Principles of electricity

The experimental foundation for the discovery of wireless telegraphy was laid by the researches of Faraday.[32]

Accepting Faraday’s physical views as a point of departure, James Clerk Maxwell (1831-1879), Professor of Experimental Physics in the University of Cambridge, began (about 1860) the development of his constructive speculations in electrical theory which culminated in the now universally accepted electromagnetic theory of light.[33]

Fourteen years after the publication of Maxwell’s classic treatise, Heinrich Hertz (1859-1894)—a brilliant pupil of Helmholtz (1821-1894)—succeeded in producing electrical discharges from a Leyden jar, which oscillations in turn gave rise to electromagnetic waves of far greater length than any previously known.[34]

Hertz demonstrated also that the velocity of propagation of these waves was the same as that of light-waves—approximately 186,000 miles a second, equivalent to about seven times the circumference of the earth in one second. It was shown that the only difference between the Hertzian (“wireless”) waves, for example, and the light-waves, is in their respective length, or, reciprocally, their rates of vibration per second. Hertz later demonstrated that these invisible waves produced by a Leyden jar could be reflected, refracted, and polarized, as in the case with the far shorter light-waves or rays.[35] These results had been predicted by Maxwell.

In this great discovery the foundation for wireless telegraphy and wireless telephony was laid—for Hertz had found what are now known as “wireless” or radio waves—destined, perhaps, to revolutionize our methods of obtaining power for machinery, and for transportation, as they have already revolutionized our methods of communication. Hertz had done more than this: for his investigations made possible a far more satisfactory research into the structure of atoms.

“If we were asked to pick out one date that stands out more prominently than others in our acquisition of knowledge bearing upon the structure of matter,” says Dr. Albert C. Crehore, “it might be this epoch-making work of Hertz.”[36]

While it is true that the waves that Hertz discovered and measured “differ from light-waves merely in wave-length or period of vibration and quality,” on the other hand the difference in wave-length is so great that no instrument had as yet been devised to measure or detect waves that were meters long, as compared with light-waves but a minute fraction of a centimeter in length.

It was Hertz’s task—following up Maxwell’s prediction—to devise an instrument which would detect waves not cognizable by our senses alone. For this purpose he used a simple loop of wire with the ends brought near together, each terminating in a metal ball. When these balls were brought almost into contact, a small electrical spark was seen to pass between the balls when the “oscillator”—the apparatus used to generate the oscillating currents, or electric waves, of high frequency—was set in operation.[37]

Hertz not only proved that the speed of electric waves is the same as that of light, and that they are subject, under certain conditions, to “interference” as are light-waves, but he also succeeded in actually measuring the length of the waves produced by his crude apparatus. This was accomplished by producing what are known as “standing waves,” analogous to the sound-waves produced by an organ-pipe. Moving his detector slowly along the wire, Hertz observed that the spark would appear when a certain interval of space was reached, and as he continued to move the detector the sparks would disappear and reappear at regular distances. He rightly concluded that these points of disappearance and reappearance of the spark corresponded to the nodes and loops of the “standing waves,” representing the wave-length of the electrical undulations.

It has since been established that the difference in wave-length between the electric undulations produced by Hertz and those of light-waves may be enormous or quite moderate. Professor Michelson tells us that “a telegraphic wave”, which is practically an electromagnetic disturbance, may be as long as 1000 miles. The waves produced by the oscillations of a condenser, like a Lyden jar, may be as short as 100 feet; the waves produced by a Hertz oscillator may be as short as one-tenth of an inch. Between this and the longest light-wave there is not an enormous gap, for the latter has a length of about ¹/₁₀₀₀ inch. Thus the difference between the Hertz vibrations and the longest light-wave is less than the difference between the longest and shortest light-waves, for some of the shortest oscillations are only a few millionths of an inch long. Doubtless even this gap will soon be bridged over.[38]

The Hertz apparatus was greatly improved by Auguste Righi, in the University of Bologna. In the same class in physics was Marconi, who began his fruitful experiments in 1895, one year after Sir Oliver Lodge had perfected the coherer. Lodge’s coherer, used by Marconi in his early work, consisted of a glass tube containing a pinch of nickel and silver filings in equal parts. Crude as this detector was, judged by present-day standards, it materially improved the conductivity of contact metals in the case of Hertzian waves.

In 1899 wireless communication was established across the English Channel, and in 1902 Marconi sent the first wireless message from England to America. Today, wireless waves measuring miles from crest to crest are being employed in the transmission of messages from points separated by thousands of miles, and the human voice has already been carried across the Atlantic by radiophone, but only in one direction.

The wireless sending and receiving station of the Dutch government, at Kootmyck, in the Province of Gelderland, is equipped to employ a 12,000-meter wave-length in sending and receiving simultaneously messages between Holland and Java, 7,500 miles distant. It has the same capacity as our Long Island (Rocky Point) station, and is therefore one of the biggest in the world.

On December 19, 1922, a long distance phonograph which records sounds made hundreds of miles away was demonstrated to the Society of Western Engineers, by E. H. Colpitts, of the Western Electric Company. The transmission of electric power by radio is as yet but a dream; but it is a dream which may come true within the next five years.[39]

Signals are now being received from stations situated at distances as great as 12,000 miles, made possible, it is believed by the existence of an electrical conducting layer—electrified dust expelled by the sun—some 150 miles in depth, the bending of the radio-waves around the earth being caused by diffraction. Some unknown factor is operating to give the signals a strength millions of times greater than can be accounted for at present by any plausible theory, according to Prof. J. A. Fleming (Fifth Henry Truman Wood Lecture before the Royal Society of Arts, London, 1922).

It is not reasonable to assume that no other electromagnetic waves remain to be discovered. We may yet hear “the roar of the sun-spots,” though Edison’s experiments along this line were unsuccessful. What, indeed, were the mysterious “signals” occasionally reported as having been received at Marconi wireless stations—registered, it was reported in the press, “only when a minimum of sixty-five-mile wave-lengths had been established,” but waves issuing from the mighty sun, 93,000,000 miles distant? However, Marconi tells us that one of the “signals” comes as three short raps—“S” in the Morse code. He believes that these “signals” may have been sent out from Mars or Venus. Similar mysterious “signals” were reported by wireless stations in different parts of the world during the apposition of Mars in August, 1924.

“Outside of the radio-waves that are floating about there may be hundreds of others which we have not as yet been able to register.... There may be many other waves coming to us from the sun, of which we have no knowledge today.... The human ear cannot hear below eight vibrations per second and not higher than about 30,000 vibrations per second. Certain animals can hear below and above that scale. By means of our vacuum tubes certain researches indicate that a tremendous amount of noise goes on below the eight vibrations per second, and still more noise above the 30,000 vibrations. Entirely new worlds lie in these two directions, of which nothing is known today. The vacuum tube is likely to solve these mysteries and take us into the uncharted worlds, far into the unknown, within the next few years.”[40]

In March, 1922, the late Dr. Charles P. Steinmetz said that he considered well founded the supposition that performances of low-power radio sending apparatus in transmitting messages to surprising distances gave an indication that the radiations peculiar to wireless transmission pass with equal ease through the earth or through the “ether.”

Such radiations would be in accordance with accepted electrical laws, as the ground, to which both the sending antennae and the receiving set are connected, would act as a return circuit for the current. Similarly, water might serve as a medium for radio conversations between ships, or between ships and the land.

Moreover, it was announced during the same month that wireless telephony had been revolutionized by the successful performances of the duplex transmitters which the General Electric Company had just completed. Conversations were held between New York and passengers aboard the steamer “America,” which, at the time, was at a distance of 360 miles from shore.

The three-electrode audion or vacuum tube was perfected in 1912, making radio-telephony possible. In 1921, Reginald A. Heising, a young physicist working for a degree of Master of Science at the University of Wisconsin, conceived the brilliant idea of putting into the vacuum tube the amount of energy produced by the voice, and then getting it out many times amplified in the form of high-frequency power in the antenna. This problem he soon solved, so far as the principle of the modulation system was concerned, and in 1922 the practical problem was worked out and the method all but perfected.

All these great utilitarian advances have been made possible by the researches of men interested in the advancement of knowledge for its own sake. As has been pointed out recently by Dr. Hale (“The New Heavens,” Pages 87-88), “Faraday, studying the laws of electricity, discovered the principles which rendered the dynamo possible. Maxwell, Henry and Hertz, equally unconcerned with material advantage, made wireless telegraphy possible.... Wireless telephony and transcontinental telephony without wires were both rendered possible by studies of the nature of the electric discharge in vacuum tubes.”

In an interview in December, 1922, Dr. Nikola Tesla gave it as his opinion, based upon experiments already carried out in his own laboratory in New York City, that power flashed through space by radio will soon be employed in all the world’s activities.

“Besides bridging enormous distances in flight and wireless conversation,” he said, “modern science will span the earth with power flashed through the air by radio. Airplanes and ships and trains will carry no fuel, but will run by transmitted energy. With wireless power no one—explorers, travelers, campers—need be cut off from civilization and its comforts.”

“Not only that, but we shall see at great distances by aid of wireless energy. And seeing our neighbors across the oceans will make for a united social and political world.”