32-ft. Quintaten on the pedals. Zamminer, p. 265, gives the following technical explanation of this valuable stop:-" An open pipe the size of a Quintaten would be considered a very wide one; as a Cornet stop it is sufficiently slender to allow of the fifth of the octave being distinctly heard if overblown, which is still more facilitated by a low cutting up and stronger wind pressure." (See Measurement.) R. Rauschquint, Rauschflöte. Composed generally of 23-ft. Quint and 2-ft. Octave; that is, of the fifth and its octave, so that both tones together form a fourth, and have, therefore, a "rustling" sound. I have never found this stop except on large organs. It belongs naturally to the Great Organ. Reed Stops. Fig. 9. (Reed pipes, Reed work.) As this term comprises a whole species of stops, in contradistinction from Flue work, and as it occurs frequently in this book, I think it advisable to give a thorough definition of it, in accordance with technical books on the subject. The current of air, arriving from the sound-board, sets in vibration an elastic tongue (a thin oblong metal plate, Fig. 10, 7), which periodically intercepts the stream of air (alternately opening and closing). These vibrations of the tongue, or rather the intermittent impulses of the wind,* which at each vibration break through the aperture closed by the tongue, produce *We therefore have to deal with a current of air passing through the pipe, for which reason Melde (" Acoustics," p. 308) compares these constant condensations and rarefications of the tongue to the periodical changes in density occasioned by the combustion of gas in connection with the air column, tending to vibrations in the so-called chemical harmonica. An exhaustive description of this instrument, so important for experiments on the generation of tone in organ pipes, is found in paragraph 80 of the lastmentioned work. the tone, which, in height or depth, depends upon the length and volume of the vibrating portion of the tongue. How very different the build of flue pipes is from that of reed pipes is evident from the fact that in the latter the visible part of the pipe (resonant tube, as in Fig. 9) contributes in no way to the production of the tone, but only serves musically to refine the sound which originates at the Longitudinal section of a reed pipe, with sounding cup. give c FIG. 9. FIG. 10. tongue (and to give it the requisite tone of the reed for which above described, must F tongue, l, set Reed pipe divested of cup, and side view of the vibrating by the current of air coming from F. As I have said, the pitch of the tone depends upon the length of the excursions of the tongue, which are regulated by the tuning-wire. The scale of the tubes depends upon the pitch produced by the greater or lesser vibrations of the tongue. The lower tones naturally receive larger and longer tubes, the higher tones smaller and shorter ones. The tongue is fastened over a groove or reed, which, when at rest, it closes, with the exception of a very fine chink all round its margin. The tongue is either allowed to vibrate freely in the groove (see Physharmonica), in which case it is said to be a free vibrator (anche libre, frei-schwingend) (see also Vox Humana), or with each vibration it strikes against the edge of the groove, and is then called a striking reed (aufschlagend). To soften the frequently harsh tone produced by metal beating against metal, modern art of organ-building has very cleverly resorted to fine leather covering for the edges of the grooves to mellower reed stops. In Fig. 10, pp represents the air chamber, where the groove and tongue are fixed between the wedge and the block ss. Figs. 9 and 10 represent longitudinal sections, to allow of an inspection of the cleverly arranged interior parts of this species of pipe. In consequence of the intense influence which heat and cold exercise upon flue stops, and the difference in pitch from that of the reeds resulting therefrom, these latter frequently require retuning. I will give one example only of the influence of temperature upon sound: the velocity of sound in air at zero, 32° Fahrenheit, is 1090 ft. per second; it increases about two feet per every degree of Celsius-9.5° of Fahr.-as the temperature rises. A cold column of air gives a deeper tone than the same column if warmed and therefore rarefied. For, in spite of the same length of the waves, the tone in warm air is higher than in cold air, because of the quicker succession of these waves. By heat the pitch of flue pipes is, therefore, raised considerably higher than that of reed stops, which is flattened by the extension, and consequent slackening, of the tongue in the same temperature.* This is a proof that, contrary to general opinion, reed stops with sounding tubes are less subject to the changes of temperature, and their effect upon true pitch, than are flue stops, and that, if there is a difference of pitch between these two species of pipes, it is generally brought about by a change in the flue pipes. The trials made in various organ factories fully bear out this argument. These trials were made with a Trumpet and an Octave, which were first justly tuned to the pitch of the tuning-fork, and were then subjected to artificially produced changes of temperature. For technical reasons (see Flue Pipes) the tuning of the flues should remain the affair of the organ-builder; the organist, therefore, in his attempts to bring his instrument back to the proper pitch, is limited to the retuning of the reeds only. But it is easily understood that even this operation, which is based upon a delicate handling of the tongue by the tuning-wire, should only be performed by conscientious and experienced hands. And though one may always expect conscientiousness in country organists, yet it would not be fair to look for experience. One, therefore, refrains from the use of reed stops in very small provincial organs, and tries to replace them in a measure by the substitution of incisive and string-toned stops (Gamba, Viola, *The thermal influence on the number of vibrations of a riveted tongue (Physharmonica and Harmonium) may, as experience proves (Zellner), be considered infinitesimally small. Geigenprincipal). Where the tuning of the reeds can be regularly undertaken by an organist possessing the abovementioned qualities, one should not, solely on account of expense, omit to provide an Oboe, a Clarionet, a Trumpet, and so forth, according to the size of the organ; but even then only if its construction has been entrusted to a skilled master. With regard to this tuning, I will venture the remark that I do not care to see it done by either simply forcing down the tuning-wire, or pulling it out by a pair of pincers, in which operation the tuning-wire is so often bent, or even broken; rather should this, if at all possible, be done with the aid of a properly constructed reed-knife, which can only move the wire up or down vertically. It is always best at once to replace damaged wires, or such on which the knife has no proper hold for want of a notch,* because the knife might slip off and damage the sides of the pipes. How important must be a moderate and æsthetically discerning choice of reeds for the flue work, is evident from the fact that no manner of construction is yet known by which it is possible to give to the reeds in the upper registers the strong, piercing tone which, in certain registers, is peculiar to the flues, and by which the latter, in a way, lose their great strength in the lower notes, where in turn the reeds begin to be more decidedly effective. Töpfer ("Orgelbaukunst," p. 104) places this distinctly perceptible relative effect of these two species of pipes upon each other in the tenor octave. The difference in the development of power is most clearly evident; and it is for this reason that the pedals play such an important part in * See Töpfer's "Orgelbaukunst,” Diagram CV., Fig. 937, which represents a reed pipe with the upper end of the tuning-wire (not visible in our Fig. 10), and in which this sharp notch may be clearly seen. |