ACCORDION (Fr. accordeon; Ger. Handharmonica, Ziehharmonica)  , a small portable reed wind instrument with keyboard, the smallest representative of the organ family, invented in 1829 by Damian, in Vienna . The accordion consists of a bellows of many folds, to which is attached a keyboard with from 5 to 50 keys . The keys on being depressed, while the bellows are being worked, open valves admitting the wind to free reeds, consisting of narrow tongues of metal riveted some to the upper, some to the lower board of the bellows, having their free ends bent, some inwards, some outwards . Each key produces two notes, one from the inwardly bent reed when the bellows are compressed, the other from the outwardly bent reed by suction (as in the American organ; see HARMONIUM) when the bellows are expanded . The pitch of the note is determined by the length and thickness of the reeds, reduction of the length tending to sharpen the note, while reduction of the thickness Iowers it . The right hand plays the melody on the keyboard, while the left works the bellows and manipulates the two or three bass harmony keys, which sound the simple chords of the tonic and dominant . The archetype of the accordion is the cheng (q.v.), or Chinese organ, between which and the harmonium it forms a connecting link structurally, although not invented for some thirty years after the harmonium . The timbre of the accordion is coarse and devoid of beauty, but in the hands of a skilful performer the best instruments are not entirely without artistic merit . Improvements in the construction of the accordion produced the concertina (q.v.), melodion and melophone . See Adolf Mueller, Accordion-Schule oder vollstandige Anleitung, das Accordion in kurzer Zeit richtig spielen zu erlernen (Wien, 1834) . See also FREE REED VIBRATOR . (K .