SCIENTIFIC LITERATURE. 



187 



Ferdinand von TTelniholtz was the son 

 of a gjnnnasiuni teacher, his mother, 

 Caroline Penne, being a descendant of 

 William Penn. He was born at Pots- 

 dam on August 31, 1821, and died in 

 Berlin on September 8, 1894. After a 

 childhood of ill health, he studied medi- 

 cine and was for four years a military 

 surgeon; for a year he was teacher in 

 the Berlin Academy of Fine Arts, and 

 afterwards professor of physiology at 

 Konigsberg from 1849 to 1855. He 

 was professor at Bonn for three years 

 and was then professor of physiology 

 at Heidelberg from 1858 to 1871, when 

 he was transferred to Berlin as pro- 

 fessor of physics. In 1888 he was 

 made president of the Reichsanstalt, 

 organized under his direction. All 

 possible academic and imperial honors 

 were of course conferred on him. 



Helmholtz married Olga von Velten 

 in 1849. She died after ten years, and 

 in 1861 he married Anna von Muhl, who 

 died in 1899. One of his sons died in 

 1889, the other in 1901. His surviving 

 daughter is the wife of Wilhelm von 



Sienians. Holmholtz traveled more than 

 is the usual habit of the German pro- 

 fessor. His visit to America in 1893 

 will be remembered by many. He seems 

 to have had misgivings in regard to a 

 civilization which has electric lights, 

 while the elements of the art of cook- 

 ery are ' ausserst Stiimperhaft,' and 

 bandits and reporters go at large. 



A list of Helmholtz's contributions 

 to science would fill many pages. The 

 essay on the conservation of energy 

 was printed in 1847. Researches of 

 great range and importance, including 

 the invention of the ophthalmoscope, 

 led to his two epoch-making books on 

 physiological psychology — ' Tonempfind- 

 ungen ' (1862) and ' Physiologische 

 Optik' (1867). Helmholtz always con- 

 tinued his work in physiological psy- 

 chology, but his transfer from a chair 

 of physiology to one of physics repre- 

 sented a change in his main interests. 

 His great contributions to mathe- 

 matical physics, especially electrody- 

 namics, are of almost unparalleled im- 

 portance. 



