314 LECTURE XXXIV. \ ^ 



mediately with hammers, or by means of keys ; the tuning>^the 

 the cymbal, and the bell. Bells and other similar instruments are usually 

 made of a mixture of copper and tin, with a little brass or zinc, which is 

 more highly elastic than either of the component parts taken separately. 

 The harmonica consists of a series of vessels of glass, either placed side by 

 side, or fixed on a common axis, and made to sound by the friction of the 

 fingers, and sometimes by that of rubbers of cork. The vibrations of an 

 elastic plate, agitated by a current of air, which it continually admits and 

 excludes, constitute the sound of the vox humana and regal organ pipes, 

 resembling the human voice as much in their effects as in the mechanism 

 on which they depend. (Plate XXVI. Fig. 360... 362.) 



Of simple wind 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 effective length of the flute and flageolet is 

 altered at pleasure by opening or shutting the holes made at proper dis- 

 tances 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 tone being 

 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, how- 

 ever, 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 whistling, by a current of air which is forced 

 through it. (Plate XXVI. Fig. 363... 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 horns 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. The 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, se, 

 arranged, that by means of registers the air proceeding from the bellows 

 may be admitted to supply each series, or excluded from it, at pleasure, and 



