28o HERMANN VON HELMHOLTZ 



who called himself a born physicist, at length obtained a position 

 suited to his specific talents and inclinations, since he had, as 

 he wrote to me, become indifferent to physiology, and was 

 only really interested in mathematical physics/ 



His son Richard, who knew that his father would be gratified 

 if he presented himself at the theatre of war ('an ardent 

 patriotism was ever one of my father's salient characteristics '), 

 had though barely seventeen enlisted as a volunteer in the 

 mounted division of the Baden Field Artillery in August 1870, 

 and was sent to the front in November, where, besides several 

 small skirmishes, he took part in the three days' fight on the 

 Lisaine, and was wounded by a mishap with his gun, though 

 not severely. 



In the last weeks of his stay at Heidelberg, Helmholtz took 

 leave of the cultured audience who had so often listened with 

 delight and admiration to his brilliant Popular Lectures, in a 

 discourse ' On the Origin of the Planetary System J . The 

 rostrum of the over-flowing hall was decked with laurels, 

 a wreath lay upon it, and the whole audience rose as he 

 entered. With astonishing lucidity, and in his consummate 

 style, he discussed the Kant-Laplace hypothesis from the 

 mechanical and physical sides, and the subtle considerations by 

 which W. Thomson had proved that the density of the ether 

 may conceivably be far less than that of air in the vacuum of 

 a good air-pump, but that its mass is not absolutely nil, and 

 that a volume of luminiferous ether equal to the volume of the 

 earth cannot weigh less than 2,775 pounds. 



'The basis of this calculation would no doubt be removed 

 if Clerk Maxwell's hypothesis should be confirmed, according 

 to which light depends on electric or magnetic oscillations/ 



On March 5, 1871, the Faculties and many of the educated 

 inhabitants of Heidelberg combined to give a banquet at the 

 Harmonic in honour of Helmholtz. The words spoken by 

 him and others can never be forgotten by those who were 

 present, but all were possessed by the feeling that the greatest 

 thinker and man of science in Germany belonged of rights to 

 the place where the Founder of the German Empire was 

 supported by the grandest Statesman and the most gifted 

 General. 



