Wurlitzer Style 165 band organ, originally from the Lincoln Park carousel in CA
Band Organs, or carousel organs are American-built instruments (The European counterparts different enough that they are in a different category on this site) which were built for the intention of use in skating rinks, amusement parks, and on carousels.
Perhaps second in popularity to player pianos, there are still dozens of band organs playing live on carousels to this day, band organ music more or less the 'official' sound associated with carousels. Like many nickelodeons and orchestrions, these primarily play multi-tune music rolls; due to being filled with pipes of various types instead of being based around a piano though, most band organs do not have every 'note' that can be found on a keyboard - making them non-chromatic.
Also unique in band organs is their division of parts. Like a band score, the instrument is not using a singular 'musical staff' but contains several, divided into sections/parts on rolls. The normal parts for band organs are melody, accompaniment,
Wurlitzer duplex roll system on a 146-B band organ. While one roll rewinds, the other plays.