Pipe
The tubes of wood or metal in the organ. They are classified as follows:- Open pipes, open at the top; closed or stopped pipes, with a movable plug; flue pipes, those constructed on the principle of the whistle or flageolet; reed pipes, those in which a beating reed is combined with the pipe. Pipes are also classified by length, the open diapason being the standard. An open pipe must be eight feet long to sound P. -0- A closed pipe four feet long gives the same sound; both are said to have an 8-foot tone.
If a pipe has a 4-foot tone, its sound is an octave higher than the diapason; if a 2-foot tone, it is two octaves above the diapason.