reed-stops, by violins of a certain build, and by the clarinet, bassoon, etc., is produced by the predominance of the uneven harmonics (1⁄3, 1⁄5, 1⁄7, etc ). On the harmonium these uneven harmonies are stronger than the even ones. The peculiar tinkling tones of the zither arise from the high uneven harmonics yielded by its comparatively thick metal strings.
If a singer produces a low note crescendo against a reflecting surface, the harmonics become distinctly audible. If the note is produced partly through the nose, the uneven harmonics perceptibly predominate. The number of upper harmonics in the human voice is very great: and they are, according to Helmholtz, distinct and powerful in their whole range.
Practical use of single Harmonic tones on stringed instruments. Harmonics may be singly produced (1) by varying the point of contact with the bow, or (2) by slightly pressing the string at the nodes, or divisions of its aliquot parts (1⁄2, 1⁄3, 1⁄4, etc.). (1) In the first case, advancing the bow from the usual place where the fundamental note is produced, towards the bridge, the whole scale of harmonics may be produced in succession, on an old and highly resonant instrument. The employment of this means produces the effect called 'sul ponticello.' [See Ponticello.] (2) The production of harmonics by the slight pressure of the finger on the open string is more useful. When produced by pressing slightly on the various nodes of the open strings they are called 'Natural harmonics.' In the following example the lower notes represent the fingering, the upper ones the effect:—
Natural harmonics are occasionally employed pizzicato on the violin and violoncello, and are an important resource in harp music. Accurate violinists are disinclined to use them, because the player has no control over their exact intonation, which is rigidly determined by that of the open string; and the tones of the open strings, which are tuned by perfect fifths, are in certain scales slightly dissonant. In the key of G, for instance, the harmonics of the first or E string are slightly dissonant, though they are perfect in the key of A.
Artificial harmonics are produced by stopping the string with the first or second finger, and thus making an artificial 'nut,' and then slightly pressing the node with the fourth finger. By this means harmonics in perfect intonation can be produced in all scales. Example—
Carnaval de Venise.
For the entire theory of artificial harmonics in single and double scales see 'L'Art de Jouer du Violon de Paganini' by Guhr. They can however only be produced by using thin strings, and are little employed by the best writers. In modern music they are designated by an open note of this form. (See the Andante of Joachim's Concerto, etc.)
Practical use of single harmonic tones on wind instruments. As in the case of stringed instruments, the harmonics of wind instruments naturally reinforce the prime note, but are separable from it by artificial means. In wind instruments this is done by varying the intensity or the direction of the air current from the mouth, which sets in vibration the air-column in the tube, so as to throw the air-column into vibrating portions of different lengths, as in the case of the aliquot parts of a string. The falsetto voice consists of harmonic octaves of the natural voice. All the notes of the flute above the lowest octave are harmonic octaves, twelfths, and double octaves of the lower notes. Like the corresponding harmonics on the oboe and clarinet, these tones are produced by overblowing. Brass instruments are richest in the practical employment of harmonics. Any brass instrument, such as the hunting horn or military bugle, yielding one fundamental note, yields the familiar harmonic scale
Violinists are well aware that the longer the string in proportion to its thickness, the greater the number of upper harmonics it can be made to yield. Similarly, the longer the tube of a brass instrument, the higher does the series of its practicable harmonic tones ascend. The old French horn consists simply of a conical tube of jreat length, which readily yields the scale of larmonic intervals. They are produced by gently varying the degree and direction of the current of air. The dissonant notes (1⁄7, 1⁄11, 1⁄13, 1⁄14) in the scale are to some extent corrected, and some of the missing tones are supplied by introducing the hand into the bell. Mechanical appliances lave been contrived for the same purposes. On,he trumpet the tube is extended for the same purposes by means of a slide. [See Horn, Trumpet, etc.]
[ E. J. P. ]
HARMONIC STOPS are organ stops, the upper pipes of which do not produce the sound that would be expected, having regard to their
HARMONIC INSTITUTION. [See Argyll Rooms.]