The Jankó Keyboard

Hungarian engineer Paul von Jankó offered this alternative to the traditional keyboard layout in 1882. Within each row, the notes ascend by whole steps, and each vertical column of identical-sounding keys is a half-step in pitch from its neighbors. This means that each chord and scale gets the same fingering regardless of key, and wide stretches aren’t as necessary. The example above has four rows, but the full Jankó keyboard has six:

This is all appealingly sensible, but music educators were skeptical and performers were reluctant to learn the new fingerings, so manufacturers stayed away. Today it’s largely a curiosity.