AGO. The American Guild of Organists is the professional association of organists in the United States. Founded in 1896, the organization now has chapters in every state and numbers some 20,000 members. The AGO web site has more information about the history of the guild and its current activities.
Action. The mechanism through which motion of a key is transmitted to a windchest so that pipes may be sounded. Actions may be mechanical, electro-pneumatic, or electro-mechanical. For more complete information, select "Chests and Actions" from the menu THE ORGAN AND HOW IT WORKS.
Barker lever. A mechanism for reducing the amount of force needed to press a key on a large mechanical-action instrument, developed by C. S. Barker and widely used by Aristide Cavaillé-Coll in nineteenth-century France. For further details, including animations that show how the levers work, select "Cavaillé-Coll" from the menu Nineteenth-Century France.
Blockwerk. The term commonly used to describe large organ of the middle ages with many pipes sounded by a single key and no stop action to shut off wind to any of the pipes. For more information select "The Middle Ages" from the menu ORGAN HISTORY.
Blower. In organs of the twentieth century, a rotary fan for producing organ wind, usually driven by an electric motor.
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. For more information select "Construction" from the menu PIPES.
Boot. The lower part of a reed pipe, containing the sound-producing mechanism: shallot and tongue. For further information, select "Construction" from the menu PIPES.
Case. An enclosure for chests and pipes, usually free-standing. Often decorated and an important part of the acoutical and visual aspect of many organs. For further information, select "Cases and Chambers" from the menu THE ORGAN AND HOW IT WORKS.
Céleste. A rank of pipes similar in scale and voicing to another rank on the same chest, intentionally tuned either sharp or flat in comparison to the unison rank. The effect when the two ranks are played together is a gentle undulation in the pitch. For further information, select "Pitches: Tuning and Célestes" from the menu PIPES.
Chair. An English name for a division of pipes located behind the organist as he or she sits on the bench, or "chair" and plays the main division. Similar in placement, and at times in content, to the Positif de dos of French organs or the Rückpositiv of German organs.
Choir. 1. A corruption of "chair," referring to a division placed behind the organ bench. Equivalent to the German "Rückpositiv." 2. An enclosed division containing stops useful for accompanying a choir of voices. For further information, select "Ranks and Divisions" from the menu PIPES.
Compass. The range of a keyboard, referring to the normal pitch of the keys themselves, not of the actual sounding pitch of a specific stop. Thus, in normal usage, "compass" refers to the keys, "range" to the pitches played by those keys.
Compound stop. A stop that controls more than one pipe for each key. For more information, select "Pitches: Compound Stops" from the menu PIPES.
Cornet. A compound stop of wide-scaled pipes sounding the fundamental and first four overtones, i.e., of 8', 4', 2 2/3', 2', and 1 3/5' pitches, drawn on onw stop knob; usually plays from g or c' to the top of the keyboard only. For more information, select "Pitches: Compound Stops" from the menu PIPES.
Coupler. A mechanical, electric, or electronic device that permits the keys of one manual to play the stops of another manual or division. A "Great to Pedal" coupler, for example, allows stops that are drawn on the Great division to be played by the pedal keyboard.
Cut-up. The height of a flue pipe mouth, expressed as a fraction of its width. For more details select "Flue Pipe Timbre" from the menu PIPES.
Divided stop. A register for which two stop controls are provided, one of which permits the register to play in the lower octaves of the keyboard, the other the upper octaves. Thus two stop controls must be engaged in order for the rank (or ranks) of pipes to play throughout the full compass. For more details, select "Pipes and Stops" from the menu PIPES.
Division. A section of the pipes and related windchests of an organ, usually consisting of several ranks of pipes on one chest, meant to be used in various combinations and controlled by a specific keyboard. A "floating" division has no home keyboard; it may be coupled to any one of several keyboards and played from any one or all of them.
Electro-mechanical Action. A system of windchest and connections to the key that permits a direct connection from the keyboard to open a pallet through an electromagnet. For more information, select "Electro-Mechanical Action" from the menu CHESTS AND ACTIONS.
Electro-pneumatic Action. A system of windchest and connections to the key that uses pneumatic power, activated by electro-magnets, to provide air from the chest to the pipes. For more information, select "Electro-Pneumatic Action" from the menu CHESTS AND ACTIONS.
Flat. That part of the façade of an organ case in which smaller pipes are arranged in a common vertical plane, usually separating two towers.
Flue/Flue Pipe. 1. The opening for wind between the lower lip and the languid. 2. A pipe which produces its sound when wind passes through the flue and strikes the upper lip.
Flute. 1. Used in the general sense in the United States, the term identifies a smooth-toned stop of low harmonic development produced by either stopped, half-stopped or open flue pipes. 2. In particular traditions, especially French, flûte identifies a wide-scaled open flue with a narrow mouth and a high cut-up. Flute stops (in either sense) may appear at any pitch level. For more detailed information, select "Flue Pipe Timbre" from the Menu PIPES.
Foot/Pipe foot. The bottom section of a flue pipe. In metal pipes usually in the shape of an inverted cone, open at the bottom (the toehole) and almost completely closed at the top by the languid. In wooden pipes the foot is usually a square or rectangular extension of the body with a cylindrical extension at the end of which is the toe.
Great. The primary manual division of an organ. Characterized by a principal chorus that establishes the primary characteristics of the sound of an individual instrument. German: Hauptwerk. French: Grand Orgue.
Half stop. A stop that allows a rank or ranks of pipes to be played from only part of a keyboard, usually the upper octaves only. For more information, select "pipes and Stops" from the menu PIPES.
Impost. In classical architecture, an ornamental horizontal projection at the top of a column, upon which the foot of an arch rests. In an organ case, the primary horizontal line above the base of the case, often extending beyond the width of two supporting components.
Jamb. In a keydesk or console, the flat panel from which stop knobs extend. In most traditional keydesks in mechanical-action instruments, the plane of the jamb is parallel to the keyboards; in later consoles, the jambs are usually at a 45° angle.
Key channel. The middle section of a pallet and slider chest. Wind is admitted to individual key channels by the action of pallets, and exits the key channel to the slider mechanism. For more information, select "Pallet and Slider Chests" from the menu CHESTS AND ACTIONS.
Keydesk. That portion of an organ consisting of the keyboards and their supporting structures. In instruments with some form of electric actions, where the keyboards might be housed in a separate structure from the organ itself, often called a "console."
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 kickboard.
Languid. A horizontal plate that separates the body from the foot of a flue pipe. For more information, see the page on "Construction" under the menu PIPES.
Mechanical Action. A system for conducting motion from keys and stop controls to the windchest through the use of mechanical connections using stickers, trackers, and squares. For more information select "Mechanical Action" from the menu CHESTS AND ACTIONS.
Mixture. 1. A term used to denote compound stops in general. 2. A chorus mixture.
For more information, select "Pitches: Compound Stops" from the menu PIPES.
Montre. A principal stop, usually at 16' or 8' pitch. From the French verb meaning "to show," indicating those pipes usually found in the façade and visible from the front of the case. See also praestant.
Mouth. The opening in the side of a flue pipe, where the foot joins the body. For more information, see the page on "Construction" under the menu PIPES.
Mutation. A stop that sounds a pitch other than the one being played or one of its octaves. A Nazard, for example, sounds g' when c is played. For further information, choose "Pitches" from the menu PIPES.
Pallet. A movable portion of a windchest, used to open or close holes that (eventually, in some cases) lead to pipes. 1. In a pallet and slider chest, a small piece of wood, fixed in position and free to move at the other. For more information, see the page "Pallet and Slider Chests" under the CHESTS AND ACTIONS. 2. In electro-pneumatic chests, a small disc of felt or similar material. For more information see "Electro-Pneumatic Chests" from the menu CHESTS AND ACTIONS. 3. A padded disc attached to the armature of a magnet in an electro-mechanical windchest. For more information, see the page "Electro-Mechanical Chests" under the menu CHESTS AND ACTIONS.
Pallet and Slider Chest. A windchest in which pallets, controlled by keys, and sliders, controlled by stops, admit wind to pipes. The oldest type of windchest in common use. For more information, see the page "Pallet and Slider Chests" under the menu CHESTS AND ACTIONS.
Pallet box. The lower portion of a pallet and slider chest, from which wind is admitted to individual key channels by the action of pallets. For more information, see the page "Pallet and Slider Chests" from the menu CHESTS AND ACTIONS.
Pitman Action. A type of electro-pneumatic stop action in which a short piston is moved by wind pressure to allow access of organ wind to specific pouches and pallets. For further information, please select "Pitman Chests" from the menu "Electro-Pneumatic Chests," from the menu CHESTS AND ACTIONS.
Positif/Positiv. A secondary manual division, unenclosed, usually containing a principal chorus that is of smaller scale and based on a higher pitch than that of the primary manual chorus (Great, Grand Orgue, or Hauptwerk).
Praestant/Prestant. A principal stop, usually one whose pipes appear in the façade of a case. From Latin pre=before and the present participle of sto/stare=to stand, thus "those pipes standing before" the others in a given division. See also Montre.
Principal. The primary tone color of the organ, produced by open flue pipes of moderate scale. Voicing of principals varies in instruments from different places and different periods. In different instruments, stops of principal tone color may be called Diapason, Montre, Praestant, Prestant, Principal, Principale, or Prinzipal, or they may be identified only with a pitch designation, such as Fifteenth, Octave or Decimanona. For more information and recorded examples, please select "Flue Pipe Timbre" from the menu PIPES.
Principal Chorus. A combination of stops of principal tone color at a variety of pitches, built and voiced so that they form a well-blended ensemble when played together. A typical principal chorus will include principal stops (Principal, Praestant, Montre, Diapason, Octave, Super Octave, Doublette) at unison pitches (16', 8', 4' and 2') in addition to chorus mixtures (Fourniture, Cymbale). Also called plenum or Ripeno (Italian), and similar in content and use to the classical French Plein jeu registration, and the classical organo pleno or plenum.
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. For further information, see the page "Ranks and Divisions" under the PIPES menu.
Reed. 1. A pipe that produces its sound through the vibration of a tongue against a shallot. For further information select "Construction" from the menu PIPES. 2. In some uses, an alternate name for either tongue or shallot.
Registration. 1. The practice of selecting specific stops to be used in playing a work. 2. A specific selection of stops to be used in playing a given composition.
Reservoir. A mechanism for both storing organ wind and controlling its pressure, located between the blower and the windchest. For further information, select "Wind Supply and Regulation" from the menu THE ORGAN AND HOW IT WORKS.
Ripieno. The term for a chorus of principal stops on an Italian organ of the sixteenth through the twentieth centuries, similar to the Plein jeu of French practice. For detailed information select "Italy" from the menu The Sixteenth Century.
Roller. A mechanism in an organ with mechanical action for transferring motion from the key to a pallet located above and to the side of the end of the key. Rollers are affixed to a "roller board," typically a horizontal board, with is face parallel to the front of the keys. For further information, select "Chests and Actions" from the menu THE ORGAN AND HOW IT WORKS.
Scale. The relationship between the diameter and length of the resonator of a pipe. For more information select "Flue Pipes and Timbre" from the menu PIPES.
Schnarrwerk. German noun referring to a class of short-resonator reeds. The root verb Schnarren means "to rattle" or "to buzz" and is descriptive of the timbre of these stops.
Schwimmer. A mechanism for controlling the pressure of organ wind, located on the lower surface of a windchest. For further information, select "Wind Supply and Regulation" from the menu THE ORGAN AND HOW IT WORKS.
Shades. Louvered panels that can be opened or closed to allow varying degrees of enclosure of the pipes of a given division. For further information select "Cases and Chambers" from the menu THE ORGAN AND HOW IT WORKS. Also called "Swell shutters."
Shallot. A brass tube located in the boot of a reed pipe, against which the tongue vibrates to produce a sound.
Short Octave. An octave of a keyboard in which some of the commonly used twelve tones are omitted. Many keyboards of the 16th through early nineteenth centuries simply omitted the first few sharp keys in the bottom octave -- only the long keys were present. Another frequently-used method was the "broken octave," which omitted the first four keys in the bottom octave (C, C#, D and D# on a C-compass keyboard) and assigned different pitches to the keys that normally played E through G#. According to this plan, the E key played C, F played F, F# played D, G played G, and G# played E - - an arrangement probably better seen in this diagram than described in words: 
Slider. A piece of wood or synthetic material with holes that align with those in both the topboard and the toeboard of a slider and pallet chest. The slider is movable and in one position closes off the wind to the pipes located above it. For further information select "Pallet and Slider" chests from the menu CHESTS AND ACTIONS.
Solo. A division characterized by distinctive solo stops, often on high pressure and usually enclosed. For further information select "Ranks and Divisions" from the PIPES menu.
Square. An L-shaped piece of wood or metal approximately three inches on a side. Used to change the direction of motion in mechanical action.
Sticker. A wooden (or metal) rod that carries motion of the key to the windchest by a pushing motion in an instrument that uses mechanical action.
Stop. 1. One or more ranks of pipes of consistent tonal design, activated by a single control from the console or keydesk. 2. The console or keydesk control for one or more ranks of pipes. In unit organs, a rank of pipes may be activated in whole or in part by more than one stop control. Also called "Stopknob" or "Stopkey." See also "divided stop" and "half stop." For a more detailed discussion, select "Pipes and Stops" from the Menu PIPES.
Swell. A division whose pipes are enclosed in a case or chamber fitted with shades that can be opened or closed from the console. For further information, select "Cases and Chambers" from the menu THE ORGAN AND HOW IT WORKS or "Ranks and Divisions" from the PIPES menu.
Swell pedal. A console control operated by the foot that opens or closes a set of shutters (see shades) placed across the opening of either a case or a chamber which contains one or more divisions of pipes. For further information, select "Cases and Chambers" from the menu THE ORGAN AND HOW IT WORKS.
Swell shades. See shades.
Terraced Draw-Knobs. A type of console arrangement in which the drawknobs for a manual division are arranged in horizontal lines extending in a curve from either side of the keyboard to which they are attached. To see a photograph of this type of console, please select "Keyboards and Consoles" from the menu THE ORGAN AND HOW IT WORKS.
Toe/Toehole. 1. The lower end of the foot of either a flue or a reed pipe, and the part of the pipe that is in contact with the chest. The toe is usually made of lead, even in wooden pipes; the size of the toehole regulates the amount of wind that can enter the pipe. 2. Toehole: the hole in the topboard of a windchest that admits wind to a pipe.
Tongue. A thin strip of brass that vibrates to produce the sound in a reed pipe.
Tower. An arrangement of larger pipes of a façade in a group with the largest pipe usually in the center. Towers may be flat, pointed, or round in shape.
Tracker. 1. A thin strip of wood (or metal) that carries motion of the key to the windchest by a pulling motion in an instrument that is built with mechanical action . Often used incorrectly to describe a sticker. 2. An organ that uses mechanical action, which is also called "tracker action."
Tracker Action. Another name for mechanical action.
Unit Action. Any type of action that permits the use of one rank of pipes by more than one stop. For further information, select "Unit Actions" from the menu CHESTS and ACTIONS.
Universal chest. 1. A chest in which wind is available to all pipes directly from the main chamber, without the intervention of channels, sliders, or other intervening chambers. 2. The Universal Air Chest patented by the Austin Organ Company/Austin Organs Incorporated. For more information, select "The Austin Universal Chest" from the menu ELECTRO-PNEUMATIC CHESTS.
Voicing. The art of altering the size of the toehole and elements of the sound producing mechanism (the mouth or the reed) to insure the correct dynamic level, timbre and speech characteristic in a pipe. For more details, select either "Flue Pipe Timbre" or "Reed Pipe Timbre" from the menu PIPES.
Windchest. The part of an organ that contains wind under pressure and a mechanism for admitting wind to selected pipes, which stand on top of the windchest. Also called "chest." For more information, select "Chests and Actions" from the menu THE ORGAN AND HOW IT WORKS.