Upright Piano with Jankó keyboard

In 1882, the Austro-Hungarian pianist and mathematician Paul von Jankó presented the music world with a newly developed keyboard that took special account of the equivalence of all twelve semitones and keys. At the same time, by arranging the keys in several rows, he achieved a considerable ergonomic improvement for players, which was also intended to make learning to play the piano easier. Despite the efforts of Jankó and a few supporters, however, this keyboard design never really caught on. The Carl A. Pfeiffer company apparently manufactured such a piano in Stuttgart in the 1930s, which, in its upright form, was well suited for teaching and home entertainment. Six rows of 44 keys each still provide a range of 88 different notes, as keys in several rows trigger the same hammer to simplify fingering and make it more ergonomic.