Knowledge of the Jankó keyboard has taught me how to do something that has until now been beyond me: transposing a tune. It’s really easy:
Incy Wincy Spider is most easily played on a piano using eight adjacent white keys: C-D-E-F-G-A-B-C. Here’s how that would look on the Jankó keyboard:
Let’s try to transpose it to start on F. We simply move our hands (the red box here) so that it starts there:
We see that the keys we need to play are F-G-A-A#-C-D-E-F, and you can test that by playing it on a normal piano.
Let’s look at another example:
Here we are starting on B, which leads to the sequence B-C#-D#-E-F#-G#-A#-B.
Finally, here’s Incy Wincy starting on F#:
The sequence of keys is F#-G#-A#-B-C#-D#-F-F#.
So to transpose a piece on a normal keyboard, all you have to do is to imagine how you play it on a Jankó keyboard, shift your hands and see which keys you’d now be playing, which you can then find again on a normal piano.