Action. A collection of levers, primarily consisting if the hammers, dampers, and all other moving parts and supporting rails found above the keyboard.

Agraffe. A brass string guide with a bridge that spaces and levels the string.

Aliquot. Steel-bearing piece that frets off treble strings in some grands.

Aliquot scaling. A system of stringing in which unstruck sympathetic strings are added to increase sonority. It is used in the upper register of Bluthner pianos in particular.

Aluminum extrusions. Shaped bar stock that is squeezed through a die. In pianos, these extrusions are typically used for action rails.

Anemocorde [animo-corde, wind-clavier]. A form of SOSTENENTE PIANO in which the vibrations of the strings were sustained by currents of air after receiving an initial impetus from a mechanical bow. It was invented by Schnell and Tschenky in 1789.

at pitch (or at concert pitch). When a piano’s key, specifically the A note above middle C, makes a tone at 440 Hz or cycles per second. Concert pitch has involve from as 380 Hz in the 1600s to the modern standard of 440 Hz today.

Baby grand. The smallest-size GRAND PIANOFORTE.

Back check. See CHECK.

Back-touch rail. A baize-covered wooden rail on which the tail of the keys rest.

Balance pin. A 2 to 3-mm plated pin on which the key pivots.

Balance rail. A central hardwood rail of the keyframe that acts as the fulcrum of the keys into which the balance pins is inserted.

Barring. A term for the system of strips or bars of wood glued under the soundboard to enhance its mode of vibration when the strings vibrate. This is crucial to the tone of an instrument.

Bassoon stop. A STOP found in Viennese 18th- and early 19th-century pianos and, rarely, on French. It causes a piece of paper covered in silk to buzz against the bass strings.

Batt pin. An oval-shaped platted pin that position and guides them through their travels.

Beak. That part of the HAMMER shank in south German and Viennese actions which projects beyond the pivot point and which engages with the escapement mechanism or Prelleiste.

Beats. A term referring to the sensation caused by two strings vibrating at slightly different frequencies

Belly. The piano’s soundboard, bridge, belly-bars, and liners.

Belly rail. The transverse, wooden brace that supports the front edge of the soundboard.

Bentside. The curved side of a piano case.

Bracing. The internal construction of a piano FRAME by which the tension of the strings is supported.

Bridge. The surface on which the strings bear; the bridge determines their speaking length. The long bridge-attached to the soundboard-is made of a hardwood such as beech. The top bridge has a metal bearing surface either cast into the iron frame or set within an agraffe.

Bridge pin. A small metal pin driven into the wooden bridge to determine the string spacing upon it.

Bridle [tape-check]. Part of the action in uprights, patented by Robert Wornum in 1842, which assists the return of the hammer to the check by means of an attached tape, thus facilitating repetition.

Buff stop. [harp stop]. A device found chiefly on square pianos of the 18th and early 19th centuries which muted the strings by pressing a piece of buff leather against them at the nut, so as to damp out high harmonics and give a pizzicato quality to the timbre.

Buffing Wheel. A wheel covered with a soft material, such as velvet or leather, for shining and polishing.

Bushings. Felt liners glued to wooden parts that rub against metal pins within the action and keyboard. Used for silent and reduced-friction operation.

Boston fallboard. Hinged key-covered on uprights that folds down twice.