Clavecin oculaire

I haven’t been “inspired” to do a tech history piece for a while. This instrument came in through one of those offerings from I’m surprised that I’d never encountered it before; it stands at the intersection of everything I’ve been doing for the last 20 years.

Louis Bertrand Castel invented the color harpsichord or clavecin oculaire around 1740. Below is an imagined drawing, which doesn’t really agree with the descriptions:

What’s with the water?  Or is that a curved light ray?  Or fireworks?

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All the Big Dudes of science and music came to see it and play it. Goethe played it and wrote about it. Charles Avison played it and wrote about it. Telemann wrote about it and then composed a few short pieces to demonstrate it. Diderot brought in a deaf man to write about it. The deaf man understood in an intellectual way that “music” was the result of organs and trumpets and such, but had no concept of what “music” really was. He enjoyed the light show, then wrote that it was a promising way to communicate words.

There aren’t any accurate pictures of Castel’s machine, so I decided to “build” an alternate version by Johann Gottlob Kruger. Writing in Miscellanea Berolinensia in 1743, Kruger described and diagrammed his idea.

Here’s my rendition, with Polistra playing and Happystar enjoying:

Top view shows the circle of candles with colored reflectors. Each key pulled down a gate in front of the appropriate chromatic (lit and fig) candle. The reflector focused this candle’s color through a prism toward the display screen, inverted in retinal style. Poser doesn’t do prisms, so I simply showed the result on a display screen with lightable stripes.

Castel gave verbal descriptions of the colors for each diatonic note, but again there are no color pictures or paintings of the actual colors. I tried to adopt the same Castel Pastel flavor as the above imagined drawing.

The specific Telemann pieces are lost, or at least not available in MIDI suitable for my programs. I used a short Telemann dance instead.

Kruger instrument playing Telemann

And finally here’s good old Sousa, which does a better job of demonstrating. I think Castel’s color choices may have been uniquely appropriate. Which patterns dominate here?

Kruger instrument playing Sousa
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