

HELMHOLTZ, HERMANN LUDWIG FERDINAND VON. 



349 





gave proof that no energy is lost in the world, 

 but that it alters only in its mode of manifesta- 

 tion, so that, for instance, chemical affinity can 

 be converted into heat or electricity, this latter 

 into heat or motion of masses, etc. At the same 

 time he showed that all processes of Nature obey 

 the laws of mechanics. Previously to this heat 

 had been looked upon as a substance, but Helm- 

 holtz showed it to be a mode of motion. His 

 writings failed of universal acceptance, and were 

 even rejected in some quarters, but he was ac- 

 quiring a reputation as a growing man. 



In 1848 he returned to Berlin, where he was 

 made an assistant in the Academy of Art and 

 in the Anatomical Museum under Johannes 

 Miiller, under whom also he found as a fellow- 

 student Emil Du Bois-Reymond. This experi- 

 ence was of great value to him, but his stay was 

 short, for in 1849 he was called to succeed Ernst 

 Bruckes in the chair of Physiology and General 

 Pathology in the University of Konigsberg, 

 where he remained until 1855. Here he began 

 the study of problems that involved the applica- 

 tion of delicate physical methods to the investi- 

 gations of the time relations of muscular con- 

 traction and of nervous contraction, and in 1850 

 he determined the duration of muscular con- 

 traction and the rate of transmission of nervous 

 impulses. A year later he gave to the world 

 the ophthalmoscope, an optical instrument by 

 the aid of which it is possible to see exactly and 

 to "recognize in the living eye the retina itself 

 and the images of luminous objects thrown upon 

 it. By this discovery he raised ophthalmic medi- 

 cine to the condition of a scientific study, and 

 made it possible thereafter to save the eyesight 

 of thousands of sufferers. Other items in physio- 

 logical optics were discovered by him, including, 

 in 1853, the application of the ophthalmometer. 

 The words that he hipiself applied to Magnus, 

 his predecessor in Berlin, are equally applicable 

 to himself : " It is work of this kind that, by 

 the classic completeness' of his methods and by 

 the accuracy and reliability of its results, de- 

 serves and obtains the best and most lasting 

 fame." In 1856 he became Professor of Anatomy 

 and Physiology at the University of Bonn, and 

 in 1859 he was called to the chair of Physiology 

 in the University of Heidelberg. 



His individual researches were continued, but 

 of them Clerk Maxwell has said : " We must not 

 dwell on isolated papers, each of which might 

 have been taken for the work of a specialist, 

 though few, if any, specialists could have treated 

 them in so able a manner. We prefer to regard 

 Flelmholtz as the author of two great books on 

 vision and hearing, each of which forms an 

 era in the branch of science to which it relates. 

 The " Text-book of Physiological Optics " (Leip- 

 zig, 1867) was begun in 1856. His original re- 

 searches in this work include every portion of 

 the subject, from the investigation of the limits 

 of human power of perception to that of the de- 

 tails of vision, and the analysis, combination, 

 and appreciation of colors. "This work has be- 

 come, as it were, a Bible to both the physiolo- 

 gist and the ophthalmic surgeon," is the testi- 

 mony of his pupil Hugo Kronecker. "The 

 Doctrine of Tone Sensations as a Physiological 

 Basis of the Theory of Music" (Brunswick, 

 1806) was a notable work. In it were treated 



the true nature of sounds, the relations of fun- 

 damental notes and overtones in the production 

 of vowel sounds, the physical analysis of sounds 

 and reproduction of them by physical means, by 

 methods and processes that laid the foundation 

 of the science of acoustics. 



On the death of Gustav Magnus, in 1871, Helm- 

 holtz was called to succeed that scientist in the 

 chair of Physics in the University of Berlin, and 

 he was thereafter largely occupied in the study 

 of electricity and thermo-dynamics. Among the 

 subjects that he took up were the modern ether 

 theory of electricity and the relations between 

 electric and chemical forces. He showed the 

 remarkable analogy of the vortex motions of 

 water with the electro-magnetic effects of elec- 

 tric currents, and then applied the theory of 

 friction of solid bodies to that of flowing' ex- 

 tremely thin films of fluids, thus creating an 

 analogy between electro-dynamics and hydro- 

 dynamics. The many theories advanced by him 

 have been assimilated in the newer physics of 

 electricity. In 1887 a physical technical institu- 

 tion was founded in Berlin, largely in conse- 

 quence of the gift for that purpose of 500,000 

 marks by Dr. Werner Siemens. Over this in- 

 stitution he was chosen by the Government to 

 preside, and he became 'also director of the 

 purely scientific department or research depart- 

 ment. This new office led to his resignation 

 from the University of Berlin, although he re- 

 tained his place of Professor Ordinarius, and oc- 

 casionally delivered lectures on special subjects 

 of theoretical physics. With this new institu- 

 tion he continued until his death. 



Nor was it alone in connection with rision, 

 color, tone, and electricity that he distinguished 

 himself, for he contributed much to the advance- 

 ment of meteorology, and his researches on tides 

 and waves are famous. His ability to present 

 to the public in intelligible language the results 

 of his researches even the most abstruse con- 

 tributed largely to his fame, and for almost half 

 a century he ranked high in Germany as a popu- 

 lar lecturer, having a reputation similar to that 

 of Tyndall in English-speaking countries. His 

 .lectures were collected and published, forming 

 two series (1865 and 1871), and were translated 

 into English and published in 1873 with a pref- 

 ace by John Tyndall. In 1870 the French Acad- 

 emy made him a foreign member, and when 

 objection was made, owing to his nationality, 

 criticism was silenced by the declaration pub- 

 licly uttered: "You will place yourselves in the 

 worst light before the world if for any reason 

 you refuse to admit Helmholtz, the foremost 

 and greatest naturalist of the age. Nothing is 

 wanting to his glory, but he is wanting to ours." 

 The Copley medal of the Royal Society of Lon- 

 don was given him in 1873, and in 1883 the 

 German Emperor conferred upon him and his 

 family the honor of hereditary nobility. The 

 event of his seventieth birthday, in 1891, was 

 made the occasion of an international celebra- 

 tion, when the principal rulers of Europe and 

 the scientific institutions of the world vied in 

 conferring honors upon him. A gold medal 

 was struck in his honor in Berlin, which has 

 since been annually awarded to the most worthy 

 of his colaborers. Societies of science and learn- 

 ing, including the National Academy of Sciences 



