Encyclopaedia Britannica, 11th Edition, "Cincinnatus" to "Cleruchy" / Volume 6, Slice 4

by Various

The modern clarinet consists of five (or four) separate pieces: (1) the mouthpiece; (2) the bulb; (3) the upper middle joint, or left-hand joint; (4) the lower middle joint, or right-hand joint[2]; (5) the bell; which (the bell excepted) when joined together, form a tube with a continuous cylindrical bore, 2 ft. or more in length, according to the pitch of the instrument. The mouthpiece, including the beating or single-reed common to the whole clarinet family, has the appearance of a beak with the point bevelled off and thinned at the edge to correspond with the end of the reed shaped like a spatula. The under part of the mouthpiece (fig. 2) is flattened in order to form a table for the support of the reed which is adjusted thereon with great nicety, allowing just the amount of play requisite to set in vibration the column of air within the tube.

Fig. 1.—Clarinet (Albert Model).

The mouthpiece, which is subject to continual fluctuations of dampness and dryness, and to changes of temperature, requires to be made of a material having great powers of resistance, such as cocus wood, ivory or vulcanite, which are mostly used for the purpose in England. A longitudinal aperture 1 in. long and ½ in. wide, communicating with the bore, is cut in the table and covered by the reed. The aperture is thus closed except towards the point, where, for the distance of 1⁄3 to ¼ in., the reed is thinned and the table curves backwards towards the point, leaving a gap between the ends of the mouthpiece and of the reed of 1 mm. or about the thickness of a sixpence for the B flat clarinet. The curve of the table and the size of the gap are therefore of considerable importance. The reed is cut from a joint of the Arundo donax or sativa, which grows wild in the regions bordering on the Mediterranean. A flat slip of the reed is cut, flattened on one side and thinned to a very delicate edge on the other. At first the reed was fastened to the table by means of many turns of a fine waxed cord. The metal band adjusted by means of two screws, known as the “ligature,” was introduced about 1817 by Ivan Müller. The reed is set in vibration by the breath of the performer, and being flexible it beats against the table, opening and closing the gap at a rate depending on the rate of the vibrations it sets up in the air column, this rate varying according to the length of the column as determined by opening the lateral holes and keys. A cylindrical tube played by means of a reed has the acoustic properties of a stopped pipe, i.e. the fundamental tone produced by the tube is an octave lower than the corresponding tone of an open pipe of the same length, and overblows a twelfth; whereas tubes having a conical bore like the oboe, and played by means of a reed, speak as open pipes and overblow an octave. This forms the fundamental difference between the instruments of the oboe and clarinet families. Wind instruments depending upon lateral holes for the production of their scale must either have as many holes pierced in the bore as they require notes, or make use of the property possessed by the air-column of dividing into harmonics or partials of the fundamental tones. Twenty to twenty-two holes is the number generally accepted as the practical limit for the clarinet; beyond that number the fingering and mechanism become too complicated. The compass of the clarinet is therefore extended through the medium of the harmonic overtones. In stopped pipes a node is formed near the mouthpiece, and they are therefore only able to produce the uneven harmonics, such as the 1st, 3rd, 5th, 7th, &c, corresponding to the fundamental, and the diatonic intervals of the 5th one octave above, and of the 3rd and 7th two octaves above the fundamental. By pressing the reed with the lip near the base where it is thicker and stiffer, and increasing the pressure of the breath, the air-column is forced to divide and to sound the harmonics, a principle well understood by the ancient Greeks and Romans in playing upon the aulos and tibia.[3] This is easier to accomplish with the double reed than with the beating reed; in fact with a tube of wide diameter, such as that of the modern clarinet, it would not be possible by this means alone to do justice to the tone of the instrument or to the music now written for it. The bore of the aulos was very much narrower than that of the clarinet.

Fig. 2.—Clarinet Mouthpiece. a, the mouthpiece showing the position of the bore inside; b, the single or beating reed.

In order to facilitate the production of the harmonic notes on the clarinet, a small hole, closed by means of a key and called the “speaker,” is bored near the mouthpiece. By means of this small hole the air-column is placed in communication with the external atmosphere, a ventral segment is formed, and the air-column divides into three equal parts, producing a triple number of vibrations resulting in the third note of the harmonic series, at an interval of a twelfth above the fundamental.[4] In a wind instrument with lateral holes the fundamental note corresponding to any particular hole is produced when all the holes below that hole are open and it itself and all above it are closed, the effective length of the resonating tube being shortened as each of the closed holes is successively uncovered. In order to obtain a complete chromatic scale on the clarinet at least eighteen holes are required. This series produces with the bell-note a succession of nineteen semitones, giving the range of a twelfth and known as the fundamental scale or chalumeau register, so called, no doubt, because it was the compass (without chromatic semitones) of the more primitive predecessor of the clarinet, known as the chalumeau, which must not be confounded with the shawm or schalmey of the middle ages.

The fundamental scale of the modern clarinet in C extends from

The next octave and a half is obtained by opening the speaker key, whereby each of the fundamental notes is reproduced a twelfth higher; the bell-note thus jumps from E to B♮, the first key gives instead of F its twelfth C♯, and so on, extending the compass to

, which ends the natural compass of the instrument, although a skilful performer may obtain another octave by cross-fingering. The names of the holes and keys on the clarinet are derived not from the notes of the fundamental scale, but from the name of the twelfth produced by overblowing with the speaker key open; for instance, the first key near the bell is known not as the E key but as the B♮. The use of the speaker key forms the greatest technical difficulty in learning to play the clarinet, on account of the thumb having to do double duty, closing one hole and raising the lever of the speaker key simultaneously. In a clarinet designed by Richard Carte this difficulty was ingeniously overcome by placing the left thumb-hole towards the front, and closing it by a thumb-lever or with a ring action by the first or second finger of the left hand, thus leaving the thumb free to work the speaker key alone.