PROFESSOR AT HEIDELBERG 253 



of working on upon my old lines. To this end, however, 

 I should have, in addition to experimental physics, which is the 

 popular subject for lectures, to undertake at least the teaching 

 of mathematical physics and the direction of the practical work. 

 Lectures in pure mathematics I could not well undertake ; in 

 those on mathematical physics I should treat mathematics as 

 the means and not as the end. Wherever possible I should 

 include the physiology of the eye and ear, but would undertake 

 no obligations in this particular/ 



Beseler urged the nomination of Helmholtz in pressing 

 terms upon the Minister von Muhler. 



But notwithstanding these negotiations the correspondence 

 did not lead to the desired result, because the Prussian 

 Government could not proceed with the liberality of the Baden 

 Ministry. On Jan. 2, 1869, Jolly addressed a very courteous 

 communication to Helmholtz : 



' I now hope for a certainty that we shall succeed in re- 

 taining you for beautiful Heidelberg. Willingly as we would 

 otherwise follow the Prussian lead, it is in this case our 

 bounden duty to declare war to the knife on the Berlin 

 Cabinet, and I must add that it would be personally a matter 

 of great pain to me, whose intellectual life is rooted in 

 Heidelberg, if while I am at the head of affairs I had to see 

 it robbed of its chief ornament.' 



The satisfaction of all his very modest demands by the 

 Baden Government, and the wishes and inclination of his 

 family, decided Helmholtz on staying in Heidelberg. In the 

 midst of the negotiations his son Friedrich Julius was born, 

 on October 15, 1868. 



' From his birth/ writes Frau v. Schmidt-Zabierow, ' he was 

 a weakly child, who was only kept alive by unremitting care 

 and attention, and whose mental as well as bodily development 

 was a source of incessant anxiety to his parents. It required 

 exceptional courage on the part of my sister not to give way 

 to the double grief of the illness of her two sons, and to avert 

 any gloomy consequences to her husband's life/ 



At this period the enormous output of Helmholtz's work 

 assumed a distinct tendency towards the most arduous 

 problems of physics, mathematics, and philosophy. 



His researches in acoustics had led him directly back to his 



