302 OF THE VOICE AND SPEECH. 



t 



shortening the strings.* But it does not follow that a short string, which, 

 with moderate tension, naturally produces a high note, should be able, by a 

 diminution of the tension, to give out a deep one ; for, although this might be 

 theoretically possible, yet it cannot be accomplished in practice ; since the 

 vibrations become irregular on account of the diminished elasticity .t These 

 considerations are in themselves sufficient to destroy the supposed analogy; 

 and to prove that the Chordse Vocales cannot be reduced to the same category 

 with vibrating strings. 



406. The next kind of instrument, with which some analogy might be sus- 

 pected, is the Flute-pipe, in which the sound is produced by the vibration of 

 an elastic column of air contained in the tube ; and the pitch of the note is 

 determined almost entirely by the length of the column, although slightly 

 modified by its diameter, and by the nature of the embouchure or mouth from 

 which it issues. This is exemplified in the German Flute, and in the English 

 Flute or Flageolet ; in both of which instruments, the acting length of the 

 pipe is determined, by the interval between the embouchure and the nearest 

 of the side apertures ; by opening or closing which, therefore, a modification 

 of the tone is produced. In the Organ, of which the greater number of pipes 

 are constructed upon this plan, there is a distinct pipe for every note ; and 

 their length increases in a regular scale. It is, in fact, with flute-pipes as 

 with strings, that a diminution in length causes an increase in the number 

 of vibrations, in an inverse proportion ; so that of two pipes, one half being 

 the length of the other, the shorter will give a tone which is the octave above 

 the other, the vibrations of its column of- air being twice as rapid. Now there 

 is nothing in the form or dimensions of the column of air between the larynx 

 and the mouth, which can be conceived to render it at all capable of such 

 vibrations as are required to produce the tones of the Human voice ; though 

 there is some doubt whether it is not the agent in the musical tones of some 

 Birds. The length of an open pipe necessary to give the lowest G of the 

 ordinary bass voice, is nearly six feet; and the conditions necessary to produce 

 the higher notes from it, are by no means those which we find to exist in the 

 process of modulating the human voice. 



407. We now come to the third class of instruments, in which sound is pro- 

 duced by the vibration of Reeds or Tongues ; these may either possess elasticity 

 in themselves, or be made by elastic tension. The reeds of the Mouth-^Eoli- 

 na, Accordion, Seraphine, &c., are examples of instruments of this character, 

 in which the lamina vibrates freely in a sort of frame that allows the air to pass 

 out on all sides of it through a narrow channel, thus increasing the strength 

 of the blast ; whilst in the Hautboy, Bassoon, &c., and in Organ-pipes of similar 

 construction, the reed is attached to one end of a pipe. In the former kind, 

 the sound is produced by the vibration of the tongue alone, and is regulated 

 entirely by its length and elasticity; whilst in the latter, its pitch is dependent 

 upon this conjointly with the length of the tube, the column of air contained 

 in which is thrown into simultaneous vibration. Some interesting researches 

 on the effect produced on the pitch of a sound given by a reed, through the 

 union of it with a tube, have been made by M. W. Weber; and, as they are 

 important in furnishing data, by which the real nature of the vocal organ 



* Thus in the Piano-forte, where there are strings for each note, a gradual shortening 

 is seen from the lowest to the highest; and in the Violin the change of tone is produced 

 by stopping the strings with the finger, so as to diminish their acting length. 



f Thus it would be impossible to produce good Bass notes on the strings of a Violin, 

 by diminishing their tension ; the length afforded by the Violoncello or Double Bass is 

 requisite. The striking difference between the tone of the Bass strings in the Grand 

 Piano-forte and the small upright Piccolo, is another exemplification of the same princi- 

 ple ; being chiefly due to the length and tension of the former, as contrasted with the 

 shortness and slackness of the latter. 



