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most delicate, and showed how sound was produced. He 

 averred that each note was not a single tone, as it appears 

 to be, but a composite of several, including the funda- 

 mental, or loudest, with the addition of overtones and 

 undertones ; there was no such thing as a tone pure and 

 simple. He explained the pitch, the quality, timbre, 

 and resonance of tones, and showed how they were pro- 

 duced. He showed that, as ripples are produced in the 

 water, so wave ripples are produced in the air by differ- 

 ent sounds, each sound causing a combination of wave- 

 lets, the curves of which can be made visible to the eye 

 and many of which are of exceeding beauty. These 

 were exhibited to the audience by means of a gas jet, 

 whose vibrations were reflected in a mirror, through an 

 ingeniously contrived apparatus, the manometric capsule 

 invented by Scott and Koenig. He explained how the 

 notes of diflerent musical instruments operated in the 

 vibrations of the air, and what caused the differences in 

 the sounds. In short, he gave a most attractive and in- 

 structive exposition of the mysteries of speech as it aft'ects 

 the air, the vocal organs, and the ear, and was listened to 

 with the most absorbed attention. 



After some complimentary remarks from Mr. W. P. 

 IJpHAM and the presiding officer, the thanks of the audi- 

 ence were unanimously voted to Prof. Bell for his able 

 and excellent lecture. 



