[ David Snelling asked for the scale of the Herophon. ]

Oh dear; let's see if I can do that without looking it up.  It's
the same scale as for the Ariston 24-key organette, just the discs
are differently shaped (round for Ariston, square for Herophon).
Here we go -- Bass to melody (treble):

  F,C,D,F,A#,C,d,d#,e,f,g,a,a#,c,d,d#,e,f,g,a,a#,c,d,d#

No warranty for that right now as I didn't look it up.  :-)
(I thought there is a 'h' ['b-natural'] in it somewhere.)

greetings by(e) InK - Ingmar Krause
ERlanger drehORGEL-Trio, Familie Krause, erorgelt@erlangen.franken.de