distinction from Reed stops, I will endeavour to give a concise definition, according to the latest results of study, on the generation of sound in flue pipes. The peculiarity of flue pipes is that, when they are sounding, air is the generating and vibrating body. The pipe only serves to cut off the vibrating column of air from the outer atmosphere, and to regulate the vibrations. The tone is originated at the sharp edge of the mouth (labium, lip); a flat current of air is driven against this lip, and in splitting produces a curious noise, which may be considered as a mixture of many tones in close proximity. (Compare Melde's "Acoustics," 1883, p. 250 and the following.) The bore of the pipe then stimulates some of those sounds which correspond to the tones peculiar to the pipe, thereby raising them to the rank of a musical note. (Even the tone of a tuning-fork, if brought into close proximity with the mouth of a tube, or an organ pipe, is strengthened if the pitch of the said fork corresponds to one of the notes peculiar to the pipe.) Fig. 1 shows the longitudinal section of a wooden flue pipe. The vibrating column of air is cut off from the outer atmosphere and regulated by the sides R R. The air coming from the wind-chest passes through the foot of the pipe into the throat or air-chamber K, from which it can now escape through the narrow slit c d, and in being forced against the sharp edge, a b, of the mouth, produces the musical tone as above described. Fig. 2, on the other hand, is a metal flue pipe, soldered at the top, therefore gedackt, or covered. It has purposely been placed by the side of the open flue pipe, to show the physical definition given under Gedackt (q.v.), according to which it gives a tone an octave deeper than does an open pipe of the same length FIG. 1. (Fig. 1). The letters R R, as above, indicate the tube which encloses the sonorous body of air; a b is the above-described site for the origin of the tone, and F F, the foot of the pipe standing in the sounding board, and extending to the slit. (See above.) A definition of the production of tone in the flues is to be found in Richter's "Catechism of the Organ," p. 24, and in Sonreck's "Theory of the Sonorous Column of Air." One word more on the difficult tuning of this - species of pipe. Although I am quite of opinion that the tuning of flue pipes should really remain the business of the organbuilder, still I would here draw attention to the new contrivance for tuning with slots and rolled-up strips of tin (for metal pipes), or tuning sliders (for wood pipes). The main body of FIG. 2. the pipe is made longer by half a tone than the intended pitch requires; an oblong opening, proportionate, to the measurement of the pipe, is then cut in the tube just below the upper end, in such a way that its lower half begins below the actual pitch of the pipe, while the upper half extends beyond it. The strip of metal, which is cut out to form the oblong opening, remains attached at the lower end, and is rolled up in a spiral. (Compare Prof. Kothes' excellent book on organ-building, to which I am indebted for several capital illustrations.) By rolling up the strip, and thereby shortening the working portion of the pipe, the tone becomes sharper; by unrolling the strip, that is, lengthening the pipe, the tone is made flatter. In wood pipes the same operation is performed by means of a movable slider, retained in position by two screws. The tuning slot gives the pipes, apart from a precise articulation, a more steady, decided tone, and adds power of expression to its qualities. This mode of tuning must, however, not be confounded with tuning shades of older date, which served exclusively to facilitate the operation of tuning. FIG. 3. FIG. 4. Fig. 3 shows the upper end of a metal pipe, on which is visible the tuning slot, a, and the strip of metal, b, rolled up in a spiral. Fig. 4 shows that side of the upper end of a wood pipe at which the tuning slider, a, is pushed up as far over the opening, b, as the dotted line goes. In new organ contracts, this tuning-slot arrangement is often stipulated for, particularly for the Principal and Gamba stops. The open wood pipes are tuned by means of a tuning shade of zinc or tin plate, bending up or down; and the metal pipes-for instance, the small mixture pipes which have no tuning slot-are tuned by means of a tuning horn. By narrowing the upper rim of the pipe the tone is flattened; by opening it out, it is sharpened. For tuning stopped pipes, see Gedackt. Flute. When this name alone is placed on the button of a stop, it means an open, particularly wide 8-ft. and 4-ft. flue pipe, louder than Flauto Dolce (Flauto Major, as 16-ft. stop on the Great manual at Riga). Flute is the foundation of a large species of stops, several of which, such as Fernflöte, Blockflöte, Spillflöte, Nasonflöte, Suabeflöte, Bauerflöte, etc., are becoming extinct in new organs. It is evident that in organs of one hundred or more stops (Ulm, Paris, Liverpool, London, Sydney, Russian Libau, Riga, Garden City, U.S.A., and a few others), some names for the same or a similar stop may occur with slightly altered etymology, solely for purposes of distinction. In the same manner as has just been done with Flauto Dolce, other members of the Flute family are discussed in this work. Three-cornered Flutes have also been employed, partly on account of limited space, partly because the desired intonation necessitated a wider lip. Combined with others, it is rather more effective than Flauto Dolce. The 8-ft. Flute as pedal stop occurs under the name of Bass Flute on nearly every pedal clavier. As we mentioned at the end of the article Sub-Bass, the Flute Bass and the similar-toned Octave Bass give the pedals in the lower registers not only great precision-a quality particularly belonging to the Violoncello-but also more body, and in the upper registers the fullness and roundness so often wanting in Sub-Bass. Flûte à Cheminée. See Rohrflöte. Flute Bass. See Flute. Flûte d'Amour (Flauto Amabile) is a charming wood flue stop of slender scale, arranged as 8-ft. and 4-ft. tone; in Switzerland more frequently as 4-ft. tone. According as the rest of the pipes are arranged, it occurs on the first manual in many organs, where it is very useful as a solo; for example, in the new organ of St. Martin's Church, Vevey, and in the German Church at Montreux. The sombre Gedackts and the strings (see Æolina) are effectively enlivened by it. It is often found as 8-ft. Amorosa on Steinmeyer's organs. Flûte Douce (Sanftflöte). See Wienerflöte. Flûte Harmonique. See Harmonic Flute. Flute Principal. An 8-ft. stop of a pleasant, bright, fluty tone. Occurs in many organs to great advantage on the second manual, and combines very prettily with Salicional or Viola, and an enlivening Flauto Traverso. Frein Harmonique is an arrangement, invented by Gavioli of Paris, applied to narrow scale stops (Gamba, Violoncello, Viola, etc.), by means of which the ready, incisive, string character of the tone is considerably strengthened and beautified. This contrivance consists (Dienel) of a narrow metal plate, of the length of the mouth, fixed obliquely to the latter on an adjustable spring. I have referred (see Gamba) to the effectiveness of this Frein, which answers even in the case of the smallest scale string stops. Fugara has much in common with Gamba, while in |