound engineer to cue up the next available disc while the first was playing. The chronophone was designed to provide sound to 4,000 people.
There doesn’t seem to be a whole lot of information about this, but you can read up a bit more at the following links: