Page:EB1911 - Volume 22.djvu/991

Rh aid of its tall (5 to to ft.) close set stems. The latter species, of which the branching root stocks may be traced 30 or even 40 ft., is of still greater importance in holding sand-dunes against the sea, and for this purpose has not only been long protected by law, but has been extensively planted on the coasts of Norfolk, Holland, Gascony, &c. Other reeds are Calamagrostis (various species), Gynerium a1'genteum(pampas grass), Deyeuxia, &c., also Arundo Donax, the largest European grass (6 to 12 ft. high), which is abundant in Europe. Reeds have been used from the earliest times in thatching and in other branches of construction, and also for arrows, the pipes of musical instruments, &c. Reed pens are still used in the East. Plants belonging to other orders occasionally share the name, especially the bur-reed (Sparganinm) and the reed-mace (Typha), both belonging to the natural order Typhaceae. The bulrushes (Scirpus), belonging to the natural order Cyperaceae, are also to be distinguished.

REEDBUCK (Dutch rietbok), the popular name of a foxy red South African antelope (Cervicapra arundineum) of medium size, with a moderately long bushy tail, a bare gland-patch behind the ear, and in the male rather short horns which bend forwards in a regular curve. There are several other species of allied African antelopes included in the genus Cervicapra to which the name of reedbuck is also applied, one of these ranging as far N. as Abyssinia, and another inhabiting W. Africa.

REED INSTRUMENTS (Fr. instruments à anche; Ger. Blas-instrumente mit Zungen; It. Strumenti a ancia), a class of wind instruments in the tubes of which sound-waves are generated by the vibrations of a reed mouthpiece. Reed instruments fall into two great classes: (1) those blown directly by the breath of the performer, who is thus able in all but a few obsolete instruments to express his emotional feelings in music; (2) those in which the wind supply is obtained by mechanical devices, such as the bag of bagpipe instruments or the bellows of such keyboard instruments as the regal, harmonium and kindred instruments.

Directly-blown reed instruments comprise the section of modern wind instruments known as the &ldquo;wood wind,&rdquo; with the exception of flute and piccolo; they are classified according to the kind of reed vibrator of which the mouthpiece is composed. There are three kinds of reed mouthpieces: (1) the single or beating reed; (2) the double reed; (3) the free reed, all of which perform the function of sound-producer (see and ). The reed used consists of a thin tongue or strip of reed, cane or some elastic material, thinned gradually to a delicate edge. It is adapted to a resonating tube in such a manner that when it is at rest the opening at the mouthpiece end of the tube consists only of a very slight aperture or chink, which is periodically opened and closed by the pulsations of the reed when acted upon by the compressed breath of the player. This principle is common to all reed mouthpieces, and the difference in timbre is in a measure due to the manner in which the pulsations are brought about and the degree of elasticity secured.

The double reed consists of two blades of reed or laminae of elastic material tightly bound together by many turns of waxed silk, so that above the construction the tube has an oval section; below, where it communicates with the main bore of the instrument, the tube is strictly cylindrical. The chink here is formed by two thin walls of reed of equal elasticity (see ../Oboe, ../Bassoon). The double reed is common to the members of the oboe family, consisting, besides the oboe, of the cor anglais or tenor, of the fagotto or bassoon, and of the contra fagotto or double bassoon. The double reed mouthpiece is used besides on the sarrusophone family, instruments of brass but classed with the wood wind on account of the mouthpiece and fingering.

The single or beating reed consists of a single blade bevelled at the edge and placed over a table or frame communicating with the main bore of the instrument, against which it beats, causing a series of pulsations. The single reed is common to all the members of the clarinet family, consisting, besides the

clarinet, of the basset-horn or tenor, and of the bass and pedal clarinets; of the batyphone, an early bass clarinet, and of the saxophone, a metal oboe with a beating reed instead of a double reed. The ancient Greek aulos was undoubtedly used with a beating reed during some period of its history.

The free reed is not represented among members of the modern wood wind, and, as adapted to a directly-blown instrument, only finds application in the Chinese cheng, the prototype of the harmonium, and in the mouth organ or harmonica.

The reed in wind instruments produces a peculiar tone quality to which it has given its name; it varies in the three different kinds of mouthpieces without losing the fundamental reedy timbre. In the single reed the impact against the hard wood or vulcanite of the table against which it beats produces a sound harsh and strident in inverse proportion to the degree of elasticity possessed by the vibrating tongue. In the clarinet the reed is carefully and delicately made of cane with due regard to the interdependence of reed and clarinet tube. The strong wooden or metallic beating reeds of the early organ reed pipes must have had an unpleasantly harsh timbre, which won for them in Germany the epithet Schnarrwerk.

In the double reed the two delicately shaped pieces of reed vibrate against each other, producing the somewhat nasal, reedy tone of the oboe family. In the free reed compressed air is the only buffer which the vibrator encounters while swinging through the aperture, alternately closing and reopening it; hence the soft and mellow timbre which it is possible to produce by proper treatment of the free reed. Experience has shown that the best results for the double reed are obtained when it is used in conjunction with a tube of conical bore, whereas the beating reed is heard to greater advantage in instruments with cylindrical bore, one notable exception in practice being, as already mentioned, the saxophone family. The double reed adapted to a conical tube confers upon the latter the acoustic properties of the open pipe, whose wave-length is equal to that of the tube and which is capable of overblowing the octave and successive harmonics (theoretically). Either a single or a double reed adapted to a cylindrical pipe converts it for all acoustic purposes into a closed pipe, in which the whole wavelength is twice the length of the tube, a node forming at the mouthpiece end. The fundamental note of such a tube will therefore be an octave lower than that of an open pipe of the same length, and it can only overblow the uneven numbers of the harmonic series, such as the third harmonic (or twelfth above the fundamental).

In order to overblow on instruments with reed mouthpieces, greater pressure of breath must be exerted, and the vibrating length of the reed must be decreased by the action of the lips upon it. This is what occurs in instruments of the oboe and clarinet type, which are blown directly from the mouth. There are, however, cases in which the reed is concealed within the instrument out of reach of the lips, either in a capsule, as in the old instruments hautbois de Poitou and cromorne, or else in a socket, as in the chaunter and drones of the bagpipe, or, again, as in the mouthpieces of organ reed pipes. In the last (each of which gives but one fixed note) the vibrating length of the reed tongue is fixed, as is also the pressure of the compressed air supply fed to them. The result in all these cases is similar: no harmonics can be obtained, and therefore the scale of the instrument depends solely on the number of holes and keys provided, whereas, where the lips control the reed, fewer holes are necessary to produce any given compass. The chaunters of bagpipes have double reeds, but the drones are as a rule provided with beating reeds and are of cylindrical bore, a combination which, for the reason explained above, gives them a note an octave deeper in pitch, the length of pipe being equal, than would be the case if the bore were conical. In the musette, in the cornemuse used in concert with the hautbois de Poitou, and in the Neapolitan surdelina (see ../Bag-pipe), both chaunter and drones had double reeds.

