m o u t h o r g a n
One of the things I got on my birthday - thank you rosebud for the monarch! - was an old mouth organ. After a bit of research this turned out to be a tremolo harmonica tuned in the East Asian style. The 24 pitches (each double-reeded to produce the tremolo effect) are tuned:
Blow: G C E G C E G C E G C E
Draw: D F A B D F A B D F A B
This is quite a logical arrangement in some ways. For most of the range it contains all the white notes without missing any out, so is very good for picking out simple modal melodies, especially in the Ionian ("major") in C, or the Dorian ("minor" with major 6th) in D.
A slight problem with the arrangement is that each octave span is covered by only 3 notes (C-E-G) on the blow side, but 4 notes (D-F-A-B) on the draw side. Therefore the blow-notes, beginning on the left some way below the adjacent draw-notes, gradually catch them up and, at the other end of the harmonica, get ahead of them. It's only in the middle stretch that the notes are arranged sequentially (more modern designs interpose a periodic spacer on the blow side so that the equivalent positions of notes remain constant throughout the range, making it very easy to play the same melody an octave higher or lower).
It's impossible to play the blues on this kind of harmonica; it would require - in this case - a root G low down on the draw side, as is normal in western harmonicas, enabling blues in G to be played cross-harp (i.e. with the tonic on the draw).
The only trick I've learnt so far is that if you use your lip to suppress one of the ranks of reeds you get a very sweet tone quite unlike the usual tremolo tone (which is achieved by having each pair of reeds slightly out of tune with each other). I can't seem to bend or squeeze notes to much effect, not yet anyway. My modest aim is to remind myself of Magic Dick, harpist for the J. Geils Band in their glory days of Full House, Bloodshot, Blow Your Face Out, etc.