harmonium. Small portable example of the reed org. family dating from early 19th cent. Perfected by Debain of Paris c.1842, but the instr. made by Alexandre achieved wider popularity. It is blown by 2 pedals operated by left and right foot working in alternate strokes to drive air through bellows. Used as substitute for org. to acc. hymns etc., but has been used by Dvořák in his Bagatelles (with 2 vn. and vc.) and by R. Strauss in Ariadne auf Naxos.

har·mo·ni·um / härˈmōnēəm/ • n. a keyboard instrument in which the notes are produced by air driven through metal reeds by foot-operated bellows.