A small reed organ. Developed in the early 19th century from experiments in the last quarter of the century before, is a keyboard instrument that produces its sounds by means of air from bellows passing through free reeds, metal tongues that are made to vibrate. the instrument has a relatively small classical repertoire, its use either domestic or as a cheap substitute for the church organ. Dvorak wrote bagatelles for two violins, cello and harmonium, and Schoenberg made some use of the harmonium in chamber arrangements of works of his own and in versions of two waltzes by Johann Strauss