The Thirtieth Anniversary of Radio

A. A. Petrovsky.

1. At the present time radio has become so widespread that in large centers it is difficult to find a person who does not have at least a superficial notion of its principal features. Penetrating ever farther into the very midst of the popular masses, the radio set in 10–15 years may perhaps become as necessary an appurtenance of a cultured family as the inkwell or the washstand. Making daily use of the benefits that this remarkable invention of the human mind gives us, we no longer have a sufficiently clear idea of all the difficulties that stood in the way of the pioneers in this new field; and therefore it is useful now, when thirty years have passed since the birth of radio, to refresh our memories of the historical course of events and of the objective circumstances that accompanied them.

Let us, then, carry ourselves in thought forty years back and imagine the setting in which the inventor of this remarkable means of communication, Professor Alexander Stepanovich Popov, worked.

2. In the eighties of the last century the theory of Faraday—Maxwell had already succeeded in winning the sympathy of physicists, and in the exposition of electricity and magnetism considerable space was devoted to the distribution of lines of force, to work in displacement in a force field, and to elucidating the role of the medium. One may easily be convinced of this by looking through the classic textbook of that time: Mascart and Joubert. Lectures on Electricity and Magnetism, Paris, 18821.

However, only questions connected with the unchanging state of a system had been developed in detail. As for processes varying in time, their theoretical treatment did not go beyond the oscillatory discharge of a single system and transformation in two closed circuits. The researches of Bjerk-

THIRTY YEARS OF RADIO

...ness \(^{1}\) and Wien \(^{2}\) on coupled systems; there was also no detailed analysis of the origin of standing electromagnetic waves on conductors \(^{3}\). Even after the publication of Hertz’s classic experiments, the theory of the dipole \(^{4}\), expressed by him with unusual elegance and of enormous importance for the fundamental question of radio engineering—the question of radiation—was not sufficiently appreciated and for a long time found no place even in very serious courses. For example, the theory of the dipole is absent from Prof. Borgman’s course, which appeared in the nineties and by which more than a few generations of physicist-electricians were educated \(^{5}\).

1. Experimental methods were rather varied, but were based exclusively on the use of direct current. As a result, laboratory work revolved chiefly around the measurement of resistances and electromotive forces. The measurement of capacitances and self-inductances, however, seemed a task of extraordinary difficulty and required a very complicated setup and great skill.

The use of bridges and resonance circuits with a telephone or other convenient indicators appeared considerably later. This deficiency in the technical methods of measurement was felt for a very long time, so that even in 1901, when I first had occasion to come into close contact with A. S. Popov in Kronstadt, he expressed his regret at the absence in the hands of engineering of at least a few rough, but simple and convenient, methods for measuring capacitances and self-inductances. These conversations also gave direction to my own work, so that the first measurements of self-induction coils used in A. S. Popov’s installations were made by the voltmeter-ammeter method at high frequency, obtained from a singing arc \(^{6}\). As for the measurement of capac-

\(^{1}\) C. A. Bjerkness. Ueber elektrische Resonanz. Ann. d. Ph., 55, 121—169, 1895.

\(^{2}\) M. Wien. Ueber die Verwendung der Resonanz bei der drahtlosen Telegraphie. Ann. d. Ph., 8, 686—713, 1902.

M. Wien. Ueber die Verstimmung gekoppelter Systeme. Ann. d. Ph., 25, 7—30, 1908.

M. Wien. Ueber die Dämpfung von Kondensatorschwingungen. Ann. d. Ph., 25, 625—659, 1908.

\(^{3}\) The theory of electrical oscillations arising in a wire appeared only in 1898.

M. Abraham. Die elektrischen Schwingungen um einen stabförmigen Leiter, behandelt nach der Maxwell’schen Theorie. Ann. d. Ph. 66, 435—472, 1898.

\(^{4}\) H. Hertz. Die Kräfte elektrischer Schwingungen, behandelt nach der Maxwell’schen Theorie. Ann. d. Ph., 36, 1—22, 1888.

\(^{5}\) I. I. Borgman. Foundations of the Doctrine of Electrical and Magnetic Phenomena, part I, 8—470 pp., in 8°. St. Petersburg, 1893, and part II, II—642 pp. in 8°. St. Petersburg, 1895.

\(^{6}\) A. Petrovsky. Measurement of small coefficients of self-induction with the aid of a singing arc. Collection of articles dedicated to the memory of F. F. Petrushevsky, 1904, pp. 25—34.

A. Petrovsky. Comparison of small coefficients of self-induction with the aid of a singing arc. Zh. R. F. Kh. O., 36, 123—142, 1904.

...we first tried the classical method using a ballistic galvanometer, but, having become convinced of the great difficulties that arise in measuring capacitances of the order of \(10—100\ \mu\mu F\), we turned to a method developed still earlier by me and Prof. I. I. Borgman1. Later A. S. Popov solved this problem with extraordinary talent, arranging a special, very portable bridge, which was used on ships of the fleet.

1. The technical applications of electricity were likewise in an embryonic state. The basis for their study at that time was Schellen’s book2, “Magneto- and Dynamo-Electric Machines,” Cologne, 1882. It contained chiefly a description of the primitive machines that then existed; it also contained the first attempts at a mathematical expression of the phenomena occurring in them and a description of devices for electric lighting3. Even in the subsequent development of electrical engineering, for example, in the well-known course of Gérard4, an engineer will find little more material. Only the nineties of the last century moved this field forward by gigantic strides and, in a short time, created an extensive literature5.

2. Such was the state in which science found itself in the eighties of the last century. Meanwhile, life demanded an urgent solution to questions that hindered the use of so mighty a force of nature as electricity for practical needs. Entering, in 1883, as a laboratory assistant in the Kronstadt Mine Officers’ Class, A. S. at once plunged into the abyss of these questions and, as a new man, was besieged on all sides by persons in need of their solution. The desire to render real assistance and the deep interest in science, by which he lived to the end of his days, compelled him to delve into the little-explored wilds of electrical

oscillations and electromagnetic waves, in which he intuitively sensed the prime causes of all the observed, incomprehensible phenomena, and A. S. conceived a still vague and unformed idea of the possibility of making practical use of these phenomena, with which until then one had only had to struggle, as with the most dangerous enemies. The physical foundations for the successful accomplishment of this task were provided by Hertz’s experiments, which proved the identical behavior of electromagnetic and light waves ¹), and Branly’s discovery of the property of metallic powders to acquire conductivity under the action of electromagnetic waves ²). As the purpose of using waves, A. S. set the transmission and reception of signals at a distance. Hertz’s vibrator solved the first half of this task quite satisfactorily—it produced short waves that allowed directionality by means of special mirrors; its main shortcoming lay in the small power of the transmitting installation. But this was already connected not so much with inventiveness as with increasing the dimensions and, consequently, with the availability of means, and therefore could not be quickly realized under the conditions in which A. S. Popov had to work. By contrast, Hertz’s resonator, by means of which signals were received, was a purely laboratory apparatus, both in conception and in execution. Being an engineer by nature, A. S. understood that wireless telegraphy would become possible only with the invention of a technical design of receiver that would make it possible, with sufficient sensitivity and when operated by a technician of average qualification, to receive signals reliably and for a long time. Devoting all his inventiveness to this matter, and having tried many dozens of different coherer designs, at the end of 1894 he arrived at this remarkable circuit ³), representing a combination of a coherer, a tapper, and a relay, which not only became the basis of all receiving radio installations of the beginning of the twentieth century, but in essence has survived to the present day.

1. The historic meeting of the Physical Section of the Russian Physico-Chemical Society, on 25 April 1825 old style, at which A. S. Popov delivered his report ⁴): “On the Relation of Metallic Powders to Electrical Oscillations” and demonstrated in operation the first radio receiver, is the date of birth of wireless telegraphy. The assertion, made by some persons, that A. S.

¹) H. Hertz. Ueber Strahlen elektrischer Kraft., Ann. d. Ph, 36, 769—783, 1888.
²) Édouard Branly. Variation de conductibilité sous diverses influences électriques. C. R., 111, 785—787, 1890.
³) A. S. Popov. Device for the detection and registration of electrical oscillations. Zh. R. F. Kh. O., Phys. Sect., 28, 1—14, 1896.
⁴) Protocol 151 (201) of the Meeting of the Phys. Sect. R.F.Kh.O., 25 April 1896, Zh.R.F.Kh.O., 27, 259—260. 1895.

had in mind only the registration of atmospheric discharges. Eyewitnesses who attended the above-mentioned meeting note that A. S., with his characteristic modesty, indicated that if a more powerful vibrator were constructed, it would be possible, using the receiver he had made, to transmit signals over a distance without wires—for which he was given the name “dreamer.” Reality confirmed the feasibility of his fantasy, and A. S. Popov himself witnessed how the cause he had begun, which had gone abroad owing to the backwardness of Russian capitalists and the distrust of Russian scientific workers, grew into a grand enterprise that linked the Old and the New World. How great an inner satisfaction he would feel now, when, with the invention of the cathode tube, radio amateurs transmit signals to the antipodes, employing a power of several hundred watts! But he was not destined to live to see the day when the freedom of the ether gained recognition in almost all countries of the globe. On December 31, 1895, A. S. died of a cerebral hemorrhage. He died, leaving us as a legacy his astonishing invention, which will outlive centuries and nations. The day of May 7, solemnly celebrated this year, must be regarded as a calendar day for every radio specialist, reminding him that the unity of science and labor is the surest pledge of the victory of the human mind over the forces of nature.

1. I. Borgman and A. Petrovsky. Application of a Geissler tube to the measurement of small electro-capacitances of poorly conducting bodies. Zh. R. F. Kh. O., 31, 229—240, 1899.

   J. Borgman et Petrowsky. Sur un cas particulier des oscillations électriques produites par une bobine de Ruhmkorff à circuit secondaire ouvert et sur une méthode nouvelle pour mesurer les capacités électriques. C. R., 128, 420—422, 1899.

   Borgman et Petrowsky. Sur la capacité électrique des corps mauvais conducteurs. C. R., 128, 1153—1155, 1899. ↩↩

2. Dr H. Schellen. Die magneto-und dynamoelektrischen Maschinen, ihre Construction und praktische Anwendung zur electrischen Beleuchtung und Kraftübertragung. 16 + 656 Seiten in 8°. Cöln, 1882. ↩

3. A corresponding Russian manual was published in the Naval Ministry. E. Tvertitinov. Electric Lighting. Course of the Mine Officers’ Class. 10—499 pp. in 8° and an atlas of drawings. St. Petersburg, 1883. ↩

4. Eric Gérard. Éléments d’électrotechnique, 16 + 477 pages in 8°. Liège, 1886. ↩

5. As an illustration of this development of the field, let us note that Gérard’s course, which appeared in 1900 in its sixth edition, already contains two volumes, together comprising 1627 pages. ↩