Principal

Principal [Lat.: vox principalis], in British and American organs a 4′ diapason in the manual or 8′ diapason in the pedal (corresponding to the Fr. préstant). Elsewhere the word, or its local equivalent, designates a foundation stop of open cylindrical flue pipes normally made of metal, rarely of wood. The principal scale became a standard scale for open flue pipes. Cf. Prinzipal.