FROM THE HISTORY OF PHYSICS

ALEXANDER LVOVICH GERSHUN

(On the Thirty-Fifth Anniversary of His Death)

N. I. Ivanov

In 1950 thirty-five years had passed since the death of one of the greatest physicists of prerevolutionary Russia of the late nineteenth and early twentieth centuries, Professor Alexander Lvovich Gershun.

The name of Alexander Lvovich Gershun, despite his great services to Russian physics and especially to Russian optotechnology and the optical industry, is not sufficiently well known to Soviet readers, apart from physicists of the older generation. This article is an attempt briefly to outline the life and scientific activity of Prof. A. L. Gershun. It does not claim to cover in full the many-sided activity of this major scientist*).

§ 1. THE LIFE AND PEDAGOGICAL ACTIVITY OF A. L. GERSHUN

Alexander Lvovich Gershun was born on October 17, 1868, in the town of Sokolka, Grodno Province, into the democratic and hardworking family of a provincial physician.

His parents gave Alexander Lvovich a good working upbringing and education. Already as a youth he was distinguished by giftedness and great erudition; he knew ancient languages and several modern foreign languages well.

In 1886 A. L. Gershun graduated from the gymnasium in the city of Vilna (Vilnius) and entered the Faculty of Physics and Mathematics of Petersburg University. The source of his livelihood was the money he earned by tutoring. At the university

*) I take this opportunity to express my deep gratitude to Prof. K. K. Baumgart for valuable suggestions and advice, and to Prof. A. A. Gershun, twice laureate of the Stalin Prize, for providing archival materials from his home library.

ALEXANDER LVOVICH
GERSHUN

[[unclear: no legible text is visible on this page image]]

ALEKSANDR IAKOVLEVICH
GERSHUN

he was especially attracted to practical work and demonstrations in physics, and while still a student began to assist Prof. I. I. Borgman.

After graduating from the university in 1890 with a first-degree diploma, A. L. Gershun was retained at the Faculty of Physics and Mathematics to prepare for a professorship.

During the first twelve years after graduating from the university, A. L. Gershun worked as a laboratory assistant* and assisted Professors O. D. Khvolson and I. I. Borgman at the university, at the Higher Women’s Courses, and at the Electrotechnical Institute. A. L. Gershun combined teaching in higher education, as was then customary, with teaching in secondary school.

In 1902, on the recommendation of his teacher and friend Prof. O. D. Khvolson, A. L. Gershun was invited to head the Department of Physics in the Artillery Officers’ Class in Kronstadt and was confirmed in the academic rank of professor. Aleksandr Lvovich did not confine himself to the compulsory lectures for officers, but delivered many popular-science lectures on new questions of physics and technology.

In 1908 A. L. Gershun moved from Kronstadt to Petersburg in connection with his transfer to the Obukhov Works, where the production of optical instruments was being established. At the same time A. L. Gershun assumed the leadership of the Department of Physics at the Petersburg Women’s Pedagogical Institute (on the basis of this higher school, after the October Socialist Revolution of 1917, the Herzen Pedagogical Institute was created), where he brilliantly organized the teaching of experimental and theoretical physics, accompanying his lectures with original demonstration experiments and acquainting the audience with the latest news of science and technology. Prof. A. L. Gershun’s lectures were engaging and were distinguished by clarity of exposition.

The lithographed editions of A. L. Gershun’s lectures on thermodynamics, theoretical optics, electrodynamics, electricity and magnetism, and geometrical optics, despite having been written in the 1910–1911 and 1911–1912 academic years, are of interest even to the contemporary teacher of physics in higher education.

The physics textbook by Kraevich, published under the editorship and in the revision of A. L. Gershun, was used for instruction in secondary schools of pre-revolutionary Russia. A. L. Gershun wrote substantial chapters in O. D. Khvolson’s Course of Physics.

In his lectures Prof. A. L. Gershun paid special attention to the works of Russian scientists, emphasizing the independent path of development of Russian science and the originality of the scientific creativity of his compatriots. A. L. Gershun devoted much time at the institute—

* In present-day terminology—an assistant.

...the equipment of the student laboratory, especially the organization of work in optics.

A. L. Gershun organized visits by the female students to the optical workshop of the Obukhov Plant. In doing so, Alexander Lvovich acquainted the students in detail not only with the instruments themselves, but also with the technological process of their manufacture. In this form of instruction one may discern the beginnings of industrial practice, which was legalized in higher educational institutions after the Great October Revolution of 1917 as an obligatory part of the students’ curriculum.

Alexander Lvovich Gershun did not cease his pedagogical activity until the last days of his life. He died at the age of 47 on May 26, 1915.

Among A. L. Gershun’s friends were the Russian physicists V. K. Lebedinsky, V. F. Mitkevich, M. A. Shatelen, and, from the older generation, N. G. Egorov, O. D. Khvolson, and F. F. Petrushevsky.

§ 2. ORGANIZATIONAL ACTIVITY OF A. L. GERSHUN

A. L. Gershun’s organizational talent manifested itself already in his student years; thus, at the end of 1889 he took an active part in the eighth congress of Russian naturalists and physicians as a student steward. He served as clerk) of the Physical Society, as secretary of the editorial board of the journal Electricity*, and participated in distant astronomical expeditions.

While working as a laboratory assistant at the university, A. L. Gershun did much work in setting up new experiments in the physics practicum. He also carried out several large scientific installations at the institute (in particular, for obtaining liquid air and producing X-rays). But his organizational activity truly developed during the Kronstadt period of his life. In Kronstadt he organized a station for calibrating rangefinders in service with the navy. At about the same time, his printed works, addresses, and communications on various questions of physics and technology at meetings of scientific societies made the name of A. L. Gershun well known to Russian scholars and engineers. He became the recognized leader of Russian optotechnics.

In 1907 A. L. Gershun was invited as a consultant to the Obukhov Plant as the foremost specialist capable of placing the production of optical instruments in Russia on an independent scientific basis. In 1909 Alexander Lvovich was appointed head of the plant’s optical workshop. Above all, he sought—

*) In modern terminology—a scientific secretary.

It was necessary to obtain from the plant management the allocation of the required premises for an optical workshop and, in general, the expansion of its production capacity.

A. L. Gershun, having begun work in the workshop with foreign specialists, resolutely and persistently recruited Russian workers and craftsmen and trained specialists from among them. At the time of his departure from the Obukhov Plant, 94% of the workshop’s employees were Russian. A. L. Gershun’s teacher, Prof. O. D. Khvolson, and the continuer of his work, Academician D. S. Rozhdestvenskii, wrote in 1925: “Thus, he created the first optical workshop in Russia, laying a solid foundation for the development in our country of one of the most important branches of technology for the state… No matter how this work may expand in the future, no matter how much more independent it may make us from foreign production, the name of the founder of Russian optical technology, A. L. Gershun, will forever remain associated with it.”

By the time Aleksandr L’vovich came to the Obukhov Plant, there was no serial production in Russia of optical instruments of military significance. Under the direction of Prof. A. L. Gershun, the optical workshop of the Obukhov Plant very quickly mastered the mass production of the following optical instruments for the needs of the navy and the army: optical sights of various systems; binoculars of various magnifications; panoramas; micrometers; telescopes of three-, eight-, tenfold and variable magnification and periscopes for submarines; stereoscopic telescopes of tenfold magnification, small and large.

In their characteristics, these instruments not only were not inferior to the instruments of foreign firms, but in some respects were superior to them (greater aperture and field of view). Domestic instruments were, moreover, cheaper than foreign ones, so that A. L. Gershun’s activity not only, to a certain extent, freed Russia from foreign dependence in obtaining military optical instruments, but also brought the state savings amounting to many millions.

In the production of the above-mentioned optical instruments, A. L. Gershun had to overcome, in addition to strong competition from foreign firms, the view—held both by tsarist officials and even by some scientists—that it was almost impossible to produce optical instruments in Russia on a mass scale, and moreover instruments of domestic, Russian, invention.

In 1912, Prof. A. L. Gershun assumed leadership of the Russian Society of Optical and Mechanical Industries, and in 1914, under his direct direction, a plant was built in Petersburg specifically intended for the manufacture of optical-mechanical instruments of military significance.

Assessing A. L. Gershun’s services to his homeland, Corresponding Member of the Academy of Sciences of the USSR T. P. Kravets wrote in 1948: “A. L. Gershun’s principal service is his leading participation in the creation of a domestic production of opto-mechanical instruments (binoculars, panoramas, stereotubes, etc.). At that time most even technically advanced countries of the world had no optical industry of their own, and in fact the monopoly in this especially complex production belonged to Germany. A. L. Gershun established production under the difficult conditions of struggle with serious and dangerous rivals in the form of foreign firms (Zeiss, Goerz), in the absence of proper support from the tsarist government and private entrepreneurs.”

§ 3. SCIENTIFIC WORKS AND INVENTIONS OF A. L. GERSHUN

Through his inventions in the field of optical instruments for military purposes (for example, the invention of the collimating sight) and his investigations in instrumental optics, Aleksandr L’vovich Gershun did much that was useful for the optical-instrument industry in our country.

A. L. Gershun’s activity in the optical industry was organically connected with his research work in geometrical optics. He embodied his ideas in this field of science in concrete optical instruments. By establishing optical production, A. L. Gershun thereby made it possible to carry out and introduce research in instrumental optics.

Prof. A. L. Gershun was not a narrow specialist in optical instrument making, but was a broadly educated scholar with a wide range of activity in the fields of science and technology. While still young he wrote the work “On Optical Instruments,” in which he expounded with utmost clarity the fundamental laws of geometrical optics as applied to instrument making. A. L. Gershun saw success in the improvement and development of optical instruments in the application of the laws of wave optics to optical engineering. He considered the very foundation of geometrical optics, proceeding from the idea of the ray as an independent individual, to be defective and not corresponding to the contemporary level of optical instrument making.

A. L. Gershun’s posthumous article “Contemporary Optical Engineering,” published in the journal of the Russian Physico-Chemical Society in 1916 (vol. 48, phys. section, issue 6), deserves to be reprinted. In his work “The Method of Töpfer Bands and Its Application,” A. L. Gershun for the first time gave a simple photographic method for determining inhomogeneities in lenses.

Beginning in 1902, A. L. Gershun was chief consultant on the question of optical glass and head of production for the pro-

A. L. GERSHUN

guided by experience in the melting of optical glass in pre-revolutionary Russia. A. L. Gershun strove to revive the work so gloriously begun by M. V. Lomonosov.

By 1914, individual experimental meltings of optical glass had been carried out in Russia. The glasses of all grades, beginning with the very first, in refractive index and dispersion corresponded to the respective types of foreign glasses then used by Russian industry. The glass was comparatively homogeneous, and the internal stresses did not greatly exceed the permissible limits of that time.

At a meeting of the astronomical section of the Russian Society of Lovers of World Studies on November 4, 1914, A. L. Gershun delivered a report on the results of the first melting of optical glass in Russia at the Imperial Glass Factory. He considered the melting of the glass—ordinary flint glass—quite successful, although in the work, which had been regarded merely as a trial, some departures from the generally accepted rules had been allowed.

Thus, the initiative for melting optical glass in Russia belongs to A. L. Gershun. The absence of proper support from the tsarist government made the solution of this task beyond the power of a lone scientist. This task was fully solved only in Soviet times under the direction of D. S. Rozhdestvensky, I. V. Grebenshchikov, A. A. Lebedev, and I. N. Kachalov, who at that time was the technical director of the factory.

Let us mention some other optical works of A. L. Gershun. One of his first works was devoted to investigating the question of whether the structure of crystals, which determines circular polarization, changes when the crystals are ground. Determining the molecular rotatory power of sodium chlorate powder suspended in a liquid, with grain size of several microns, A. L. Gershun showed “that grains of sodium chlorate at such small sizes still possess the structure that determines circular polarization.”

The next work of A. L. Gershun was devoted to the mathematical analysis of phenomena that may occur when quartz lenses are used, owing to the rotation of the plane of polarization of light as it passes through the lens. This question is very important, for example, in investigations in the ultraviolet region of the spectrum in polarized light. The results of this work, soon after its publication, received experimental confirmation in the studies of the well-known physicist R. W. Wood.

The results of A. L. Gershun’s calculations of the coefficients of reflection from dielectrics by Fresnel’s formula were published in O. D. Khvolson’s Course of Physics, and they are still cited today in many optics textbooks both in our country and abroad.

A. L. Gershun was the first to undertake the experimental observation of the Kerr phenomenon in gases, although he did not obtain the required result owing to the insufficiency of the experimental technique available at that time.

A. L. Gershun was the author of many printed works of a non-optical character. In the paper “Certain Properties of Rectified Alternating Current,” published in 1901 in the journal Electricity, A. L. Gershun for the first time gave a mathematical theory of pulsating (rectified alternating) current in a circuit with capacitance and self-induction.

In the paper “On the Electrical Effects of Röntgen Rays,” carried out by A. L. Gershun jointly with I. I. Borgman, new facts for that time were established concerning the ionizing action of radiation and the laws of its reflection.

While still a laboratory assistant at Petersburg University, A. L. Gershun carried out a study of thermionic emission.

A very interesting work by A. L. Gershun is “On One Method for Determining the Mean Density of the Earth and the Gravitational Constant.”

A. L. Gershun wrote a number of major articles on physics, electrical engineering, and optical technology in the Brockhaus and Efron Encyclopedic Dictionary.

§ 4. CHARACTERISTIC FEATURES OF THE SCIENTIFIC WORK OF A. L. GERSHUN

A. L. Gershun was a representative of the materialist trend in Russian physics of his time. He regarded matter and its motion as the only real things. Aleksandr Lvovich spoke out against Ostwald’s energetic school, which attempted to dispense with one of the fundamental concepts of physics—energy. A. L. Gershun considered matter to exist objectively and the processes of nature not to depend on human consciousness.

The cornerstone of the materialist view of nature is formed by the laws of conservation of matter and energy—the laws of the eternity of matter and the indestructibility of its motion. Aleksandr Lvovich, as a consistent materialist, regarded the principle of conservation of energy, whose herald had been M. V. Lomonosov, as one of the most general laws of physics. He wrote: “Whatever the path by which we have come to the conviction that all phenomena are subject to the principle of conservation of energy, we must at the present time recognize this principle as one of the unshakable foundations of physics.”

The surviving diaries of A. L. Gershun testify to the breadth of his interests and the depth of his thought. Thus, for example, in an entry of October 13, 1896, he writes: “The law of conserva-

...of the weight (erroneously, of matter) is not a logical necessity proceeding from the very concepts of matter, but a purely empirical law, true only insofar as experiments have not yet refuted it... Why, indeed, should oxygen + iron separately weigh as much as iron oxide?... Experiment shows approximate agreement and, perhaps, will give deviations when the technique of experiment and the accuracy of weighing increase... Everything depends on what parameter of a substance, proportional in one and the same simple body to its mass, we accept as the characteristic of the quantity of mass.”

Thus, A. L. Gershun, as it were, foresaw the necessity of a broader interpretation of Lomonosov’s principle of the conservation of matter, which indeed was modified after the discovery of the equivalence of mass and energy.

Alexander Lvovich regarded science as the property of the people and was a patriot of Russian science. In his scientific work he popularized with great love the works of Russian scholars. While still a university student, A. L. Gershun was the first to establish, in 1888, that priority in the discovery of the electric arc belonged to the Russian scholar Prof. V. V. Petrov, and not to Davy, as had been thought earlier. Alexander Lvovich said: “You see who discovered the voltaic arc, and I am proud that in 1888 it fell to me to point this out and to draw the public’s attention to it.”

If in his time Prof. V. V. Petrov said: “I hope that enlightened and impartial physicists will at least someday agree to give my labors that justice which the importance of these latter experiments deserves,” then such an enlightened physicist proved to be A. L. Gershun.

A. L. Gershun took a direct and energetic part in establishing the priority of his great compatriot A. S. Popov.

A. L. Gershun intended to write biographies of Russian scientists. For example, in his diary it is noted: “8 September 1898: ‘Write biographies of Richman, Petrov.’”

Academician A. N. Krylov, who knew Prof. A. L. Gershun and his work well, wrote of him in 1915: “...His profound knowledge and experience were very often made use of by naval officers, inventors, and, finally, simply by those working for the benefit of the Russian cause... He was often called upon as a critic of foreign proposals, and here, with his knowledge, he helped to sort out a mass of proposals, often representing mere commercial speculation, and saved needless expenditure on experiments.”

In general, the scientific creativity of A. L. Gershun is permeated with the idea of service to the people, to the motherland. He saw the ultimate goal of his scientific investigations and works in public benefit, in the good of the people.

Alexander Lvovich Gershun belonged to the vanguard group of pre-revolutionary scientists who combined in their scientific activity patriotism, democratism, and the materialist tradition of Russian physics on the paths of its independent development.

That is why the scientific legacy of Alexander Lvovich is so vividly and organically connected with the science and technology of our socialist Motherland.

LITERATURE ON A. L. GERSHUN

N. G. Egorov, Alexander Lvovich Gershun (obituary). ZhRFKhO, Physics Section, vol. 48, no. 6 (1916). An incomplete bibliography of A. L. Gershun’s works is appended.

N. I. Ivanov, Leningrad School of Opticians. (Dissertation) (1950). Contains a detailed biography of A. L. Gershun, an exposition of his works, and, in the appendix, a complete bibliography of the works of A. L. Gershun and of articles about him.

A. M. Bakhrakh, Academician A. N. Krylov and Precision Instrument-Making (From the History of Domestic Technology), Lenizdat (1950).

S. Meisel, A. L. Gershun (obituary). Elektrichestvo, No. 9 (1915).