o96 BARON VON HELMHOLTZ. 



Medical Coagress at Washington, and making a trip to the Chicago 

 P^xposition and the Western States. Coming afterwards to Boston 

 and to Harvard College, they were greatly pleased with their visit. 

 In paying a visit of respect to them, I remarked, " Professor, we 

 know a hundred fold as much in opthalmology as before you gave us 

 the ophthalmoscope." With a deprecating smile and gesture, he 

 replied, " I was not even a Doctor of Medicine ! I was only Pro- 

 fessor of Physics at the University ! but I set myself this problem, 

 'To illuminate if I could the interior of the eye,' — and I succeeded ! " 

 Alas! but a few mouths have passed since the eclipse of that great 

 liofht which had done so much for those who sit in darkness, for 

 science, and for the world. As the creator of modern opthalmology, 

 substituting by means of the opthalmoscope certainty for surmise, 

 Helmholtz has bestowed an incalculable benefit upon mankind. 

 1895. H. W. Williams. 



At the request of the late Dr. Williams the following account of 

 the original work of Helmholtz was prepared to be added to the bio- 

 graphical notice. 



The work of Helmholtz as an investigator seems to have begun 

 while he was studying at Berlin in preparation for the profession of mili- 

 tary surgeon, and his first scientific paper was his Proraotionsschrift, 

 " De Fabrica Systematis Nervosi Evertebratorum," published in 1842. 

 Helmholtz's knowledge of mathematics, afterwards so profound, ap- 

 pears to have been at this time comparatively slight. His attention 

 was chiefly devoted to physiology, though he was especially interested 

 in physics for its own sake, as well as for the reason that accurate 

 physiological measurements could be made only by persons who were 

 able to devise and to use intelligently physical apparatus. 



During most of the interval between 1842, when he became MilitJir 

 ArtZ; and 1847, when, through the kind intercession of Alexander 

 von Humboldt, he was honorably discharged from the army, Helm- 

 holtz was stationed in his native town of Potsdam, and there, besides 

 carrying on his researches in physiology, some of the results * of 

 which he published, he studied mathematics and physics, with the 

 help of books borrowed from the library of the Gymnasium, to such 



* " Ueber das "Wesen der Faulniss und Gahrung," 1843. " Ueber den StoflT- 

 verbrauch bei der Muskclaction," 1845. " ]^ie Physiolog^ische Warme," 1845. 

 " B^icht iiber die Tlieorieder Physiolojjischen Warmecrsclieinungen furl845." 

 ■" Ueber die Warmeentwickelung bei der Muskelaction," 1847. 



