Principles of electricity — Key Ideas to Explore

in (1706-1790) and his successors.

The soul-force (“moving power”) of Thales—always moving and causing movement—and the “effluences” of Empedocles have become the “field of force” of Faraday, Sir J. J. Thomson, and Sir Oliver Lodge. The self-moving “soul” of nature, manifest in the lodestone, or acting on the lodestone, or on the particles said to be “attracted” by the lodestone, is but a synonym for the lines of force of the magnetic field of modern physics. Thales and Empedocles spoke in the language (terminology) of their day and age. The “emanations” of Empedocles are the “corpuscles” of Thomson—a body becoming positively electrified by “losing some of its corpuscles”, and hence capable of drawing negatively charged particles to itself.

Electricity and magnetism are related but not identical. A moving magnet can induce an electric current in a wire, and an electric current can produce magnetism in iron. The construction of telegraph and telephone instruments depends on the fact that an electric current can produce magnetism and that magnetism can produce an electric current.

We know _effects_ which we call “electricity”, just as we know the phenomena associated with living protoplasm without knowing what “life” is. It may be that “life” and “electricity”, as well as “electricity” and “magnetism”, are all different aspects of the same thing.

Today we say, in the words of Dr. Charles P. Steinmetz (“Relativity and Space”, Pages 18-19):—

“The space surrounding a magnet is a magnetic field. If we electrify a piece of sealing-wax by rubbing it, it surrounds itself by a dielectric or electrostatic field, and bodies susceptible to electrostatic forces—such as light pieces of paper—are attracted. The earth is surrounded by a gravitational field, the lines of gravitational force issuing radially from the earth. If a stone falls to the earth, it is due to the stone’s being in the gravitational field of the earth and being acted upon by it.”

Again:—“Suppose we have a permanent bar magnet and bring a piece of iron near it. It is attracted, or moved; that is, a force is exerted on it. We bring a piece of copper near the magnet, and nothing happens. We say that the space surrounding the magnet is a _magnetic field_. A _field_, or _field of force_, we define as ‘a condition in space exerting a force on a body susceptible to this field’. Thus, a piece of iron being magnetizable—that is, susceptible to a magnetic field—will be acted upon; a piece of copper, not being magnetizable, shows no action.... To produce a field of force requires energy, and this energy is stored in the space we call the field. Thus we can go further and define the field as ‘_a condition of energy storage in space exerting a force on a body susceptible to this energy_’.”

Thales said that the “divine moving power”, the soul of nature, under certain conditions “moves iron”, through the mysterious properties of the lodestone. Modern science, borrowing from Aristotle the term _energia_, substitutes for “soul of nature” the single word _energy_. Aristotle declared that “not capacity, but energy ... is the first principle anterior to and superior to anything else” (_Metaphysics_ xii, 7: cf. also _Physics_ ii, 9, 6).

Modern science describes in more precise phrases what _occurs_ when a body susceptible to the influence of the magnet is brought into proximity to a lodestone (magnetite). It gives us a picture of “lines of force” (energy) in a defined “field”. But it tells us no more about what energy _is_ than Thales tells us what his “moving power” is. Dr. Steinmetz tells us that “energy is the only real existing entity, the primary conception, which exists for us because our senses respond to it” (_Op. cit._, Page 23). For Thales the universal “moving power” of nature operates _on_ or _in_ all matter; for the physicist of today the moving power (energy) is matter—man’s perception of matter being the response of his senses to the vibrations of energy. “All sense perceptions are exclusively energy effects,” and “energy is the only real existing entity.”

Thales may or may not have considered the cosmos as “matter” _and_ “soul” or “moving power”. In any event the pre-Socratic Ionian philosophers recognized no distinction between matter and soul in our modern sense. The moving power of nature (soul) was as much a material substance as gross matter itself, only more rarefied, more elusive. It was equivalent to the “energy”—electricity—of modern science.

Here we have, then, the answer to the question: “What is electricity?” It is _energy_—“the only real existing entity, the primary conception, which exists for us because our senses respond to it.” “All sense perceptions are exclusively energy effects.” This is the answer to the question: “What are the Hertzian waves, used in ‘wireless’?” It is the answer also to the question: “What is light?” as well as “What is electricity?” By carrying the explanation of the beam of light and the electromagnetic wave (like that of the radio communication station or that surrounding a power transmission line) back to the _energy_ field (or, less accurately, the field of force), we have carried it back, as Dr. Steinmetz well declared, as far as possible, “to the fundamental or primary conceptions of the human mind, the perceptions of the senses.”

All that we know of the world is derived from the _perceptions of our senses_, which are for us the only _real facts_, all things else being conclusions from them; and “all sense perceptions are exclusively _energy_ effects.” Electricity is an energy effect, perceived by our senses. No other definition or explanation can or need be given, since _energy is the primary conception_. And this explains also what matter is, since _energy_ and _matter_ are interchangeable—or equivalent—terms. What we call electricity is one of the _effects of energy_ on our senses. In itself, it _is_ energy, the stuff that matter is made of; at once the “moving power” and the thing moved.

Everything has been said that can be said now as to what electricity _is_: our concern in the remainder of this volume will be to discover what electricity _does_ and how it acts.

The reader of this little book who may be more or less familiar with larger volumes dealing with electricity, energy, electrons, electromagnetic waves or oscillations, magnetic and dielectric fields (usually combined), light-waves, etc., will notice that no mention has been made of the classical ether hypothesis, the universal _plenum_ in which energy is said to be stored, and in which transverse waves of light are said to occur, ether atoms or vibrations moving at right angles (perpendicularly) to the light-beam.

Now, transverse waves can exist only in rigid (solid) bodies. The universal ether of space, referred to in the text-books, must—for reasons which I need not discuss here—be a solid body of a rigidity much greater than that of steel, while at the same time possessing a very great elasticity so that bodies (such as the planets) moving through it meet with no resistance, no friction. The electron theory of Lorentz, Larmor, Thomson, Lodge and others is based upon the assumption that such a _plenum_, or medium, is a real substance. As a matter of fact, it is not known that any such medium (or ether) does exist, and it is now recognized that while light is a _wave_, a periodic phenomenon, like an alternating current, it is not necessarily a wave _motion_ of something or in something, any more than it is necessary to assume the alternating current or voltage wave to be a motion of matter.

Electrical engineers make no assumption regarding the existence of an ether filling all space and interpenetrating all matter—have no need for an ether as the hypothetical carrier of the electric wave. And just so the physicist of today has no real need for the classical assumption that the light-wave is a wave motion of or in something of great rigidity yet highly elastic and frictionless, filling all space. Light is now known to be a high-frequency electromagnetic wave, and cannot logically be considered as a wave motion of a hypothetical ether. “The ether thus vanishes, following the phlogistin and other antiquated conceptions.”[2] As Prof. A. S. Eddington remarks in his “Report on the Relativity Theory of Gravitation” (1920), “Light does not cause electromagnetic oscillations; it _is_ the oscillations.”

We know nothing whatever about the so-called ether of space; but we can formulate very clearly “The Principles of Electricity” without the aid of that hypothesis.[3]

[1] If a light piece of iron is placed near a magnet, it moves to the magnet and clings to it; but if the magnet is the lighter of the two bodies, it moves toward the piece of iron.

[2] Steinmetz, Dr. Charles P., “Four Lectures on Relativity and Space,” Pages 21-22, London and New York, 1923. See Lecture II, “Conclusions from the Relativity Theory,” Pages 12-45. See also, Campbell, Dr. Norman R., “Modern Electrical Theory. Supplementary Chapters: Relativity,” Cambridge University Press, 1923.

It was long ago observed that if glass is rubbed by silk, or a piece of sealing-wax or hard rubber by fur or wool, an effect occurs similar to that noted by Thales when amber is rubbed by similar materials—i. e., light bodies such as bits of dry paper, pith, etc., will cling to the surface of the substance. After coming in contact with the attracting substance, the bits of paper, straw, etc., are then repelled.

If a ball made of pith be suspended at the end of a silk thread, and a glass rod which has just been rubbed with silk be brought close to the ball, the pith-ball immediately flies to the rod, clinging to it for a time. Then it jumps away, and instead of hanging vertically, seems to be pushed away from the glass by a mysterious force. A second ball, treated like the first, and brought near the first, is violently repelled. But if one ball is charged from the glass and one from the wax, they attract instead of repelling each other. Two pieces of glass or two pieces of wax repel each other.

A similar attraction and repulsion was early observed between the poles of the magnet. This influence seems to be transmitted by some invisible agency or medium across the intervening space between the bodies, and in this respect the force does not differ from that acting between the moon and the earth, or the earth and the sun. And just so, if a light piece of iron is placed near a magnet, it moves to the magnet and clings to it; but if the magnet is the lighter of the two bodies, it moves toward the piece of iron.

Although Thales had attempted to explain the cause or nature of magnetic attraction as long ago as the end of the seventh century B. C., or in the first quarter of the sixth century (about 2,500 years ago), it was not until the year 1582 A. D. that Dr. William Gilbert (1540-1603), of Colchester, physician to Queen Elizabeth, made the first experimental study of magnetic phenomena. It is to Dr. Gilbert that we owe the name _electricity_ as applied to this force, derived from his _vis electrica_.

By 1600, Dr. Gilbert had published his epochal work “_De Magnete_”, which not only contained the first rational treatment of magnetic and electrical phenomena, but was also virtually the first scientific work published in England. It is to this truly great treatise that must be traced the beginnings of the science of electricity.[4]

Throwing aside, as useless, mere philosophical speculation as to the nature of magnets, Gilbert explained in his book how practical experiments should be carried out. He insisted that it is to nature herself that we must apply for the answers to problems in “natural history”. Gilbert’s particular objective was not, however, discovery of the laws of magnetism or electricity; what he most desired to learn was _the composition of the earth_: he wished to know through actual research just what is its innermost constitution. His experiments led him to the conclusion that _the earth is a magnet_. It may, indeed, be considered a huge spheroidal lodestone.

Gilbert told his readers to take a piece of lodestone (natural magnetic iron) of convenient size, turn it on a lathe to the form of a ball, then place on the _terella_ (as he called the spherical lodestone) a piece of iron wire. It will then be observed that the ends of the wire “move round its middle point.”[5]

Lodestones, fragments of magnetite (Fe_{3}O_{4}), are said to have been first discovered at Magnesia, in Asia Minor,—hence the word _magnetism_. Some of the earliest references to the lodestone relate to its property of lying in a north-and-south direction when an elongate stone is freely suspended, one particular end always pointing northward, just as the great magnet the earth, or the mariner’s compass-needle, has two opposite magnetic poles. The location of the poles of a disk-shaped stone is readily found by turning it round in the presence of a compass-needle.[6]

Iron and steel are more strongly magnetic than any other metals. While only one kind of iron ore is naturally magnetic—forming magnets—the property of magnetism may always be given to any kind of iron or steel. One need only strike an iron bar while it is lying in a north-south position, or rub the iron with a magnet, and it becomes a magnet. If it is desired to make a _permanent_ magnet, steel must be employed. A compass-needle is therefore made of magnetized steel. If balanced upon a pivot, the positive pole of the needle will point (roughly) towards the earth’s north geographical pole.[7]

A compass-needle is also a “dipping needle”, unless the suspended magnetized needle lies about half way between the earth’s magnetic poles. The north magnetic pole lies below the earth’s surface—at an unknown depth—at the extreme northeastern corner of the continent of North America; and the corresponding south magnetic pole on the edge of the Antarctic continent—King George’s Land—about 2,300 miles south of Australia. These magnetic poles do not correspond even roughly with the geographic poles, nor does the magnetic equator by any means correspond with the geographic equator.

Only a small section of the magnetic equator runs north of the true (geographic) equator—e. g., from the coast of Brazil to the coast of Kamerun (Africa).

According to Prof. T. J. J. See, “the whole magnetic system has been pushed southward 200 miles by bodily displacement of both poles towards the ocean hemisphere.” This eminent physicist-astronomer also stated (in 1922) that his researches led him to the discovery that the two magnetic poles are at unequal depths in the earth, the North Pole being much deeper than the South Pole, “with the result that the total magnetic forces in the southern hemisphere are considerably stronger than in the northern hemisphere.”[8]

It was long ago discovered that if one starts northward from the magnetic equator, the compass-needle soon begins to dip downward (and northward). At the southern border of the United States, the downward inclination amounts to about 57 degrees. At the borders of North Dakota and Maine the dip is about 76 degrees. By the time Hudson Bay is reached the needle assumes a vertical position. This means that it is here suspended immediately over the north magnetic pole itself. At the magnetic equator in Peru, a needle suspended by a thread is exactly balanced. Dr. See states that at the North and South Poles there is a downward pull—by the magnetic force—of just one millionth of the gravitational force, while in Peru the total magnetic force is precisely one ten millionths of gravitation.

It has been found that both the North and the South Poles are anything but fixed in position. They “wander about in their subterranean region”. In the course of centuries, the compass-needle swings from west of north, and then to the east. Even the amount of the dip slowly changes, in a periodic way, and at every point on the earth. For example, in 1576, the north end of the needle at London dipped at an angle of 71 degrees 50 minutes. By 1720 the angle had increased to 74 degrees 42 minutes—almost up and down. Since then, the dip at London has continually decreased. At the present time we are puzzled by the fact that the inclination of the dip is 66½ degrees at London and more than 70 degrees at Washington.

It has long been known that variations in magnetic declination of the delicately mounted needles, in observatories, are directly correlated with solar disturbances. The late Dr. A. Wolfer (sometime director of the Zurich Observatory) was the first to show us how closely the curve of the sun-spot activity rises and falls with the fluctuations of magnetic declinations.

Before attempting to explain the peculiarities of magnetic action in terms of the modern electromagnetic theory, it will be well to recall certain stages of progress in the development of this theory. This plan will permit elucidation of the theory itself by “easy steps”.

[3] Cf. Whittaker, E. T., “A History of the Theories of the Ether and Electricity from the Age of Descartes to the Close of the Nineteenth Century,” Dublin and London, 1910. See also, Comstock and Troland, “The Nature of Matter and Electricity,” New York, 1917; Steinmetz, Dr. Charles P., “Elementary Lectures on Electric Discharges, Waves and Impulses and Other Transients,” New York, 1914; and Starling, Dr. Sydney G., “Electricity,” London and New York, 1922.

[4] On the Continent, experimental work in other fields was already in progress, thanks to the genius of Descartes, Galileo and other founders of modern science. Gilbert, like Harvey, spent some years in Italy, coming under the direct influence of the great Italian physicist-astronomer-physician Galileo. Harvey was in Padua (1598-1602) during Galileo’s professoriate. The introduction of scientific methods in England at this time may well be credited to Italian and French influences.

[5] Gilbert’s book is usually referred to simply as “The Magnet,” but the full title is: “Concerning the Magnet and Magnetic Bodies, and Concerning the Great Magnet the Earth: A New Natural History (Physiologia) Demonstrated by Many Arguments and Experiments.”

[6] Magnetite does not always possess polarity. It is called “lodestone” only when it does. It occurs not only in the form of more or less massive stones, but also as loose sand and in earthy forms.

[7] The fact that a lodestone possesses two “poles” was discovered in the thirteenth century by Petrus Peregrinus, of Picardy, while he was experimenting with a spherical lodestone and a needle.

[8] From notes taken at a lecture by Dr. See before the California Academy of Sciences in 1922. Dr. See, in charge of the United States Naval Observatory at Mare Island (California), presented in the lecture “A New Theory of the Ether,” in which he outlined the grounds upon which he based his new theory of a direct connection between magnetism and universal gravitation. It is highly interesting, in this connection, to learn that Dr. Albert Einstein, in collaboration with Professor Eddington (of Cambridge)—working on the principle of Relativity—has discovered a connection between the earth’s power of attraction (gravitation) and electricity.

PIONEERS IN ELECTROMAGNETIC THEORY

The Danish physicist, Hans Christian Örsted, professor of natural philosophy at the University of Copenhagen, showed us, more than a century ago, that a magnetic needle can be deflected by an electric current. He had been led by theoretical considerations to assume that there must be a correlation between electric and magnetic forces. While yet a young man, Örsted endeavored by persevering experimentation to prove the correctness of his theory. While he did not expect a parallel action of the two forces, he was firmly convinced that magnetism and electricity were inseparable twins.

He noted that both heat and light radiated from a conductor when heated to incandescence. He also assumed that magnetic forces are radiated from a conductor traversed by electricity.

In 1820, while lecturing before his class, he became convinced that the apparatus he was then using could be made to demonstrate the correctness of his views. He asked his pupils to accompany him to his laboratory, where, as he predicted, a slight deflection of the magnetic needle, turned at right angles to the electric current, was shown when placed close to the copper wire. Some months afterwards, with a stronger current (made up of twenty cells), he obtained much more intense effects. Investigating these in detail, he found that they met all the requirements of his theory. So, on July 21, 1820, he sent out to the scientific world his now famous circular, “_Experimenta circa effectum conflictus electrici in acum magneticum_” (Experiments on the effect of the electrical conflict in the magnetic needle).