Audsley lists Pyramidflöte with the synonym Pyramidal Flute and the following description: A wood stop, of 8 ft. pitch, the pipes of which are square and, as the name implies, are smaller at the top than at the mouth line. The tone differs in stops made by different organ-builders, but in the best examples it is light and clear, resembling a combination of the tones of the Melodia and the Gemshorn. A good example exists in the Unterwerk of the Organ in the Church of SS. Peter and Paul, Liegnitz, in Silesia [Germany], built by Buckow in 1839. Wedgwood lists Pyramidflöte, saying only �A variety of Querflöte of �pyramidal� or tapering structure. Liegnitz.�. Irwin lists Pyramid Flute with this description: An open wood Flute of 16', 8', or 4' pitch, whose pipes are shaped like the lower sections of very slender pyramids. The Conical Flute, of similar form, is usually a little brighter than this Flute, especially in the treble notes. The partials of these two Fluts are not peaked in loudness as they are in many straight-walled metal and wooden Flutes. The are also dampened almost out of existence by the tapered walls, except down near the fundamental. Compared to the Major Open Flute and Principal Flute, this is a comparatively dull Flute. It is chiefly a combinational or ensemble Flute. Triangular Flutes of tapered form are also made, and are quite dull in tone, although sometimes loud. There is little appeal in the tone of this Flute as a solo stop to sound by itself.
No examples are known other than the one cited by Audsley. Contributions welcome.