HELMHOLTZ

HELMHOLTZ, Hermann - Ludwig - Ferdinand (Hermann von Helmholtz, 1821-94), famous physiologist, physicist, mathematician and psychologist, born in Potsdam. After completing his gymnasium course, H. entered the Medico-Surgical Institute in Berlin, where he was a student of the great Johannes Müller. At the same time, Brücke, Du Bois-Reymond, Ludwig and Virchow worked under Müller. While still at the institute, the 23-year-old H. completed his first scientific research on the structure of the nervous system of invertebrates. This first work allowed Helmholtz to establish the fact that the nervous system is constructed of cells and fibers connected into a single whole. The next exceptional work, which established H.'s position as the greatest of all researchers, was the memoir published in 1848 on the law of conservation of energy, in which H. gave a complete picture of all mechanical and physical transformations based on the principle of conservation of work, living force and energy. This work had outstanding significance not only for physics, which from this moment became the doctrine of energy transformations, but also for physiology, from which this work forever banished the concept of vital force as a special kind of force not subject to the general foundations of natural science. Like every great discovery, this research had its predecessors, among whom Joule, the Petersburg physicist Lenz, and Robert Meyer must be mentioned in particular. But only H. managed to carry the research of the questions he touched to its conclusion and give a complete, coherent picture of energy transformations in mechanical, thermal, electrical and optical phenomena. These works first gave Helmholtz a position as a teacher at the Academy of Arts in Berlin, and then a position as professor of anatomy and physiology in Königsberg. During this time, H. published a series of brilliant works, among which the study of the speed of propagation of excitation along the nerve, determined by his remarkable method which is a model of experimental art, attracted special attention. Furthermore, here he conducted complex research devoted to the question of muscle contraction. This work constitutes an era in the field of graphical methods used in physiology. In Königsberg, Helmholtz succeeded in theoretically elaborating and practically implementing the ophthalmoscope, which allows observation of the interior of the eye in living humans. This research by Helmholtz immortalized his name in the field of ophthalmology. The significance of the ophthalmoscope is sufficiently evidenced by the fact that all modern doctrine of eye diseases and a number of nervous system diseases can be diagnosed only thanks to G.'s mirror. At the same time, H. began to take an interest in questions of physiological acoustics and optics, questions of sensation in general, which later led him to profound research on the foundations of geometry. On the other hand, under the influence of his acoustic works, H.'s brilliant research in the field of hydrodynamics arose.

dsequently, after his work in Königsberg, H. moved to Bonn as professor of physiology, and then to Berlin as professor of physics. In these positions, he continued his research in the field of physiological acoustics and optics, which led to the creation of his theory of hearing and his theory of vision. In his theory of hearing, H. explained the physiological basis of the perception of musical sounds and the perception of speech sounds. In his theory of vision, H. explained the physiological basis of color perception and the perception of spatial forms. H.'s research in the field of physiological acoustics and optics had a great influence on the development of these sciences. H. also made significant contributions to the field of mathematics and physics. He developed the theory of vortex motion and made important contributions to the theory of electricity and magnetism. H. was a member of many scientific academies and received numerous awards and honors for his scientific work. H. died in Berlin in 1894. His scientific work had a great influence on the development of science and technology. H. was one of the greatest scientists of the 19th century.

In 1857, H. moved as a professor of anatomy and physiology to Heidelberg. There he completed his research on vortex movements, which became the most significant contribution to the field of hydrodynamics since the establishment of the hydrodynamic equations by the St. Petersburg academician Euler. The study of jets arising in liquids became his second great research, which was destined to play an enormous role in the history of mechanics. H. generalized the hydrodynamic equations to include the case of friction in liquids and solved a number of problems related to the flow of viscous liquids. H.'s hydrodynamic work culminated in brilliant articles from a later period, devoted to the movement of air over the surface of water and the movement of air layers in relation to each other, in which these memoirs provide a comprehensive study of the movement of the atmosphere over the earth's surface. His professorial activity in Heidelberg was associated with the appearance of the remarkable book 'On the Sensations of Tone,' where H. laid the foundation of modern physical, physiological, and musical acoustics as a coherent, complete whole. H.'s works on acoustics fully exhausted the essence of the topics he addressed, and his doctrine of auditory sensations has to this day appeared in numerous editions without changes, becoming the basis for all future physical and physiological research. - The second most important work of H. is his physiological optics, which is to a large extent connected with his Heidelberg period. In this book, H. developed geometric optics in the form as it is now accepted in ophthalmology; he gave the theory of accommodation of the eye, wrote brilliant chapters devoted to the sense of relief and psychological processes of vision, and developed the doctrine of the sensation of colors. The theory of color perception developed by H., following Young, considers it possible for the perception of all spectral colors and their combinations that the retina's cones contain only three different elements: red-perceiving, green-perceiving, and violet-perceiving. Red, green, and violet colors predominantly stimulate the corresponding elements, their combinations stimulate two and three elements; for example, yellow color stimulates the violet element little, but sufficiently stimulates the red and especially the green element. The mixing of red and green sensations gives the sensation of yellow color. Simultaneous and equally strong stimulation of all three color-perceiving elements gives the sensation of white color. The absence of white color causes the sensation of black color. This theory is called the 'three-component' Young-Helmholtz theory of color perception, and in its full development it is much more complex than described here. Works on the physiology of vision were associated with a huge number of physical works; some of them are first-class works that placed H. among the greatest modern physicists. His works on electrodynamics related to muscle contraction, his works on optics, and the brilliant chapters on theoretical acoustics and resonance should be particularly noted. The doctrine of resonance allowed H. to establish not only the complexity of all sounds arising in surrounding space, not only to decompose them into simplest constituent parts, but also to synthesize complex sounds from the simplest; the production of sounds of the human voice and sounds of complex musical instruments became the culmination of H.'s work in this field. In 1871, H. moved to Berlin as a professor of experimental physics. In addition to the works mentioned above, in his last Berlin period, H. began to ponder the general law connecting our sensations with external stimuli, and clarified the enormous role played by the Weber-Fechner law (see) in these processes. H. gave a number of completed works on the Weber-Fechner law, which subsequently became the basis for the development of an important chapter of physiological optics. To this period should also be attributed a number of mathematical studies related to geometric axioms. These works were begun earlier, and in a series of works, partly physiological, partly mathematical in character, H. developed the physiological theory of perception of space. Further, he expounded the doctrine of anomalous dispersion of light, the doctrine of the principle of least action, the statics of monocyclic systems; these works are a brilliant contribution to the respective departments of physics. In the last years of his life, H. was appointed president of the Physical-Technical State Institution, while at the same time being a professor of theoretical physics. The role of H. is not limited only to what he himself accomplished in the field of physics: his laboratory was always a center that attracted the most outstanding, distinguished researchers of the time, not to mention that the most prominent workers in the field of physiology of the sense organs were students of H. and that a huge number of physicists were his direct collaborators. Thus, in 1872, the famous American scientist Rowland conducted his famous experiment on the magnetic effect of moving electric charges, which proved to be completely identical to the effect of an electric current; this laid the foundation of the electron theory. Further, the development of the concept of the indivisibility of the electric charge, made by H. in his Faraday lecture, makes it necessary to consider him one of the forerunners of the electron theory. In H.'s laboratory, the future Kiev professor Schiller first established the phenomenon of electric oscillations, and H.'s student Hertz experimentally substantiated the electromagnetic theory of light. Russian physics and physiology owe H. an enormous debt. Among H.'s students should be mentioned the physiologist Sechenov, the physicists Stoletov, Michelson, Schiller, Lebedev, and Sokolov. Thus, the role of H. in international science must be recognized as enormous; with H. is connected a large period in the development of modern science, in which his name will remain memorable forever.-From H.'s works accessible to the general public, his 2-volume collection of articles 'Vorträge und Reden' (Braunschweig, 1884; Russian ed.-St. Petersburg, 1898-1899) should be noted; from individual monographs one can mention: 'Die Lehre von den Tonempfindungen als physiologische Grundlage für die Theorie der Musik' (Braunschweig, 1865; Russian ed.-St. Petersburg, 1879); then 'Handbuch der physiologischen Optik' (V. I-III, Hamburg-Leipzig, 1909-10). Finally, H.'s works are collected in a 3-volume edition ('Wissenschaftliche Abhandlungen,' V. I-III, Leipzig, 1881-95), which includes all his works except popular articles and speeches. In Russian translation, recently appeared: 'On the Conservation of Force' (Moscow-Leningrad, 1924) and 'The Speed of Propagation of Nerve Excitation' (Moscow-Leningrad, 1923).