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+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <title>
+      Principles of Electricity | Project Gutenberg
+    </title>
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+</head>
+<body>
+<div style='text-align:center'>*** START OF THE PROJECT GUTENBERG EBOOK 75464 ***</div>
+
+<div class="figcenter" style="width: 85%">
+<img src="images/cover.jpg" alt="">
+</div>
+
+
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+
+<table class="autotable">
+<tr>
+<td class="tdl">LITTLE BLUE BOOK NO.</td>
+<td class="tdr fs250" rowspan="2">133</td>
+</tr>
+<tr>
+<td class="tdl">Edited by E. Haldeman-Julius</td>
+</tr>
+</table>
+
+<h1>Principles of<br>
+Electricity</h1>
+
+<p class="center no-indent fs120">Maynard Shipley</p>
+<br>
+<br>
+
+<p class="center no-indent">HALDEMAN-JULIUS COMPANY<br>
+GIRARD, KANSAS
+</p>
+</div>
+
+
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<p class="center no-indent fs80">
+Copyright, 1925,<br>
+Haldeman-Julius Company.<br>
+<br>
+<br>
+<span class="smcap">PRINTED IN THE UNITED STATES OF AMERICA</span><br>
+</p>
+</div>
+
+
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<p class="center no-indent fs120">PRINCIPLES OF ELECTRICITY</p>
+</div>
+
+
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<h2 class="nobreak" id="CONTENTS">CONTENTS</h2>
+</div>
+
+<table class="autotable lh">
+<tr>
+<td class="tdl fs90">Chapter</td>
+<td class="tdr fs90">Page</td>
+</tr>
+<tr>
+<td class="tdl">1. “What Is Electricity?”</td>
+<td class="tdr"><a href="#CHAPTER_1">5</a></td>
+</tr>
+<tr>
+<td class="tdl">2. Magnetic Phenomena</td>
+<td class="tdr"><a href="#CHAPTER_2">13</a></td>
+</tr>
+<tr>
+<td class="tdl">3. Pioneers in Electromagnetic Theory</td>
+<td class="tdr"><a href="#CHAPTER_3">19</a></td>
+</tr>
+<tr>
+<td class="tdl">4. Theories of Electricity</td>
+<td class="tdr"><a href="#CHAPTER_4">30</a></td>
+</tr>
+<tr>
+<td class="tdl">5. Modern Magnetic Theory</td>
+<td class="tdr"><a href="#CHAPTER_5">41</a></td>
+</tr>
+<tr>
+<td class="tdl">6. Proofs that Electrons Are Atoms of Electricity</td>
+<td class="tdr"><a href="#CHAPTER_6">44</a></td>
+</tr>
+<tr>
+<td class="tdl">7. The Discovery of Wireless Telegraphy</td>
+<td class="tdr"><a href="#CHAPTER_7">55</a></td>
+</tr>
+</table>
+
+
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<p><span class="pagenum" id="Page_5">[Pg 5]</span></p>
+
+<p class="center no-indent fs150">PRINCIPLES OF ELECTRICITY</p>
+
+<h2 class="nobreak" id="CHAPTER_1">CHAPTER 1<br>
+<span class="fs70">“WHAT IS ELECTRICITY?”</span></h2>
+</div>
+
+<p>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.</p>
+
+<p>“Electricity: yes, but what is electricity?”
+This is a natural and perfectly legitimate question
+for a layman to ask.</p>
+
+<p>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.</p>
+
+<p>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 <em>matter is
+what it appears to be</em>. “Matter’s matter, and
+there’s an end of it.”</p>
+
+<p>And just so the physicist insists upon his<span class="pagenum" id="Page_6">[Pg 6]</span>
+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 <em>energy</em>, or a
+<em>mode of motion</em>.</p>
+
+<p>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.”<a id="FNanchor_1" href="#Footnote_1" class="fnanchor">[1]</a></p>
+
+<p>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
+<em>elektron</em>; and today we call the indivisible
+corpuscles, or natural unit charges of negative
+electricity, <em>electrons</em>—the true <em>atoms</em> of electricity.</p>
+
+<p>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.<span class="pagenum" id="Page_7">[Pg 7]</span>
+The ancient Greek philosophers could not explain
+these phenomena in precise terms.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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<span class="pagenum" id="Page_8">[Pg 8]</span>
+can produce magnetism and that magnetism
+can produce an electric current.</p>
+
+<p>We know <em>effects</em> 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.</p>
+
+<p>Today we say, in the words of Dr. Charles
+P. Steinmetz (“Relativity and Space”, Pages
+18-19):—</p>
+
+<p>“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.”</p>
+
+<p>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 <em>magnetic
+field</em>. A <em>field</em>, or <em>field of force</em>, 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<span class="pagenum" id="Page_9">[Pg 9]</span>
+energy, and this energy is stored in the space
+we call the field. Thus we can go further and
+define the field as ‘<em>a condition of energy storage
+in space exerting a force on a body susceptible
+to this energy</em>’.”</p>
+
+<p>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 <em>energia</em>, substitutes
+for “soul of nature” the single word <em>energy</em>.
+Aristotle declared that “not capacity, but energy
+... is the first principle anterior to and
+superior to anything else” (<cite>Metaphysics</cite> xii, 7:
+cf. also <cite>Physics</cite> ii, 9, 6).</p>
+
+<p>Modern science describes in more precise
+phrases what <em>occurs</em> 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 <em>is</em> 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” (<em>Op. cit.</em>, Page
+23). For Thales the universal “moving power”
+of nature operates <em>on</em> or <em>in</em> 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.”</p>
+
+<p>Thales may or may not have considered the<span class="pagenum" id="Page_10">[Pg 10]</span>
+cosmos as “matter” <em>and</em> “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.</p>
+
+<p>Here we have, then, the answer to the question:
+“What is electricity?” It is <em>energy</em>—“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 <em>energy</em> 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.”</p>
+
+<p>All that we know of the world is derived from
+the <em>perceptions of our senses</em>, which are for us
+the only <em>real facts</em>, all things else being conclusions
+from them; and “all sense perceptions
+are exclusively <em>energy</em> effects.” Electricity is
+an energy effect, perceived by our senses. No
+other definition or explanation can or need
+be given, since <em>energy is the primary conception</em>.<span class="pagenum" id="Page_11">[Pg 11]</span>
+And this explains also what matter is,
+since <em>energy</em> and <em>matter</em> are interchangeable—or
+equivalent—terms. What we call electricity
+is one of the <em>effects of energy</em> on our senses.
+In itself, it <em>is</em> energy, the stuff that matter is
+made of; at once the “moving power” and the
+thing moved.</p>
+
+<p>Everything has been said that can be said
+now as to what electricity <em>is</em>: our concern in
+the remainder of this volume will be to discover
+what electricity <em>does</em> and how it acts.</p>
+
+<hr class="tb">
+
+<p>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
+<em>plenum</em> 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.</p>
+
+<p>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<span class="pagenum" id="Page_12">[Pg 12]</span>
+<em>plenum</em>, 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 <em>wave</em>, a periodic
+phenomenon, like an alternating current, it is
+not necessarily a wave <em>motion</em> 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.</p>
+
+<p>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.”<a id="FNanchor_2" href="#Footnote_2" class="fnanchor">[2]</a>
+As Prof. A. S. Eddington remarks in his “Report
+on the Relativity Theory of Gravitation”
+(1920), “Light does not cause electromagnetic
+oscillations; it <em>is</em> the oscillations.”</p>
+
+<p>We know nothing whatever about the so-called<span class="pagenum" id="Page_13">[Pg 13]</span>
+ether of space; but we can formulate
+very clearly “The Principles of Electricity”
+without the aid of that hypothesis.<a id="FNanchor_3" href="#Footnote_3" class="fnanchor">[3]</a></p>
+
+
+<div class="footnotes"><h3>FOOTNOTES:</h3>
+
+<div class="footnote">
+
+<p><a id="Footnote_1" href="#FNanchor_1" class="label">[1]</a> 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.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_2" href="#FNanchor_2" class="label">[2]</a> 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.</p>
+
+</div>
+</div>
+
+
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<h2 class="nobreak" id="CHAPTER_2">CHAPTER 2<br>
+<span class="fs70">MAGNETIC PHENOMENA</span></h2>
+</div>
+
+<p>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.</p>
+
+<p>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<span class="pagenum" id="Page_14">[Pg 14]</span>
+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.</p>
+
+<p>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.</p>
+
+<p>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 <em>electricity</em> as applied to this
+force, derived from his <cite>vis electrica</cite>.</p>
+
+<p>By 1600, Dr. Gilbert had published his
+epochal work “<cite>De Magnete</cite>”, which not only
+contained the first rational treatment of magnetic<span class="pagenum" id="Page_15">[Pg 15]</span>
+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.<a id="FNanchor_4" href="#Footnote_4" class="fnanchor">[4]</a></p>
+
+<p>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 <em>the composition of the earth</em>: he wished
+to know through actual research just what is
+its innermost constitution. His experiments led
+him to the conclusion that <em>the earth is a magnet</em>.
+It may, indeed, be considered a huge
+spheroidal lodestone.</p>
+
+<p>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 <i lang="la" xml:lang="la">terella</i> (as he called
+the spherical lodestone) a piece of iron wire. It<span class="pagenum" id="Page_16">[Pg 16]</span>
+will then be observed that the ends of the wire
+“move round its middle point.”<a id="FNanchor_5" href="#Footnote_5" class="fnanchor">[5]</a></p>
+
+<p>Lodestones, fragments of magnetite (Fe<sub>3</sub>O<sub>4</sub>),
+are said to have been first discovered at Magnesia,
+in Asia Minor,—hence the word <em>magnetism</em>.
+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.<a id="FNanchor_6" href="#Footnote_6" class="fnanchor">[6]</a></p>
+
+<p>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 <em>permanent</em> 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<span class="pagenum" id="Page_17">[Pg 17]</span>
+(roughly) towards the earth’s north geographical
+pole.<a id="FNanchor_7" href="#Footnote_7" class="fnanchor">[7]</a></p>
+
+<p>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.</p>
+
+<p>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).</p>
+
+<p>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<span class="pagenum" id="Page_18">[Pg 18]</span>
+are considerably stronger than in the
+northern hemisphere.”<a id="FNanchor_8" href="#Footnote_8" class="fnanchor">[8]</a></p>
+
+<p>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.</p>
+
+<p>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<span class="pagenum" id="Page_19">[Pg 19]</span>
+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.</p>
+
+<p>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.</p>
+
+<p>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”.</p>
+
+
+<div class="footnotes"><h3>FOOTNOTES:</h3>
+
+<div class="footnote">
+
+<p><a id="Footnote_3" href="#FNanchor_3" class="label">[3]</a> 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.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_4" href="#FNanchor_4" class="label">[4]</a> 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.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_5" href="#FNanchor_5" class="label">[5]</a> 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.”</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_6" href="#FNanchor_6" class="label">[6]</a> 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.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_7" href="#FNanchor_7" class="label">[7]</a> 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.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_8" href="#FNanchor_8" class="label">[8]</a> 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.</p>
+
+</div>
+</div>
+
+
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<h2 class="nobreak" id="CHAPTER_3">CHAPTER 3<br>
+<span class="fs70">PIONEERS IN ELECTROMAGNETIC THEORY</span></h2>
+</div>
+
+<p>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<span class="pagenum" id="Page_20">[Pg 20]</span>
+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.</p>
+
+<p>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.</p>
+
+<p>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, “<i lang="la" xml:lang="la">Experimenta circa effectum
+conflictus electrici in acum magneticum</i>”
+(Experiments on the effect of the electrical
+conflict in the magnetic needle).</p>
+
+<p>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<span class="pagenum" id="Page_21">[Pg 21]</span>
+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.</p>
+
+<p>It is well worthy of especial mention that
+Örsted employed the term “<i lang="la" xml:lang="la">conflictus</i>” 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 (“<i lang="la" xml:lang="la">conflictus</i>”) that produces what we
+call electrical phenomena.</p>
+
+<p>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
+<em>an electric current can produce magnetism,
+and that magnetism can produce an electric
+current</em>.</p>
+
+<p>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<span class="pagenum" id="Page_22">[Pg 22]</span>
+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.</p>
+
+<p>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.</p>
+
+<p>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 <em>magneto</em>, 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.<span class="pagenum" id="Page_23">[Pg 23]</span>
+The current generated in the armature winding
+is alternating, but may be rectified to a direct
+current by a <em>commuter</em> if desired; otherwise
+it is conveyed to the line circuit by <em>collector</em> or
+slip rings and brushes.</p>
+
+<p>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.</p>
+
+<p>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”.</p>
+
+<p>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.”</p>
+
+<p>From these considerations it was natural for
+him to suppose that magnetism might be made
+to produce electricity, as it had already been<span class="pagenum" id="Page_24">[Pg 24]</span>
+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.</p>
+
+<p>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.</p>
+
+<p>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.<a id="FNanchor_9" href="#Footnote_9" class="fnanchor">[9]</a></p>
+
+<p>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<span class="pagenum" id="Page_25">[Pg 25]</span>
+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.</p>
+
+<p>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.<a id="FNanchor_10" href="#Footnote_10" class="fnanchor">[10]</a></p>
+
+<p>Meanwhile, Ampère, “by a combination of
+mathematical skill and experimental ingenuity,
+first proved that two electric currents act on<span class="pagenum" id="Page_26">[Pg 26]</span>
+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.”<a id="FNanchor_11" href="#Footnote_11" class="fnanchor">[11]</a></p>
+
+<p>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.</p>
+
+<p>As early as 1773, Henry Cavendish (1731-1810)—one
+of the foremost chemists and experimentalists
+of his day—answered this question
+affirmatively by experiment.<a id="FNanchor_12" href="#Footnote_12" class="fnanchor">[12]</a> Coulomb
+(1736-1806)—inventor of the torsion balance—showed<span class="pagenum" id="Page_27">[Pg 27]</span>
+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.</p>
+
+<p>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.”</p>
+
+<p>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<span class="pagenum" id="Page_28">[Pg 28]</span>
+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 <em>possessing no resistance</em>.</p>
+
+<p>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.</p>
+
+<p>In 1919, Professor Kramerlingh-Onnes, at the
+University of Leyden, was able to produce what
+he called <em>imitations of ampere currents</em>—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<span class="pagenum" id="Page_29">[Pg 29]</span>
+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!<a id="FNanchor_13" href="#Footnote_13" class="fnanchor">[13]</a></p>
+
+<p>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
+<em>a mode of motion of the atoms themselves</em>,
+not of their contained electrons; though increase
+of heat doubtless results in an increase
+in the average orbital velocity of the electrons.</p>
+
+<p>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<span class="pagenum" id="Page_30">[Pg 30]</span>
+of a perfectly pure platinum wire. If
+this is true, then would a current of electricity,
+once set up in a conductor, continue forever?</p>
+
+
+<div class="footnotes"><h3>FOOTNOTES:</h3>
+
+<div class="footnote">
+
+<p><a id="Footnote_9" href="#FNanchor_9" class="label">[9]</a> <cite>Philosophical Transactions</cite>, Page 127, 1832;
+First Series, Article 10.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_10" href="#FNanchor_10" class="label">[10]</a> 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.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_11" href="#FNanchor_11" class="label">[11]</a> Maxwell, Clerk, “On Action at a Distance,”
+(<cite>Scientific Papers</cite>, Vol. II, Page 317).</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_12" href="#FNanchor_12" class="label">[12]</a> 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.”</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_13" href="#FNanchor_13" class="label">[13]</a> See <cite>Die Naturwissenschaften</cite> (Berlin), January
+28, 1921.</p>
+
+</div>
+</div>
+
+
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<h2 class="nobreak" id="CHAPTER_4">CHAPTER 4<br>
+<span class="fs70">THEORIES OF ELECTRICITY</span></h2>
+</div>
+
+<p>The science of electricity is based upon observation
+of those phenomena of attraction
+and repulsion which are comprehended under
+the term <em>electrostatics</em>. Statical electricity, so
+named from a Greek word (statikos), which
+means “causing to stand (or stay),”—also
+called <em>frictional electricity</em>—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 <em>statical electricity</em> applies
+properly, however, to the electricity of all stationary
+charges, however produced.</p>
+
+<p>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<span class="pagenum" id="Page_31">[Pg 31]</span>
+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.</p>
+
+<p>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 <em>conductor</em> 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 <em>non-conductors</em>, or <em>insulators</em>.</p>
+
+<p>The term <em>dielectric</em> is used in preference to
+<em>insulation</em> when reference is made to the property
+of transmitting <em>induction</em>—a process quite
+distinct from ordinary transmission of an electric
+current. In <em>electrostatic induction</em>, 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<span class="pagenum" id="Page_32">[Pg 32]</span>
+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.</p>
+
+<p><em>Dielectric strength</em> 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. <em>Insulation
+resistance</em>, on the other hand, refers
+to the <em>ohmic</em> resistance <em>offered</em> by an insulating
+material to an impressed voltage, tending to
+induce a breakage of current through it. The
+term <em>dielectric</em> is used as a synonym for <em>insulator</em>,
+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 <em>in</em>duction but not by <em>con</em>duction. A
+charge on one part of a non-conductor or dielectric
+is not communicated to any other part.</p>
+
+<p>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<a id="FNanchor_14" href="#Footnote_14" class="fnanchor">[14]</a>—i.
+e., energy due to motion of particles,
+rather than to energy of position, as of a coiled
+spring.</p>
+
+<p><span class="pagenum" id="Page_33">[Pg 33]</span></p>
+
+<p>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.</p>
+
+<p>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.<a id="FNanchor_15" href="#Footnote_15" class="fnanchor">[15]</a> 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.</p>
+
+<p>About the beginning of the nineteenth century,
+the Italian scientist, Alessandro Volta
+(1745-1827),—and other physicists—discovered
+what has been called, after Volta, <em>voltaic electricity</em>,
+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)<span class="pagenum" id="Page_34">[Pg 34]</span>
+in producing a current of one ampere—was
+similarly derived.</p>
+
+<p>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<sub>2</sub>SO<sub>4</sub>
+to four parts H<sub>2</sub>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 <em>cell</em>, and two or more
+cells make a <em>battery</em>. The current starts with
+the zinc, is conducted by the solution to the
+copper, and thence by wire back to the zinc,
+completing a <em>circuit</em>. The zinc constitutes the
+negative pole (or electrode), the copper or carbon
+the positive pole (or electrode).</p>
+
+<p>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.<a id="FNanchor_16" href="#Footnote_16" class="fnanchor">[16]</a> The<span class="pagenum" id="Page_35">[Pg 35]</span>
+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 <em>voltaic action</em>
+and the cell is a primary battery. Voltaic action
+and <em>electrolysis</em>—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.<a id="FNanchor_17" href="#Footnote_17" class="fnanchor">[17]</a></p>
+
+<p>The familiar <em>dry cell</em> 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 <em>dry battery</em>.</p>
+
+<p>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<span class="pagenum" id="Page_36">[Pg 36]</span>
+were two kinds of electricity, one of which
+he called <em>vitreous</em> (from glass) and the other
+<em>resinous</em> (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.</p>
+
+<p>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.<a id="FNanchor_18" href="#Footnote_18" class="fnanchor">[18]</a></p>
+
+<p>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, “<cite>Tentamen Theoriae Electriciatis
+et Magnetismi</cite>” (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<span class="pagenum" id="Page_37">[Pg 37]</span>
+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.<a id="FNanchor_19" href="#Footnote_19" class="fnanchor">[19]</a></p>
+
+<p>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.</p>
+
+<p>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 <em>cube</em> 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.<span class="pagenum" id="Page_38">[Pg 38]</span>
+This he secured by means of his torsion-balance
+(about 1784).<a id="FNanchor_20" href="#Footnote_20" class="fnanchor">[20]</a></p>
+
+<p>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.</p>
+
+<p>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<span class="pagenum" id="Page_39">[Pg 39]</span>
+the elementary formulae and properties
+of electrical phenomena.”<a id="FNanchor_21" href="#Footnote_21" class="fnanchor">[21]</a></p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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<span class="pagenum" id="Page_40">[Pg 40]</span>
+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.”</p>
+
+<p>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.</p>
+
+<p>“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.”<a id="FNanchor_22" href="#Footnote_22" class="fnanchor">[22]</a></p>
+
+<p><span class="pagenum" id="Page_41">[Pg 41]</span></p>
+
+
+<div class="footnotes"><h3>FOOTNOTES:</h3>
+
+<div class="footnote">
+
+<p><a id="Footnote_14" href="#FNanchor_14" class="label">[14]</a> Jeans, J. H., “Electricity and Magnetism,”
+Page 483, 1911.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_15" href="#FNanchor_15" class="label">[15]</a> 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.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_16" href="#FNanchor_16" class="label">[16]</a> “Potential” is analogous to level (or pressure)
+in hydrostatics or mechanics.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_17" href="#FNanchor_17" class="label">[17]</a> For further explanation, see Shipley, Maynard,
+“The A. B. C. of the Electronic Theory of Matter,”
+Little Blue Book Series, No. 603.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_18" href="#FNanchor_18" class="label">[18]</a> See, in this connection, Shipley, <em>Op. cit.</em></p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_19" href="#FNanchor_19" class="label">[19]</a> 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.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_20" href="#FNanchor_20" class="label">[20]</a> 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.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_21" href="#FNanchor_21" class="label">[21]</a> Merz, Henry, “History of European Thought in
+the Nineteenth Century,” Vol. I, Page 362.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_22" href="#FNanchor_22" class="label">[22]</a> 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 “<cite>Theorie des Phenomenes
+Electrodynamiques</cite>,” 1826.</p>
+
+</div>
+</div>
+
+
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<h2 class="nobreak" id="CHAPTER_5">CHAPTER 5<br>
+<span class="fs70">MODERN MAGNETIC THEORY</span></h2>
+</div>
+
+<p>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, <em>transformation of energy</em>.</p>
+
+<p>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<span class="pagenum" id="Page_42">[Pg 42]</span>
+universe is infinite in quantity. The reservoir
+of energy is exhaustless, and the dynamo is
+man’s open sesame.</p>
+
+<p>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 <em>create</em> 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.”</p>
+
+<p>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—<em>energy</em>. 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 <em>in space</em>—not in a universal,
+incomprehensible, paradoxical something called
+“ether.”</p>
+
+<p>A field of <em>energy</em> 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).</p>
+
+<p>“Lines of force,” says Dr. N. R. Campbell,<span class="pagenum" id="Page_43">[Pg 43]</span>
+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.”</p>
+
+<p>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.”</p>
+
+<p>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.”</p>
+
+<p>It can be shown that the kinetic energy of<span class="pagenum" id="Page_44">[Pg 44]</span>
+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,
+<em>released by chemical combustion</em>.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<h2 class="nobreak" id="CHAPTER_6">CHAPTER 6<br>
+<span class="fs70">PROOF THAT ELECTRONS ARE ATOMS OF ELECTRICITY</span></h2>
+</div>
+
+<h3>THE ZEEMAN EFFECT</h3>
+
+<p>Heinrich Hertz demonstrated in 1887 that he
+could produce in the “ether”—or at least in<span class="pagenum" id="Page_45">[Pg 45]</span>
+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.</p>
+
+<p>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.</p>
+
+<p>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).</p>
+
+<p>This could be accounted for only on the<span class="pagenum" id="Page_46">[Pg 46]</span>
+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?</p>
+
+<p>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.<a id="FNanchor_23" href="#Footnote_23" class="fnanchor">[23]</a></p>
+
+<p><span class="pagenum" id="Page_47">[Pg 47]</span></p>
+
+<p>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.</p>
+
+<p>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.<a id="FNanchor_24" href="#Footnote_24" class="fnanchor">[24]</a> 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<span class="pagenum" id="Page_48">[Pg 48]</span>
+circularly polarized in opposite directions—“the
+direction of the vibration depending in a simple
+manner on the direction of the magnetic
+lines of force.”<a id="FNanchor_25" href="#Footnote_25" class="fnanchor">[25]</a></p>
+
+<p>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.”<a id="FNanchor_26" href="#Footnote_26" class="fnanchor">[26]</a></p>
+
+<p>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<span class="pagenum" id="Page_49">[Pg 49]</span>
+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.<a id="FNanchor_27" href="#Footnote_27" class="fnanchor">[27]</a></p>
+
+<p>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 <span class="xs"><sup>1</sup>/<sub>1840</sub></span> that of the hydrogen atom. By a
+different method, Sir J. J. Thomson obtained
+a value of <span class="xs"><sup>1</sup>/<sub>1800</sub></span> the mass of the hydrogen
+atom; while Dr. Robert A. Millikan, by means
+of his famous “electrical balance,” derived a
+value of <span class="xs"><sup>1</sup>/<sub>1845</sub></span> that of the hydrogen atom.<a id="FNanchor_28" href="#Footnote_28" class="fnanchor">[28]</a></p>
+
+<p>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<span class="pagenum" id="Page_50">[Pg 50]</span>
+available for wide generalization, important
+in their bearing on theories of radiation
+and atomic structure” (<em>Op. cit.</em>, Page <a href="#Page_36">36</a>).</p>
+
+<p>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).</p>
+
+<p>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.”</p>
+
+<p>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,<a id="FNanchor_29" href="#Footnote_29" class="fnanchor">[29]</a> “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,<span class="pagenum" id="Page_51">[Pg 51]</span>
+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.”</p>
+
+<p>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 ‘<cite>De Magnete</cite>.’ Barnett
+has succeeded in producing magnetism
+by rapidly whirling masses of metal in the laboratory”
+(Hale, “The New Heavens,” Pages 69-70).</p>
+
+<p>More recently (October, 1922), Hale, Ellerman
+and Nicholson, all of the Mount Wilson
+Observatory, have detected <em>invisible</em> sun-spots
+by searching for evidences of the Zeeman effect
+in promising regions, such as areas of
+flocculi following a large spot. “A special<span class="pagenum" id="Page_52">[Pg 52]</span>
+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.”</p>
+
+<p>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.</p>
+
+
+<h3>THE STARK EFFECT</h3>
+
+<p>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.</p>
+
+<p>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.<a id="FNanchor_30" href="#Footnote_30" class="fnanchor">[30]</a></p>
+
+<p>Stark’s task was a more difficult one than
+Zeeman’s, owing to the fact that he had to deal<span class="pagenum" id="Page_53">[Pg 53]</span>
+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.<a id="FNanchor_31" href="#Footnote_31" class="fnanchor">[31]</a> 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.</p>
+
+<p>The attentive reader will note that this result
+was in marked contrast with the <em>magnetic</em>
+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 <em>motions of electrons</em>,
+giving rise to broadening, displacement
+or other modifications of spectral laws. Both
+“effects” confirm the theoretical view of Maxwell,<span class="pagenum" id="Page_54">[Pg 54]</span>
+namely, that light is an electromagnetic
+phenomenon.</p>
+
+<p>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 <em>decomposition</em>
+of certain spectral lines, which are
+usually <em>polarized</em>, as in the Zeeman effect.</p>
+
+<p>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.”</p>
+
+<p>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).</p>
+
+<p>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,<span class="pagenum" id="Page_55">[Pg 55]</span>
+it must be admitted that there has not been,
+so far as I can ascertain, any theory proposed
+which explains <em>all</em> of the phenomena involved.</p>
+
+
+<div class="footnotes"><h3>FOOTNOTES:</h3>
+
+<div class="footnote">
+
+<p><a id="Footnote_23" href="#FNanchor_23" class="label">[23]</a> For a good summary of the main results concerning
+the Zeeman effect, see von Auerbach, Felix,
+“<cite>Moderne Magnetik</cite>,” 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.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_24" href="#FNanchor_24" class="label">[24]</a> 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.”</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_25" href="#FNanchor_25" class="label">[25]</a> Zeeman, “<cite>Les Lignes Spectrales et les Theories
+Modernes</cite>,” <cite>Scientia</cite>, January 1, 1921, Page 18
+(Vol. XIX, No. CV—I).</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_26" href="#FNanchor_26" class="label">[26]</a> 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,” <cite>Contributions from Mount Wilson Observatory</cite>,
+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, <cite>Publications of the Astronomical society
+of the Pacific</cite>, Page 24, Vol. XXXIV, No. 197
+(February, 1922).</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_27" href="#FNanchor_27" class="label">[27]</a> Zeeman, <cite>Loc. cit.</cite>, Page 18. See also the classical
+monograph by the same author, “Researches in
+Magneto-Optics,” London, 1913.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_28" href="#FNanchor_28" class="label">[28]</a> Millikan, <cite>Physical Review</cite>, 2, 143 (1913); “The
+Electron,” 1917 (revised edition, 1924). See also,
+<cite>Proceedings of the National Academy of Sciences</cite>,
+3, 314 (1917).</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_29" href="#FNanchor_29" class="label">[29]</a> “The New Heavens,” Page 70, New York, 1922.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_30" href="#FNanchor_30" class="label">[30]</a> Cf. Stark, “<cite>Die Atomionen chemischere Elemente
+und ihre Kanastrahlenspektra</cite>,” Berlin, 1913. See
+also, “<cite>Elektrische Spektralanalyse chemischen
+Atome</cite>,” Leipsic, 1914.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_31" href="#FNanchor_31" class="label">[31]</a> 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.</p>
+
+</div>
+</div>
+
+
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<h2 class="nobreak" id="CHAPTER_7">CHAPTER 7<br>
+<span class="fs70">THE DISCOVERY OF WIRELESS TELEGRAPHY</span></h2>
+</div>
+
+<p>The experimental foundation for the discovery
+of wireless telegraphy was laid by the
+researches of Faraday.<a id="FNanchor_32" href="#Footnote_32" class="fnanchor">[32]</a></p>
+
+<p>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.<a id="FNanchor_33" href="#Footnote_33" class="fnanchor">[33]</a></p>
+
+<p>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.<a id="FNanchor_34" href="#Footnote_34" class="fnanchor">[34]</a></p>
+
+<p>Hertz demonstrated also that the velocity of
+propagation of these waves was the same as
+that of light-waves—approximately 186,000<span class="pagenum" id="Page_56">[Pg 56]</span>
+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.<a id="FNanchor_35" href="#Footnote_35" class="fnanchor">[35]</a> These results had been predicted
+by Maxwell.</p>
+
+<p>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.</p>
+
+<p>“If we were asked to pick out one date that<span class="pagenum" id="Page_57">[Pg 57]</span>
+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.”<a id="FNanchor_36" href="#Footnote_36" class="fnanchor">[36]</a></p>
+
+<p>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.</p>
+
+<p>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.<a id="FNanchor_37" href="#Footnote_37" class="fnanchor">[37]</a></p>
+
+<p>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,<span class="pagenum" id="Page_58">[Pg 58]</span>
+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.</p>
+
+<p>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 <span class="xs"><sup>1</sup>/<sub>1000</sub></span> 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<span class="pagenum" id="Page_59">[Pg 59]</span>
+only a few millionths of an inch long. Doubtless
+even this gap will soon be bridged over.<a id="FNanchor_38" href="#Footnote_38" class="fnanchor">[38]</a></p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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<span class="pagenum" id="Page_60">[Pg 60]</span>
+same capacity as our Long Island (Rocky
+Point) station, and is therefore one of the
+biggest in the world.</p>
+
+<p>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.<a id="FNanchor_39" href="#Footnote_39" class="fnanchor">[39]</a></p>
+
+<p>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).</p>
+
+<p>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,<span class="pagenum" id="Page_61">[Pg 61]</span>
+“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.</p>
+
+<p>“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.”<a id="FNanchor_40" href="#Footnote_40" class="fnanchor">[40]</a></p>
+
+<p>In March, 1922, the late Dr. Charles P. Steinmetz
+said that he considered well founded the
+supposition that performances of low-power<span class="pagenum" id="Page_62">[Pg 62]</span>
+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.”</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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<span class="pagenum" id="Page_63">[Pg 63]</span>
+practical problem was worked out and the
+method all but perfected.</p>
+
+<p>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.”</p>
+
+<p>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.</p>
+
+<p>“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.”</p>
+
+<p>“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.”</p>
+
+
+<div class="footnotes"><h3>FOOTNOTES:</h3>
+
+<div class="footnote">
+
+<p><a id="Footnote_32" href="#FNanchor_32" class="label">[32]</a> See his “Experimental Researches in Electricity,”
+<cite>Everyman’s Library Series</cite>.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_33" href="#FNanchor_33" class="label">[33]</a> Maxwell, James Clerk, “Treatise on Electricity
+and Magnetism,” 1873.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_34" href="#FNanchor_34" class="label">[34]</a> 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 <cite>Philosophical Magazine</cite> for June of that year.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_35" href="#FNanchor_35" class="label">[35]</a> 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 <em>polarized</em>. 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.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_36" href="#FNanchor_36" class="label">[36]</a> Crehore, Dr. Albert C., “The Mystery of Matter
+and Energy,” Page 28, New York, 1917.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_37" href="#FNanchor_37" class="label">[37]</a> By means of an induction coil coupled to a
+circuit containing capacity terminals, thus forming
+an “oscillatory circuit.”</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_38" href="#FNanchor_38" class="label">[38]</a> 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.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_39" href="#FNanchor_39" class="label">[39]</a> See an interesting article on this question in
+<cite>Science and Invention</cite>, December, 1922, Page 744
+(Vol. X, Whole No. 116).</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_40" href="#FNanchor_40" class="label">[40]</a> Gernback, H., Editorial in <cite>Science and Invention</cite>,
+December, 1922.</p>
+
+</div>
+</div>
+<hr class="chap x-ebookmaker-drop">
+
+
+<div class="chapter transnote">
+<h2 class="bold fs150 wsp">
+Transcriber’s Notes</h2>
+
+<table class="autotable lh">
+<tr>
+<td class="tdr">pg 24 Changed:</td>
+<td class="tdl">conducting plate in the neighborhod of a magnet</td>
+</tr>
+<tr>
+<td class="tdr">to:</td>
+<td class="tdl">conducting plate in the neighborhood of a magnet</td>
+</tr>
+<tr>
+<td class="tdr">pg 25 Changed:</td>
+<td class="tdl">was affected by on ordinary magnet</td>
+</tr>
+<tr>
+<td class="tdr">to:</td>
+<td class="tdl">was affected by an ordinary magnet</td>
+</tr>
+</table>
+</div>
+
+<div style='text-align:center'>*** END OF THE PROJECT GUTENBERG EBOOK 75464 ***</div>
+</body>
+</html>
+
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