_THE ROMANCE OF SCIENCE_

THE MACHINERY OF THE UNIVERSE

MECHANICAL CONCEPTIONS OFPHYSICAL PHENOMENA

BYA. E. DOLBEAR, A. B. , A. M. , M. E. , PH. D. 

PROFESSOR OF PHYSICS AND ASTRONOMY, TUFTS COLLEGE, MASS. 

PUBLISHED UNDER GENERAL LITERATURE COMMITTEE. 

LONDON:SOCIETY FOR PROMOTING CHRISTIAN KNOWLEDGE, NORTHUMBERLAND AVENUE, W. C. ;43, QUEEN VICTORIA STREET, E. C. 

BRIGHTON: 129, NORTH STREET. 

NEW YORK: E. & J. B. YOUNG & CO. 

1897. 

PREFACE

For thirty years or more the expressions "Correlation of the PhysicalForces" and "The Conservation of Energy" have been common, yet fewpersons have taken the necessary pains to think out clearly whatmechanical changes take place when one form of energy is transformedinto another. 

Since Tyndall gave us his book called _Heat as a Mode of Motion_ neitherlecturers nor text-books have attempted to explain how all phenomena arethe necessary outcome of the various forms of motion. In general, phenomena have been attributed to _forces_--a metaphysical term, whichexplains nothing and is merely a stop-gap, and is really not at allneedful in these days, seeing that transformable modes of motion, easilyperceived and understood, may be substituted in all cases for forces. 

In December 1895 the author gave a lecture before the Franklin Instituteof Philadelphia, on "Mechanical Conceptions of Electrical Phenomena, " inwhich he undertook to make clear what happens when electrical phenomenaappear. The publication of this lecture in _The Journal of the FranklinInstitute_ and in _Nature_ brought an urgent request that it should beenlarged somewhat and published in a form more convenient for thepublic. The enlargement consists in the addition of a chapter on the"_Contrasted Properties of Matter and the Ether_, " a chapter containingsomething which the author believes to be of philosophical importance inthese days when electricity is so generally described as a phenomenon ofthe ether. 

A. E. DOLBEAR. 

TABLE OF CONTENTS

CHAPTER I

Ideas of phenomena ancient and modern, metaphysical and mechanical--Imponderables--Forces, invented and discarded--Explanations--Energy, its factors, Kinetic and Potential--Motions, kinds and transformations of--Mechanical, molecular, and atomic--Invention of Ethers, Faraday's conceptions p. 7

CHAPTER II

Properties of Matter and Ether compared--Discontinuity _versus_ Continuity--Size of atoms--Astronomical distances--Number of atoms in the universe--Ether unlimited--Kinds of Matter, permanent qualities of--Atomic structure; vortex-rings, their properties--Ether structureless--Matter gravitative, Ether not--Friction in Matter, Ether frictionless--Chemical properties--Energy in Matter and in Ether--Matter as a transformer of Energy--Elasticity--Vibratory rates and waves--Density--Heat--Indestructibility of Matter--Inertia in Matter and in Ether--Matter not inert--Magnetism and Ether waves--States of Matter--Cohesion and chemism affected by temperature--Shearing stress in Solids and in Ether--Ether pressure--Sensation dependent upon Matter--Nervous system not affected by Ether states--Other stresses in Ether--Transformations of Motion--Terminology p. 24

CHAPTER III

Antecedents of Electricity--Nature of what is transformed--Series of transformations for the production of light--Positive and negative Electricity--Positive and negative twists--Rotations about a wire--Rotation of an arc--Ether a non-conductor--Electro-magnetic waves--Induction and inductive action--Ether stress and atomic position--Nature of an electric current--Electricity a condition, not an entity p. 94

CHAPTER I

Ideas of phenomena ancient and modern, metaphysical and mechanical--Imponderables--Forces, invented and discarded--Explanations--Energy, its factors, Kinetic and Potential--Motions, kinds and transformations of--Mechanical, molecular, and atomic--Invention of Ethers, Faraday's conceptions. 

'And now we might add something concerning a most subtle spirit which pervades and lies hid in all gross bodies, by the force and action of which spirit the particles of bodies attract each other at near distances, and cohere if contiguous, and electric bodies operate at greater distances, as well repelling as attracting neighbouring corpuscles, and light is emitted, reflected, inflected, and heats bodies, and all sensation is excited, and members of animal bodies move at the command of the will. '--NEWTON, _Principia_. 

In Newton's day the whole field of nature was practically lying fallow. No fundamental principles were known until the law of gravitation wasdiscovered. This law was behind all the work of Copernicus, Kepler, andGalileo, and what they had done needed interpretation. It was quitenatural that the most obvious and mechanical phenomena should first bereduced, and so the _Principia_ was concerned with mechanical principlesapplied to astronomical problems. To us, who have grown up familiar withthe principles and conceptions underlying them, all varieties ofmechanical phenomena seem so obvious, that it is difficult for us tounderstand how any one could be obtuse to them; but the records ofNewton's time, and immediately after this, show that they were not soeasy of apprehension. It may be remembered that they were not adopted inFrance till long after Newton's day. In spite of what is thought to bereasonable, it really requires something more than completedemonstration to convince most of us of the truth of an idea, should thetruth happen to be of a kind not familiar, or should it chance to beopposed to our more or less well-defined notions of what it is or oughtto be. If those who labour for and attain what they think to be thetruth about any matter, were a little better informed concerning mentalprocesses and the conditions under which ideas grow and displace others, they would be more patient with mankind; teachers of every rank mightthen discover that what is often called stupidity may be nothing elsethan mental inertia, which can no more be made active by simply willingthan can the movement of a cannon ball by a like effort. We _grow_ intoour beliefs and opinions upon all matters, and scientific ideas are noexceptions. 

Whewell, in his _History of the Inductive Sciences_, says that theGreeks made no headway in physical science because they lackedappropriate ideas. The evidence is overwhelming that they were asobserving, as acute, as reasonable as any who live to-day. With thisview, it would appear that the great discoverers must have been men whostarted out with appropriate ideas: were looking for what they found. If, then, one reflects upon the exceeding great difficulty there is indiscovering one new truth, and the immense amount of work needed todisentangle it, it would appear as if even the most successful have butindistinct ideas of what is really appropriate, and that theirmechanical conceptions become clarified by doing their work. This is notalways the fact. In the statement of Newton quoted at the head of thischapter, he speaks of a spirit which lies hid in all gross bodies, etc. , by means of which all kinds of phenomena are to be explained; but hedeliberately abandons that idea when he comes to the study of light, forhe assumes the existence and activity of light corpuscles, for which hehas no experimental evidence; and the probability is that he did thisbecause the latter conception was one which he could handlemathematically, while he saw no way for thus dealing with the other. Hismechanical instincts were more to be trusted than his carefullycalculated results; for, as all know, what he called "spirits, " is whatto-day we call the ether, and the corpuscular theory of light has now nomore than a historic interest. The corpuscular theory was a mechanicalconception, but each such corpuscle was ideally endowed with qualitieswhich were out of all relation with the ordinary matter with which itwas classed. 

Until the middle of the present century the reigning physical philosophyheld to the existence of what were called imponderables. The phenomenaof heat were explained as due to an imponderable substance called"caloric, " which ordinary matter could absorb and emit. A hot body wasone which had absorbed an imponderable substance. It was, therefore, noheavier than before, but it possessed ability to do work proportional tothe amount absorbed. Carnot's ideal engine was described by him in termsthat imply the materiality of heat. Light was another imponderablesubstance, the existence of which was maintained by Sir David Brewsteras long as he lived. Electricity and magnetism were imponderable fluids, which, when allied with ordinary matter, endowed the latter with theirpeculiar qualities. The conceptions in each case were properlymechanical ones _part_ (but not all) _of the time_; for when theimmaterial substances were dissociated from matter, where they hadmanifested themselves, no one concerned himself to inquire as to theirwhereabouts. They were simply off duty, but could be summoned, like thegenii in the story of Aladdin's Lamp. Now, a mechanical conception ofany phenomenon, or a mechanical explanation of any kind of action, mustbe mechanical all the time, in the antecedents as well as theconsequents. Nothing else will do except a miracle. 

During the fifty years, from about 1820 to 1870, a somewhat differentkind of explanation of physical events grew up. The interest that wasaroused by the discoveries in all the fields of physical science--inheat, electricity, magnetism and chemistry--by Faraday, Joule, Helmholtz, and others, compelled a change of conceptions; for it wasnoticed that each special kind of phenomenon was preceded by some otherdefinite and known kind; as, for instance, that chemical action precededelectrical currents, that mechanical or electrical activity resultedfrom changing magnetism, and so on. As each kind of action was believedto be due to a special force, there were invented such terms asmechanical force, electrical force, magnetic, chemical and vital forces, and these were discovered to be convertible into one another, and the"doctrine of the correlation of the physical forces" became a commonexpression in philosophies of all sorts. By "convertible into oneanother, " was meant, that whenever any given force appeared, it was atthe expense of some other force; thus, in a battery chemical force waschanged into electrical force; in a magnet, electrical force was changedinto magnetic force, and so on. The idea here was the _transformation offorces_, and _forces_ were not so clearly defined that one could have amechanical idea of just what had happened. That part of the philosophywas no clearer than that of the imponderables, which had largely droppedout of mind. The terminology represented an advance in knowledge, butwas lacking in lucidity, for no one knew what a force of any kind was. 

The first to discover this and to repudiate the prevailing terminologywere the physiologists, who early announced their disbelief in a vitalforce, and their belief that all physiological activities were of purelyphysical and chemical origin, and that there was no need to assume anysuch thing as a vital force. Then came the discovery that chemicalforce, or affinity, had only an adventitious existence, and that, atabsolute zero, there was no such activity. The discovery of, or ratherthe appreciation of, what is implied by the term _absolute zero_, andespecially of the nature of heat itself, as expressed in the statementthat heat is a mode of motion, dismissed another of the so-called forcesas being a metaphysical agency having no real existence, though standingfor phenomena needing further attention and explanation; and byexplanation is meant _the presentation of the mechanical antecedents fora phenomenon, in so complete a way that no supplementary or unknownfactors are necessary_. The train moves because the engine pulls it; theengine pulls because the steam pushes it. There is no more necessity forassuming a steam force between the steam and the engine, than forassuming an engine force between the engine and the train. All theprocesses are mechanical, and have to do only with ordinary matter andits conditions, from the coal-pile to the moving freight, though thereare many transformations of the forms of motion and of energy betweenthe two extremes. 

During the past thirty years there has come into common use anotherterm, unknown in any technical sense before that time, namely, _energy_. What was once called the conservation of force is now called theconservation of energy, and we now often hear of forms of energy. Thus, heat is said to be a form of energy, and the forms of energy areconvertible into one another, as the so-called forces were formerlysupposed to be transformable into one another. We are asked to considergravitative energy, heat energy, mechanical energy, chemical energy, andelectrical energy. When we inquire what is meant by energy, we areinformed that it means ability to do work, and that work is measurableas a pressure into a distance, and is specified as foot-pounds. A massof matter moves because energy has been spent upon it, and has acquiredenergy equal to the work done on it, and this is believed to hold true, no matter what the kind of energy was that moved it. If a body moves, itmoves because another body has exerted pressure upon it, and its energyis called _kinetic energy_; but a body may be subject to pressure andnot move appreciably, and then the body is said to possess potentialenergy. Thus, a bent spring and a raised weight are said to possesspotential energy. In either case, _an energized body receives its energyby pressure, and has ability to produce pressure on another body_. Whether or not it does work on another body depends on the rigidity ofthe body it acts upon. In any case, it is simply a mechanicalaction--body A pushes upon body B (Fig. 1). There is no need to assumeanything more mysterious than mechanical action. Whether body B movesthis way or that depends upon the direction of the push, the point ofits application. Whether the body be a mass as large as the earth or assmall as a molecule, makes no difference in that particular. Suppose, then, that _a_ (Fig. 2) spends its energy on _b_, _b_ on _c_, _c_ on_d_, and so on. The energy of _a_ gives translatory motion to _b_, _b_sets _c_ vibrating, and _c_ makes _d_ spin on some axis. Each of thesehas had energy spent on it, and each has some form of energy differentfrom the other, but no new factor has been introduced between _a_ and_d_, and the only factor that has gone from _a_ to _d_ has beenmotion--motion that has had its direction and quality changed, but notits nature. If we agree that energy is neither created nor annihilated, by any physical process, and if we assume that _a_ gave to _b_ all itsenergy, that is, all its motion; that _b_ likewise gave its all to _c_, and so on; then the succession of phenomena from _a_ to _d_ has beensimply the transference of a definite amount of motion, and therefore ofenergy, from the one to the other; for _motion has been the onlyvariable factor_. If, furthermore, we should agree to call thetranslatory motion [alpha], the vibratory motion [beta], therotary [gamma], then we should have had a conversion of [alpha]into [beta], of [beta] into [gamma]. If we should considerthe amount of transfer motion instead of the kind of motion, we shouldhave to say that the [alpha] energy had been transformed into[beta] and the [beta] into [gamma]. 

[Illustration: FIG. 1. ]

[Illustration: FIG. 2. ]

What a given amount of energy will do depends only upon its _form_, thatis, the kind of motion that embodies it. 

The energy spent upon a stone thrown into the air, giving it translatorymotion, would, if spent upon a tuning fork, make it sound, but not moveit from its place; while if spent upon a top, would enable the latter tostand upon its point as easily as a person stands on his two feet, andto do other surprising things, which otherwise it could not do. One can, without difficulty, form a mechanical conception of the whole serieswithout assuming imponderables, or fluids or forces. Mechanical motiononly, by pressure, has been transferred in certain directions at certainrates. Suppose now that some one should suddenly come upon a spinningtop (Fig. 3) while it was standing upon its point, and, as its motionmight not be visible, should cautiously touch it. It would bound awaywith surprising promptness, and, if he were not instructed in themechanical principles involved, he might fairly well draw the conclusionthat it was actuated by other than simple mechanical principles, and, for that reason, it would be difficult to persuade him that there wasnothing essentially different in the body that appeared and acted thus, than in a stone thrown into the air; nevertheless, that statement wouldbe the simple truth. 

[Illustration: FIG. 3. ]

All our experience, without a single exception, enforces the propositionthat no body moves in any direction, or in any way, except when someother body _in contact_ with it presses upon it. The action is direct. In Newton's letter to his friend Bentley, he says--"That one bodyshould act upon another through empty space, without the mediation ofanything else by and through which their action and pressure may beconveyed from one to another, is to me so great an absurdity that Ibelieve no man who has in philosophical matters a competent faculty ofthinking can ever fall into it. "

For mathematical purposes, it has sometimes been convenient to treat aproblem as if one body could act upon another without any physicalmedium between them; but such a conception has no degree of rationality, and I know of no one who believes in it as a fact. If this be granted, then our philosophy agrees with our experience, and every body movesbecause it is pushed, and the mechanical antecedent of every kind ofphenomenon is to be looked for in some adjacent body possessingenergy--that is, the ability to push or produce pressure. 

It must not be forgotten that energy is not a simple factor, but isalways a product of two factors--a mass with a velocity, a mass with atemperature, a quantity of electricity into a pressure, and so on. Onemay sometimes meet the statement that matter and energy are the tworealities; both are spoken of as entities. It is much more philosophicalto speak of matter and motion, for in the absence of motion there is noenergy, and the energy varies with the amount of motion; andfurthermore, to understand any manifestation of energy one must inquirewhat kind of motion is involved. This we do when we speak of mechanicalenergy as the energy involved in a body having a translatory motion;also, when we speak of heat as a vibratory, and of light as a wavemotion. To speak of energy without stating or implying thesedistinctions, is to speak loosely and to keep far within the bounds ofactual knowledge. To speak thus of a body possessing energy, orexpending energy, is to imply that the body possesses some kind ofmotion, and produces pressure upon another body because it has motion. Tait and others have pointed out the fact, that what is called potentialenergy must, in its nature, be kinetic. Tait says--"Now it is impossibleto conceive of a truly dormant form of energy, whose magnitude shoulddepend, in any way, upon the unit of time; and we are forced to concludethat potential energy, like kinetic energy, depends (even if unexplainedor unimagined) upon motion. " All this means that it is now too late tostop with energy as a final factor in any phenomenon, that the _form ofmotion_ which embodies the energy is the factor that determines _what_happens, as distinguished from how _much_ happens. Here, then, are to befound the distinctions which have heretofore been called forces; hereis embodied the proof that direct pressure of one body upon another iswhat causes the latter to move, and that the direction of movementdepends on the point of application, with reference to the centreof mass. 

It is needful now to look at the other term in the product we callenergy, namely, the substance moving, sometimes called matter or mass. It has been mentioned that the idea of a medium filling space waspresent to Newton, but his gravitation problem did not require that heshould consider other factors than masses and distances. The law ofgravitation as considered by him was--Every particle of matter attractsevery other particle of matter with a stress which is proportional tothe product of their masses, and inversely to the squares of thedistance between them. Here we are concerned only with the statementthat every particle of matter attracts every other particle of matter. Everything then that possesses gravitative attraction is matter in thesense in which that term is used in this law. If there be any othersubstance in the universe that is not thus subject to gravitation, thenit is improper to call it matter, otherwise the law should read, "Someparticles of matter attract, " etc. , which will never do. 

We are now assured that there is something else in the universe whichhas no gravitative property at all, namely, the ether. It was firstimagined in order to account for the phenomena of light, which wasobserved to take about eight minutes to come from the sun to the earth. Then Young applied the wave theory to the explanation of polarizationand other phenomena; and in 1851 Foucault proved experimentally that thevelocity of light was less in water than in air, as it should be if thewave theory be true, and this has been considered a crucial experimentwhich took away the last hope for the corpuscular theory, anddemonstrated the existence of the ether as a space-filling mediumcapable of transmitting light-waves known to have a velocity of 186, 000miles per second. It was called the luminiferous ether, to distinguishit from other ethers which had also been imagined, such as electricether for electrical phenomena, magnetic ether for magnetic phenomena, and so on--as many ethers, in fact, as there were different kinds ofphenomena to be explained. 

It was Faraday who put a stop to the invention of ethers, by suggestingthat the so-called luminiferous ether might be the one concerned in allthe different phenomena, and who pointed out that the arrangement ofiron filings about a magnet was indicative of the direction of thestresses in the ether. This suggestion did not meet the approval of themathematical physicists of his day, for it necessitated the abandonmentof the conceptions they had worked with, as well as the terminologywhich had been employed, and made it needful to reconstruct all theirwork to make it intelligible--a labour which was the more distasteful asit was forced upon them by one who, although expert enough inexperimentation, was not a mathematician, and who boasted that the mostcomplicated mathematical work he ever did was to turn the crank of acalculating machine; who did all his work, formed his conclusions, andthen said--"The work is done; hand it over to the computers. "

It has turned out that Faraday's mechanical conceptions were right. Every one now knows of Maxwell's work, which was to start with Faraday'sconceptions as to magnetic phenomena, and follow them out to theirlogical conclusions, applying them to molecules and the reactions of thelatter upon the ether. Thus he was led to conclude that light was anelectro-magnetic phenomenon; that is, that the waves which constitutelight, and the waves produced by changing magnetism were identical intheir nature, were in the same medium, travelled with the same velocity, were capable of refraction, and so on. Now that all this is a matter ofcommon knowledge to-day, it is curious to look back no further than tenyears. Maxwell's conclusions were adopted by scarcely a physicist inthe world. Although it was known that inductive action travelled withfinite velocity in space, and that an electro-magnet would affect thespace about it practically inversely as the square of the distance, andthat such phenomena as are involved in telephonic induction betweencircuits could have no other meaning than the one assigned by Maxwell, yet nearly all the physicists failed to form the only conception of itthat was possible, and waited for Hertz to devise apparatus forproducing interference before they grasped it. It was even then so new, to some, that it was proclaimed to be a demonstration of the existenceof the ether itself, as well as a method of producing waves short enoughto enable one to notice interference phenomena. It is obvious that Hertzhimself must have had the mechanics of wave-motion plainly in mind, orhe would not have planned such experiments. The outcome of it all is, that we now have experimental demonstration, as well as theoreticalreason for believing, that the ether, once considered as onlyluminiferous, is concerned in all electric and magnetic phenomena, andthat waves set up in it by electro-magnetic actions are capable of beingreflected, refracted, polarized, and twisted, in the same way asordinary light-waves can be, and that the laws of optics are applicableto both. 

CHAPTER II

PROPERTIES OF MATTER AND ETHER

Properties of Matter and Ether compared--Discontinuity _versus_ Continuity--Size of atoms--Astronomical distances--Number of atoms in the universe--Ether unlimited--Kinds of Matter, permanent qualities of--Atomic structure; vortex-rings, their properties--Ether structureless--Matter gravitative, Ether not--Friction in Matter, Ether frictionless--Chemical properties--Energy in Matter and in Ether--Matter as a transformer of Energy--Elasticity--Vibratory rates and waves--Density--Heat--Indestructibility of Matter--Inertia in Matter and in Ether--Matter not inert--Magnetism and Ether waves--States of Matter--Cohesion and chemism affected by temperature--Shearing stress in Solids and in Ether--Ether pressure--Sensation dependent upon Matter--Nervous system not affected by Ether states--Other stresses in Ether--Transformations of Motion--Terminology. 

A common conception of the ether has been that it is a finer-grainedsubstance than ordinary matter, but otherwise so like the latter thatthe laws found to hold good with matter were equally applicable to theether, and hence the mechanical conceptions formed from experience inregard to the one have been transferred to the other, and the propertiesbelonging to one, such as density, elasticity, etc. , have been assertedas properties of the other. 

There is so considerable a body of knowledge bearing upon thesimilarities and dissimilarities of these two entities that it will bewell to compare them. After such comparison one will be better able tojudge of the propriety of assuming them to be subject to identical laws. 

1. MATTER IS DISCONTINUOUS. 

Matter is made up of atoms having dimensions approximately determined tobe in the neighbourhood of the one fifty-millionth of an inch indiameter. These atoms may have various degrees of aggregation;--they maybe in practical contact, as in most solid bodies such as metals androcks; in molecular groupings as in water, and in gases such ashydrogen, oxygen, and so forth, where two, three, or more atoms cohereso strongly as to enable the molecules to act under ordinarycircumstances like simple particles. Any or all of these molecules andatoms may be separated by any assignable distance from each other. Thus, in common air the molecules, though rapidly changing their positions, are on the average about two hundred and fifty times their own diameterapart. This is a distance relatively greater than the distance apart ofthe earth and the moon, for two hundred and fifty times the diameter ofthe earth will be 8000 × 250 = 2, 000, 000 miles, while the distance tothe moon is but 240, 000 miles. The sun is 93, 000, 000 miles from theearth, and the most of the bodies of the solar system are still morewidely separated, Neptune being nearly 3000 millions of miles from thesun. As for the fixed stars, they are so far separated from us that, atthe present rate of motion of the solar system in its drift throughspace--500 millions of miles in a year--it would take not less than40, 000 years to reach the nearest star among its neighbours, while forthe more remote ones millions of years must be reckoned. The huge spaceseparating these masses is practically devoid of matter; it is a vacuum. 

THE ETHER IS CONTINUOUS. 

The idea of continuity as distinguished from discontinuity may be gainedby considering what would be made visible by magnification. Waterappears to the eye as if it were without pores, but if sugar or salt beput into it, either will be dissolved and quite disappear among themolecules of the water as steam does in the air, which shows that thereare some unoccupied spaces between the molecules. If a microscope beemployed to magnify a minute drop of water it still shows the same lackof structure as that looked at with the unaided eye. If the magnifyingpower be the highest it may reveal a speck as small as thehundred-thousandth part of an inch, yet the speck looks no different incharacter. We know that water is composed of two different kinds ofatoms, hydrogen and oxygen, for they can be separated by chemical meansand kept in separate bottles, and again made to combine to form waterhaving all the qualities that belonged to it before it was decomposed. If a very much higher magnifying power were available, we shouldultimately be able to see the individual water molecules, and recognizetheir hydrogen and oxygen constituents by their difference in size, rateof movements, and we might possibly separate them by mechanical methods. What one would see would be something very different in structure fromthe water as it appears to our eyes. If the ether were similarly to beexamined through higher and still higher magnifying powers, even up toinfinity, there is no reason for thinking that the last examinationwould show anything different in structure or quality from that whichwas examined with low power or with no microscope at all. This is allexpressed by saying that the ether is a continuous substance, withoutinterstices, that it fills space completely, and, unlike gases, liquids, and solids, is incapable of absorbing or dissolving anything. 

2. MATTER IS LIMITED. 

There appears to be a definite amount of matter in the visible universe, a definite number of molecules and atoms. How many molecules there arein a cubic inch of air under ordinary pressure has been determined, andis represented approximately by a huge number, something like a thousandmillion million millions. 

When the diameter of a molecule has been measured, as it has beenapproximately, and found to be about one fifty-millionth of an inch, then fifty million in a row would reach an inch, and the cube of fiftymillion is 125, 000, 000000, 000000, 000000, one hundred and twenty-fivethousand million million millions. In a cubic foot there will of coursebe 1728 times that number. One may if one likes find how many there maybe in the earth, and moon, sun and planets, for the dimensions of themare all very well known. Only the multiplication table need be used, andthe sum of all these will give how many molecules there are in the solarsystem. If one should feel that the number thus obtained was not veryaccurate, he might reflect that if there were ten times as many it wouldadd but another cipher to a long line of similar ones and would notmaterially modify it. The point is that there is a definite, computablenumber. If one will then add to these the number of molecules in themore distant stars and nebulæ, of which there are visible about100, 000, 000, making such estimate of their individual size as he thinksprudent, the sum of all will give the number of molecules in the visibleuniverse. The number is not so large but it can be written down in aminute or two. Those who have been to the pains to do the sum say it maybe represented by seven followed by ninety-one ciphers. One could easilycompute how many molecules so large a space would contain if it werefull and as closely packed as they are in a drop of water, but therewould be a finite and not an infinite number, and therefore there is alimited number of atoms in the visible universe. 

THE ETHER IS UNLIMITED. 

The evidence for this comes to us from the phenomena of light. Experimentally, ether waves of all lengths are found to have a velocityof 186, 000 miles in a second. It takes about eight minutes to reach usfrom the sun, four hours from Neptune the most distant planet, and fromthe nearest fixed star about three and a half years. Astronomers tell usthat some visible stars are so distant that their light requires notless than ten thousand years and probably more to reach us, thoughtravelling at the enormous rate of 186, 000 miles a second. This meansthat the whole of space is filled with this medium. If there were anyvacant spaces, the light would fail to get through them, and starsbeyond them would become invisible. There are no such vacant spaces, forany part of the heavens shows stars beaming continuously, and everyincrease in telescopic power shows stars still further removed than anyseen before. The whole of this intervening space must therefore befilled with the ether. Some of the waves that reach us are not more thanthe hundred-thousandth of an inch long, so there can be no crack orbreak or absence of ether from so small a section as thehundred-thousandth of an inch in all this great expanse. More than this. No one can think that the remotest visible stars are upon the boundaryof space, that if one could get to the most distant star he would haveon one side the whole of space while the opposite side would be devoidof it. Space we know is of three dimensions, and a straight line may beprolonged in any direction to an infinite distance, and a ray of lightmay travel on for an infinite time and come to no end provided space befilled with ether. 

How long the sun and stars have been shining no one knows, but it ishighly probable that the sun has existed for not less than 1000 millionyears, and has during that time been pouring its rays as radiant energyinto space. If then in half that time, or 500 millions of years, thelight had somewhere reached a boundary to the ether, it could not havegone beyond but would have been reflected back into the ether-filledspace, and such part of the sky would be lit up by this reflected light. There is no indication that anything like reflection comes to us fromthe sky. This is equivalent to saying that the ether fills space inevery direction away from us to an unlimited distance, and so far isitself unlimited. 

3. MATTER IS HETEROGENEOUS. 

The various kinds of matter we are acquainted with are commonly calledthe elements. These when combined in various ways exhibit characteristicphenomena which depend upon the kinds of matter, the structure andmotions which are involved. There are some seventy different kinds ofthis elemental matter which may be identified as constituents of theearth. Many of the same elements have been identified in the sun andstars, such for instance as hydrogen, carbon, and iron. Such phenomenalead us to conclude that the kinds of matter elsewhere in the universeare identical with such as we are familiar with, and that elsewhere thevariety is as great. The qualities of the elements, within a certainrange of temperature, are permanent; they are not subject tofluctuations, though the qualities of combinations of them may varyindefinitely. The elements therefore may be regarded as retaining theiridentity in all ordinary experience. 

THE ETHER IS HOMOGENEOUS. 

One part of the ether is precisely like any other part everywhere andalways, and there are no such distinctions in it as correspond with theelemental forms of matter. 

4. MATTER IS ATOMIC. 

There is an ultimate particle of each one of the elements which ispractically absolute and known as an atom. The atom retains its identitythrough all combinations and processes. It may be here or there, movefast or slow, but its atomic form persists. 

THE ETHER IS NON-ATOMIC. 

One might infer, from what has already been said about continuity, thatthe ether could not be constituted of separable particles like masses ofmatter; for no matter how minute they might be, there would beinterspaces and unoccupied spaces which would present us with phenomenawhich have never been seen. It is the general consensus of opinionamong those who have studied the subject that the ether is not atomic instructure. 

5. MATTER HAS DEFINITE STRUCTURE. 

Every atom of every element is so like every other atom of the sameelement as to exhibit the same characteristics, size, weight, chemicalactivity, vibratory rate, etc. , and it is thus shown conclusively thatthe structural form of the elemental particles is the same for eachelement, for such characteristic reactions as they exhibit could hardlybe if they were mechanically unlike. 

Of what form the atoms of an element may be is not very definitelyknown. The earlier philosophers assumed them to be hard round particles, but later thinkers have concluded that atoms of such a character arehighly improbable, for they could not exhibit in this case theproperties which the elements do exhibit. They have therefore dismissedsuch a conception from consideration. In place of this hypothesis hasbeen substituted a very different idea, namely, that an atom is avortex-ring[1] of ether floating in the ether, as a smoke-ring puffedout by a locomotive in still air may float in the air and show variousphenomena. 

[Footnote 1: Vortex-rings for illustration may be made by having awooden box about a foot on a side, with a round orifice in the middle ofone side, and the side opposite covered with stout cloth stretched tightover a framework. A saucer containing strong ammonia water, and anothercontaining strong hydrochloric acid, will cause dense fumes in the box, and a tap with the hand upon the cloth back will force out a ring fromthe orifice. These may be made to follow and strike each other, rebounding and vibrating, apparently attracting each other and beingattracted by neighbouring bodies. 

By filling the mouth with smoke, and pursing the lips as if to make thesound _o_, one may make fifteen or twenty small rings by snapping thecheek with the finger. ]

A vortex-ring produced in the air behaves in the most surprising manner. 

[Illustration: FIG. 4. --Method of making vortex-rings and theirbehaviour. ]

1. It retains its ring form and the same material rotating as itstarts with. 

2. It can travel through the air easily twenty or thirty feet in asecond without disruption. 

3. Its line of motion when free is always at right angles to theplane of the ring. 

4. It will not stand still unless compelled by some object. Ifstopped in the air it will start up itself to travel on withoutexternal help. 

5. It possesses momentum and energy like a solid body. 

6. It is capable of vibrating like an elastic body, making adefinite number of such vibrations per second, the degree ofelasticity depending upon the rate of vibration. The swifter therotation, the more rigid and elastic it is. 

7. It is capable of spinning on its own axis, and thus having rotaryenergy as well as translatory and vibratory. 

8. It repels light bodies in front of it, and attracts into itselflight bodies in its rear. 

9. If projected along parallel with the top of a long table, it willfall upon it every time, just as a stone thrown horizontally willfall to the ground. 

10. If two rings of the same size be travelling in the same line, and the rear one overtakes the other, the front one will enlarge itsdiameter, while the rear one will contract its own till it can gothrough the forward one, when each will recover its originaldiameter, and continue on in the same direction, but vibrating, expanding and contracting their diameters with regularity. 

11. If two rings be moving in the same line, but in oppositedirections, they will repel each other when near, and thus retardtheir speed. If one goes through the other, as in the former case, it may quite lose its velocity, and come to a standstill in the airtill the other has moved on to a distance, when it will start up inits former direction. 

12. If two rings be formed side by side, they will instantly collideat their edges, showing strong attraction. 

13. If the collision does not destroy them, they may either breakapart at the point of the collision, and then weld together into asingle ring with twice the diameter, and then move on as if a singlering had been formed, or they may simply bounce away from eachother, in which case they always rebound _in a plane_ at rightangles to the plane of collision. That is, if they collided on theirsides, they would rebound so that one went up and the other down. 

14. Three may in like manner collide and fuse into a single ring. 

Such rings formed in air by a locomotive may rise wriggling in the airto the height of several hundred feet, but they are soon dissolved anddisappear. This is because the friction and viscosity of the air robsthe rings of their substance and energy. If the air were withoutfriction this could not happen, and the rings would then be persistent, and would retain all their qualities. 

Suppose then that such rings were produced in a medium without frictionas the ether is believed to be, they would be permanent structures witha variety of properties. They would occupy space, have definite form anddimensions, momentum, energy, attraction and repulsion, elasticity; obeythe laws of motion, and so far behave quite like such matter as we know. For such reasons it is thought by some persons to be not improbablethat the atoms of matter are minute vortex-rings of ether in the ether. That which distinguishes the atom from the ether is the form of motionwhich is embodied in it, and if the motion were simply arrested, therewould be nothing to distinguish the atom from the ether into which itdissolved. In other words, such a conception makes the atoms of matter aform of motion of the ether, and not a created something put into theether. 

THE ETHER IS STRUCTURELESS. 

If the ether be the boundless substance described, it is clear it canhave no form as a whole, and if it be continuous it can have no minutestructure. If not constituted of atoms or molecules there is nothingdescriptive that can be said about it. A molecule or a particular massof matter could be identified by its form, and is thus in markedcontrast with any portion of ether, for the latter could not beidentified in a similar way. One may therefore say that the ether isformless. 

6. MATTER IS GRAVITATIVE. 

The law of gravitation is held as being universal. According to it everyparticle of matter in the universe attracts every other particle. Theevidence for this law in the solar system is complete. Sun, planets, satellites, comets and meteors are all controlled by gravitation, andthe movements of double stars testify to its activity among the moredistant bodies of the universe. The attraction does not depend upon thekind of matter nor the arrangement of molecules or atoms, but upon theamount or mass of matter present, and if it be of a definite kind ofmatter, as of hydrogen or iron, the gravitative action is proportionalto the number of atoms. 

THE ETHER IS GRAVITATIONLESS. 

One might infer already that if the ether were structureless, physicallaws operative upon such material substances as atoms could not beapplicable to it, and so indeed all the evidence we have shows thatgravitation is not one of its properties. If it were, and it behaved inany degree like atomic structures, it would be found to be denser in theneighbourhood of large bodies like the earth, planets, and the sun. Light would be turned from its straight path while travelling in suchdenser medium, or made to move with less velocity. There is not theslightest indication of any such effect anywhere within the range ofastronomical vision. 

Gravitation then is a property belonging to matter and not to ether. The impropriety of thinking or speaking of the ether as matter of anykind will be apparent if one reflects upon the significance of the lawof gravitation as stated. Every particle of matter in the universeattracts every other particle. If there be anything else in the universewhich has no such quality, then it should not be called matter, else thelaw should read: Some particles of matter attract some other particles, which would be no law at all, for a real physical law has no exceptionsany more than the multiplication table has. Physical laws are physicalrelations, and all such relations are quantitative. 

7. MATTER IS FRICTIONABLE. 

A bullet shot into the air has its velocity continuously reduced by theair, to which its energy is imparted by making it move out of its way. Arailway train is brought to rest by the friction brake upon the wheels. The translatory energy of the train is transformed into the molecularenergy called heat. The steamship requires to propel it fast, a largeamount of coal for its engines, because the water in which it movesoffers great friction--resistance which must be overcome. Whenever onesurface of matter is moved in contact with another surface there is aresistance called friction, the moving body loses its rate of motion, and will presently be brought to rest unless energy be continuouslysupplied. This is true for masses of matter of all sizes and with allkinds of motion. Friction is the condition for the transformation of allkinds of mechanical motions into heat. The test of the amount offriction is the rate of loss of motion. A top will spin some time in theair because its point is small. It will spin longer on a plate than onthe carpet, and longer in a vacuum than in the air, for it does not havethe air friction to resist it, and there is no kind or form of matternot subject to frictional resistance. 

THE ETHER IS FRICTIONLESS. 

The earth is a mass of matter moving in the ether. In the equatorialregion the velocity of a point is more than a thousand miles in an hour, for the circumference of the earth is 25, 000 miles, and it turns once onits axis in 24 hours, which is the length of the day. If the earth werethus spinning in the atmosphere, the latter not being in motion, thewind would blow with ten times hurricane velocity. The friction would beso great that nothing but the foundation rocks of the earth's crustcould withstand it, and the velocity of rotation would be reducedappreciably in a relatively short time. The air moves along with theearth as a part of it, and consequently no such frictional destructiontakes place, but the earth rotates in the ether with that same rate, andif the ether offered resistance it would react so as to retard therotation and increase the length of the day. Astronomical observationsshow that the length of the day has certainly not changed so much as thetenth of a second during the past 2000 years. The earth also revolvesabout the sun, having a speed of about 19 miles in a second, or 68, 000miles an hour. This motion of the earth and the other planets about thesun is one of the most stable phenomena we know. The mean distance andperiod of revolution of every planet is unalterable in the long run. Ifthe earth had been retarded by its friction in the ether the length ofthe year would have been changed, and astronomers would have discoveredit. They assert that a change in the length of a year by so much as thehundredth part of a second has not happened during the past thousandyears. This then is testimony, that a velocity of nineteen miles asecond for a thousand years has produced no effect upon the earth'smotion that is noticeable. Nineteen miles a second is not a very swiftastronomical motion, for comets have been known to have a velocity of400 miles a second when in the neighbourhood of the sun, and yet theyhave not seemed to suffer any retardation, for their orbits have notbeen shortened. Some years ago a comet was noticed to have its periodictime shortened an hour or two, and the explanation offered at first wasthat the shortening was due to friction in the ether although no othercomet was thus affected. The idea was soon abandoned, and to-day thereis no astronomical evidence that bodies having translatory motion in theether meet with any frictional resistance whatever. If a stone could bethrown in interstellar space with a velocity of fifty feet a second itwould continue to move in a straight line with the same speed for anyassignable time. 

As has been said, light moves with the velocity of 186, 000 miles persecond, and it may pursue its course for tens of thousands of years. There is no evidence that it ever loses either its wave-length orenergy. It is not transformed as friction would transform it, else therewould be some distance at which light of given wave-length and amplitudewould be quite extinguished. The light from distant stars would bedifferent in character from that coming from nearer stars. Furthermore, as the whole solar system is drifting in space some 500, 000, 000 of milesin a year, new stars would be coming into view in that direction, andfaint stars would be dropping out of sight in the opposite direction--aphenomenon which has not been observed. Altogether the testimony seemsconclusive that the ether is a frictionless medium, and does nottransform mechanical motion into heat. 

8. MATTER IS ÆOLOTROPIC. 

That is, its properties are not alike in all directions. Chemicalphenomena, crystallization, magnetic and electrical phenomena show eachin their way that the properties of atoms are not alike on oppositefaces. Atoms combine to form molecules, and molecules arrange themselvesin certain definite geometric forms such as cubes, tetrahedra, hexagonalprisms and stellate forms, with properties emphasized on certain facesor ends. Thus quartz will twist a ray of light in one direction or theother, depending upon the arrangement which may be known by the externalform of the crystal. Calc spar will break up a ray of light into twoparts if the light be sent through it in certain directions, but not ifin another. Tourmaline polarizes light sent through its sides andbecomes positively electrified at one end while being heated. Somesubstances will conduct sound or light or heat or electricity better inone direction than in another. All matter is magnetic in some degree, and that implies polarity. If one will recall the structure of avortex-ring, he will see how all the motion is inward on one side andoutward on the other, which gives different properties to the two sides:a push away from it on one side and a pull toward it on the other. 

THE ETHER IS ISOTROPIC. 

That is, its properties are alike in every direction. There is nodistinction due to position. A mass of matter will move as freely in onedirection as in another; a ray of light of any wave-length will travelin it in one direction as freely as in any other; neither velocity nordirection are changed by the action of the ether alone. 

9. MATTER IS CHEMICALLY SELECTIVE. 

When the elements combine to form molecules they always combine indefinite ways and in definite proportions. Carbon will combine withhydrogen, but will drop it if it can get oxygen. Oxygen will combinewith iron or lead or sodium, but cannot be made to combine withfluorine. No more than two atoms of oxygen can be made to unite with onecarbon atom, nor more than one hydrogen with one chlorine atom. There isthus an apparent choice for the kind and number of associates inmolecular structure, and the instability of a molecule dependsaltogether upon the presence in its neighbourhood of other atoms forwhich some of the elements in the molecule have a stronger attractionor affinity than they have for the atoms they are now combined with. Thus iron is not stable in the presence of water molecules, and itbecomes iron oxide; iron oxide is not stable in the presence of hotsulphur, it becomes an iron sulphide. All the elements are thusselective, and it is by such means that they may be chemicallyidentified. 

There is no phenomenon in the ether that is comparable with this. Evidently there could not be unless there were atomic structures havingin some degree different characteristics which we know the ether to bewithout. 

10. THE ELEMENTS OF MATTER ARE HARMONICALLY RELATED. 

It is possible to arrange the elements in the order of their atomicweights in columns which will show communities of property. Newlands, Mendeléeff, Meyer, and others have done this. The explanation for suchan arrangement has not yet been forthcoming, but that it expresses areal fact is certain, for in the original scheme there were several gapsrepresenting undiscovered elements, the properties of which werepredicted from that of their associates in the table. Some of these havesince been discovered, and their atomic weight and physical propertiesaccord with those predicted. 

With the ether such a scheme is quite impossible, for the very evidentreason that there are no different things to have relation with eachother. Every part is just like every other part. Where there are nodifferences and no distinctions there can be no relations. The ether isquite harmonic without relations. 

11. MATTER EMBODIES ENERGY. 

So long as the atoms of matter were regarded as hard round particles, they were assumed to be inert and only active when acted upon by whatwere called forces, which were held to be entities of some sort, independent of matter. These could pull or push it here or there, butthe matter was itself incapable of independent activity. All this is nowchanged, and we are called upon to consider every atom as being itself aform of energy in the same sense as heat or light are forms of energy, the energy being embodied in particular forms of motion. Light, forinstance, is a wave motion of the ether. An atom is a rotary ring ofether. Stop the wave motion, and the light would be annihilated. Stopthe rotation, and the atom would be annihilated for the same reason. Asthe ray of light is a particular embodiment of energy, and has noexistence apart from it, so an atom is to be regarded as an embodimentof energy. On a previous page it is said that energy is the ability ofone body to act upon and move another in some degree. An atom of anykind is not the inert thing it has been supposed to be, for it can dosomething. Even at absolute zero, when all its vibratory or heat energywould be absent, it would be still an elastic whirling body pulling uponevery other atom in the universe with gravitational energy, twistingother atoms into conformity with its own position with its magneticenergy; and, if such ether rings are like the rings which are made inair, will not stand still in one place even if no others act upon it, but will start at once by its own inherent energy to move in a rightline at right angles to its own plane and in the direction of the whirlinside the ring. Two rings of wood or iron might remain in contact witheach other for an indefinite time, but vortex-rings will not, but willbeat each other away as two spinning tops will do if they touch ever sogently. If they do not thus separate it is because there are other formsof energy acting to press them together, but such external pressure willbe lessened by the rings' own reactions. 

It is true that in a frictionless medium like the ether one cannot atpresent see how such vortex-rings could be produced in it. Certainly notby any such mechanical methods as are employed to make smoke-rings inair, for the friction of the air is the condition for producing them. However they came to be, there is implied the previous existence of theether and of energy in some form capable of acting upon it in a mannerradically different from any known in physical science. 

There is good spectroscopic evidence that in some way elements ofdifferent kinds are now being formed in nebulæ, for the simplest showthe presence of hydrogen alone. As they increase in complexity otherelements are added, until the spectrum exhibits all the elements we knowof. It has thus seemed likely either that most of what are calledelements are composed of molecular groupings of some fundamentalelement, which by proper physical methods might be decomposed, as onecan now decompose a molecule of ammonia or sulphuric acid, or that theelements are now being created by some extra-physical process in thosefar-off regions. In either case an atom is the embodiment of energy insuch a form as to be permanent under ordinary physical circumstances, but of which, if in any manner it should be destroyed, only the formwould be lost. The ether would remain, and the energy which was embodiedwould be distributed in other ways. 

THE ETHER IS ENDOWED WITH ENERGY. 

The distinction between energy in matter and energy in the ether will beapparent, on considering that both the ether and energy in some formmust be conceived as existing independent of matter; though every atomwere annihilated, the ether would remain and all the energy embodied inthe atoms would be still in existence in the ether. The atomic energywould simply be dissolved. One can easily conceive the ether as the samespace-filling, continuous, unlimited medium, without an atom in it. Onthis assumption it is clear that no form of energy with which we have todeal in physical science would have any existence in the ether; forevery one of those forms, gravitational, thermal, electric, magnetic, orany other--all are the results of the forms of energy in matter. Ifthere were no atoms, there would be no gravitation, for that is theattraction of atoms upon each other. If there were no atoms, there couldbe no atomic vibration, therefore no heat, and so on for each and all. Nevertheless, if an atom be the embodiment of energy, there must havebeen energy in the ether before any atom existed. One of the propertiesof the ether is its ability to distribute energy in certain ways, butthere is no evidence that of itself it ever transforms energy. Once agiven kind of energy is in it, it does not change; hence for theapparition of a form of energy, like the first vortex-ring, there musthave been not only energy, but some other agency capable of transformingthat energy into a permanent structure. To the best of our knowledgeto-day, the ether would be absolutely helpless. Such energy as wasactive in forming atoms must be called by another name than what isappropriate for such transformations as occur when, for instance, themechanical energy of a bullet is transformed into heat when the targetis struck. Behind the ether must be assumed some agency, directing andcontrolling energy in a manner totally different from any agency, whichis operative in what we call physical science. Nothing short of what iscalled a miracle will do--an event without a physical antecedent in anyway necessarily related to its factors, as is the fact of a stonerelated to gravity or heat to an electric current. 

Ether energy is an endowment instead of being an embodiment, and impliesantecedents of a super-physical kind. 

12. MATTER IS AN ENERGY TRANSFORMER. 

As each different kind of energy represents some specific form ofmotion, and _vice versâ_, some sort of mechanism is needful fortransforming one kind into another, therefore molecular structure ofone kind or another is essential. The transformation is a mechanicalprocess, and matter in some particular and appropriate form is thecondition of its taking place. If heat appears, then its antecedent hasbeen some other form of motion acting upon the substance heated. It mayhave been the mechanical motion of another mass of matter, as when abullet strikes a target and becomes heated; or it may be friction, aswhen a car-axle heats when run without proper oiling to reduce friction;or it may be condensation, as when tinder is ignited by condensing theair about it; or chemical reactions, when molecular structure is changedas in combustion, or an electrical current, which implies a dynamo andsteam-engine or water-power. If light appears, its antecedent has beenimpact or friction, condensation or chemical action, and if electricityappears the same sort of antecedents are present. Whether the one or theother of these forms of energy is developed, depends upon what kind of astructure the antecedent energy has acted upon. If radiant energy, so-called, falls upon a mass of matter, what is absorbed is at oncetransformed into heat or into electric or magnetic effects; _which_ oneof these depends upon the character of the mechanism upon which theradiant energy acts, but the radiant energy itself, which consists ofether-waves, is traceable back in every case to a mass of matter havingdefinite characteristic motions. 

One may therefore say with certainty that every physical phenomenon is achange in the direction, or velocity, or character, of the energypresent, and such change has been produced by matter acting as atransformer. 

THE ETHER IS A NON-TRANSFORMER. 

It has already been said that the absence of friction in the etherenables light-waves to maintain their identity for an indefinite time, and to an indefinitely great distance. In a uniform, homogeneoussubstance of any kind, any kind of energy which might be in it wouldcontinue in it without any change. Uniformity and homogeneity implysimilarity throughout, and the necessary condition for transformation isunlikeness. One might not look for any kind of physical phenomenon whichwas not due to the presence and activity of some heterogeneity. 

As a ray of light continues a ray of light so long as it exists in freeether, so all kinds of radiations, of whatever wave-length, continueidentical until they fall upon some mechanical structure called matter. Translatory motion continues translatory, rotary continues rotary, andvibratory continues to be vibratory, and no transforming change cantake place in the absence of matter. The ether is helpless. 

13. MATTER IS ELASTIC. 

It is commonly stated that certain substances, like putty and dough, areinelastic, while some other substances, like glass, steel, and wood, areelastic. This quality of elasticity, as manifested in such differentdegrees, depends upon molecular combinations; some of which, as in glassand steel, are favourable for exhibiting it, while others mask it, forthe ultimate atoms of all kinds are certainly highly elastic. 

The measure of elasticity in a mass of matter is the velocity with whicha wave-motion will be transmitted through it. Thus the elasticity of theair determines the velocity of sound in it. If the air be heated, theelasticity is increased and the sound moves faster. The rates of suchsound-conduction range from a few feet in a second to about 16, 000, fivetimes swifter than a cannon ball. In such elastic bodies as vibrate toand fro like the prongs of a tuning-fork, or give sounds of a definitepitch, the rate of vibration is determined by the size and shape of thebody as well as by their elementary composition. The smaller a body is, the higher its vibratory rate, if it be made of the same material andthe form remains the same. Thus a tuning-fork, that may be carried inthe waistcoat-pocket, may vibrate 500 times a second. If it were onlythe fifty-millionth of an inch in size, but of the same material andform, it would vibrate 30, 000, 000000 times a second; and if it were madeof ether, instead of steel, it would vibrate as many times faster as thevelocity of waves in the ether is greater than it is in steel, and wouldbe as many as 400, 000000, 000000 times per second. The amount ofdisplacement, or the amplitude of vibration, with the pocket-fork mightbe no more than the hundredth of an inch, and this rate measured astranslation velocity would be but five inches per second. If the forkwere of atomic magnitude, and should swing its sides one half thediameter of the atom, or say the hundred-millionth of an inch, thetranslational velocity would be equivalent to about eighty miles asecond, or a hundred and fifty times the velocity of a cannon ball, which may be reckoned at about 3000 feet. 

That atoms really vibrate at the above rate per second is very certain, for their vibrations produce ether-waves the length of which may beaccurately measured. When a tuning-fork vibrates 500 times a second, andthe sound travels 1100 feet in the same interval, the length of eachwave will be found by dividing the velocity in the air by the number ofvibrations, or 1100 ÷ 500 = 2. 2 feet. In like manner, when one knowsthe velocity and wave-length, he may compute the number of vibrations bydividing the velocity by the wave-length. Now the velocity of the wavescalled light is 186, 000 miles a second, and a light-wave may be oneforty thousandth of an inch long. The atom that produces the wave mustbe vibrating as many times per second as the fifth thousandth of an inchis contained in 186, 000 miles. Reducing this number to inches we have

186, 000 × 5280 × 12------------------- = 400, 000, 000, 000, 000, nearly. 1/40, 000

This shows that the atoms are minute elastic bodies that change theirform rapidly when struck. As rapid as the change is, yet the rate ofmovement is only one-fifth that of a comet when near the sun, and istherefore easily comparable with other velocities observed in masses ofmatter. 

These vibratory motions, due to the elasticity of the atoms, is whatconstitutes heat. 

THE ETHER IS ELASTIC. 

The elasticity of a mass of matter is its ability to recover itsoriginal form after that form has been distorted. There is implied thata stress changes its shape and dimensions, which in turn implies alimited mass and relative change of position of parts and some degreeof discontinuity. From what has been said of the ether as beingunlimited, continuous, and not made of atoms or molecules, it will beseen how difficult, if not impossible, it is to conceive how such aproperty as elasticity, as manifested in matter, can be attributed tothe ether, which is incapable of deformation, either in structure orform, the latter being infinitely extended in every direction andtherefore formless. Nevertheless, certain forms of motion, such aslight-waves, move in it with definite velocity, quite independent of howthey originate. This velocity of 186, 000 miles a second so much exceedsany movement of a mass of matter that the motions can hardly becompared. Thus if 400 miles per second be the swiftest speed of any massof matter known--that of a comet near the sun--the ether-wave moves186, 000 ÷ 400 = 465 times faster than such comet, and 900, 000 timesfaster than sound travels in air. It is clear that if this rate ofmotion depends upon elasticity, the elasticity must be of an entirelydifferent type from that belonging to matter, and cannot be defined inany such terms as are employed for matter. 

If one considers gravitative phenomena, the difficulty is enormouslyincreased. The orbit of a planet is never an exact ellipse, on account of the perturbations produced by the planetaryattractions--perturbations which depend upon the direction and distanceof the attracting bodies. These, however, are so well known that slightdeviations are easily noticed. If gravitative attraction took any suchappreciable time to go from one astronomical body to another as doeslight, it would make very considerable differences in the paths of theplanets and the earth. Indeed, if the velocity of gravitation were lessthan a million times greater than that of light, its effects would havebeen discovered long ago. It is therefore considered that the velocityof gravitation cannot be less than 186000, 000000 miles per second. Howmuch greater it may be no one can guess. Seeing that gravitation isether-pressure, it does not seem probable that its velocity can beinfinite. However that may be, the ability of the ether to transmitpressure and various disturbances, evidently depends upon properties sodifferent from those that enable matter to transmit disturbances thatthey deserve to be called by different names. To speak of the elasticityof the ether may serve to express the fact that energy may betransmitted at a finite rate in it, but it can only mislead one'sthinking if he imagines the process to be similar to energy transmissionin a mass of matter. The two processes are incomparable. No other wordhas been suggested, and perhaps it is not needful for most scientificpurposes that another should be adopted, but the inappropriateness ofthe one word for the different phenomena has long been felt. 

14. MATTER HAS DENSITY. 

This quality is exhibited in two ways in matter. In the first, thedifferent elements in their atomic form have different masses or atomicweights. An atom of oxygen weighs sixteen times as much as an atom ofhydrogen; that is, it has sixteen times as much matter, as determined byweight, as the hydrogen atom has, or it takes sixteen times as manyhydrogen atoms to make a pound as it takes of oxygen atoms. This isgenerally expressed by saying that oxygen has sixteen times the densityof hydrogen. In like manner, iron has fifty-six times the density, andgold one hundred and ninety-six. The difference is one in the structureof the atomic elements. If one imagines them to be vortex-rings, theymay differ in size, thickness, and rate of rotation; either of thesemight make all the observed difference between the elements, includingtheir density. In the second way, density implies compactness ofmolecules. Thus if a cubic foot of air be compressed until it occupiesbut half a cubic foot, each cubic inch will have twice as many moleculesin it as at first. The amount of air per unit volume will have beendoubled, the weight will have been doubled, the amount of matter asdetermined by its weight will have been doubled, and consequently we sayits density has been doubled. 

If a bullet or a piece of iron be hammered, the molecules are compactedcloser together, and a greater number can be got into a cubic inch whenso condensed. In this sense, then, density means the number of moleculesin a unit of space, a cubic inch or cubic centimeter. There is impliedin this latter case that the molecules do not occupy all the availablespace, that they may have varying degrees of closeness; in other words, matter is discontinuous, and therefore there may be degrees in density. 

THE ETHER HAS DENSITY. 

It is common to have the degree of density of the ether spoken of in thesame way, and for the same reason, that its elasticity is spoken of. Therate of transmission of a physical disturbance, as of a pressure or awave-motion in matter, is conditioned by its degree of density; that is, the amount of matter per cubic inch as determined by its weight; thegreater the density the slower the rate. So if rate of speed andelasticity be known, the density may be computed. In this way thedensity of the ether has been deduced by noting the velocity of light. The enormous velocity is supposed to prove that its density is verysmall, even when compared with hydrogen. This is stated to be aboutequal to that of the air at the height of two hundred and ten milesabove the surface of the earth, where the air molecules are so few thata molecule might travel for 60, 000, 000 miles without coming in collisionwith another molecule. In air of ordinary density, a molecule can on theaverage move no further than about the two-hundred-and-fifty-thousandthof an inch without such collision. It is plain the density of the etheris so far removed from the density of anything we can measure, that itis hardly comparable with such things. If, in addition, one recalls thefact that the ether is homogeneous, that is all of one kind, and alsothat it is not composed of atoms and molecules, then degree ofcompactness and number of particles per cubic inch have no meaning, andthe term density, if used, can have no such meaning as it has whenapplied to matter. There is no physical conception gained from the studyof matter that can be useful in thinking of it. As with elasticity, sodensity is inappropriately applied to the ether, but there is nosubstitute yet offered. 

15. MATTER IS HEATABLE. 

So long as heat was thought to be some kind of an imponderable thing, which might retain its identity whether it were in or out of matter, its real nature was obscured by the name given to it. An imponderablewas a mysterious something like a spirit, which was the cause of certainphenomena in matter. Heat, light, electricity, magnetism, gravitation, were due to such various agencies, and no one concerned himself with thenature of one or the other. Bacon thought that heat was a briskagitation of the particles of substances, and Count Rumford and SirHumphrey Davy thought they proved that it could be nothing else, butthey convinced nobody. Mayer in Germany and Joule in England showed thatquantitative relations existed between work done and heat developed, butnot until the publication of the book called _Heat as a Mode of Motion_, was there a change of opinion and terminology as to the nature of heat. For twenty years after that it was common to hear the expressions heat, and radiant heat, to distinguish between phenomena in matter and what isnow called radiant energy radiations, or simply ether-waves. Not untilthe necessity arose for distinguishing between different forms ofenergy, and the conditions for developing them, did it become clear toall that a change in the form of energy implied a change in the form ofmotion that embodied it. The energy called heat energy was proved to bea vibratory motion of molecules, and what happened in the ether as aresult of such vibrations is no longer spoken of as heat, but as etherwaves. When it is remembered that the ultimate atoms are elastic bodies, and that they will, if free, vibrate in a periodic manner when struck orshaken in any way, just as a ball will vibrate after it is struck, it iseasy to keep in mind the distinction between the mechanical form ofmotion spent in striking and the vibratory form of the motion producedby it. The latter is called heat; no other form of motion than that isproperly called heat. It is this alone that represents temperature, therate and amplitude of such atomic and molecular vibrations as constitutechange, of form. Where molecules like those in a gas have some freedomof movement between impacts, they bound away from each other withvarying velocities. The path of such motion may be long or short, depending upon the density or compactness of the molecules, but suchchanges in position are not heat for a molecule any more than the flightof a musket ball is heat, though it may be transformed into heat onstriking the target. 

This conception of heat as the rapid change in the form of atoms andmolecules, due to their elasticity, is a phenomenon peculiar to matter. It implies a body possessing form that may be changed; elasticity, thatits changes may be periodic, and degrees of freedom that secure spacefor the changes. Such a body may be heated. Its temperature will dependupon the amplitude of such vibrations, and will be limited by themaximum amplitude. 

THE ETHER IS UNHEATABLE. 

The translatory motion of a mass of matter, big or little, through theether, is not arrested in any degree so far as observed, but theinternal vibratory motion sets up waves in the ether, the ether absorbsthe energy, and the amplitude is continually lessened. The motion hasbeen transferred and transformed; transferred from matter to the ether, and transformed from vibratory to waves travelling at the rate of186, 000 miles per second. The latter is not heat, but the result ofheat. With the ether constituted as described, such vibratory motion asconstitutes heat is impossible to it, and hence the characteristic ofheat-motion in it is impossible; it cannot therefore be heated. Thespace between the earth and the sun may have any assignable amount ofenergy in the form of ether waves or light, but not any temperature. Onemight loosely say that the temperature of empty spaces was absolutezero, but that would not be quite correct, for the idea of temperaturecannot properly be entertained as applicable to the ether. To say thatits temperature was absolute zero, would serve to imply that it might behigher, which is inadmissible. 

When energy has been transformed, the old name by which the energy wascalled must be dropped. Ether cannot be heated. 

16. MATTER IS INDESTRUCTIBLE. 

This is commonly said to be one of the essential properties of matter. All that is meant by it, however, is simply this: In no physical orchemical process to which it has been experimentally subjected has therebeen any apparent loss. The matter experimented upon may change from asolid or liquid to a gas, or the molecular change called chemical mayresult in new compounds, but the weight of the material and its atomicconstituents have not appreciably changed. That matter cannot beannihilated is only the converse of the proposition that matter cannotbe created, which ought always to be modified by adding, by physical orchemical processes at present known. A chemist may work with a fewgrains of a substance in a beaker, or test-tube, or crucible, and afterseveral solutions, precipitations, fusions and dryings, may find byfinal weighing that he has not lost any appreciable amount, but how muchis an appreciable amount? A fragment of matter the ten-thousandth of aninch in diameter has too small a weight to be noted in any balance, yetit would be made up of thousands of millions of atoms. Hence if, in theprocesses to which the substance had been subjected, there had been thetotal annihilation of thousands of millions of atoms, such phenomenonwould not have been discovered by weighing. Neither would it have beendiscovered if there had been a similar creation or development of newmatter. All that can be asserted concerning such events is, that theyhave not been discovered with our means of observation. 

The alchemists sought to transform one element into another, as leadinto gold. They did not succeed. It was at length thought to beimpossible, and the attempt to do it an absurdity. Lately, however, telescopic observation of what is going on in nebulæ, which has alreadybeen referred to, has somewhat modified ideas of what is possible andimpossible in that direction. It is certainly possible roughly toconceive how such a structure as a vortex-ring in the ether might beformed. With certain polarizing apparatus it is possible to produce raysof circularly polarized light. These are rays in which the motion is anadvancing rotation like the wire in a spiral spring. If such a line ofrotations in the ether were flexible, and the two ends should cometogether, there is reason for thinking they would weld together, inwhich case the structure would become a vortex-ring and be as durable asany other. There is reason for believing, also, that somewhat similarmovements are always present in a magnetic field, and though we do notknow how to make them close up in the proper way, it does not followthat it is impossible for them to do so. 

The bearing of all this upon the problem of the transmutation ofelements is evident. No one now will venture to deny its possibility asstrongly as it was denied a generation ago. It will also lead one to beless confident in the theory that matter is indestructible. Assuming thevortex-ring theory of atoms to be true, if in any way such a ring couldbe cut or broken, there would not remain two or more fragments of a ringor atom. The whole would at once be dissolved into the ether. The ringand rotary energy that made it an atom would be destroyed, but not thesubstance it was made of, nor the energy which was embodied therein. Fora long time philosophers have argued, and commonsense has agreed withthem, that an atom which could not be ideally broken into two parts wasimpossible, that one could at any rate think of half an atom as a realobjective possibility. This vortex-ring theory shows easily how possibleit is to-day to think what once was philosophically incredible. It showsthat metaphysical reasoning may be ever so clear and apparentlyirrefragable, yet for all that it may be very unsound. The trouble doesnot come so much from the logic as from the assumption upon which thelogic is founded. In this particular case the assumption was that theultimate particles of matter were hard, irrefragable somethings, withoutnecessary relations to anything else, or to energy, and irrefragableonly because no means had been found of breaking them. 

The destructibility or indestructibility of the ether cannot beconsidered from the same standpoint as that for matter, either ideallyor really. Not ideally, because we are utterly without any mechanicalconceptions of the substance upon which one can base either reason oranalogy; and not really, because we have no experimental evidence as toits nature or mode of operation. If it be continuous, there are nointerspaces, and if it be illimitable there is no unfilled spaceanywhere. Furthermore, one might infer that if in any way a portion ofthe ether could be annihilated, what was left would at once fill up thevacated space, so there would be no record left of what had happened. Apparently, its destruction would be the destruction of a substance, which is a very different thing from the destruction of a mode ofmotion. In the latter, only the form of the motion need be destroyed tocompletely obliterate every trace of the atom. In the former, therewould need to be the destruction of both substance and energy, for it iscertain, for reasons yet to be attended to, that the ether is saturatedwith energy. 

One may, without mechanical difficulties, imagine a vortex-ringdestroyed. It is quite different with the ether itself, for if it weredestroyed in the same sense as the atom of matter, it would be changedinto something else which is not ether, a proposition which assumes theexistence of another entity, the existence for which is needed only as amechanical antecedent for the other. The same assumption would be neededfor this entity as for the ether, namely, something out of which it wasmade, and this process of assuming antecedents would be interminable. The last one considered would have the same difficulties to meet as theether has now. The assumption that it was in some way and at some timecreated is more rational, and therefore more probable, than that iteither created itself or that it always existed. Considered as theunderlying stratum of matter, it is clear that changes of any kind inmatter can in no way affect the quantity of ether. 

17. MATTER HAS INERTIA. 

The resistance that a mass of matter opposes to a change in its positionor rate and direction of movement, is called inertia. That it shouldactively oppose anything has been already pointed out as reason fordenying that matter is inert, but inertia is the measure of the reactionof a body when it is acted upon by pressure from any source tending todisturb its condition of either rest or motion. It is the equivalent ofmass, or the amount of matter as measured by gravity, and is a fixedquantity; for inertia is as inherent as any other quality, and belongsto the ultimate atoms and every combination of them. It implies theability to absorb energy, for it requires as much energy to bring amoving body to a standstill as was required to give it its forwardmotion. 

Both rotary and vibratory movements are opposed by the same property. Agrindstone, a tuning-fork, and an atom of hydrogen require, to move themin their appropriate ways, an amount of energy proportionate to theirmass or inertia, which energy is again transformed through friction intoheat and radiated away. 

One may say that inertia is the measure of the ability of a body totransfer or transform mechanical energy. The meteorite that falls uponthe earth to-day gives, on its impact, the same amount of energy itwould have given if it had struck the earth ten thousand years ago. Theinertia of the meteor has persisted, not as energy, but as a factor ofenergy. We commonly express the energy of a mass of matter by_mv_^{2}/2, where _m_ stands for the mass and _v_ for its velocity. Wemight as well, if it were as convenient, substitute inertia for mass, and write the expression _iv_^{2}/2, for the mass, being measured by itsinertia, is only the more common and less definitive word for the samething. The energy of a mass of matter is, then, proportional to itsinertia, because inertia is one of its factors. Energy has often beentreated as if it were an objective thing, an entity and a unity; butsuch a conception is evidently wrong, for, as has been said before, itis a product of two factors, either of which may be changed in anydegree if the other be changed inversely in the same degree. A cannonball weighing 1000 pounds, and moving 100 feet per second, will have156, 000 foot-pounds of energy, but a musket ball weighing an ounce willhave the same amount when its velocity is 12, 600 feet per second. Nevertheless, another body acting upon either bullet or cannon ball, tending to move either in some new direction, will be as efficientwhile those bodies are moving at any assignable rate as when they arequiescent, for the change in direction will depend upon the inertia ofthe bodies, and that is constant. 

The common theory of an inert body is one that is wholly passive, havingno power of itself to move or do anything, except as some agency outsideitself compels it to move in one way or another, and thus endows it withenergy. Thus a stone or an iron nail are thought to be inert bodies inthat sense, and it is true that either of them will remain still in oneplace for an indefinite time and move from it only when some externalagency gives them impulse and direction. Still it is known that suchbodies will roll down hill if they will not roll up, and each of themhas itself as much to do with the down-hill movement as the earth has;that is, it attracts the earth as much as the earth attracts it. If onecould magnify the structure of a body until the molecules becameindividually visible, every one of them would be seen to be in intenseactivity, changing its form and relative position an enormous number oftimes per second in undirected ways. No two such molecules move in thesame way at the same time, and as all the molecules cohere together, their motions in different directions balance each other, so that thebody as a whole does not change its position, not because there is nomoving agency in itself, but because the individual movements arescattering, and not in a common direction. An army may remain in oneplace for a long time. To one at a distance it is quiescent, inert. Toone in the camp there is abundant sign of activity, but the movementsare individual movements, some in one direction and some in another, andoften changing. The same army on the march has the same energy, the samerate of individual movement; but all have a common direction, it movesas a whole body into new territory. So with the molecules of matter. Inlarge masses they appear to be inert, and to do nothing, and to becapable of doing nothing. That is only due to the fact that their energyis undirected, not that they can do nothing. The inference that ifquiescent bodies do not act in particular ways they are inert, andcannot act in any kind of a way, is a wrong inference. An illustrationmay perhaps make this point plainer. A lump of coal will be still aslong as anything if it be undisturbed. Indeed, it has thus lain in acoal-bed for millions of years probably, but if coal be placed where itcan combine with oxygen, it forthwith does so, and during the processyields a large amount of energy in the shape of heat. One pound of coalin this way gives out 14, 000 heat units, which is the equivalent of11, 000, 000 foot-pounds of work, and if it could be all utilized wouldfurnish a horse-power for five and a half hours. Can any inert bodyweighing a pound furnish a horse-power for half a day? And can a bodygive out what it has not got? Are gunpowder and nitro-glycerine inert?Are bread and butter and foods in general inert because they will notpush and pull as a man or a horse may? All have energy, which isavailable in certain ways and not in others, and whatever possessesenergy available in any way is not an ideally inert body. Lastly, howmany inert bodies together will it take to make an active body? If thequestion be absurd, then all the phenomena witnessed in bodies, large orsmall, are due to the fact that the atoms are not inert, but areimmensely energetic, and their inertia is the measure of their rates ofexchanging energy. 

THE ETHER IS CONDITIONALLY POSSESSED OF INERTIA. 

A moving mass of matter is brought to rest by friction, because itimparts its motion at some rate to the body it is in contact with. Generally the energy is transformed into heat, but sometimes it appearsas electrification. Friction is only possible because one or both of thebodies possess inertia. That a body may move in the ether for anindefinite time without losing its velocity has been stated as a reasonfor believing the ether to be frictionless. If it be frictionless, thenit is without inertia, else the energy of the earth and of a ray oflight would be frittered away. A ray of light can only be transformedwhen it falls upon molecules which may be heated by it. As the ethercannot be heated and cannot transform translational energy, it iswithout inertia for _such_ a form of motion and its embodied energy. 

It is not thus with other forms of energy than the translational. Atomicand molecular vibrations are so related to the ether that they aretransformed into waves, which are conducted away at a definite rate. This shows that such property of inertia as is possessed by the ether isselective and not like that of matter, which is equally "inertiative"under all conditions. Similarly with electric and magnetic phenomena, itis capable of transforming the energy which may reside as stress in theether, and other bodies moving in the space so affected meet withfrictional resistance, for they become heated if the motion bemaintained. On the other hand, there is no evidence that the body whichproduced the electric or magnetic stress suffers any degree of frictionon moving in precisely the same space. A bar magnet rotating on itslongitudinal axis does not disturb its own field, but a piece of ironrevolving near the magnet will not only become heated, but will heat thestationary magnet. Much experimental work has been done to discover, ifpossible, the relation of a magnet to its ether field. As the latter isnot disturbed by the rotation of the magnet, it has been concluded thatthe field does not rotate; but as every molecule in the magnet has itsown field independent of all the rest, it is mechanically probable thateach such field does vary in the rotation, but among the thousands ofmillions of such fields the average strength of the field does not varywithin measurable limits. Another consideration is that the magneticfield itself, when moved in space, suffers no frictional resistance. There is no magnetic energy wasted through ether inertia. Thesephenomena show that whether the ether exhibits the quality calledinertia depends upon the kind of motion it has. 

18. MATTER IS MAGNETIC. 

The ordinary phenomenon of magnetism is shown by bringing a piece ofiron into the neighbourhood of a so-called magnet, where it is attractedby the latter, and if free to move will go to and cling to the magnet. Adelicately suspended magnetic needle will be affected appreciably by astrong magnet at the distance of several hundred feet. As the strengthof such action varies inversely as the square of the distance from themagnet, it is evident there can be no absolute boundary to it. At adistance from an ordinary magnet it becomes too weak to be detected byour methods, not that there is a limit to it. It is customary to thinkof iron as being peculiarly endowed with magnetic quality, but all kindsof matter possess it in some degree. Wood, stone, paper, oats, sulphur, and all the rest, are attracted by a magnet, and will stick to it if themagnet be a strong one. Whether a piece of iron itself exhibits theproperty depends upon its temperature, for near 700 degrees it becomesas magnetically indifferent as a piece of copper at ordinarytemperature. Oxygen, too, at 200 degrees below the zero of Centigradeadheres to a magnet like iron. 

In this as in so many other particulars, how a piece of matter behavesdepends upon its temperature, not that the essential qualities aremodified in any degree, but temperature interferes with atomicarrangement and aggregation, and so disguises their phenomena. 

As every kind of matter is thus affected by a magnet, the manifestationsdiffering but in degree, it follows that all kinds of atoms--all theelements--are magnetic. An inherent property in them, as much so asgravitation or inertia; apparently a quality depending upon thestructure of the atoms themselves, in the same sense as gravitation isthus dependent, as it is not a quality of the ether. 

An atom must, then, be thought of as having polarity, differentqualities on the two sides, and possessing a magnetic field as extensiveas space itself. The magnetic field is the stress or pressure in theether produced by the magnetic body. This ether pressure produced by amagnet may be as great as a ton per square inch. It is this pressurethat holds an armature to the magnet. As heat is a molecular conditionof vibration, and radiant energy the result of it, so is magnetism aproperty of molecules, and the magnetic field the temporary condition inthe ether, which depends upon the presence of a magnetic body. We nolonger speak of the wave-motion in the ether which results from heat, asheat, but call it radiation, or ether waves, and for a like reason themagnetic field ought not to be called magnetism. 

THE ETHER IS NON-MAGNETIC. 

A magnetic field manifests itself in a way that implies that the etherstructure, if it may be said to have any, is deformed--deformed in sucha sense that another magnet in it tends to set itself in the plane ofthe stress; that is, the magnet is twisted into a new position toaccommodate itself to the condition of the medium about it. The newposition is the result of the reaction of the ether upon the magnet andether pressure acting at right angles to the body that produced thestress. Such an action is so anomalous as to suggest the propriety ofmodifying the so-called third law of motion, viz. , action and reactionare equal and opposite, adding that sometimes action and reaction are atright angles. 

There is no condition or property exhibited by the ether itself whichshows it to have any such characteristic as attraction, repulsion, ordifferences in stress, except where its condition is modified by theactivities of matter in some way. The ether itself is not attracted orrepelled by a magnet; that is, it is not a magnetic body in any suchsense as matter in any of its forms is, and therefore cannot properly becalled magnetic. 

It has been a mechanical puzzle to understand how the vibratory motionscalled heat could set up light waves in the ether seeing that there isan absence of friction in the latter. In the endeavour to conceive it, the origin of sound-waves has been in mind, where longitudinal air-wavesare produced by the vibrations of a sounding body, and molecular impactis the antecedent of the waves. The analogy does not apply. Thefollowing exposition may be helpful in grasping the idea of suchtransformation and change of energy from matter to the ether. 

Consider a straight bar permanent magnet to be held in the hand. It hasits north and south poles and its field, the latter extending in everydirection to an indefinite distance. The field is to be considered asether stress of such a sort as to tend to set other magnets in it in newpositions. If at a distance of ten feet there were a delicately-poisedmagnet needle, every change in the position of the magnet held in thehand would bring about a change in the position of the needle. If theposition of the hand magnet were completely reversed, so the south polefaced where the north pole faced before, the field would have beencompletely reversed, and the poised needle would have been pushed by thefield into an opposite position. If the needle were a hundred feet away, the change would have been the same except in amount. The same might besaid if the two were a mile apart, or the distance of the moon or anyother distance, for there is no limit to an ether magnetic field. Suppose the hand magnet to have its direction completely reversed oncein a second. The whole field, and the direction of the stress, wouldnecessarily be reversed as often. But this kind of change in stress isknown by experiment to travel with the speed of light, 186, 000 miles asecond; the disturbance due to the change of position of the magnet willtherefore be felt in some degree throughout space. In a second and athird of a second it will have reached the moon, and a magnet there willbe in some measure affected by it. If there were an observer there witha delicate-enough magnet, he could be witness to its changes once asecond for the same reason one in the room could. The only differencewould be one of amount of swing. It is therefore theoretically possibleto signal to the moon with a swinging magnet. Suppose again that themagnet should be swung twice a second, there would be formed two waves, each one half as long as the first. If it should swing ten times asecond, then the waves would be one-tenth of 186, 000 miles long. If insome mechanical way it could be rotated 186, 000 times a second, the wavewould be but one mile long. Artificial ways have been invented forchanging this magnet field as many as 100 million times a second, andthe corresponding wave is less than a foot long. The shape of a magnetdoes not necessarily make it weaker or stronger as a magnet, but if thepoles are near together the magnetic field is denser between them thanwhen they are separated. The ether stress is differently distributed forevery change in the relative positions of the poles. 

A common U-magnet, if struck, will vibrate like a tuning-fork, and givesout a definite pitch. Its poles swing towards and away from each otherat uniform rates, and the pitch of the magnet will depend upon its size, thickness, and the material it is made of. 

Let ten or fifteen ohms of any convenient-sized wire be wound upon thebend of a commercial U-magnet. Let this wire be connected to a telephonein its circuit. When the magnet is made to sound like a tuning-fork, thepitch will be reproduced in the telephone very loudly. If another magnetwith a different pitch be allowed to vibrate near the former, the pitchof the vibrating body will be heard in the telephone, and these showthat the changing magnetic field reacts upon the quiescent magnet, andcompels the latter to vibrate at the same rate. The action is an etheraction, the waves are ether waves, but they are relatively very long. Ifthe magnet makes 500 vibrations a second, the waves will be 372 mileslong, the number of times 500 is contained in 186, 000 miles. Imagine themagnet to become smaller and smaller until it was the size of an atom, the one-fifty-millionth of an inch. Its vibratory rate would beproportionally increased, and changes in its form will still bring aboutchanges in its magnetic field. But its magnetic field is practicallylimitless, and the number of vibrations per second is to be reckonedas millions of millions; the waves are correspondingly short, small fractions of an inch. When they are as short as theone-thirty-seven-thousandth of an inch, they are capable of affectingthe retina of the eye, and then are said to be visible as red light. Ifthe vibratory rate be still higher, and the corresponding waves be nomore than one-sixty-thousandth of an inch long, they affect the retinaas violet light, and between these limits there are all the waves thatproduce a complete spectrum. The atoms, then, shake the ether in thisway because they all have a magnetic hold upon the ether, so that anydisturbance of their own magnetism, such as necessarily comes when theycollide, reacts upon the ether for the same reason that a large magnetacts thus upon it when its poles approach and recede from each other. Itis not a phenomenon of mechanical impact or frictional resistance, sinceneither are possible in the ether. 

19. MATTER EXISTS IN SEVERAL STATES. 

Molecular cohesion exists between very wide ranges. When strong, so ifone part of a body is moved the whole is moved in the same way, withoutbreaking continuity or the relative positions of the molecules, we callthe body a solid. In a liquid, cohesion is greatly reduced, and any partof it may be deformed without materially changing the form of the rest. The molecules are free to move about each other, and there is nodefinite position which any need assume or keep. With gases, themolecules are without any cohesion, each one is independent of everyother one, collides with and bounds away from others as free elasticparticles do. Between impacts it moves in what is called its free path, which may be long or short as the density of the gas be less or greater. 

These differing degrees of cohesion depend upon temperature, for if thedensest and hardest substances are sufficiently heated they will becomegaseous. This is only another way of saying that the states of matterdepend upon the amount of molecular energy present. Solid ice becomeswater by the application of heat. More heat reduces it to steam; stillmore decomposes the steam molecules into oxygen and hydrogen molecules;and lastly, still more heat will decompose these molecules into theiratomic state, complete dissociation. On cooling, the process ofreduction will be reversed until ice has been formed again. 

Cohesive strength in solids is increased by reduction of temperature, and metallic rods become stronger the colder they are. 

No distinction is now made between cohesion and chemical affinity, andyet at low temperatures chemical action will not take place, whichphenomenon shows there is a distinction between molecular cohesion andmolecular structure. In molecular structure, as determined by chemicalactivity, the molecules and atoms are arranged in definite ways whichdepend upon the rate of vibrations of the components. The atoms are setin definite positions to constitute a given molecule. But atoms ormolecules may cohere for other reasons, gravitative or magnetic, andrelative positions would be immaterial. In the absence of temperature, asolid body would be solider and stronger than ever, while a gaseous masswould probably fall by gravity to the floor of the containing vessellike so much dust. The molecular structure might not be changed, forthere would be no agency to act upon it in a disturbing way. 

THE ETHER HAS NO CORRESPONDING STATES. 

Degrees of density have already been excluded, and the homogeneity andcontinuity of the ether would also exclude the possibility of differentstates at all comparable with such as belong to matter. As for cohesion, it is doubtful if the term ought to be applied to such a substance. Theword itself seems to imply possible separateness, and if the ether be asingle indivisible substance, its cohesion must be infinite and istherefore not a matter of degree. The ether has sometimes beenconsidered as an elastic solid, but such solidity is comparable withnothing we call solid in matter, and the word has to be defined in aspecial sense in order that its use may be tolerated at all. In additionto this, some of the phenomena exhibited by it, such as diffraction anddouble refraction, are quite incompatible with the theory that the etheris an elastic solid. The reasons why it cannot be considered as a liquidor gas have been considered previously. 

The expression _states of matter_ cannot be applied to the ether in anysuch sense as it is applied to matter, but there is one sense whenpossibly it may be considered applicable. Let it be granted that an atomis a vortex-ring of ether in the ether, then the state of being in ringrotation would suffice to differentiate that part of the ether from therest, and give to it a degree of individuality not possessed by therest; and such an atom might be called a state of ether. In like manner, if other forms of motion, such as transverse waves, circular andelliptical spirals, or others, exist in the ether, then such movementsgive special character to the part thus active, and it would be properto speak of such states of the ether, but even thus the word would notbe used in the same sense as it is used when one speaks of the states ofmatter as being solid, liquid, and gaseous. 

20. SOLID MATTER CAN EXPERIENCE A SHEARING STRESS, LIQUIDS AND GASESCANNOT. 

A sliding stress applied to a solid deforms it to a degree which dependsupon the stress and the degree of rigidity preserved by the body. Thusif the hand be placed upon a closed book lying on the table, andpressure be so applied as to move the upper side of the book but not thelower, the book is said to be subject to a shearing stress. If thepressing hand has a twisting motion, the book will be warped. Any solidmay be thus sheared or warped, but neither liquids nor gases can be soaffected. Molecular cohesion makes it possible in the one, and the lackof it, impossible in the others. The solid can maintain such adeformation indefinitely long, if the pressure does not rupture itsmolecular structure. 

THE ETHER CAN MAINTAIN A SHEARING STRESS. 

The phenomena in a magnetic field show that the stress is of such a sortas to twist into a new directional position the body upon which it actsas exhibited by a magnetic needle, also as indicated by the transversevibrations of the ether waves, and again by the twist given to planepolarized light when moving through a magnetic field. These are allinterpreted as indicative of the direction of ether stress, as beingsimilar to a shearing stress in solid matter. The fact has been adducedto show the ether to be a solid, but such a phenomenon is certainlyincompatible with a liquid or gaseous ether. This kind of stress ismaintained indefinitely about a permanent magnet, and the mechanicalpressure which may result from it is a measure of the strength of themagnetic field, and may exceed a thousand pounds per square inch. 

21. OTHER PROPERTIES OF MATTER. 

There are many secondary qualities exhibited by matter in some of itsforms, such as hardness, brittleness, malleability, colour, etc. , andthe same ultimate element may exhibit itself in the most diverse ways, as is the case with carbon, which exists as lamp-black, charcoal, graphite, jet, anthracite and diamond, ranging from the softest to thehardest of known bodies. Then it may be black or colourless. Gold isyellow, copper red, silver white, chlorine green, iodine purple. Theonly significance any or all of such qualities have for us here is thatthe ether exhibits none of them. There is neither hardness norbrittleness, nor colour, nor any approach to any of the characteristicsfor the identification of elementary matter. 

22. SENSATION DEPENDS UPON MATTER. 

However great the mystery of the relation of body to mind, it is quitetrue that the nervous system is the mechanism by and through which allsensation comes, and that in our experience in the absence of nervesthere is neither sensation nor consciousness. The nerves themselves arebut complex chemical structures; their molecular constitution is said toembrace as many as 20, 000 atoms, chiefly carbon, hydrogen, oxygen, andnitrogen. There must be continuity of this structure too, for to sever anerve is to paralyze all beyond. If all knowledge comes throughexperience, and all experience comes through the nervous system, thepossibilities depend upon the mechanism each one is provided with forabsorbing from his environment, what energies there are that can actupon the nerves. Touch, taste, and smell imply contact, sound hasgreater range, and sight has the immensity of the universe for itsfield. The most distant but visible star acts through the optic nerve topresent itself to consciousness. It is not the ego that looks outthrough the eyes, but it is the universe that pours in upon the ego. 

Again, all the known agencies that act upon the nerves, whether fortouch or sound or sight, imply matter in some of its forms andactivities, to adapt the energy to the nervous system. The mechanismfor the perception of light is complicated. The light acts upon asensitive surface where molecular structure is broken up, and thisdisturbance is in the presence of nerve terminals, and the sensation isnot in the eye but in the sensorium. In like manner for all the rest; soone may fairly say that matter is the condition for sensation, and inits absence there would be nothing we call sensation. 

THE ETHER IS INSENSIBLE TO NERVES. 

The ether is in great contrast with matter in this particular. There isno evidence that in any direct way it acts upon any part of the nervoussystem, or upon the mind. It is probable that this lack of relationbetween the ether and the nervous system was the chief reason why itsdiscovery was so long delayed, as the mechanical necessities for it evennow are felt only by such as recognize continuity as a condition for thetransmission of energy of whatever kind it may be. Action at a distancecontradicts all experience, is philosophically incredible, and isrepudiated by every one who once perceives that energy has twofactors--substance and motion. 

The table given below presents a list of twenty-two of the knownproperties of matter contrasted with those exhibited by the ether. Innone of them are the properties of the two identical, and in most ofthem what is true for one is not true for the other. They are not simplydifferent, they are incomparable. 

From the necessities of the case, as knowledge has been acquired andterminology became essential for making distinctions, the ether has beendescribed in terms applicable to matter, hence such terms as mass, solidity, elasticity, density, rigidity, etc. , which have a definitemeaning and convey definite mechanical conceptions when applied tomatter, but have no corresponding meaning and convey no such mechanicalconceptions when applied to the ether. It is certain that they areinappropriate, and that the ether and its properties cannot be describedin terms applicable to matter. Mathematical considerations derived fromthe study of matter have no advantage, and are not likely to lead us toa knowledge of the ether. 

Only a few have perceived the inconsistency of thinking of the two inthe same terms. In his _Grammar of Science_, Prof. Karl Pearson says, "We find that our sense-impressions of hardness, weight, colour, temperature, cohesion, and chemical constitution, may all be describedby the aid of the motions of a single medium, which itself is conceivedto have no hardness, weight, colour, temperature, nor indeed elasticityof the ordinary conceptual type. "

None of the properties of the ether are such as one would or could havepredicted if he had had all the knowledge possessed by mankind. Everyphenomenon in it is a surprise to us, because it does not follow thelaws which experience has enabled us to formulate for matter. Asubstance which has none of the phenomenal properties of matter, and isnot subject to the known laws of matter, ought not to be called matter. Ether phenomena and matter phenomena belong to different categories, andthe ends of science will not be conserved by confusing them, as is donewhen the same terminology is employed for both. 

There are other properties belonging to the ether more wonderful, ifpossible, than those already mentioned. Its ability to maintain enormousstresses of various kinds without the slightest evidence ofinterference. There is the gravitational stress, a direct pull betweentwo masses of matter. Between two molecules it is immeasurably smalleven when close together, but the prodigious number of them in a bulletbrings the action into the field of observation, while between suchbodies as the earth and moon or sun, the quantity reaches an astonishingfigure. Thus if the gravitative tension due to the gravitativeattraction of the earth and moon were to be replaced by steel wiresconnecting the two bodies to prevent the moon from leaving its orbit, there would be needed four number ten steel wires to every square inchupon the earth, and these would be strained nearly to the breakingpoint. Yet this stress is not only endured continually by this pliant, impalpable, transparent medium, but other bodies can move through thesame space apparently as freely as if it were entirely free. In additionto this, the stress from the sun and the more variable stresses from theplanets are all endured by the same medium in the same space andapparently a thousand or a million times more would not make theslightest difference. Rupture is impossible. 

Electric and magnetic stresses, acting parallel or at right angles tothe other, exist in the same space and to indefinite degrees, neithermodifying the direction nor amount of either of the others. 

These various stresses have been computed to represent energy, which ifit could be utilized, each cubic inch of space would yield five hundredhorse-power. It shows what a store-house of energy the ether is. Ifevery particle of matter were to be instantly annihilated, the universeof ether would still have an inexpressible amount of energy left. Todraw at will directly from this inexhaustible supply, and utilize it forthe needs of mankind, is not a forlorn hope. 

The accompanying table presents these contrasting properties forconvenient inspection. 

CONTRASTED PROPERTIES OF MATTER AND THE ETHER. 

 MATTER. ETHER. 

 1. Discontinuous Continuous 2. Limited Unlimited 3. Heterogeneous Homogeneous 4. Atomic Non-atomic 5. Definite structure Structureless 6. Gravitative Gravitationless 7. Frictionable Frictionless 8. Æolotropic Isotropic 9. Chemically selective ----10. Harmonically related ----11. Energy embodied Energy endowed12. Energy transformer Non-transformer13. Elastic Elastic?14. Density Density?15. Heatable Unheatable16. Indestructible? Indestructible17. Inertiative Inertiative conditionally18. Magnetic ----19. Variable states ----20. Subject to shearing stress in solid Shearing stress maintained21. Has Secondary qualities ----22. Sensation depends upon Insensible to nerves

CHAPTER III

Antecedents of Electricity--Nature of what is transformed--Series of transformations for the production of light--Positive and negative Electricity--Positive and negative twists--Rotations about a wire--Rotation of an arc--Ether a non-conductor--Electro-magnetic waves--Induction and inductive action--Ether stress and atomic position--Nature of an electric current--Electricity a condition, not an entity. 

So far as we have knowledge to-day, the only factors we have to considerin explaining physical phenomena are: (1) Ordinary matter, such asconstitutes the substance of the earth, and the heavenly bodies; (2) theether, which is omnipresent; and (3) the various forms of motion, whichare mutually transformable in matter, and some of which, but not all, are transformable into ether forms. For instance, the translatory motionof a mass of matter can be imparted to another mass by simple impact, but translatory motion cannot be imparted to the ether, and, for thatreason, a body moving in it is not subject to friction, and continuesto move on with velocity undiminished for an indefinite time; but thevibratory motion which constitutes heat is transformable intowave-motion in the ether, and is transmitted away with the speed oflight. The kind of motion which is thus transformed is not even ato-and-fro swing of an atom, or molecule, like the swing of a pendulumbob, but that due to a change of form of the atoms within the molecule, otherwise there could be no such thing as spectrum analysis. Vibratorymotion of the matter becomes undulatory motion in the ether. Thevibratory motion we call heat; the wave-motion we call sometimes radiantenergy, sometimes light. Neither of these terms is a good one, but wenow have no others. 

It is conceded that it is not proper to speak of the wave-motion in theether as _heat_; it is also admitted that the ether is not heated by thepresence of the wave--or, in other words, the temperature of the etheris absolute zero. Matter only can be heated. But the ether waves canheat other matter they may fall on; so there are three steps in theprocess and two transformations--(1) vibrating matter; (2) waves in theether; (3) vibration in other matter. Energy has been transferredindirectly. What is important to bear in mind is, that when a form ofenergy in matter is transformed in any manner so as to lose itscharacteristics, it is not proper to call it by the same name after asbefore, and this we do in all cases when the transformation is from onekind in matter to another kind in matter. Thus, when a bullet is shotagainst a target, before it strikes it has what we call mechanicalenergy, and we measure that in foot-pounds; after it has struck thetarget, the transformation is into heat, and this has its mechanicalequivalent, but is not called mechanical energy, nor are the motionswhich embody it similar. The mechanical ideas in these phenomena areeasy to grasp. They apply to the phenomena of the mechanics of large andsmall bodies, to sound, to heat, and to light, as ordinarily considered, but they have not been applied to electric phenomena, as they evidentlyshould be, unless it be held that such phenomena are not related toordinary phenomena, as the latter are to one another. 

When we would give a complete explanation of the phenomena exhibited by, say, a heated body, we need to inquire as to the antecedents of themanifestation, and also its consequents. Where and how did it get itsheat? Where and how did it lose it? When we know every step of thoseprocesses, we know all there is to learn about them. Let us undertakethe same thing for some electrical phenomena. 

First, under what circumstances do electrical phenomena arise?

(1) _Mechanical_, as when two different kinds of matter are subject tofriction. 

(2) _Thermal_, as when two substances in molecular contact are heated atthe junction. 

(3) _Magnetic_, as when any conductor is in a changing magnetic field. 

(4) _Chemical_, as when a metal is being dissolved in any solution. 

(5) _Physiological_, as when a muscle contracts. 

[Illustration: FIG. 5. --Frictional electrical machine. ]

Each of these has several varieties, and changes may be rung oncombinations of them, as when mechanical and magnetic conditionsinteract. 

(1) In the first case, ordinary mechanical or translational energy isspent as friction, an amount measurable in foot-pounds, and the factorswe know, a pressure into a distance. If the surface be of the same kindof molecules, the whole energy is spent as heat, and is presentlyradiated away. If the surfaces are of unlike molecules, the product is acompound one, part heat, part electrical. What we have turned into themachine we know to be a particular mode of motion. We have not changedthe amount of matter involved; indeed, we assume, without specifying andwithout controversy, that matter is itself indestructible, and theproduct, whether it be of one kind or another, can only be some form ofmotion. Whether we can describe it or not is immaterial; but if we agreethat heat is vibratory molecular motion, and there be any other kind ofa product than heat, it too must also be some other form of motion. Soif one is to form a conception of the mechanical origin of electricity, this is the only one he can have--transformed motion. 

[Illustration: FIG. 6. --Thermo-pile. ]

[Illustration: FIG. 7. --Dynamo. ]

(2) When heat is the antecedent of electricity, as in the thermo-pile, that which is turned into the pile we know to be molecular motion of adefinite kind. That which comes out of it must be some equivalentmotion, and if all that went in were transformed, then all that came outwould be transformed, call it by what name we will and let its amount bewhat it may. 

(3) When a conductor is moved in a magnetic field, the energy spent ismeasurable in foot-pounds, as before, a pressure into a distance. Theenergy appears in a new form, but the quantity of matter beingunchanged, the only changeable factor is the kind of motion, and thatthe motion is molecular is evident, for the molecules are heated. Mechanical or mass motion is the antecedent, molecular heat motion isthe consequent, and the way we know there has been some intermediateform is, that heat is not conducted at the rate which is observed insuch a case. Call it by what name one will, some form of motion has beenintermediate between the antecedent and the consequent, else we havesome other factor of energy to reckon with than ether, matter andmotion. 

(4) In a galvanic battery, the source of electricity is chemical action;but what is chemical action? Simply an exchange of the constituents ofmolecules--a change which involves exchange of energy. Molecules capableof doing chemical work are loaded with energy. The chemical products ofbattery action are molecules of different constitution, with smalleramounts of energy as measured in calorics or heat units. If the resultsof the chemical reaction be prevented from escaping, by confining themto the cell itself, the whole energy appears as heat and raises thetemperature of the cell. If a so-called circuit be provided, the energyis distributed through it, and less heat is spent in the cell, butwhether it be in one place or another, the mass of matter involved isnot changed, and the variable factor is the motion, the same as in theother cases. The mechanical conceptions appropriate are thetransformation of one kind of motion into another kind by the mechanicalconditions provided. 

[Illustration: FIG. 8. --Galvanic Battery. ]

(5) Physiological antecedents of electricity are exemplified by thestructure and mode of operation of certain muscles (Fig. 9, _a_) in thetorpedo and other electrical animals. The mechanical contraction of themresults in an electrical excitation, and, if a proper circuit beprovided, in an electric current. The energy of a muscle is derived fromfood, which is itself but a molecular compound loaded with energy of akind available for muscular transformation. Bread-and-butter has moreavailable energy, pound for pound, than has coal, and can be substitutedfor coal for running an engine. It is not used, because it costs so muchmore. There is nothing different, so far as the factors of energy go, between the food of an animal and the food of an engine. What becomes ofthe energy depends upon the kind of structure it acts on. It may bechanged into translatory, and the whole body moves in one direction; orinto molecular, and then appears as heat or electrical energy. 

If one confines his attention to the only variable factor in the energyin all these cases, and traces out in each just what happens, he willhave only motions of one sort or another, at one rate or another, andthere is nothing mysterious which enters into the processes. 

We will turn now to the mode in which electricity manifests itself, andwhat it can do. It may be well to point out at the outset what hasoccasionally been stated, but which has not received the philosophicalattention it deserves--namely, that electrical phenomena are reversible;that is, any kind of a physical process which is capable of producingelectricity, electricity is itself able to produce. Thus to name a few:If mechanical motion develops electricity, electricity will producemechanical motion; the movement of a pith ball and an electric motor areexamples. If chemical action can produce it, it will produce chemicalaction, as in the decomposition of water and electro-plating. As heatmay be its antecedent, so will it produce heat. If magnetism be anantecedent factor, magnetism may be its product. What is calledinduction may give rise to it in an adjacent conductor, and, likewise, induction may be its effect. 

[Illustration: FIG. 9. --Torpedo. ]

[Illustration: FIG. 10. --Dynamo and Motor. ]

Let us suppose ourselves to be in a building in which a steam-engine isat work. There is fuel, the furnace, the boiler, the pipes, the enginewith its fly-wheel turning. The fuel burns in the furnace, the water issuperheated in the boiler, the steam is directed by the pipes, thepiston is moved by the steam pressure, and the fly-wheel rotatesbecause of proper mechanism between it and the piston. No one who hasgiven attention to the successive steps in the process is so puzzled asto feel the need of inventing a particular force, or a new kind ofmatter, or any agency, at any stage of the process, different from thesimple mechanical ones represented by a push or a pull. Even if hecannot see clearly how heat can produce a push, he does not venture toassume a genii to do the work, but for the time is content with sayingthat if he starts with motion in the furnace and stops with the motionof the fly-wheel, any assumption of any other factor than some form ofmotion between the two would be gratuitous. He can truthfully say thathe understands the _nature_ of that which goes on between the furnaceand the wheel; that it is some sort of motion, the particular kind ofwhich he might make out at his leisure. 

Suppose once more that, across the road from an engine-house, there wasanother building, where all sorts of machines--lathes, planers, drills, etc. --were running, but that the source of the power for all this wasout of sight, and that one could see no connection between this and theengine on the other side of the street. Would one need to suppose therewas anything mysterious between the two--a force, a fluid, an immaterialsomething? This question is put on the supposition that one should notbe aware of the shaft that might be between the two buildings, and thatit was not obvious on simple inspection how the machines got theirmotions from the engine. No one would be puzzled because he did not knowjust what the intervening mechanism might be. If the boiler were in theone building, and the engine in the other with the machines, he couldsee nothing moving between them, even if the steam-pipes were of glass. If matter of any kind were moving, he could not see it there. He wouldsay there _must_ be something moving, or pressure could not betransferred from one place to the other. 

Substitute for the furnace and boiler a galvanic battery or a dynamo;for the machines of the shop, one or more motors with suitable wireconnections. When the dynamo goes the motors go; when the dynamo stopsthe motors stop; nothing can be seen to be turning or moving in any waybetween them. Is there any necessity for assuming a mysterious agency, or a force of a _nature_ different from the visible ones at the two endsof the line? Is it not certain that the question is, How does the motionget from one to the other, whether there be a wire or not? If there be awire, it is plain that there is motion in it, for it is heated its wholelength, and heat is known to be a mode of motion, and every moleculewhich is thus heated must have had some antecedent motions. Whether itbe defined or not, and whether it be called by one name or another, arequite immaterial, if one is concerned only with the _nature_ of theaction, whether it be matter or ether, or motion or abracadabra. 

Once more: suppose we have a series of active machines. (Fig. 11. ) Anarc lamp, radiating light-waves, gets its energy from the wire which isheated, which in turn gets its energy from the electric current; thatfrom a dynamo, the dynamo from a steam-engine; that from a furnace andthe chemical actions going on in it. Let us call the chemical actions A, the furnace B, the engine C, the dynamo D, the electric lamp E, theether waves F. (Fig. 12. )

[Illustration: FIG. 11. ]

The product of the chemical action of the coal is molecular motion, called heat in the furnace. The product of the heat is mechanical motionin the engine. The product of the mechanical motion is electricity inthe dynamo. The product of the electric current in the lamp islight-waves in the ether. No one hesitates for an instant to speak ofthe heat as being molecular motion, nor of the motions of the engine asbeing mechanical; but when we come to the product of the dynamo, whichwe call electricity, behold, nearly every one says, not that he does notknow what it is, but that no one knows! Does any one venture to say hedoes not know what heat is, because he cannot describe in detail justwhat goes on in a heated body, as it might be described by one who sawwith a microscope the movements of the molecules? Let us go back for amoment to the proposition stated early in this book, namely, that if anybody of any magnitude moves, it is because some other body in motion andin contact with it has imparted its motion by mechanical pressure. Therefore, the ether waves at F (Fig. 11) imply continuous motions ofsome sort from A to F. That they are all motions of ordinary matter fromA to E is obvious, because continuous matter is essential for themaintenance of the actions. At E the motions are handed over to theether, and they are radiated away as light-waves. 

[Illustration: FIG. 12. ]

[Illustration: FIG. 13. ]

A puzzling electrical phenomenon has been what has been called itsduality-states, which are spoken of as positive and negative. Thus, wespeak of the positive plate of a battery and the negative pole of adynamo; and another troublesome condition to idealize has been, how itcould be that, in an electric circuit, there could be as much energy atthe most remote part as at the source. But, if one will take a limprope, 8 or 10 feet long, tie its ends together, and then begin to twistit at any point, he will see the twist move in a right-handed spiral onthe one hand, and in a left-handed spiral on the other, and each may betraced quite round the circuit; so there will be as much twist, as muchmotion, and as much energy in one part of the rope as in any other; andif one chooses to call the right-handed twist positive, and theleft-handed twist negative, he will have the mechanical phenomenon ofenergy-distribution and the terminology, analogous to what they are inan electric conductor. (Fig. 13. ) Are the cases more dissimilar than themechanical analogy would make them seem to be?

Are there any phenomena which imply that rotation is going on in anelectric conductor? There are. An electric arc, which is a current inthe air, and is, therefore, less constrained than it is in a conductor, rotates. Especially marked is this when in front of the pole of amagnet; but the rotation may be noticed in an ordinary arc by looking atit with a stroboscope disk, rotated so as to make the light to the eyeintermittent at the rate of four or five hundred per second. A ray ofplane polarized light, parallel with a wire conveying a current, has itsplane of vibration twisted to the right or left, as the current goesone way or the other through the wire, and to a degree that depends uponthe distance it travels; not only so, but if the ray be sent, byreflection, back through the same field, it is twisted as much more--aphenomenon which convinces one that rotation is going on in the spacethrough which the ray travels. If the ether through which the ray besent were simply warped or in some static stress, the ray, afterreflection, would be brought back to its original plane, which is notthe case. This rotation in the ether is produced by what is going on inthe wire. The ether waves called light are interpreted to imply thatmolecules originate them by their vibrations, and that there are as manyether waves per second as of molecular vibrations per second. In likemanner, the implication is the same, that if there be rotations in theether they must be produced by molecular rotation, and there must be asmany rotations per second in the ether as there are molecular rotationsthat produce them. The space about a wire carrying a current is oftenpictured as filled with whorls indicating this motion (Fig. 14), and onemust picture to himself, not the wire as a whole rotating, but eachindividual molecule independently. But one is aware that the moleculesof a conductor are practically in contact with each other, and that ifone for any reason rotates, the next one to it would, from frictionalaction, cause the one it touched to rotate in the opposite direction, whereas, the evidence goes to show that all rotation is in the samedirection. 

[Illustration: FIG. 14. ]

How can this be explained mechanically? Recall the kind of action thatconstitutes heat, that it is not translatory action in any degree, butvibratory, in the sense of a change of form of an elastic body, andthis, too, of the atoms that make up the molecule of whatever sort. Eachatom is so far independent of every other atom in the molecule that itcan vibrate in this way, else it could not be heated. The greater theamplitude of vibration, the more free space to move in, and continuouscontact of atoms is incompatible with the mechanics of heat. There must, therefore, be impact and freedom alternating with each other in alldegrees in a heated body. If, in any way, the atoms themselves _were_made to rotate, their heat impacts not only would restrain therotations, but the energy also of the rotation motion would increase thevibrations; that is, the heat would be correspondingly increased, whichis what happens always when an electric current is in a conductor. Itappears that the cooler a body is the less electric resistance it has, and the indications are that at absolute zero there is no resistance;that is, impacts do not retard rotation, but it is also apparent thatany current sent through a conductor at that temperature would at onceheat it. This is the same as saying that an electric current could notbe sent through a conductor at absolute zero. 

So far, mechanical conceptions are in accordance with electricalphenomena, but there are several others yet to be noted. Electricalphenomena has been explained as molecular or atomic phenomena, and thereis one more in that category which is well enough known, and which is soimportant and suggestive, that the wonder is its significance has notbeen seen by those who have sought to interpret electrical phenomena. The reference is to the fact that electricity cannot be transmittedthrough a vacuum. An electric arc begins to spread out as the density ofthe air decreases, and presently it is extinguished. An induction sparkthat will jump two or three feet in air cannot be made to bridge thetenth of an inch in an ordinary vacuum. A vacuum is a perfectnon-conductor of electricity. Is there more than one possibleinterpretation to this, namely, that electricity is fundamentally amolecular and atomic phenomenon, and in the absence of molecules cannotexist? One may say, "Electrical _action_ is not hindered by a vacuum, "which is true, but has quite another interpretation than the implicationthat electricity is an ether phenomenon. The heat of the sun in some waygets to the earth, but what takes place in the ether is notheat-transmission. There is no heat in space, and no one is at libertyto say, or think, that there can be heat in the absence of matter. 

When heat has been transformed into ether waves, it is no longer heat, call it by what name one will. Formerly, such waves were calledheat-waves; no one, properly informed, does so now. In like manner, ifelectrical motions or conditions in matter be transformed, no matterhow, it is no longer proper to speak of such transformed motions orconditions as electricity. Thus, if electrical energy be transformedinto heat, no one thinks of speaking of the latter as electrical. If theelectrical energy be transformed into mechanical of any sort, no onethinks of calling the latter electrical because of its antecedent. Ifelectrical motions be transformed into ether actions of any kind, whyshould we continue to speak of the transformed motions or energy asbeing electrical? Electricity may be the antecedent, in the same senseas the mechanical motion of a bullet may be the antecedent of the heatdeveloped when the latter strikes the target; and if it be granted thata vacuum is a perfect non-conductor of electricity, then it ismanifestly improper to speak of any phenomenon in the ether as anelectrical phenomenon. It is from the failure to make this distinctionthat most of the trouble has come in thinking on this subject. Some havegiven all their attention to what goes on in matter, and have calledthat electricity; others have given their attention to what goes on inthe ether, and have called that electricity, and some have consideredboth as being the same thing, and have been confounded. 

Let us consider what is the relation between an electrified body and theether about it. 

When a body is electrified, the latter at the same time creates an etherstress about it, which is called an electric field. The ether stress maybe considered as a warp in the distribution of the energy about the body(Fig. 15), by the new positions given to the molecules by the process ofelectrification. It has been already said that the evidence from othersources is that atoms, rather than molecules, in larger masses, are whataffect the ether. One is inclined to inquire for the evidence we have asto the constitution of matter or of atoms. There is only one hypothesisto-day that has any degree of probability; that is, the vortex-ringtheory, which describes an atom as being a vortex-ring of ether in theether. It possesses a definite amount of energy in virtue of the motionwhich constitutes it, and this motion differentiates it from thesurrounding ether, giving it dimensions, elasticity, momentum, and thepossibility of translatory, rotary, vibratory motions, and combinationsof them. Without going further into this, it is sufficient, for amechanical conception, that one should have so much in mind, as it willvastly help in forming a mechanical conception of reactions betweenatoms and the ether. An exchange of energy between such an atom and theether is not an exchange between different kinds of things, but betweendifferent conditions of the same thing. Next, it should be rememberedthat all the elements are magnetic in some degree. This means that theyare themselves magnets, and every magnet has a magnetic field unlimitedin extent, which can almost be regarded as a part of itself. If a magnetof any size be moved, its field is moved with it, and if in any way themagnetism be increased or diminished, the field changes correspondingly. 

[Illustration: FIG. 15. ]

Assume a straight bar electro-magnet in circuit, so that a current canbe made intermittent, say, once a second. When the circuit is closed andthe magnet is made, the field at once is formed and travels outwards atthe rate of 186, 000 miles per second. When the current stops, the fieldadjacent is destroyed. Another closure develops the field again, which, like the other, travels outwards; and so there may be formed a series ofwaves in the ether, each 186, 000 miles long, with an electro-magneticantecedent. If the circuit were closed ten times a second, the waveswould be 18, 600 miles long; if 186, 000 times a second, they would be butone mile long. If 400 million of millions times a second, they would bebut the forty-thousandth of an inch long, and would then affect the eye, and we should call them light-waves, but the latter would not differfrom the first wave in any particular except in length. As it is provedthat such electro-magnetic waves have all the characteristics of light, it follows that they must originate with electro-magnetic action, thatis, in the changing magnetism of a magnetic body. This makes it needfulto assume that the atoms which originate waves are magnets, as they areexperimentally found to be. But how can a magnet, not subject to avarying current, change its magnetic field? The strength or density of amagnetic field depends upon the form of the magnet. When the poles arenear together, the field is densest; when the magnet is bent back to astraight bar, the field is rarest or weakest, and a change in the formof the magnet from a U-form to a straight bar would result in a changeof the magnetic field within its greatest limits. A few turns ofwire--as has been already said--wound about the poles of an ordinaryU-magnet, and connected to an ordinary magnetic telephone, will enableone, listening to the latter, to hear the pitch of the former loudlyreproduced when the magnet is struck like a tuning-fork, so as tovibrate. This shows that the field of the magnet changes at the samerate as the vibrations. 

Assume that the magnet becomes smaller and smaller until it is of thedimensions of an atom, say for an approximation, the fifty-millionth ofan inch. It would still have its field; it would still be elastic andcapable of vibration, but at an enormously rapid rate; but its vibrationwould change its field in the same way, and so there would be formedthose waves in the ether, which, because they are so short that they canaffect the eye, we call light. The mechanical conceptions arelegitimate, because based upon experiments having ranges through nearlythe whole gamut as waves in ether. 

The idea implies that every atom has what may be loosely called anelectro-magnetic grip upon the whole of the ether, and any change in theformer brings some change in the latter. 

Lastly, the phenomenon called induction may be mechanically conceived. 

It is well known that a current in a conductor makes a magnet of thewire, and gives it an electro-magnetic field, so that other magnets inits neighbourhood are twisted in a way tending to set them at rightangles to the wire. Also, if another wire be adjacent to the first, anelectric current having an opposite direction is induced in it. Thus:

Consider a permanent magnet A (Fig. 15), free to turn on an axis in thedirection of the arrow. If there be other free magnets, B and C, inline, they will assume such positions that their similar poles all pointone way. Let A be twisted to a position at right angles, then B willturn, but in the opposite direction, and C in similar. That is, if Aturn in the direction of the hands of a clock, B and C will turn inopposite directions. These are simply the observed movements of largemagnets. Imagine that these magnets be reduced to atomic dimensions, yetretaining their magnetic qualities, poles and fields. Would they notevidently move in the same way and for the same reason? If it be true, that a magnet field always so acts upon another as to tend by rotationto set the latter into a certain position, with reference to the stressin that field, then, _wherever there is a changing magnetic field, therethe atoms are being adjusted by it_. 

[Illustration: FIG. 16. ]

Suppose we have a line of magnetic needles free to turn, hundreds orthousands of them, but disarranged. Let a strong magnetic field beproduced at one end of the line. The field would be strongest and bestconducted along the magnet line, but every magnet in the line would becompelled to rotate, and if the first were kept rotating, the rotationwould be kept up along the whole line. This would be a mechanicalillustration of how an electric current travels in a conductor. Therotations are of the atomic sort, and are at right angles to thedirection of the conductor. 

That which makes the magnets move is inductive magnetic ether stress, but the advancing motion represents mechanical energy of rotation, andit is this motion, with the resulting friction, which causes the heat ina conductor. 

What is important to note is, that the action in the ether is notelectric action, but more properly the result of electro-magneticaction. Whatever name be given to it, and however it comes about, thereis no good reason for calling any kind of ether action electrical. 

Electric action, like magnetic action, begins and ends in matter. It issubject to transformations into thermal and mechanical actions, alsointo ether stress--right-handed or left-handed--which, in turn, cansimilarly affect other matter, but with opposite polarities. 

In his _Modern Views of Electricity_, Prof. O. J. Lodge warns us, quiterightly, that perhaps, after all, there is no such _thing_ aselectricity--that electrification and electric energy may be terms to bekept for convenience; but if electricity as a term be held to imply aforce, a fluid, an imponderable, or a thing which could be described bysome one who knew enough, then it has no degree of probability, forspinning atomic magnets seem capable of developing all the electricalphenomena we meet. It must be thought of as a _condition_ and not as anentity. 

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Transcriber's Note

Minor typographical corrections have been made without comment. Inconsistencies in hyphenation, and the author's use of commaswhen writing large numbers, have been retained.