184 SPECIAL SENSES. 



the greater intensity of the fundamental, that they cannot be 

 easily distinguished by the unaided ear, unless the fundamen- 

 tal be quenched in some such way as we have indicated. In 

 the same way, the harmonic 5ths and 3ds overpower other 

 overtones ; for we have the string subdividing again and 

 again into overtones, which are not harmonious like the notes 

 of the common chord of the fundamental. 



The presence of overtones, resultant tones, and additional 

 tones, which latter will be described hereafter, can be demon- 

 strated, without damping the strings, by the resonators, in- 

 vented by Helmholtz. It is well known that, if a glass tube, 

 closed at one end, which contains a column of air of a certain 

 length, be brought near a resounding body sounding a note 

 identical with that produced by the vibrations of the column 

 of air, the air in the tube will resound in consonance with the 

 note. If, for example, we have a tube sounding C, a tuning- 

 fork of the same tone sounded near the tube will throw 

 the air in the tube into action, and will produce a powerful 

 sound, while no other note will have this effect. The reso- 

 nators of Helmholtz are constructed on this principle. A 

 glass globe or tube (Fig. 14) is constructed so as to produce a 

 certain tone. This has a larger opening, a, and a smaller 

 opening, b, which latter is fitted in the ear by warm sealing- 

 wax, the other ear being closed. When the proper note is 

 sounded, it is reenforced by the resonator and is greatly in- 

 creased in intensity, while all other notes are heard very 

 faintly. Suppose, now, that we apply this to the detection 

 of overtones ! We fix in the ear a resonator adjusted to G, 

 and sound the fundamental, C. The fundamental, C, is im- 

 perfectly heard, but the overtone, G, is reenforced, and we 

 have a loud and distinct sound of the 5th. By using resona- 

 tors graduated to the musical scale, we can easily analyze a 

 tone and distinguish the overtones. In the same way, if we 

 fix in the ear a resonator tuned to a particular note and strike 

 a succession of chords on the piano, the general sound is im- 

 perfectly heard; but, whenever we strike the note of the 



