From the History of Physics

VLADIMIR NIKOLAEVICH CHIKOLEV AND HIS OPTICAL RESEARCH

(On the Fiftieth Anniversary of His Death)

V. L. Chenakal

The names and works of a number of first-rate Russian scientists who lived and worked many years ago remained undeservedly forgotten by the pre-revolutionary history of national science and are for the first time becoming widely known only in our Soviet time, when the study of the past of our people, its science and culture, has assumed the proper scope. Among them was the talented Russian physicist of the second half of the nineteenth century, Vladimir Nikolaevich Chikolev, the fiftieth anniversary of whose death fell on February 22 of the current year.

The principal questions that occupied Chikolev over the course of many years were electricity and optics. Neither of these fields of his scientific activity had been covered in Russian pre-revolutionary literature.

Only in recent years have Chikolev’s works in the field of electricity received some coverage in the Soviet press*); his optical research, to a brief exposition of which the present article is devoted, still remains little known.

) The following articles are devoted specifically to Chikolev’s works in the field of electricity: Anon. Russian electrical engineer V. N. Chikolev. Electrification and Electrometer, No. 2, pp. 23–24, 1930; M. I. Radoskin. Pioneer of Russian electrical engineering V. N. Chikolev. Electricity, No. 12, pp. 1–5, 1938; N. A. Shostin. Vladimir Nikolaevich Chikolev. Electricity, No. 8, pp. 7–12, 1945; I. D. Artamonov. V. N. Chikolev—military electrical engineer. Electricity, No. 8, pp. 13–16, 1945; I. I. Rudometov. Russian electrical engineers. Moscow–Leningrad, 1947, pp. 72–80; V. V. Danilevsky. Russian Technology. Leningrad, 1947, pp. 345, 355, 361–362, 365, 368. An exposition of Chikolev’s electrotechnical works can also be found in the literature devoted to other Russian electrical scientists of that time, for example, in P. P. Zabarinsky’s Yablochkov*, Moscow, 1938, and in other similar works.

To understand what led Chikolev to engage with questions of applied optics, and what served as the main stimulus for him in all these works, one should briefly dwell on his biography.

Chikolev was born on July 23, 1845, into a poor family, in the village of Peski, Smolensk Province. Having lost his parents in early childhood, he

was placed in the Alexandrovsky Cadet Corps in Moscow, from which he graduated in 1863. Military service was of little interest to Chikolev’s lively and inquisitive mind. While still within the walls of the school he became deeply interested in the natural sciences and, in particular, in electricity, which was then coming greatly “into fashion.” His interest in this field of knowledge grew more and more with each year and led, in the end, to his renouncing the military career that awaited him after graduation and enrolling in Moscow University in the Faculty of Physics and Mathematics.

The difficult financial situation and the constant concern for earnings that followed from it did not allow him to devote himself completely to the study of his favorite sciences. He entered the university only as a non-matriculated student, so that, alongside his studies, he would also have time for work, which was his main source of livelihood. Despite this, Chikolev studied at the university very successfully.

Immediately after graduating from the university, in 1867, he was invited to work at the Petrovsky-Razumovsky (now Timiryazev) Agricultural Academy as assistant to Professor of Physics Tsvetkov.

After serving for about a year in this position, Chikolev decided to prepare for the master’s examinations. However, he did not succeed in making an academic career. Constant material difficulties forced him once again to look for work that would give him both a reliable income and the opportunity to satisfy his need for the scientific work he loved.

After working for some time in the physical laboratory of the Moscow Technical Society, where investigations were being conducted chiefly in the field of the practical application of electricity in various branches of technology, and then in a number of other similar laboratories, in 1876 he moved to Petersburg and took a position in the Main Artillery Directorate, at first as clerk of the Artillery Committee in the electrotechnical section, and then as chief electrical engineer of this Directorate, where he continued to work until his very death.

Chikolev died on February 22, 1898, after a prolonged illness that was the result of an injury he had received in a railway accident in 1896.

Alongside extensive research work in many Moscow and Petersburg laboratories, Chikolev also did much to organize the Russian scientific community and to popularize scientific knowledge among the Russian people.

While in Moscow, he took an active part in the work of the Moscow Technical Society and the Physical Section of the Society of Lovers of Natural Science, in arranging the Moscow Polytechnic Exhibition of 1872, and in organizing the Moscow circle of physicists and electricians, which was very active in its time. Public lectures on various scientific and technical subjects were often delivered by him in the hall of the Polytechnic Museum.

This activity of his became still more vigorous in Petersburg. There, in 1879, with his closest participation, the sixth Electrotechnical Section was established at the Russian Technical Society. Soon after the establishment of this section, again with Chikolev’s closest participation, an Electrotechnical Exhibition was opened in Petersburg—the first exhibition of this type in the whole world.

With Chikolev, beginning in 1880, the publication of the journal Electricity was begun, which, as is known, is still being published to this day. Twice—in 1880 and in 1890—Chikolev himself was the editor of this journal.

Very frequent in Petersburg, as well as in Moscow, were Chikolev’s appearances with public lectures for the people.

Chikolev’s scientific work on various physical problems began already during the period of his work in the physics laboratory of the Petrovsky-Razumovsky Academy, i.e., in 1869.

His first major work, begun by him while still at the aforementioned academy and continued until 1874, was work on the so-called differential arc lamp.

The widely practiced electric lighting by arc lamps, before the appearance of incandescent lamps, had the substantial drawback that the carbon electrodes of such lamps required, for continuous burning, their constant bringing together, i.e., regulation of the distance between their burning ends; reliable methods of such regulation did not exist. There were many regulators based on the use of springs, clock mechanisms, and other devices, but not one of them met the requirements. The question of the possibility of connecting several lamps with such regulators simultaneously into one electric circuit had likewise not been worked out.

Proceeding from the desire to eliminate all these shortcomings of arc lamps, Chikolev, after prolonged theoretical and experimental investigations, proposed his differential method of regulating the distance between the carbons of an arc lamp, which made it possible at the same time reliably to regulate the coming together of the carbons and to connect into the circuit any desired number of lamps. Chikolev’s differential lamp very quickly found wide application in lighting engineering in all European countries and displaced almost all the devices that had existed before it and were intended for the same purposes. In 1873, guided by Chikolev’s published description of the differential lamp, the Siemens firm began to build such lamps. Several years later, Chikolev lamps also began to be manufactured by other foreign firms. In 1888, the Schuckert firm in Germany, taking advantage of the fact that Chikolev had not taken out a privilege for this lamp of his, patented it in its own name and began to manufacture it in large quantities.

At approximately these same years Chikolev introduced a number of important improvements in the design of the electric motor and the galvanic cell.

Chikolev also took an active part in the work of well-known Russian investigators in the field of the search for new sources of light—Alexander Nikolaevich Lodygin and Pavel Nikolaevich Yablochkov.

Thanks to these works, Chikolev very quickly acquired worldwide renown as an exceptionally gifted researcher in the field of physics and, chiefly, electricity. Many foreign electrical-engineering firms repeatedly offered him good, highly paid positions, but he, as a Russian man who loved his homeland, his people, and its science, answered all these proposals with refusal.

Chikolev’s scientific activity became especially active after he entered service in the Main Artillery Directorate. At first, as in the Moscow period of his life, he worked here on questions connected with the practical use of electricity in military affairs. Some time later he also included optics among his researches.

One of the principal questions occupying Russian military technology in those years was the question of introducing electric searchlights into the Russian army and navy.

Being an instrument that contained at once both elements of electricity and elements of optics, the searchlight became the object around which, subsequently, all of Chikolev’s electrotechnical as well as optical investigations were concentrated.

Chikolev’s first major work relating to the optics of the searchlight was the investigation of the basic properties of searchlights, carried out by him soon after he entered service in the Main Artillery Directorate, with the aim of establishing general laws of illumination at long distances.

He spent several summer months of 1876 in the Ust-Izhora military camp near Petersburg, where almost every night he tested the illuminating capacity of the searchlight systems then in existence. As a result of this work he experimentally established the dependence between the luminous intensity of the searchlight, the brightness of its light source, and the diameter of the reflector; he found the most convenient method for calculating the illumination produced by a searchlight situated at various distances from the object illuminated; he found the conditions for the most advantageous observation of objects lying in the beam of the searchlight, and so on—that is, he established almost all the basic laws of illuminating distant objects with the aid of searchlights. All these data, exceptionally important for the proper operation of searchlights, had remained unknown before Chikolev.

An exceptionally interesting part of these Chikolev works was the methods he developed for masking operating searchlights from the enemy during battle, and methods for determining, by means of searchlights, the distances to illuminated objects. It may be noted that some of the methods of masking searchlights which he proposed are still successfully used in military practice to this day.

Before Chikolev’s indicated works, almost all lighting engineers in the world strove to build projectors of the greatest possible power and large dimensions.

Turning his attention to the light sources of projectors, i.e., their arc lamps, Chikolev found that, “when the current is increased beyond certain known limits, the light power emitted by a unit of the luminous surface of the electric arc scarcely increases; rather, only the luminous surface increases, i.e., not the intensity but the quantity of light rays, owing to the lengthening and widening of the electric arc,” and that, as a consequence of this circumstance, “the illumination intensity of surfaces, when they are illuminated with the assistance of optical condensers, increases only very slightly, while only the illuminated area increases.” From all this he concluded that “two (or more) light sources, each of a known power, acting upon one and the same area, will illuminate it more strongly than one source of double power.” As soon as these works of his became known—and they were published in a timely manner—the tendency to create super-powerful projectors was abandoned, and in almost all countries projectors of only medium and small dimensions began to be built.

Following these investigations, Chikolev carried out extensive work on improving the arc lamp of the projector. After numerous experiments, in February 1877, he established that if the vertically standing carbons of the arc were arranged not on one axis, as was usually done in those years, but in such a way that the axis of the lower, negative carbon was shifted toward the projector reflector by half the radius of the carbon, then, as the carbons burned away, the crater of the upper, positive carbon would have an inclined position toward the axis of the lower carbon, and the light power, as a result, in the corresponding direction would be twice as great as it would be in that direction when the axes of both carbons coincided.

In July of the same year, 1877, the correctness of Chikolev’s conclusions on the expediency of such an arrangement of the carbons of the arc lamp was verified in England by a special commission, with the participation in the latter of the well-known English physicist John Tyndall. This commission, having somewhat changed the arrangement of the carbons proposed by Chikolev (by shifting the axis of the lower carbon by the full radius of the upper one), also found that “if the light power in all horizontal directions, with the normal position of the axes of the carbons (their coincidence), is expressed by the number 100, then when the axis of the lower carbon is deflected by the full length of the radius of the upper carbon, the distribution of light power in the horizontal plane changes in the form of the following figures: in the direction of deflection of the lower carbon—287, in the opposite direction—38, and in the two lateral directions—116.” After the publication of the work of this commission, no one any longer doubted the advantages of the method proposed by Chikolev for setting the carbons in an arc projector lamp.

became, and its use became widespread.

An exceptionally valuable aspect of Chikolev’s style of research work was that all of it was carried out by him not so much within the walls of a laboratory as directly in the field, under the natural operating conditions of searchlights. This enabled him to test and improve each of his ideas immediately after it arose, without resorting to various kinds of assumptions and suppositions.

In the spring of 1877, i.e., only a few months after the above-mentioned work in the Ust-Izhora camp, he again carried out similar work in another military camp near Petersburg. Six years later, i.e., in 1883, he spent almost the entire summer engaged in the same occupation at the Main Artillery Range in Rzhevka, and so on. The first of these works, i.e., the work of 1877, was devoted to the study of “the illuminating capacity of searchlights as a function of the distance to the objects illuminated”; the second, i.e., the work of 1883, to the study of the relationship between “illuminating capacity and the transparency of the atmosphere,” between “illuminating capacity and the color of the observed objects,” to determining the most advantageous conditions for observing objects lying in the beam of a searchlight, and so forth. These works, like the preceding ones, yielded much that was new and interesting for the technology of searchlight illumination and for lighting engineering in general.

One of Chikolev’s most interesting works in the field of improving searchlights—work that played an exceptionally important role in the further improvement of the quality of these instruments—was the design of a new searchlight reflector that he proposed in 1884.

The principal shortcoming of all searchlights built before Chikolev was the very low quality of their main component—the mirror reflector that concentrated the luminous flux. In all countries, searchlights were built only with spherical reflectors of very poor quality, although the shortcomings of the latter for these purposes were well known. It had long been known that only parabolic mirrors could be ideal searchlight reflectors. However, no one knew how to manufacture such mirrors with the required accuracy.

In 1876, i.e., in the year when Chikolev began his work on searchlight optics, the French engineer officer A. Mangin likewise proposed a spherical, but specially designed, mirror reflector, which did not have all the shortcomings inherent in ordinary spherical reflectors and even seemed to surpass the first parabolic reflectors. Thanks to these advantages, the Mangin reflector in literally a few years gained universal recognition, and along with this wide distribution in searchlight—

...business. After several years of operation of this reflector, however, it was established that it, too, possessed a whole series of shortcomings.

The first such report, i.e., the report that the Mangin reflector also had substantial shortcomings, came to the Western European countries from Russia, and it was submitted by Chikolev. By prolonged testing of the Mangin reflector, Chikolev established that the calculations given by Mangin in the description of his instrument contained many inaccuracies and errors; that this reflector was merely a mediocre surrogate for the parabolic reflector and, consequently, could not replace the latter in a searchlight with the required success.

Setting himself the aim of simplifying and reducing the cost of producing parabolic searchlight reflectors, Chikolev in 1884 developed a completely original design for such a reflector, which, according to all calculations, was to possess high qualities and greatly simplify manufacture. Taking into account the enormous difficulties of making large parabolic surfaces with the required precision—which, in fact, was the main obstacle to the realization of parabolic reflectors—Chikolev proposed making reflectors composed of nine separate parts, with three different radii of curvature, together forming a surface close to a paraboloid.

These reflectors were to consist of two concentric glass rings, each of which in turn was made up of four annular sectors, and of a central, likewise glass, disk. Both rings and the disk were to have spherical surfaces of different curvature. All four sectors of the outer ring were to have one radius of curvature, the sectors of the second ring another (smaller) one, and the central part a third (still smaller) one. All these parts were to be fastened in one common frame in such a way that the centers of their curvature lay at one point, which was at the same time the center of curvature of the paraboloid formed by them together.

In its optical qualities this Chikolev annular reflector surpassed all spherical reflectors known up to that time, including the Mangin reflector. Comparison with the latter showed that, with equal relative apertures and identical light sources, it sends much more light into space than the Mangin reflector. In 1885 the firm Siemens & Halske, in Germany, undertook serial production of Chikolev annular reflectors. However, their manufacture did not continue for long. Production practice showed that, despite their exceptionally high optical qualities, making them—owing to the great difficulties of accurately mounting the parts in a common frame—is a very complex undertaking, as is the grinding of large...

...ing parabolic reflectors. This was fully realized by Chikolev himself as well. This alone can explain the fact that in 1887 he undertook a new piece of work, very important for the further improvement of the projector reflector.

The essence of this work of his was as follows. All the above-mentioned searches for the most advantageous design of a projector reflector did not, as we have seen, lead to the desired results. Primacy in this matter still remained with the parabolic reflector. In 1885 the German firm Schuckert, undeterred by all possible difficulties, nevertheless began to build glass projector reflectors with a ground and polished parabolic surface. The firm arrived at its reflector by a purely practical route. It made no theoretical calculation.

Already during the testing of the first specimens of such a reflector it was found that it possessed a whole series of shortcomings which remained unexplained, and that, for understanding them and consequently eliminating them, a theoretical treatment of the question was necessary. It was this work that Chikolev undertook in 1887.

Together with the young Russian physicist V. A. Tyurin, whom he enlisted for this work, he made a complete mathematical calculation of the parabolic reflector, established the exact dependence between all the parameters essential for its use in projector work, and in this way gave valuable practical instructions for the design and construction of reflectors of any desired dimensions. This work by Chikolev, exceptionally valuable for the further development of projector practice, made it possible to solve the following problems:

1. To determine the absolute illuminance at various distances from a given reflector.

2. To find the dependence of the distribution of luminous intensity in the projector beam on its aperture, focal distance, and current strength (crater size), or, briefly, to determine the characteristic of the reflector.

3. To find the limit of useful increase of the current strength (crater size) of the electric arc.

4. To compare the illuminating capacities and characteristics of reflectors of different apertures and focal distances.

5. To form an approximate judgment of the degree of visibility of an illuminated target at various distances from different reflectors and from the observer, and to determine how advantageous it is to bring them closer to the target.

6. To evaluate the advantages of using inclined and horizontal lamps in reflectors having different ratios of aperture to focal distance, and so forth.

Being published in 1891, this work of Chikolev served as the principal guide for the calculation and manufacture of parabolic searchlight reflectors in all countries of the world. Although searchlight optics has advanced far in the last half-century, the foundations of this work by Chikolev have not lost their significance even to the present day.

An even more valuable work by Chikolev for the further improvement of the searchlight reflector was the “method for testing searchlight reflectors by photography,” which he proposed in 1892.

Before 1892, searchlight-building and optical factories in all countries experienced great difficulties because practical optics did not possess reliable methods for checking the quality of the surface of a spherical or parabolic concave mirror. The existing methods made it possible to judge only the quality of individual elements of the surface, but they did not give the characteristics of all the defects of the reflector as a whole.

If, in the manufacture of spherical reflectors, where the correctness of the surface is in large measure ensured by the very method of grinding it, the possibility of checking is not of decisive importance, then in the production of parabolic reflectors, where the final result depends both on the adjustment of the grinding and polishing machines, and on the skill of the craftsman, and on a number of other factors difficult to take into account, the absence of reliable control complicated the matter to the utmost.

Chikolev set himself the task of finding such a method for testing searchlight reflectors as would make it possible to judge the quality of the latter as a whole.

Having tested a number of methods, Chikolev found that the most convenient and most fully meeting the required conditions might be the following:

“The reflector is removed from the lantern, and in front of it, at a distance of about 1–1.5 meters, is placed a white shield (screen), ruled with black lines 5 mm wide into white squares 15 mm on a side, or ruled with black lines 5 mm wide, at a distance of 15 mm from line to line. In the center of the shield a square aperture is cut, about 20 cm on a side, through which the image in the reflector is photographed of the grid of squares, or of the parallel lines, drawn on the shield. The shield, in height and width, must exceed the diameter of the mirror by not less than 30–35%.”

Subsequently Chikolev abandoned photographing the image of a screen with straight parallel lines and retained only the square grid of horizontal and vertical lines.

If the reflector has one or another deviation of the surface from the prescribed parabolic form, then these portions will

produce distortions of the grid of screen lines in the photograph, and thus their presence can easily be detected.

Despite the fact that this method is purely qualitative, it nevertheless indicates the places on the surface of the reflector where defects are present, and the path by which the surface should be corrected.

Using this method, Chikolev tested the quality of the surfaces of all searchlight reflectors manufactured in those years and pointed out their defects. This compelled the manufacturing firms to make every effort to improve their products, which immediately produced results. In subsequent years this method of Chikolev’s came to be used at all searchlight-building and optical factories of the world. Later many other methods were proposed for testing searchlight reflectors, but they not only did not displace Chikolev’s method, they even broadened the fields of its application*).

Chikolev’s very first works in the field of searchlight optics, as we have seen above, gave him a worldwide reputation. His last two works—i.e. the theory of the parabolic searchlight reflector and the method of testing searchlight reflectors by photography—made his name immortal in practical optics.

When a general history of our national science is written, the name of Vladimir Nikolaevich Chikolev will undoubtedly be entered among its finest creators.

LIST OF THE PRINCIPAL WORKS OF V. N. CHIKOLEV ON OPTICS AND RELATED QUESTIONS

1. The Application of Electric Lighting for Military Purposes. St. Petersburg, 1879.

2. On the improvement of the simplest instruments for projecting electric lighting over long distances (Electricity, 1880, No. 12.)

3. Electric Lighting and Its Application for Military Purposes. St. Petersburg, 1885.

4. Electric Lighting in Its Application to Life and to the Art of War. St. Petersburg, 1886.

5. The Illuminating Power of Searchlights of Electric Light. Issue 1, theoretical part (jointly with V. A. Tyurin), St. Petersburg, 1892; Issue 2, practical part (jointly with V. A. Tyurin and R. E. Klasson), St. Petersburg, 1895.

) A high appraisal of the indicated Chikolev method for checking the surfaces of concave mirrors may be found in foreign literature as well; for example, in the following works: A. Sonnefeld. Die Hohlspiegel. Berlin, 1926, pp. 115—119; Handbuch der Physik. Vol. XVIII. (Geometrische Optik, optische Konstante, optische Instrumente.*), Berlin, 1927, pp. 817—820, and in a number of others.

1. Photographic study of searchlights for electric lighting. (Elektrichestvo, 1892, No. 21.)

2. On the testing of electric-light reflectors by photography. St. Petersburg, 1892.

3. The matériel of electric-lighting apparatus. Apparatus for coastal and land artillery, models of 1877–1893. Atlas of drawings and accompanying text. St. Petersburg, 1893.

4. Electric light in fortress, siege, coastal, and field artillery. St. Petersburg, 1893.

5. Electric lighting for combat purposes. St. Petersburg, 1893.

6. The latest devices for projecting electric lighting onto distant localities. St. Petersburg, 1898.