GLOSSARY OF ORGAN TERMINOLOGY
GLOSSARY OF ORGAN TERMINOLOGY
This basic glossary has been produced to help those interested in organs but unfamiliar with organ terminology. If you have any queries about words that aren’t listed below, then please send us an email and we’ll add it to our list. More detailed information can be found in various textbooks, such as Organ Works by John Norman (2020), obtainable from the British Institute of Organ Studies.
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A-C
 | ACTION: The organ’s mechanism; or, more specifically, the mechanism which links the keyboards to the organ pipes. When a key is pressed, the ‘key action’ operates a set of valves, or Pallets, in the Windchest to admit wind into the pipes. The ‘stop action’ (or ‘drawstop action’) allows the organist, by drawing Stops, to control which ranks of pipes are engaged. The oldest form of action is Tracker (or Mechanical) action, with a direct mechanical connection between the keyboard and the pipes. From the mid-nineteenth century onwards, as organs grew bigger and more complicated, various forms of power-assistance have been devised to lighten the touch at the keyboard: e.g. Pneumatic action, Electro-pneumatic action. ., |
 | BACKFALL: A pivoted piece of wood or metal, working like a see-saw, which transmits motion forwards or backwards in a Tracker action. A set of backfalls is mounted on a ‘backfall beam’. |
 | BELLOWS: The traditional apparatus used for blowing organs (by hand or foot) until the introduction of the electric fan in the latter part of the nineteenth century. The picture shows a ‘wedge bellows’, used from medieval times. See also Blower, Reservoir. |
 | BLOWER: For centuries organs were blown by hand or foot, but mechanical blowing began to be introduced from the mid-nineteenth century (at first using steam, gas or water power), and now electric rotary fans are almost universal. The wind passes from the blower to one or more Reservoirs, which supply a constant pressure to the wind chests |
 | BODY: The upper part of a flue pipe, measured upward from the mouth to the end of the pipe. A pipe body may be either open, closed or partially closed. |
 | BOOT: The lower part of a reed pipe, containing the sound-producing mechanism: shallot and tongue. |
 | BUILDING FRAME: The structure upon which the organ components are set. Usually constructed of wood, jointed and bolted together. |
 | CASE: The wooden enclosure for the organ pipes and mechanism. An important visual and acoustic element of many organs; may be handsomely decorated. |
 | CÉLESTE: A rank of flue pipes, intentionally tuned slightly sharp to another rank of similar scale on the same chest. The effect when the two ranks are played together is a gentle undulation in the pitch. |
 | CHEST: See Windchest |
 | CHOIR ORGAN: The third Division of a three-manual English organ, normally played from the lowest keyboard (the other two keyboards controlling the Great and Swell Organs). The name is a corruption of the old term ‘Chair organ’, which referred to a division placed behind the organist’s bench (like the German ‘Rückpositiv’). Later it came to refer to a division within the main part of the organ, with the possible implication that it may be used for accompanying a choir of voices. . |
| COMBINATIONS, COMPOSITION PEDALS: See Pistons . | |
| COMPASS: The number of notes on a keyboard: e.g. the manual compass of an organ may be 61 notes (= five octaves), the pedal compass 30 notes (= two-and-half octaves). . . . | |
 | CONSOLE: The part of the organ containing the manual and pedal keyboards and the Stop controls. The console may be placed with the organ (‘attached’), or recessed into the case ‘en fenêtre’; or it may be separate from the organ (‘detached’). |
 | CONVEYANCES: Small ducts conveying wind to individual pipes that are placed at a distance from their Windchest. |
 | COUPLER: A coupler allows the organist to add the stops of one Division to the keyboard of another division: e..g. ‘Swell to Great’. |
D-F
 | DETACHED CONSOLE: See Console. |
| DIAPASON: 1. The alternative English term for Principal tone. ‘Open Diapason’ is the name for a rank of principal pipes at unison pitch. 2. In contrast, ‘Stopped Diapason’ refers to a rank of stoppered pipes; the stoppers repress the harmonics, producing a fluty tone. | |
 | DIVISION: A group of stops in an organ, playable as a separate entity (e.g. Great Organ, Swell Organ). |
 | DRAWSTOP ACTION: See Action |
ELECTRIC ACTION: 1. In its widest sense, any type of Action that uses electricity. 2. More strictly, a particular type of Action that uses an electromagnet to actuate a Pallet valve directly: also known as direct-electric or electro-mechanical action. Not to be confused with Electro-pneumatic action (see next entry). … | |
 | ELECTRO-PNEUMATIC ACTION: A sophisticated type of power-assisted Action. When the organist presses a key, a low-voltage electric circuit is completed which activates an electromagnet in the organ: this in turn charges or exhausts one or more pneumatic Motors, thus opening the respective Pallet valve to admit wind to the pipes. An electric cable connects the console to the organ. The best examples of electro-pneumatic action are highly efficient and promote natural speech in the pipes. . . |
 | FLUE/FLUE PIPE: FLUE: The narrow slot in the Mouth of a pipe, between the Languid and the lower lip, so formed that it directs the wind to strike the upper lip and set up a vibrating column of air in the body, which creates the musical note. (See also next entry.) FLUE PIPE: There are two types of organ pipe: Flue pipes and Reed pipes. Flue pipes (the great majority) are typified by those seen on the front of most organs They work on the same principle as a whistle or recorder, in that a stream of air is directed via the Mouth to the Body of a pipe. (See also previous entry.) |
 | FOOT/PIPE FOOT: The bottom section of a Flue pipe. |
G-M
 | GREAT ORGAN: The primary manual Division of an organ, characterised by a chorus of Principal (or Diapason) Stops. In English organs the Great Organ is played from the lowest Manual of a two-manual or the second manual of a three- or four-manual instrument. |
 | HOOD: The shape formed when the top of a pipe is mitred to turn it at an angle. This prevents dirt from falling down the pipe and upsetting the tongue. See also Knuckle. |
 | KEY ACTION: See Action |
 | KNEEBOARD, or KICKBOARD: The horizontal panel above the pedalboard, between the pedals and the lowest manual. Expression pedals, coupler controls and toe studs may be located on or set into the kneeboard. |
 | KNUCKLE: the shape formed when a reed Resonator is mitred to turn it through 360o. This gives the pipe extra strength, traps any dust, and allows it to fit within a restricted headroom. See also Hood |
 | LANGUID: A horizontal plate that separates the body from the foot of a flue pipe. |
 | MANUAL: The keyboard of an organ, similar to a piano keyboard and controlling its own set of pipes. Many organs have two or more manuals, each controlling a separate Division: this makes it possible to move rapidly from one sound to another or to play a solo on one manual and accompany it on another. |
 | MECHANICAL ACTION: See Tracker action |
 | MITRE: a joint made in the body of an organ pipe to turn it at an angle. See also Hood, Knuckle. |
 | MIXTURE: An organ Stop containing more than one rank of pipes (as seen in foreground of photo). |
 | MOTOR: A miniature bellows, used to provide motive force in Pneumatic and Electro-pneumatic actions. |
 | MOUTH: The opening in the side of a flue pipe, where the foot joins the body. |
P-R
 | PALLET: A valve in the Windchest that admits air to the channel feeding the pipe when a key is pressed. |
| PASSAGEBOARD: Passageway within an organ, used for tuning or maintenance. . . | |
 | PEDALBOARD: A special keyboard in the console designed to be played by the feet. In addition to playing the pipes of the Pedal Organ, the pedals also play other Divisions by means of one or more Couplers such as ‘Great to Pedal’. |
 | PIPES: These produce the sound and are constructed of either wood or metal. Each pipe produces a single tone, and it takes a series of them, one per key, to play the entire range of the keyboard. There are two types of organ pipe: Flue pipes and Reed pipes, q.v. |
 | PISTONS: Buttons placed between the organ keyboards, which allow the organist to choose pre-selected combinations of Stops. ‘’Foot pistons’ (or ‘Toe pistons’), are larger buttons with the same function, placed near the pedalboard; they sometimes take the form of pedals, known as ‘combination pedals’ or ‘composition pedals’. |
 | PNEUMATIC ACTION: or more specifically, Tubular-pneumatic action: An early type of power-assisted Action. Pneumatic tubes connect the console to the organ. Two principles are used: 1. When the organist presses a key, a charge of wind is sent along a tube to inflate a pneumatic Motor which activates the Pallet valve to admit wind to the pipe . 2. Alternatively, the tube is exhausted, causing a charged motor to collapse. Restoration of pneumatic actions presents special challenges. . |
 | PRINCIPAL: ‘Principal’ tone, the most characteristic sound of the organ, is produced by open Flue pipes of moderate Scale. Also known as Diapason tone. The ‘principal chorus’, consisting of principal ranks at different pitches, is a determining factor in an organ’s musical identity. |
 | RACKBOARD: A method of supporting organ pipes: a horizontal board with holes, set above the Upperboard. Fitting the pipes in the rackboard is called ‘racking in’. |
 | RANK: A set of pipes of similar construction, arranged on a windchest so that there is one pipe for each note of the keyboard which sounds the pipes. |
 | REED PIPE: One of the two types of organ pipe (the other being the Flue pipe). Reed pipes work on the same principle as a clarinet or oboe. The sound is generated by a brass tongue which is set in motion by a stream of wind and beats against a Shallot, thus setting up a vibrating column of air in a tube or Resonator to create a musical note. The resonators take many different forms, several of which are shown here. |
| REGISTER, REGISTRATION: ‘Register’ is another name for a Stop, or set of pipes in an organ. ‘Registration’ is the word for an organist’s choice of stops. . . | |
 | RESERVOIR: The lungs of the organ. A wind reservoir was originally required to store the wind that was raised by pumping a Bellows. Since the arrival of mechanical blowing (see Blower) storage is no longer necessary, but traditional reservoirs are still a respected method of controlling the wind supply from the blower and feeding it to the pipes at a steady pressure. A reservoir normally has either one or two sets of leathered ribs and folds – ‘single-rise’ or (illustrated) ‘double-rise’. . |
 | RESONATOR: The tube which forms the upper part of a reed pipe. |
 | ROLLER, ROLLERBOARD: A roller is a rotating rod, held between two pivots, which forms part of a Tracker action. This spreads the motion horizontally, for example from the manual or pedal keys to the wider-spaced Pallets at the Windchest. Each set of rollers is mounted on a rollerboard. |
S-Z
| SCALE: The proportion of the diameter to the length of a pipe. This governs the tone quality: e.g. Flue pipes of large scale give a broad, fluty sound, whereas small-scale pipes give a thinner sound. | |
 | SHALLOT: The brass tube located in the boot of a Reed pipe, against which the tongue vibrates to produce a sound. |
 | SLIDER: A strip of wood or other material with holes that align with the pipe feet of a particular Stop on a Slider chest. The slider moves to stop the wind from entering the pipes located above it and prevent them from sounding. It is actuated by a Stop knob or Drawstop at the console. See also Stop. |
 | SLIDER CHEST, or Slider soundboard: A type of Windchest, the oldest in common use, valued for its musical benefits. It consists of a wooden grid with a wind channel for each note, and valves or Pallets to admit the wind to the pipes; the Stops being controlled by Sliders with holes corresponding to the pipe feet. Much skill is required in the design and construction of a slider chest. |
 | SOLO ORGAN: The fourth Division of an English four-manual organ, played from the top keyboard. . |
 | SOUNDBOARD: an alternative term for Windchest. |
 | SQUARE: An L-shaped component in a Tracker action, pivoted between its two arms, which turns the motion through 90o degrees. A set of squares is mounted on a ‘square beam’. |
| STICKER: A strip of wood that carries the motion of the key to the windchest by a pushing motion, in an organ that is built with Tracker action. (Distinct from a Tracker, which has a pulling motion.) . . | |
 | STOP: 1. A set of pipes, all of similar construction, arranged on a Windchest so that there is one pipe for each note of the respective keyboard. 2. The control which admits wind to a set of pipes, or ‘stops’ wind from entering – hence the term. (See also Stop knob.) |
 | STOP ACTION or Drawstop action: See Action |
 | STOP KNOB, or Drawstop: The control at the console which the organist pulls to select a particular set of pipes. Hence the expression ‘Pulling out all the stops’. |
 | SWELL-BOX, SWELL SHUTTERS: In many organs one or more groups of pipes (e.g. Swell Organ, Solo Organ) are enclosed in a ‘swell-box’ with shutters, also known as shades or louvres, which can be opened or closed by the player to make a crescendo or diminuendo, using a Swell pedal. |
 | SWELL ORGAN: One of the main Divisions of an organ, enclosed in a Swell-box. Played from the top manual of a two- or three-manual English organ |
 | SWELL PEDAL (or expression pedal): See Swell-box. Two swell pedals can be seen at the top centre of the photo. |
| TOE/TOE-HOLE: The toe is the lower end of the foot of a pipe. The size of the toe-hole regulates the amount of wind that can enter the pipe. | |
 | TONGUE: The thin strip of brass that vibrates to produce the sound in a reed pipe. |
 | TRACKER: A thin strip of wood (or sometimes metal) that carries the motion of the key to the windchest by a pulling motion in an instrument that is built with a Tracker action. (Distinct from a Sticker, which has a pushing motion.) |
 | TRACKER ACTION, also known as Mechanical action: The oldest form of Action, still used today and admired for the way in which it allows the player to control the speech of the pipes. It involves a system of rods (Trackers) and levers, whereby the player’s touch at the keyboard is transmitted directly to the valves which admit wind to the pipes. See also Electro-pneumatic action. |
 | (WIND) TRUNKS: Ducts that distribute wind to the various parts of an organ; normally made of wood or metal. See also Conveyances. |
 | TUNING: The process of finely adjusting each pipe in the organ to the correct pitch so that they all sound in tune with each other. Flue pipes are tuned by slightly lengthening or shortening the Body length to make the note flatter or sharper; Reed pipes are tuned by altering the beating length of the Tongue. The pitch of organ pipes is affected by temperature of the air in and around them; flue pipes are affected differently from reed pipes, which is one reason why organs need periodic tuning. |
 | UPPERBOARD: The top layer of a windchest upon which pipes stand. |
 | VOICING: The art of adjusting the various parts of a pipe to produce the desired musical tone. The Voicer is responsible for the musical character of each instrument, preparing the pipes in the workshop and then adjusting each one in the building so that each rank has the appropriate balance with its neighbours and all combine to form a harmonious and exciting whole. . |
| WIND: The pressurised air which makes the organ pipes sound. See also Bellows, Blower, Reservoir. . | |
 | WINDCHEST: The intricately-constructed box of wind upon which the pipes stand. It contains the mechanism which allows the wind to enter the pipes, depending on the notes played and the Stops selected by the organist. There are many different types – notably the Slider chest. An alternative term is Soundboard (regardless of the fact that an organ windchest is quite different in function from the soundboard of a piano or harpsichord). |