Here is a link that could be of special interest to keyboardists
I had first seen the Janko keyboard in a
book called Pianos and Their Makers by Alfred Dolge in the mid 1980's - then again in Keyboard Magazine June 89 (there
is a photo of Vandervoorts adaptation of the janko keyboard) in the Questions section page 20 - which refers back to the Dec.
76 issue of Keyboard.
I did a research project when I was living in Boston in 1995 - searching for a janko keyboard
that I could get my hands on. After several phone calls I reached the university of South Dakota museam of musical instruments
which was most helpful and yale university museam of musical instruments where I actually got to get a good look at a real
Janko keyboard (removed from the piano, this keyboard was a closet item in yales museam)