Clavier à lumières - Wikipedia
There is a wealth of info online on this. His contemporaries must have thought he was an interesting chap!
I’ve seen that already. Thank you though. I don’t like the random colour choice it doesn’t progress like the spectrum of light.... I think that once the right starting point is chosen it should move from Red through the ROY G. BIV PROGRESSION OF THE RAINBOW to Violet and and a lighter shade of the same previous colour even as you go higher per octave.
light and dark colour for all except B and E