Type of flue pipe (also listed in this Glossary) often used in orchestrions, photoplayers, organs, and other instruments. Usually made of wood, the flute produces a clear tone relatively free of harmonics. Flutes in the high treble range are called piccolos; those in the bass range are called bass flutes or bourdons. Varieties of flutes include open flutes, stopped flutes (a stopped flute is equal in pitch or tone length to an open flute of twice the length, when all other dimensions are equal), and harmonic flutes (with a small hole at the nodal point in the center front of the pipe). Double-mouthed flutes are called doppelflutes. Flutes are the easiest to maintain of all common types of pipes. For this reason they found wide use in automatic instruments.