G'day again,

I had a look at the info on the Maccann Duet Concertina site (linked above) ... and it seems that the 1883/5 Paul von Jankó piano keyboard - reworked by the Swiss Kaspar Wicki, in 1896, as a bandoneon scheme is yet another variation of the basic layout idea. This one is six-buttons deep, with both left and right diagonals spaced at a fifth (7 semitones) and a horizontal spacing of one tone (2 semitones).

I think the Hohner Harmonetta was an independent rethink based, as the name would imply, on the basic precepts of harmonicas ... the simple implementation of the basic chords and harmonies related to the key in which you are playing. One feature that stuck in my mind was the fact that a major triad was always produced by pressing down the three (raised) adjoining corners of the buttons. I would have to check the diagram to remember which one of the buttons was thus the root note of the chord.

Good fun for the technophiles of the day!

Regards,

Bob