A harmonium is a keyboard instrument that is free-standing, similar to a reed organ or pipe organ. Its sound is produced by air, supplied by foot-operated or hand-operated bellows, being blown through sets of free reeds, resulting in a sound similar to that of an accordion.
The harmonium was invented in Paris in 1842 by Alexandre Debain. They were especially popular in small churches and chapels where a pipe organ would be too large or too expensive. They were also quite popular in tropical regions because they held their tune regardless of heat and humidity, unlike the piano.
