Chimney flute
Half-stopped organ stop with a small tube in the cap, brighter than a fully stopped flute.
What it means
The chimney flute (German Rohrflöte) is a flue stop of the organ whose pipes are capped at the top, but the cap holds a thin, usually narrow metal tube, or "chimney". This chimney lets part of the air column escape at the top, changing the timbre compared with a fully stopped pipe.
In the notation
Like other organ stops, the chimney flute appears in a specification only as a stop name with a pitch length, such as "Chimney flute 8′" or "Chimney flute 4′", not as a notation symbol in the score.
Musical use
The chimney flute is one of the most common stopped stops in organs of many periods and countries, used both as a solo voice and combined with other flute or principal stops. It is distinct from a plain stopped flute (Gedackt), whose pipe is fully sealed and thus produces a duller tone with fewer overtones: the chimney of the chimney flute brightens its tone and adds overtones without losing the basic character of a stopped stop.
Performance practice
Use the chimney flute when you want a soft but not overly dull flute tone, for instance as the basis for delicate registrations or as a solo voice in quiet movements.