The organ’s specification is a list of its stops and main features. The stoplist is grouped in divisions, each corresponding to one of the organ’s four manuals (keyboards) and the pedalboard.
A ‘stop’ is a group of pipes of the same timbre, one pipe (or sometimes more) for each note of the keyboard or pedalboard. In the specification, each stop is numbered for reference. The foot-length after its name indicates whether it sounds at written pitch (8ft), one or two octaves above (4ft or 2ft respectively), an octave below (16ft), or other intervals. You may notice slight discrepancies in spelling in the stop names. These are the result of different national organbuilding traditions. For instance, the Great ‘Trompete’ (German) is different in style from the Swell ‘Trompette harmonique’ (French), and the Echo division ‘Trumpet’. The unnumbered items following the stops in each division are its accessory controls. Most of these are ‘couplers’ – for instance, the ‘Swell to Positiv’ couples the Swell to the Positiv, allowing the stops from the Swell keyboard to be played on the Positiv keyboard as well. The Positiv, Swell and Solo divisions have a tremulant, which introduces a gentle ‘wobble’ into the stops by varying the wind supply.