HARMONIUM (French, also Orgue expressif). A well-known popular keyed instrument, the tones of which are produced by thin tongues of brass or steel, set in periodic motion by pressure of air, and called ‘vibrators.
’ They are known also as ‘free reeds
’; reeds, because their principle is that of the shepherd's pipe; free, because they do not entirely close the openings in which they vibrate at any period of their movement, while those generally used in the organ,...
