This name, which means �pipe�, is usually qualified with other terms (see variants below). By itself, according to Irwin, it indicates an open flute of 8' pitch, usually of wood but occasionally of metal. On a theatre organ, the name Tibia indicates a Tibia Clausa. While this term was in use long before Hope-Jones arrived on the scene, his use of it has effectively redefined it to indicate a family of huge scaled flutes with little harmonic development.
Nearly every theatre organ has at least one, unified to a wide variety of pitches.