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diff --git a/75464-0.txt b/75464-0.txt new file mode 100644 index 0000000..de704a1 --- /dev/null +++ b/75464-0.txt @@ -0,0 +1,1754 @@ + +*** START OF THE PROJECT GUTENBERG EBOOK 75464 *** + + + + + + Transcriber’s Note + Italic text displayed as: _italic_ + + + + + LITTLE BLUE BOOK NO. 133 + Edited by E. Haldeman-Julius + + Principles of + Electricity + + Maynard Shipley + + + HALDEMAN-JULIUS COMPANY + GIRARD, KANSAS + + + + + Copyright, 1925, + Haldeman-Julius Company. + + + PRINTED IN THE UNITED STATES OF AMERICA + + + + +PRINCIPLES OF ELECTRICITY + + + + +CONTENTS + + + Chapter Page + + 1. “What Is Electricity?” 5 + + 2. Magnetic Phenomena 13 + + 3. Pioneers in Electromagnetic Theory 19 + + 4. Theories of Electricity 30 + + 5. Modern Magnetic Theory 41 + + 6. Proofs that Electrons Are Atoms of Electricity 44 + + 7. The Discovery of Wireless Telegraphy 55 + + + + +PRINCIPLES OF ELECTRICITY + + + + +CHAPTER 1 + +“WHAT IS ELECTRICITY?” + + +Many persons who have devoted no time to the study of physics wonder +what the force is that drives the street-car along—turning its wheels, +while at the same time furnishing incandescent lamps (light) for the +passengers. They have been told, of course, that the “power” used is +“electricity”, generated by dynamos “at the power-house”, and conveyed +to the rapidly moving car by the overhead wire. + +“Electricity: yes, but what is electricity?” This is a natural and +perfectly legitimate question for a layman to ask. + +Scientists and philosophers are asking the same question. But they +understand quite well that it is like asking: “What is matter?” Very +probably the average inquirer does not ask the question, “What is +electricity?” in the same spirit. We can answer one question no better +than the other, if the ultimate nature of either matter or electricity +is what the inquirer has in mind. + +For matter, in the last analysis, is electricity. Yet the same person +who might ask: “What is electricity?” would not think of asking: “What +is matter?” He thinks he knows what matter is—his common sense tells +him that _matter is what it appears to be_. “Matter’s matter, and +there’s an end of it.” + +And just so the physicist insists upon his common-sense right to +reply: “Electricity is electricity.” It is what it appears to him to +be. And it appears to be a form of _energy_, or a _mode of +motion_. + +Thales, the reputed founder of Greek science and philosophy, would +call electricity “the soul of the universe”, because it “endows all +things with motion”. This “soul”, interpenetrating all matter—if not +constituting it—is by nature always moving—it is self-moving; motion +is part of its very essence. In the lodestone, said Thales, “it moves +iron.”[1] + +As has been said so many times before, Thales was the first to call +attention to the fact that amber (fossilized resin), when rubbed +with wool or fur, possesses the curious property of attracting small +particles, such as straw, pith, lint, dried leaves, etc.;—though there +is no reason to suppose that he was the discoverer of this phenomenon. +He called the amber _elektron_; and today we call the indivisible +corpuscles, or natural unit charges of negative electricity, +_electrons_—the true _atoms_ of electricity. + +But hard rubber, or sealing-wax, is just as “mysterious” as the +lodestone (magnetite—natural magnetic iron). Rub the sealing-wax with +fur, and it will exhibit all the peculiar properties of the lodestone. +Rub glass with silk, and it, too, becomes a lodestone in effect. The +ancient Greek philosophers could not explain these phenomena in precise +terms. + +Empedocles (born between 500 and 480 B. C.) accounted for the +attraction of iron to the magnet on the hypothesis that “emanations” +or “effluences” from the magnet penetrate into the “symmetrical pores” +of the iron, drawing the iron itself and holding it fast. The concept +“electricity” was unknown to the Greeks. But it is possible that +Empedocles had in mind some such “effluence” or “emanation” as the +“fluid” electricity of Benjamin Franklin (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] + + +FOOTNOTES: + +[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. + + + + +CHAPTER 2 + +MAGNETIC PHENOMENA + + +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”. + + +FOOTNOTES: + +[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. + + + + +CHAPTER 3 + +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). + +Örsted showed, furthermore, how changes in the position of the magnetic +needle occurred with variation of the position of the conductor +(copper wire) in regard to it. He demonstrated also that the magnetic +effect was not weakened by insulators—that it would penetrate various +materials, whether these were conductors of electric currents or not. +He showed that the magnetic field created by the electric current does +not have any influence on a needle of non-magnetic material—i. e., +brass, glass, etc. It is, in fact, chiefly in the fact that it cannot +be insulated that magnetism differs from electricity. It will freely +pass through air, stone, mica, glass, clay, brick, or any insulating +material. + +It is well worthy of especial mention that Örsted employed the term +“_conflictus_” to designate the electric current, many decades +before the origin of the electron theory of matter. For, on modern +theories of electricity, it is the movement to and fro of electric +particles (electrons) through the conductor, and their impact +(“_conflictus_”) that produces what we call electrical phenomena. + +Örsted’s fundamental discovery of the mutual effects between +electricity and magnetism led to further discoveries which made +possible the construction of telegraph and telephone instruments, +since these depend on the fact that _an electric current can produce +magnetism, and that magnetism can produce an electric current_. + +If we wind around an iron bar a number of turns of insulated wire, +and an electric current is allowed to pass through the coil, the bar +becomes a strong electromagnet. But it remains a magnet only as long +as the current is passing. Now, the magnetic effects obtained with +the electromagnet are identical with those obtained from a permanent +magnet—such as the familiar horseshoe magnet, commonly seen on the +flywheel of the Ford automobile, or in the ordinary telephone generator +for calling up “Central”. In the case of a telegraph instrument, it is +important that the iron is a temporary magnet. On the other hand, a +permanent magnet is an essential part of every Bell telephone receiver. +This permanency is secured by employing a bar of steel instead of a +piece of iron—a temporary magnet. + +The power produced from a dynamo—or electric generator—depends +upon the fact that when a magnet is put into a coil of wire, only +a momentary current of electricity passes through the wire, in one +direction. If the magnet is withdrawn, a current starts in the opposite +direction. Copper wire coiled about an iron core forms the “armature” +of the dynamo. The rotating coils are said to “cut the magnetic +field.” On this principle of electricity, intense electric currents +are produced, furnishing the “power” for the electric motors in +electric cars, elevators, musical instruments, etc., and for electric +lights—incandescent and arc. + +Dynamos may contain either permanent magnets or electromagnets. They +produce the magnetic field in which the “armature” or conductor—the +coils of wire wound around the iron core—rotates. A machine with +permanent magnets is usually termed a _magneto_, and is never +made in large sizes. The current for the electromagnets may be +derived wholly from an outside source, or part of the current which +it generates may be used for that purpose. The current generated in +the armature winding is alternating, but may be rectified to a direct +current by a _commuter_ if desired; otherwise it is conveyed to +the line circuit by _collector_ or slip rings and brushes. + +We owe much of our knowledge of magnetism and electricity to Michael +Faraday (1791-1867), who brilliantly covered the whole field of these +sciences. Faraday was distinguished alike as a chemist and as an +experimenter in electricity and magnetism. + +Örsted had shown that magnetism could be produced by a current of +electricity, but it remained for Faraday to produce current electricity +by a magnetic “field of force”, thus laying the foundation for those +modern industries which derived motive force for their machinery from +the gigantic dynamos of our “power houses”. + +But I must here introduce a few facts concerning the contributions +to electric theory and practice of the great French mathematician +and physicist, André Marie Ampère (1775-1836). His discoveries in +electrodynamics aided greatly in laying a broad foundation for this +science. Very notable was the influence exercised by Ampère on the +development of electrodynamics. And it was he who first clearly +established the fact that magnetic action is a peculiar form of +electromotive action, and that, in phenomena of this class, “action and +reaction are equal and opposite.” + +From these considerations it was natural for him to suppose that +magnetism might be made to produce electricity, as it had already been +shown that electricity might be made to imitate all the effects of +magnetism. Numerous attempts were made to effect this predicted result, +but for some years all such efforts proved to be fruitless. + +Meanwhile the French physicist and astronomer, François Arago +(1785-1853), was also conducting experiments with the object of +producing electricity by magnetism. One of his experiments actually +involved the effect sought, but it was not clearly recognized. Arago +observed that the rapid revolution of a conducting plate in the +neighborhood of a magnet gave rise to a force acting on the magnet. But +it was not recognized by either Arago or other physicists of the day +that the forces involved were electric currents—produced by the rapidly +revolving conducting plate. + +Faraday, in 1831, after several years of preoccupation with other +problems, returned to his task of discovering electrodynamical +induction, begun in 1825. After a number of fruitless efforts, he was +finally rewarded with success, but not in the form which had been +anticipated. It was observed that at the precise time of making or +breaking the contact which closed the galvanic circuit, a momentary +effect was induced in a neighboring wire, which, however, disappeared +instantly.[9] + +Faraday then discovered that a similar effect could be induced +merely by moving the wire nearer to or farther away from the closed +circuit—instead of suddenly making or breaking the contact of the +“inducing circuit”. Later he found that the effects were increased by +the proximity of soft iron, and that when the soft iron was affected by +an ordinary magnet instead of the voltaic wire, the same effect still +recurred. The momentary electric current was produced either by moving +the magnet or by moving the wire with reference to the magnet. Finally, +it was found that the earth itself might be substituted for a magnet, +not only in this experiment but also in others. Mere motion of a wire, +under proper conditions, produced the effect. + +Here, then, was the true explanation of Arago’s experiment: by the +rapid revolution of the plate the momentary effect became continuous. +Without using the magnet, a revolving plate became an electrical +machine. A revolving globe was found to exhibit electromagnetic action, +the circuit being complete in the globe itself without the addition of +any wire. It was later found by Faraday that mere motion of the wire of +a galvanometer produced an electrodynamic effect upon the needle.[10] + +Meanwhile, Ampère, “by a combination of mathematical skill and +experimental ingenuity, first proved that two electric currents act +on one another, and then analyzed this action into the resultant of a +system of push-and-pull forces between the elementary parts of these +currents.”[11] + +Örsted having shown that electric currents produced certain effects on +magnets without being in actual contact, and Ampère having demonstrated +that magnets can in their turn be supplemented by electric currents,—a +magnetic needle being deflected not only by a current passing through a +wire, but also by another magnet brought into its neighborhood, and two +electric currents acting on one another at a distance—the question now +arose as to whether or not electrical attraction and repulsion could be +reduced to an action at a distance proportional to the inverse square +of the distance. + +As early as 1773, Henry Cavendish (1731-1810)—one of the foremost +chemists and experimentalists of his day—answered this question +affirmatively by experiment.[12] Coulomb (1736-1806)—inventor of the +torsion balance—showed that ponderable matter charged with electricity +followed the same formula for attraction and repulsion as gravitating +bodies did. Poisson (1781-1840) worked out the difficult mathematics of +fluids actuated by repelling forces depending on the inverse square of +the distance. Laplace (1749-1827) had very early become convinced that +the actions of ponderable substances in which electric currents were +flowing could be reduced to an action at a distance proportional to the +inverse square of the elements of the electric current. + +Faraday regarded the electric field as full of lines of electric force, +in a state of tension, and naturally repelling each other. To him, as +to a number of his contemporaries, the idea of “action at a distance” +was repugnant; though such a possibility seemed to be indicated by the +action of gravitation—the relation of the forces between two charged +bodies to the distance between them being very similar to that of the +gravitational forces between two bodies to the distance between them. +But Faraday, like the great Descartes long before him, rejected the +theory of action at a distance in favor of “action through a medium.” + +Ampère had sought for some sort of mechanism for the transmission of +electromagnetic currents. His own discoveries and those of Örsted +led him to formulate the hypothesis that the field in the vicinity +of a magnetic body is produced by a number of exceedingly small +circular currents which flow undamped in or around the molecules +and that magnetization consists merely of the bringing of these +molecular currents into a parallel direction. But it was difficult for +some physicists, even in Ampère’s day, to accept the hypothesis of +undiminished currents _possessing no resistance_. + +If we transform the idea of the “molecular currents” of Ampère into +the language of today, substituting for these molecular currents +electrons revolving in atoms, it can be shown that the great French +scientist was substantially correct in his assumptions. In 1915 Dr. +Albert Einstein and W. J. de Haas astonished the world of physicists by +showing experimentally—by means of a most ingenious apparatus—that the +“molecular currents” or revolving electrons really exist. + +In 1919, Professor Kramerlingh-Onnes, at the University of Leyden, was +able to produce what he called _imitations of ampere currents_—i. +e., “undiminished currents producing no resistance.” It was +demonstrated that the resistance of pure gold and pure platinum differ +very little if at all from nil at low temperatures. But wires of these +metals, of absolute purity, are difficult to obtain, so mercury was +selected for the experiments. The resistance of the metal at the lowest +attainable temperature of liquefied helium,-271.5° C., (at a pressure +of 3 mm. of the mercury column), proved to be immeasurably small. The +resistance down to a position shortly below 4.2° K. (Kelvin’s absolute +scale) suddenly dropped from a measurable amount to a value practically +nil. It was found that the induced current remained in a state of +circulation, and that the decrease in the strength of the current +amounted to less than 1 per cent per hour, from which it followed that +the “time of relaxation” must amount to more than four days![13] + +At the absolute zero of temperature, it is supposed that the orbits of +electrons in atoms are perfect circles, whatever their paths may be at +measurable temperatures. This motion of the electrons remains when all +heat has disappeared, since it is not this motion of the revolution of +the electrons in their orbits that is associated with the energy of +heat. Heat is _a mode of motion of the atoms themselves_, not of +their contained electrons; though increase of heat doubtless results in +an increase in the average orbital velocity of the electrons. + +Since Ampère’s day we have learned at all events, that an electric +current means the flow of electrons, either from atom to atom, or +passing between the atoms, along conductors. In 1920, Lord Kelvin came +to the conclusion that at the absolute zero resistance of metals must +be infinitely great, the degrees of dissociation of the electron being, +he supposed, nil at the zero hour. If any free electrons remained, he +believed they would lose their power of motion, condensing like a vapor +upon the metal atoms and freezing fast to them (to borrow a phrase +from Kamerlingh-Onnes). The experiments of the celebrated Holland +physicist show that the resistance of metals decreases with lowering of +temperature, and would probably become nil at the absolute zero with +employment of a perfectly pure platinum wire. If this is true, then +would a current of electricity, once set up in a conductor, continue +forever? + + +FOOTNOTES: + +[9] _Philosophical Transactions_, Page 127, 1832; First Series, +Article 10. + +[10] One of the first electrical experimenters to devise the instrument +known as a “galvanometer” was Professor Schweigger, of Halle. There are +now eight or more varieties of this instrument (or apparatus) in use. +It enables the investigator to measure extremely minute electrodynamic +actions, or the very weakest intensity of an electric current, as well +as to detect its presence or direction, usually by the deflection of a +magnetic needle. + +[11] Maxwell, Clerk, “On Action at a Distance,” (_Scientific +Papers_, Vol. II, Page 317). + +[12] The scientific papers of Cavendish were published (in 1879) +under the title, “The Electrical Researches of the Hon. Henry +Cavendish,” edited by Clerk Maxwell. Cavendish anticipated many later +investigations of British and Continental writers, including Ohm’s +law—i. e., the proportionality between the electromotive force and +the current in the same conductor; and anticipated also Faraday’s +discovery of the specific inductive capacity of different substances, +even measuring its numerical value in several substances. He had also +arrived at the conceptions of electrical capacity and of “potential.” + +[13] See _Die Naturwissenschaften_ (Berlin), January 28, 1921. + + + + +CHAPTER 4 + +THEORIES OF ELECTRICITY + + +The science of electricity is based upon observation of those phenomena +of attraction and repulsion which are comprehended under the term +_electrostatics_. Statical electricity, so named from a Greek +word (statikos), which means “causing to stand (or stay),”—also called +_frictional electricity_—is the electricity of stationary charges +caused by rubbing together unlike bodies, such as glass and silk (noted +in Chapter II). In such cases equal and opposite charges of electricity +are always produced. The term _statical electricity_ applies +properly, however, to the electricity of all stationary charges, +however produced. + +The electricity upon the surface of glass is called positive +electricity; that upon rubber, negative electricity. When silk is +rubbed upon glass it receives a negative charge from the glass and +confers a positive charge upon the silk. Wool or fur rubbed on wax or +rubber receives a positive charge in exchange for a negative charge; +“equal and opposite charges of electricity are always produced.” A +piece of glass and a piece of silk attract one another; two pieces of +silk or two pieces of glass or wax repel one another, because a body +which is positively charged is attracted by one negatively charged +and repelled by one negatively charged, and vice versa. A piece of +glass rubbed by a piece of silk, under suitable conditions, attracts +any other body with which it has not been in contact. The piece of +silk will do likewise. In all these cases, the attraction or repulsion +becomes weaker with increase of distance between the attracting and +repelling bodies. + +A third body which has been in contact with a piece of glass or a piece +of silk acquires to some extent the properties of the glass or silk +with which the third body has been in contact. And, conversely, the +glass or silk with which the third body has been in contact attracts +or repels with less force than before. If a hand is drawn over the +surface of an object after it has been charged with electricity, the +electricity disappears. It has been conducted through the hand and +the body to the earth. This phenomenon shows that the human body is +a _conductor_ of electricity. But most metals are much better +conductors. Moist air and damp wood are rather poor conductors, while +dry air, dry wood, porcelain, glass, hard rubber and sealing-wax are +_non-conductors_, or _insulators_. + +The term _dielectric_ is used in preference to _insulation_ +when reference is made to the property of transmitting +_induction_—a process quite distinct from ordinary transmission +of an electric current. In _electrostatic induction_, a body +electrostatically charged induces in a neighboring conductor a like +charge in the parts farthest from the charged body, and an unlike +charge in the nearer parts; the repelled like charge being removed by +connecting any part of the conductor momentarily with the earth, while +the bound unlike charge spreads over the whole surface of the conductor +and remains there even when the inducing body is moved away, or its +charge neutralized, if the conductor is properly insulated. + +_Dielectric strength_ refers to the ability of an insulating +material to resist rupture by high voltage, measured by the voltage +necessary to effect a disruptive discharge through it. _Insulation +resistance_, on the other hand, refers to the _ohmic_ +resistance _offered_ by an insulating material to an impressed +voltage, tending to induce a breakage of current through it. The term +_dielectric_ is used as a synonym for _insulator_, in the +sense that a charge on one part of a non-conductor is not communicated +to any other part. A charge given to a conductor spreads to all parts +of the body. A dielectric possesses the property of transmitting +electric force by _in_duction but not by _con_duction. A +charge on one part of a non-conductor or dielectric is not communicated +to any other part. + +Jeans suggests that since the presence of magnetic energy is always +associated with charges in motion, whereas electrostatic energy is +present when all the charges are at rest relatively to each other, it +may be proper to identify electrostatic energy with potential energy, +and magnetic energy with kinetic energy[14]—i. e., energy due to motion +of particles, rather than to energy of position, as of a coiled spring. + +Statical energy is distinguished from “current electricity” by the +fact that it accumulates on various bodies—is stored up—and as soon +as proper connections are made, it discharges instantly. Statical +electricity is used by physicians in electrical treatment of diseases +and in X-ray work. Machines have been constructed that will produce +very strong charges of statical electricity. + +If a sufficiently large charge of electricity accumulates upon an +insulated conductor in an electrical machine, it finally discharges +itself, passing through the air to the nearest body. A flash of +lightning is the result of an overcharge of statical electricity +accumulated upon cloud particles, and may pass from cloud to cloud +or descend to the earth.[15] Careful drivers of gasoline-tank wagons +allow an iron or steel chain to drag on the roadway from a metallic +connection, which conducts any surplus “static” to the ground. Failure +to provide for such an emergency sometimes results in a terrific +explosion with consequent loss of life. + +About the beginning of the nineteenth century, the Italian scientist, +Alessandro Volta (1745-1827),—and other physicists—discovered what +has been called, after Volta, _voltaic electricity_, a current +generated by chemical action between metals and different liquids as +arranged in a voltaic battery. The term “volt”—the electromotive force +which performs work at the rate of one joule per second (one watt) in +producing a current of one ampere—was similarly derived. + +It was learned that if two different metals, such as copper and +zinc amalgam, are placed in a weak acid solution (such as one part +H_{2}SO_{4} to four parts H_{2}O), and connected by a wire fastened +securely to the metals, a current of electricity (about two volts) will +pass through the wire. Carbon (a non-metal) and a metal upon which the +solution acts chemically may be used instead of two metals. There must +be chemical action between the liquid and one metal, or there will be +no current. Such a combination constitutes a _cell_, and two or +more cells make a _battery_. The current starts with the zinc, +is conducted by the solution to the copper, and thence by wire back +to the zinc, completing a _circuit_. The zinc constitutes the +negative pole (or electrode), the copper or carbon the positive pole +(or electrode). + +A cell frequently employed, where a weak (about 1.1 volts) but constant +electromotive force (“E. M. F.”) is required, is one devised by the +English physicist, John D. Daniell (1790-1845). In this cell a copper +sulphate solution containing a copper electrode is placed in contact +(by means of a porous wall or partition—usually an unglazed porcelain +cup) with a zinc sulphate solution containing a zinc electrode. The +zinc electrode is negative to the copper. At each electrode there +exists a potential difference between solution and electrode.[16] The +two electrodes being connected externally by a wire, a current of +electricity will flow through the wire from the copper to the zinc, and +zinc will dissolve at the anode (positive pole) and copper deposited +on the cathode (negative pole). The current in this case, as in the +preceding, is said to be produced by _voltaic action_ and the +cell is a primary battery. Voltaic action and _electrolysis_—the +process of chemical decomposition (or dissociation of compounds or +molecules)—by the action of an electric current produced externally (as +by a dynamo) and forced through the cell, are essentially identical +phenomena, and obey the same laws.[17] + +The familiar _dry cell_ contains no liquid which might be spilled, +and is very useful for certain purposes, as in automobiles, and in +operating door-bells. It is merely a voltaic cell whose chemical +contents are made practically solid (or paste-like) by the use of some +absorbent, as gelatine, sawdust, etc. In cells of the Leclanché type, +a mixture of plaster of Paris, flour, and sal ammoniac takes the place +of the solution which acts chemically upon one of the contained metals. +When used up, a dry cell must be replaced by an entirely new cell. Two +or more dry cells constitute a _dry battery_. + +We have seen that there are two types of charged bodies, of which +charged glass and charged silk are familiar examples. It was Dufay +(1699-1739) who discovered that there were two kinds of electricity, +one of which he called _vitreous_ (from glass) and the other +_resinous_ (from resin—amber). The terms “positive” and “negative” +in relation to electricity were first applied by Benjamin Franklin, +in 1756. To the electricity of the glass rod Franklin gave the name +“positive” and to that of the sealing-wax (or hard rubber, amber, etc.) +the name “negative.” These names are now universally in use—though +French physicists still speak of vitreous and resinous electricity. + +I have spoken also of a positive pole (or electrode) and a negative +pole (or electrode). The electrodes constituting the two poles of a +current are also called the anode and the cathode, the former being the +positive electrode and the latter the negative electrode.[18] + +When it was learned that electrical charges could be distinguished by +two opposing terms—positive and negative—it was natural to suppose that +there were two distinct kinds of electricity, or “fluids.” This was +the view taken by the French chemist Dufay. But the German electrician +Æpinus (1724-1802), in his great pioneer work, “_Tentamen Theoriae +Electriciatis et Magnetismi_” (An Attempt at a Theory of Electricity +and Magnetism—1759), considered the mathematical consequences of the +hypothesis of a single fluid, attracting all matter but repelling +itself. It soon became apparent, however, that he must assume either +the existence of two electrical fluids or the mutual repulsion of +material particles. He chose the latter theory. He explained the +phenomena of the opposite poles as results of the excess and deficiency +of a “magnetic fluid,” which was dislodged and accumulated in the +ends of the body, by the repulsion of its own particles, and by the +attraction of iron and steel, as in the case of induced electricity.[19] + +Æpinus, who was unquestionably one of the greatest physicists of the +eighteenth century, devised a method of examining the nature of the +electricity at any part of the surface of a body, by which means he was +enabled to ascertain its distribution. He found that the distribution +was in agreement with the attractions and repulsions which objects +exert when they are in the neighborhood—“electrical atmosphere”—of +electrified bodies. Today we say that such bodies are electrified by +induction. + +The Æpinian theory of electricity and of magnetism was modified and +presented in a new form (in 1788) by Coulomb, with two fluids instead +of one. His first task, before reducing the theory to calculation, +was to determine the law of the forces involved—not being satisfied, +for example, with Newton’s assumption that the attractive force of +magnetism is inversely to the _cube_ of the distance. Mayer in +1760, and Lambert a few years later, had found the law to be that of +the inverse square. Coulomb desired experimental confirmation of this +law before accepting it as established. This he secured by means of +his torsion-balance (about 1784).[20] + +It was in pursuance of this investigation that Coulomb brought to light +for the first time the fact that the directive magnetic forces which +the earth exerts upon a needle is a constant quantity, parallel to the +magnetic meridian, and passing through the same point of the needle +whatever be its position. + +Barlow, who had adopted the two-fluid hypothesis, showed that the +magnetic “fluids” were collected at the surface of spheres (of iron), +the surface being the only part in which there could be detected any +magnetism. He demonstrated that a shell of iron produces the same +effect as a solid ball of the same diameter. Poisson’s later analysis +(1824) showed that this was a consequent to be expected. Merz has well +said that what Laplace did for Newton was done by Poisson (1781-1840) +“for Coulomb’s elementary law of electric and magnetic action, and +on a still larger scale by Gauss, who worked out the mathematical +theory and applied it to the case of the magnetic distribution on the +earth’s surface. In England, already before Coulomb’s researches were +published, Cavendish had, likewise by a combination of experiment and +calculation, established the elementary formulae and properties of +electrical phenomena.”[21] + +Benjamin Franklin, the first American to gain international renown as a +scientist, adopted and developed a “one-fluid theory of electricity.” +On this supposition the parts of the fluid repel each other, and +the excess in one surface of the glass—for example—repels the fluid +from the other surface. The fluid itself was regarded by Franklin as +positive, the part of the other (negative electricity) being taken by +ordinary matter, the particles of which were supposed to repel each +other and attract the positive fluid, just as the particles of the +negative fluid did on the two-fluid theory. + +On both the two-fluid and the one-fluid theories, as we have seen, the +particles of the positive fluid repelled each other by forces varying +inversely as the square of the distance between them—as shown by both +Æpinus and Coulomb. This is true also of the particles of the negative +fluid. The particles of the positive fluid attracted those of the +negative fluid. In Franklin’s one-fluid theory it was the ordinary +particles of matter which attracted the positive fluid and repelled +one another. Both theories from their very nature imply, as Sir J. J. +Thomson long ago (1906) pointed out, the idea of action at a distance. + +In his very interesting book, “Matter and Energy” (1912), Professor +Soddy says: “All electrical phenomena can be explained as well on the +one-fluid as on the two-fluid idea, but our ignorance at the present +time as to whether there are two kinds of electricity or one is +fundamental. Until the question is settled, the hopes that have been +entertained that, through the study of electricity, we shall be able to +arrive at a philosophical explanation of matter, are likely to prove +unfounded.” + +Our modern view of electrification bears a close resemblance to the +one-fluid theory of Franklin, whether we suppose there is one kind of +electricity, or two kinds. At all events, if there be such a separate +force, or such units of energy, as “positive” electricity, it has never +been isolated, as have been the negative atoms or electrons. Negative +electrification is but a collection of these negative corpuscles +or unit charges. The particles of the “electric fluid” of Franklin +correspond to these electrons. + +“Instead of taking, as Franklin did, the electric fluid to be positive +electricity, we take it to be negative,” says J. J. Thomson, in +his “Corpuscular Theory of Matter” (1906). And “the transference +of electrification from one place to another is effected by this +motion of corpuscles from the place where there is a gain of positive +electrification to the place where there is a gain of negative. +A positively electrified body is one that has lost some of its +corpuscles.”[22] + + +FOOTNOTES: + +[14] Jeans, J. H., “Electricity and Magnetism,” Page 483, 1911. + +[15] Benjamin Franklin was first to show (in a letter to Peter +Collinson, written October 19, 1752) that lightning and electricity are +one and the same thing. He was also inventor of the lightning-rod. + +[16] “Potential” is analogous to level (or pressure) in hydrostatics or +mechanics. + +[17] For further explanation, see Shipley, Maynard, “The A. B. C. of +the Electronic Theory of Matter,” Little Blue Book Series, No. 603. + +[18] See, in this connection, Shipley, _Op. cit._ + +[19] A very similar hypothesis was read before the Royal Society by +Henry Cavendish, in 1771, the work of Æpinus being unknown to him at +the time. + +[20] By means of this instrument very minute forces can be accurately +measured, such as electrostatic or magnetic attraction and repulsion, +by the torsion (turning or twisting) of a wire or filament, the angle +of torsion being proportional to the amount of force exerted. + +[21] Merz, Henry, “History of European Thought in the Nineteenth +Century,” Vol. I, Page 362. + +[22] For a recent work on modern electrical theory, see Starling, +Sydney G., (head of the department of physics in the West Ham Municipal +College, London), “Electricity,” London, 1922. For the pioneer work of +Ampère, see his “_Theorie des Phenomenes Electrodynamiques_,” 1826. + + + + +CHAPTER 5 + +MODERN MAGNETIC THEORY + + +We have already shown how the magnetism of a magnet is converted into +electricity, by means of rotating coils cutting the lines of magnetic +force in the “field.” The energy used to drive the machinery may, of +course, be derived either from water-power or by steam. Gravity gives +energy to falling water; chemical energy produced by the oxidation +of coal becomes heat energy, which in turn causes the expansion of +steam, which produces energy of motion in a piston; and this motion, +transmitted to the parts of an engine to a dynamo, produces electrical +energy. When the electric current from the dynamo has been conducted +to any desired point by cables, another motor, acting in the opposite +sense, causes the electricity to change back again into the original +mechanical energy, less the loss due to imperfections in the operation. +Here we have, then a clear picture of what is meant by the phrase, +_transformation of energy_. + +But another question naturally arises at this point. We know that with +a finite quantity of magnetism we can produce an unlimited quantity of +electricity. Yet we add no new material, no source of supply, to the +dynamo. Let the rotating coils continue to cut the lines of magnetic +force in the magnetic field, and the magnetism of the magnet will be +transformed into current electricity—furnishing a literally exhaustless +supply from the great storehouse of nature. For us the energy of +the universe is infinite in quantity. The reservoir of energy is +exhaustless, and the dynamo is man’s open sesame. + +But just here the very interesting question arises: Is the +inexhaustible supply of electric current with the expenditure of a +limited quantity of magnetism fully explained by saying that it is due +to the rotational movement of the coil? Can the mere rotation of a +metal in a magnetic field actually _create_ an endless supply of +available energy? Not likely! As Dr. Gustave Le Bon well says: “Such a +metamorphosis would be as marvelous as transformation of lead into gold +by simply shaking it in a bottle. Another interpretation must be sought +for the phenomenon.” + +Now, a current of electricity is known to be a stream of electrons +(negative charges) flowing along or in a conductor; and an electron +is an atom of—_energy_. But where was this energy stored? “In +the all-pervasive ether,” say many physicists. “There is no ether,” +say others. The electromagnetic field represents energy storage _in +space_—not in a universal, incomprehensible, paradoxical something +called “ether.” + +A field of _energy_ is intelligible. It takes the place of the +conception of action at a distance and of the ether. No “ether” need +be postulated as the carrier of the field energy in space. It is its +own carrier. “Energy is the only real existing entity, the primary +conception, which exists for us because our senses respond to it” +(Steinmetz). + +“Lines of force,” says Dr. N. R. Campbell, the famous English +physicist, “are just lines of force, independent for their existence of +all surrounding bodies, and there is no more to be said about them.... +Our Electrical theory, so far from providing additional support for +the conception of the ether filling all space, does not require such a +conception at all.” + +Dr. Le Bon finds the exhaustless source of electricity in the interior +of atoms. The atoms in one pound of earth contain enough energy to run +all the factories, mills, railroads, etc., and light all the cities and +villages of the United States, for a month, Steinmetz tells us. “It +would,” he states further (“Relativity and Space,” Page 45), “supply +the fuel for the biggest transatlantic liner for 300 trips from America +to Europe and back. And if this energy of one pound of dirt could be +let loose instantaneously, it would be equal in destructive powers to +over a million tons of dynamite.” + +From the above statement, we may well understand Dr. Le Bon’s +interpretation of the work of a dynamo: “Matter being easily +dissociated and constituting an immense reservoir of intra-atomic +energy, it is enough to admit that the lines of force seized upon by +the conducting body (the coils), which cuts them and causes them to +flow in the form of an electric current, are constantly replaced at the +expense of the intra-atomic energy. This latter being relatively almost +inexhaustible, a single magnet can furnish an almost infinite number of +lines of force.” + +It can be shown that the kinetic energy of one kilogram (2.2 pounds) +weight of matter is about 9000 millions of millions of kilogram-meters, +or 25 thousand million kilowatt-hours (a kilowatt-hour = 1000 watt +hours). This means, in other words, that the quantity of energy in the +atoms of 2.2 pounds of ordinary matter is thousands of million times +greater than the energy of an equal quantity of coal, _released by +chemical combustion_. + +Estimating the total energy consumed during the year on earth for +heat, light, power, etc., as about 15 millions of millions (= +15,000,000,000,000) of kilowatt-hours, Steinmetz tells us that 600 +kilograms, or less than two-thirds of a ton, of “dirt,” if it could be +disintegrated into energy, would supply all the heat, light and energy +demand of the whole earth for a year. + +Several eminent physicists are now specializing on the problem of how +to liberate and control intra-atomic energy for man’s uses—or abuses. +Bearing in mind the present intellectual, moral and economic status of +our “leaders of thought” and their followers, and remembering that one +pound of common soil contains intra-atomic energy equal in destructive +power to more than a million tons of dynamite, let us hope that the +secret of releasing and “controlling” intra-atomic energy will not be +discovered in our day and age. + + + + +CHAPTER 6 + +PROOF THAT ELECTRONS ARE ATOMS OF ELECTRICITY + + +THE ZEEMAN EFFECT + +Heinrich Hertz demonstrated in 1887 that he could produce in the +“ether”—or at least in space—what are now known as “wireless waves,” +by allowing a charge of electricity to oscillate to and fro. Larmor and +Lorentz were, at the same time, endeavoring to formulate a theory which +would account for the production of the far shorter light-waves. + +Lorentz supposed that each atom contained one or more infinitesimal +particles, or electric charges (electrons), whose excessively rapid +vibrations caused the emission of light-rays. Maxwell showed that there +must be a close connection between light and electricity, a theory +converted into demonstrable fact by the work of Hertz. + +That there is a similar relation between light and magnetism was the +firm conviction of Faraday. In 1845, he placed a block of very dense +glass between the poles of the most powerful electromagnet produceable +at the time. Before turning on the switch, he allowed a beam of light +to pass through the glass, producing “polarization”—a modification +of light-rays resulting from their reflection (in this case from a +crystalline substance), imparting to the beam a definite direction—the +plane of vibration or plane of polarization. When the switch was +closed, permitting the flow of the electric current, which produced +the magnetic field, the beam of light was “rotated.” That is, the beam +of light was “plane-polarized” by the crystal, and “rotated” by the +magnetic field; i. e., now changed into two “circularly polarized” +rays, one a left-handed motion and the other a right-handed motion (in +the direction of the hands of a watch). + +This could be accounted for only on the theory that light is affected +by magnetism, since the beam was not rotated by the glass alone—in +itself a very important discovery. But the experiment did not yield +Faraday an answer to the question uppermost in his mind: namely, can +a magnetic field change the rate of vibration of a light-emitting +particle? That is to say, in effect, can a magnetic field cause a ray +of light to shift its normal place in the spectrum? + +It was not until 1862, seventeen years after the experiment just +described, that Faraday attempted to solve this important theoretical +problem. He now placed a sodium flame in front of the slit of the +spectroscope, which normally yields two characteristic yellow lines +(the D lines of the spectrum), and observed them with the best +spectroscope at his command, under the most powerful electromagnetic +field which he could produce. No change from the normal could be +detected. Other observers tried the same experiment, but with negative +results. We know that his theory was well founded, and that only the +lack of a better spectroscope and a more powerful magnet prevented his +discovery of what is now known as the Zeeman effect—a discovery which +has already thrown a flood of light on a number of difficult physical +problems.[23] + +Working with much more powerful apparatus, but following the same +method of procedure employed by the immortal Faraday, Dr. Pieter +Zeeman, of Leyden, succeeded, in 1896, in experimentally demonstrating +the close relationship between light and magnetism. Dr. H. A. Lorentz, +then Professor of Physics in the University of Leyden, now mathematical +physicist at the Norman Bridge Laboratory of Physics, Pasadena, +California, had predicted the nature of the change in the spectral +lines to be expected, and this knowledge was used by Dr. Zeeman as a +check on his results. + +Using a Rowland grating, instead of a less efficient prism +spectroscope, Dr. Zeeman found that when a relatively weak electric +current was applied, the two sodium lines were merely widened. In a +still more powerful magnetic field, each of the lines was decomposed +into two or three components, when the lines of force were parallel +to the line of sight.[24] Moreover, the rays of the components of +each line “were not those of natural light,” but were “polarized in +a characteristic way,” i. e., were circularly polarized in opposite +directions—“the direction of the vibration depending in a simple manner +on the direction of the magnetic lines of force.”[25] + +The same effect has more recently been produced in the case of the +spectral rays of nearly—if not quite—all the other elements. The +process, as described by Dr. George Ellery Hale, is very simple: “We +place our iron ore or spark between the poles of a powerful magnet, +and photograph its spectrum. The lines behave in the most diverse way, +some splitting into triplets, others into quadruplets, quintuplets, +sextuplets, etc. One chromium line is resolved by the magnet into +twenty-one components.... The distance between the components of a line +is directly proportional to the strength of the magnetic field.”[26] + +The meaning of this splitting and polarization of light-rays in the +magnetic field is that, as Lorentz had predicted, there are present +in the luminous vapor vibrating particles negatively charged, or +“electrons.” Measurement of the distances apart of the components of +the triple line reveals the relation between the charge and the mass of +the particles.[27] + +It is interesting to add that the disturbances in the magnetic field, +as observed by Zeeman, were precisely of the amount calculated by +Lorentz purely on theoretical grounds, and the mass of the electron +was found by this method to be 1/1840 that of the hydrogen atom. By +a different method, Sir J. J. Thomson obtained a value of 1/1800 the +mass of the hydrogen atom; while Dr. Robert A. Millikan, by means of +his famous “electrical balance,” derived a value of 1/1845 that of the +hydrogen atom.[28] + +In his monograph of 1913, Zeeman remarked that in discoveries of optics +“we may always cherish the hope that they will lead ultimately to +applications to astronomy.” So far as study of solar phenomena and the +Zeeman effect are concerned, this hope has been fully realized, and +attempts are being made to extend the applications of this method of +investigation to other stellar bodies. Of the general value of Zeeman’s +discovery, Dr. Hale writes: “The complex phenomena of the Zeeman effect +(as revealed in a comparative study, with powerful spectrographs, and +an intense magnetic field, of the lines of a long list of elements) +furnish material available for wide generalization, important in +their bearing on theories of radiation and atomic structure” (_Op. +cit._, Page 36). + +Discovery by Hale and his co-workers at Mount Wilson of the Zeeman +effect in sun-spots led to the very important conclusion that these +disturbances represent whirling vortices of electrons, producing a +magnetic field. “The strength of the magnetic field produced, which is +measured by the degree of separation of the triple lines, increases +with the diameter of the spot.... It has long been known that sun-spots +usually occur in pairs, and our study of the Zeeman effect indicates +that the two principal spots in such a group are almost invariably of +opposite polarity” (Hale, Op. cit., Pages 28-31). + +The sun, like the earth is now known to be a magnet, whose general +magnetic field is about 80 times as intense as that of the earth. At +the distance of the earth the solar magnetic field is not appreciable, +“since the effect of one pole counteracts the equal and opposite effect +of the other pole.” + +Were it not for our knowledge concerning the Zeeman effect, it would +not yet be known for a certainty that the sun is a vast magnetic globe, +since this fact could not be assumed to be a source of the sun’s +gravitational power. “Indeed,” says Dr. Hale,[29] “its attraction +cannot be felt by the most delicate instruments at the distance of +the earth, and would still be unknown were it not for the influence +of magnetism on light. Auroras, magnetic storms, and such electric +currents as those that recently deranged several Atlantic cables are +due, not to the magnetism of the sun or its spots, but probably to +streams of electrons, shot out from highly disturbed areas of the solar +surface surrounding great sun-spots, traversing 93 million miles of the +ether of space, and penetrating deep into the earth’s atmosphere.” + +By means of the famous 150-foot tower telescope at Mount Wilson, +which produces at a fixed point in a laboratory an image of the sun +about sixteen inches in diameter, the magnetic phenomena of sun-spots +are being studied to great advantage, the enlarged sun-spots making +possible separate observation of their various parts. “This analysis +is accomplished with a spectroscope 80 feet in length, mounted in +a subterranean chamber beneath the tower.” By this means the very +important discovery was made by Director Hale that the entire sun, +rotating on its axis, is a great magnet. “Hence,” says Dr. Hale, “we +may reasonably infer that every star, and probably every planet, is +also a magnet, as the earth has been known to be since the days of +Gilbert’s ‘_De Magnete_.’ Barnett has succeeded in producing +magnetism by rapidly whirling masses of metal in the laboratory” (Hale, +“The New Heavens,” Pages 69-70). + +More recently (October, 1922), Hale, Ellerman and Nicholson, all of the +Mount Wilson Observatory, have detected _invisible_ sun-spots by +searching for evidences of the Zeeman effect in promising regions, such +as areas of flocculi following a large spot. “A special polarizing +apparatus permits very small magnetic fields to be found by the +alternate widening to red and violet of the iron triplet Lambda 6173,” +say Hale and Adams (“Summary of the Year’s Work at Mount Wilson,” +Publications of the Astronomical Society of the Pacific, October, 1922, +Pages 269-70 [Vol. XXXIV, No. 201]). “The results confirm the view that +a spot represents a vortex, which becomes visible only when the cooling +due to the expansion (of gases) is sufficiently great to produce a +perceptible decrease in the brightness of the photosphere.” + +From what has been said, it is evident that Dr. Zeeman’s desire to +see the results of his discovery applied to the study of astronomical +problems has been fully realized. + + +THE STARK EFFECT + +Lorentz’s prediction regarding the effect of a strong magnetic field +on spectral rays, and the movements of electrons in the field having +been confirmed so brilliantly by Zeeman, it remained to ascertain what +effect, if any, would be exerted by electrical force on light-rays. + +The answer to this problem was given by Prof. Johannes Stark, at +Aix-la-Chapelle, in 1913, by his skillful demonstration of the +electrical decomposition of the spectral rays of hydrogen, helium and +lithium.[30] + +Stark’s task was a more difficult one than Zeeman’s, owing to the fact +that he had to deal with luminescent gases, which, being conductors, +exhaust the electrical field almost before any observations can be +made, even hurriedly. This condition gives rise to difficulties in +connection with the application of the electric field. But these were +very ingeniously met by employment of highly evacuated tubes and the +light emitted by the “canal rays”—positively charged particles similar +to the alpha rays.[31] Where the rays issue from the perforated +electrode (or “canal”), the conduction of electricity is weak, and +Stark was able to apply intense electric fields in a small space. It +was then found that the diffuse rays of the spectrum produced were +strongly influenced, while the “sharp” rays were less so. + +The attentive reader will note that this result was in marked contrast +with the _magnetic_ decomposition produced in the Zeeman +experiment, in which the rays did not differ one from another in +respect to the degree of their decomposition. In all the details there +is a difference between the electric and magnetic decompositions, and +analogy existing only in this, namely, that in both cases polarized +rays were obtained. In both cases the results produced were due +to disturbance of the _motions of electrons_, giving rise to +broadening, displacement or other modifications of spectral laws. Both +“effects” confirm the theoretical view of Maxwell, namely, that light +is an electromagnetic phenomenon. + +Faraday’s famous question is thus more than answered in the +affirmative: not only is the rate of vibration of “atoms” (electrons) +changed by a magnetic field, but also under the action of an +electrostatic field, producing _decomposition_ of certain spectral +lines, which are usually _polarized_, as in the Zeeman effect. + +As a result of his intensive investigations of the Zeeman effect, Dr. +Henri A. Deslandres, Director of the Astrophysical Observatory at +Meudon (a southern suburb of Paris), proposed a new general formula +which represents the series relationship of the component lines and +heads of bands both for emission and absorption spectra. According to +his experimentally-derived law, “the origin of these radiations may be +found in the transverse and longitudinal vibrations of the atoms.” + +The lamented Dr. P. S. Epstein, a gifted pupil of Sommerfeld, who—like +Mosely—fell a martyr to the World War, succeeded in applying the +quantum dynamics to the Stark effect, whereby the motions of the +electron in producing the H-beta (in the blue-green) and H-gamma (in +the violet) lines observed, “are accounted for with great accuracy” +(Loring, “Atomic Theories,” Page 67). + +It may be said in conclusion, that the most promising attempts fully +to explain the phenomena of the Zeeman and Stark effects seem to be +made from the point of view of Planck’s Quantum Theory of Light. On the +other hand, it must be admitted that there has not been, so far as I +can ascertain, any theory proposed which explains _all_ of the +phenomena involved. + + +FOOTNOTES: + +[23] For a good summary of the main results concerning the Zeeman +effect, see von Auerbach, Felix, “_Moderne Magnetik_,” Leipsic, +1921. An excellent account of the quantum treatment of the Zeeman +effect may be found in Chapter XV (Series Spectra) of Dr. N. R. +Campbell’s “Modern Electrical Theory, Supplementary Chapters,” +Cambridge University Press, 1921. + +[24] It seems that this phenomenon had previously been observed by +M. Fievez. (Cf. Michelson, Dr. Albert A., “Light Waves and Their +Uses,” Page 107.) “He thought that each separate line was doubled or +quadrupled.” Lockyer, in 1866, observed that some of the lines in a +sun spot spectrum were widened. Prof. Charles Young and W. M. Mitchell +observed that some of the lines were even double, but it was not +suspected that these phenomena were caused by a strong magnetic field +in sun-spots, brought about by free electrons being driven around +in a vortex movement. In fact, Mitchell referred to the doublets as +“reversals.” + +[25] Zeeman, “_Les Lignes Spectrales et les Theories Modernes_,” +_Scientia_, January 1, 1921, Page 18 (Vol. XIX, No. CV—I). + +[26] Hale, “Ten Years Work of a Mountain Observatory,” Pages 29-30, +Washington, D. C. (Carnegie Institution of Washington), 1915. See also, +Babcock, Harold D., “The Zeeman Effect for Chromium,” _Contributions +from Mount Wilson Observatory_, Vol. II, Paper No. 52; also “The +Correspondence between Zeeman Effect and Pressure Displacement for the +Spectra of Iron, Chromium and Titanium,” Arthur S. King, Loc. cit., +Paper No. 46; and “The Zeeman Effect on the Sun,” Adriaan van Maanen, +_Publications of the Astronomical society of the Pacific_, Page +24, Vol. XXXIV, No. 197 (February, 1922). + +[27] Zeeman, _Loc. cit._, Page 18. See also the classical +monograph by the same author, “Researches in Magneto-Optics,” London, +1913. + +[28] Millikan, _Physical Review_, 2, 143 (1913); “The Electron,” +1917 (revised edition, 1924). See also, _Proceedings of the National +Academy of Sciences_, 3, 314 (1917). + +[29] “The New Heavens,” Page 70, New York, 1922. + +[30] Cf. Stark, “_Die Atomionen chemischere Elemente und ihre +Kanastrahlenspektra_,” Berlin, 1913. See also, “_Elektrische +Spektralanalyse chemischen Atome_,” Leipsic, 1914. + +[31] Called “canal rays” by the German physicist, Eugen Goldstein, who, +in 1886, first obtained them by the use of a perforated cathode; that +is, he used a metallic tube for a cathode, through which tube, called +by Goldstein a “canal,” the rays issued. + + + + +CHAPTER 7 + +THE DISCOVERY OF WIRELESS TELEGRAPHY + + +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.” + + +FOOTNOTES: + +[32] See his “Experimental Researches in Electricity,” _Everyman’s +Library Series_. + +[33] Maxwell, James Clerk, “Treatise on Electricity and Magnetism,” +1873. + +[34] The theoretical investigation of the mode of discharge of a +condenser had been given by Sir William Thomson (later Lord Kelvin) in +1853, in the _Philosophical Magazine_ for June of that year. + +[35] When all the atoms and molecules of a substance vibrate in one +plane, e. g., as the plane of a train of waves would be if drawn +on this page, the wave is said to be _polarized_. Ordinarily, +light-rays are sent out from particles vibrating in different planes; +they may be vertical or horizontal, or diagonal, or they may move in a +curved path—circles or ellipses. Ordinary light-vibrations are mixed up +together, vibrating in all planes, and special devices—“polarizers”—are +required in order to separate any one particular vibration from the +rest. + +[36] Crehore, Dr. Albert C., “The Mystery of Matter and Energy,” Page +28, New York, 1917. + +[37] By means of an induction coil coupled to a circuit containing +capacity terminals, thus forming an “oscillatory circuit.” + +[38] Michelson, Dr. A. A., “Light Waves and Their Uses,” Pages 160-61. +The gap was closed during the year 1924, heat-waves being measured +which were of such great length as to merge into the shortest Hertzian +or “wireless” waves. + +[39] See an interesting article on this question in _Science and +Invention_, December, 1922, Page 744 (Vol. X, Whole No. 116). + +[40] Gernback, H., Editorial in _Science and Invention_, December, +1922. + + + + + Transcriber’s Notes + + pg 24 Changed: conducting plate in the neighborhod of a magnet + to: conducting plate in the neighborhood of a magnet + + pg 25 Changed: was affected by on ordinary magnet + to: was affected by an ordinary magnet + + + +*** END OF THE PROJECT GUTENBERG EBOOK 75464 *** |