Musical Instruments HarmoniumHarmonium The harmonium is a type of reed organ, a freestanding keyboard instrument in which air is forced by manual or voluntary means over a set of free floating reeds by bellows. Its free floating reeds are placed in slits in a wind chest, whose valves are directly activated by the keys from a traditional organ like keyboard via a set of pushrods and or pull rods. The typical harmonium has one keyboard, but larger models with two or even three