It has twelve keys, ten with a reed valve under each key, and two at the end of the barrel that produce harmonic tones for the notes played. It is 13" long, and about 1-7/8" in diameter.
What I want to know is, does each key generate two different notes – and what key is it in? 10 plus 2 really sounds like the layout of the Hohner 4-stop single row accordion we own.
No. I’m not the seller, but I suspect it may be an early form of Hohner’s Melodica. A free-reed instrument for woodwind players, from a firm which has specialized in free reeds for a very long time.
Yeah, I think this instrument does use the same concept as the single row (so-called Cajun-style) accordion. The Marine Band harmonica was intended to be played in a similar style, but by beating the chords on the leftmost holes (for which reason the ten-hole diatonic harmonica is sometimes known as a “vamper”). Of course, it was discovered that some bendable notes and the gapped scale of the chord notes were usable for a whole other style of playing, insuring the 10-hole diatonic harmonica a long career.
My wife found a webpage which mentions the Hohnerette. It’s in French, so I can’t understand what little text there is (though I think “accordéon à vent” is “wind accordion”), but the pictures very strongly suggest it is indeed a mouth-blown 1-row. There’s even one model Hohnerette which looks exactly like a 1-row with the bellows removed.
(BTW, as I understand it, Cajun-style is a particular tuning for a 1-row accordion. Possibly just intonation plus slightly dryer than Irish-style? I’ll try to remember to ask a Newfoundland “4 Stop” (ie 1-row) player I know when he comes to visit next month.)