CHAPTER XI 



HELMHOLTZ IN BONN AND HEIDELBERG 



SENSATIONS OF TONE 



HELMHOLTZ was appointed to be Professor 

 of Physiology at Bonn in 1856, when he was 

 thirty-five years of age, and near the zenith of his 

 powers. Here he remained till 1859, wnen he was 

 invited to the chair in Heidelberg, a position he filled 

 till 1871. The three years at Bonn were charac- 

 terised by the same intellectual activity. Having in 

 Konigsberg laid the foundation of his great work on 

 physiological optics, he next proceeded to the ex- 

 amination of the sense of hearing, and here he 

 conquered a new world, and made it peculiarly 

 his own. Again, the guiding principle was Johannes 

 Miiller's doctrine of specific energy, and again he 

 proceeded step by step to survey the whole region 

 of inquiry on this occasion it was acoustics from 

 the point of view of the physiologist, but fully 

 equipped, not only with anatomical knowledge, but 

 with all the methods and modes of reasoning of the 

 mathematician and physicist. 



