HELMHOLTZ IN BONN 



forms and with variously-shaped apertures. He investi- 

 gated the special mode of action of many musical instru- 

 ments, and in particular, divided those having tongues 

 into inbeating and outbeating. In the first case the 

 passage is opened when the tongue moves inwards, 

 that is against the wind, as happens in the clarinette. 

 Lip instruments, such as the trombone, belong to the 

 second class, the passage being open when the lips are 

 moved outwards or with wind. 1 It may be said that 

 the whole theory of the mode of action of tongue 

 pipes is due to Helmholtz. He also gave a formula 

 for the velocity of sound in narrow tubes. 



When Helmholtz first heard of the telephone, he 

 remarked to Du Bois Reymond : c The invention 

 seems so self evident, that I do not consider it necessary 

 to advance a theory. Of course, I have for years gone 

 to bed with Fourier's theorem in my head, and I have 

 got up with it still there, so I must not judge others 

 by myself.' His friend observes, that possibly it was 

 on one of these nights that he was obliged to get up 

 and lull his intellect by playing Bach's fugues on a 

 magnificent grand piano presented to him by Messrs 

 Steinway of New York in recognition of his services 

 to music. On another occasion, he was interested 

 and amused by the delightful experiment of causing a 

 highly-trained vocalist to sing the vowels with the 

 dampers off the strings, when of course they were 

 returned little changed in quality. From the time 



1 Rayleigh, op. cit., vol. ii., p. 234. 

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