402 LECTURE XXXIV. 



Of Simple Avlnd instruments, in which the quality of the sound is deter- 

 mined by the vibrations of the air, the principal are the syrinx, the flute, 

 the flageolet, the diapason organ pipe, whether open, stopped, or with a 

 chimney, the humming top, and the cavity of the mouth in whistling, or in 

 playing on the Jew's harp. The pipes of the syrinx are adjusted to their 

 respective notes by cutting them, or filling them up, until they are reduced to 

 a proper length; and the efl^ective length of the flute and flageolet is altered 

 . at pleasure by opening or shutting the holes made at proper distances in them ; 

 the opening a hole at any part having the same effect as if the pipe were cut 

 off a little beyond it, and the elevation of the tonebeing somewhat greater as 

 the hole is larger. The instruments differ little except in the mechanism, by 

 which the breath is directed, in such a manner as to excite a sound; and 

 the flageolet, when furnished with bellows, becomes a bagpipe. The tongue 

 of the Jew's harp is an elastic plate, but the sound, which it immediately 

 produces, serves only as a drone; its vibration, however, appears to act like 

 the motion of the bow of a violin in exciting another sound : this sound, 

 although faint, is still sufficiently musical, and appears to be determined by 

 the magnitude of the cavity of the mouth, nearly in the same manner as that 

 of the humming top, or as the sound of the same cavity produced in whist- 

 ling, by a current of air which is forced through it. (Plate XXVI. Fig. 

 563 . . 367.) 



In mixed wind instruments, the vibrations or alternations of solid bodies 

 are made to cooperate with the vibrations of a given portion of air. Thus, 

 in the trumpet, and in bonis of various kinds, the force of inflation, and 

 perhaps the degree of tension of the lips, determines the number of parts 

 into which the tube is divided, and the harmonic which is produced. In the 

 serpent, the lips cooperate with a tube, of which the effective length may 

 be varied by opening or shutting holes, and the instrument which has been 

 called an organized trumpet appears to act in a similar manner; the trom- 

 bone has a tube which slides in and out at pleasure, and changes the actual 

 length of the whole instrument. Tlie hautboy, and clarinet have mouth 

 pieces of different forms, made of reeds or canes, and the reed pipes of an 

 organ, of various constructions, are furnished with an elastic plate of metal, 

 which vibrates in unison with the column of air that they contain. An 

 organ generally consists of a number of different series of such pipes, so 



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