These pages comprise a dictionary of terms relating to the pipe organ. Please keep definitions to a few sentences, and do not include pictures or sound clips. When more space is needed for a term, a new page can be created for it.


Half-length [adjective] - used of resonators on reed pipes which are half the length usually required for their pitches. Done often to save space or money, and usually only in the bass octave, except in the case of fractional length reeds where half length creates a desired tonal characteristic. Reeds can also be built at quarter- or even eighth-length.


Halving Ratio [noun] - a measure of the number of pipes (semitones) between one pipe and another of exactly half its diameter. This number is typically in the neighborhood of 17.

Harmonic [adjective] a pipe, rank or stop whose pipes are twice as long as usual for an open pipe of that pitch. This produces a rounder or darker tone than a non-harmonic pipe would.

Harmonic Bridge

Harmonic Flute [noun] - a type of flute stop that is manufactured to be twice the normal speaking length, and then voiced to speak at the first harmonic (the octave). A hole is frequently bored about halfway up the pipe to encourage harmonic speech. The tone is powerful and piercingly pure. Conventional open pipes are typically used for the bass notes (from about 2 2/3' G down) and extreme treble, both for cost and voicing reasons. Extensively developed in the organs of Cavaillé-Coll, the stop is indispensible in Romantic French music.

Harris, Renatus

Harrison, G[eorge]. Donald (1889-1956) - Anglo-American organ builder. Joined the Aeolian-Skinner firm in 1927, and began developing a "new" organ style, clarified and international as compared to what was then being done by American builders, designed to play most styles of music in a more authentic way. The new designs were a great success, and the style was dubbed the American Classic organ (q.v.).

Haskell, William E.

Haskelling [verb] - an ingenious method of inserting a capped tube inside a wider pipe which effectively doubles the length of the pipe, and produces a lower pitch than a pipe of that length normally could. Usually used only in the bass octave.

Hauptwerk [noun] - the principal division of a German organ, equivalent to the English "Great" division, or to the French "Grand Orgue".

Hinterwerk [noun] - a division of a German organ placed behind other divisions, usually because of height restrictions in the room.

Hohlflöte [noun] - an open flute stop.

Hoofdwerk [noun] a Dutch synonym for Hauptwerk.

Holtkamp, Walter Sr. (1894-1962) [proper noun] - US 20th century organbuilder, one of the first American organ reform builders, known for brilliant upperwork, gentle voicing, and his visual designs where the pipes are presented "raw", with no casework.

Hook, E. & G. G.

Hook & Hastings

Hope-Jones, Robert (1859-1914) - a flawed genius, born in England but later emigrated to the US. Developed complex electric actions and extreme voicing styles (very thin strings, wide flutes etc.). His tonal schemes were based around 8' stops, often featuring 4' Quintadenas and diaphones. He worked with several organbuilding firms as well as on his own, and his ideas reached their logical conclusion in the development of the Wurlitzer.


Hoyt Metal - Common Metal; a high-lead-content sheet with a tin "washcoat" to give it a shiny appearance. (Richard Schneider; in Mechanical Music Digest, 1998)

Hydraulis [noun] - a Greek forerunner of the pipe organ, which used water in some of the blowing mechanism to provide air pressure.