Aether and Gravitation

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Aether And Gravitation

by

William George Hooper, F.S.S.

[Illustration]

London Chapman and Hall, Ltd. 1903

Introductory Notes

The author in this work endeavours to solve the greatest scientific problem that has puzzled scientists for the past two hundred years. The question has arisen over and over again, since the discovery of universal gravitation by Sir Isaac Newton, as to what is the physical cause of the attraction of gravitation.

"Action at a distance" has long ceased to be recognized as a possible phenomenon, although up to the present, the medium and method of gravitational attraction have not yet been discovered.

It is, however, generally accepted by scientists, that the only possible medium which can give rise to the phenomena incidental to, and associated with the Law of Gravitation, must be the universal aether, which forms the common medium of all phenomena associated with light, heat, electricity and magnetism.

It is impossible, however, to reconcile gravitational phenomena with the present conception of the universal aether medium, and a new theory is therefore demanded, before the long-sought-for explanation will be forthcoming.

Professor Glazebrook definitely states the necessity for a new theory in his work on J. C. Maxwell, page 221, where he writes: "We are waiting for some one to give us a theory of the aether, which shall include the facts of electricity and magnetism, luminous radiation, and it may be gravitation."

A new theory of the aether is also demanded in view of the recent experimental results of Professor Lebedew, and Nichols and Hull of America. It is logically impossible to reconcile a frictionless aether, with their results relative to the pressure of light waves.

In the following pages of this work the author has endeavoured to perfect a theory, which will bring aetherial physics more into harmony with modern observation and experiments; and by so doing, believes that he has found the key that will unlock the problem not only of the cause of universal gravitation, but also other problems of physical science. The author has taken Newton's Rules of Philosophy as his guide in the making of the new theory, as he believes that if any man knew anything of the rules of Philosophy, that man was Sir Isaac Newton. The first chapter therefore deals with the generally recognized rules which govern philosophical reasoning, the same being three in number; the fundamental rule being, that in making any hypothesis, the results of experience as obtained by observation and experiments must not be violated.

In applying the rules to the present theory of the aether, he found that the theory as at present recognized violated two of the most important rules of Philosophy, because, while aether is supposed to be matter, yet it failed to fulfil the primary property of all matter, that is, it is not subject to the Law of Gravitation. If aether is matter, then, to be strictly logical and philosophical, it must possess the properties of matter as revealed by observation and experiment.

Those properties are given in Chapter III., where it is shown that they are atomicity, heaviness or weight, elasticity, density, inertia, and compressibility. To be strictly logical and philosophical, the author was compelled to postulate similar properties for the aether, or else his hypotheses would contravert the results of all experience.

The application of these properties to the aether will be found in Chapter IV., where the author has postulated atomicity, heaviness or weight, density, elasticity, inertia, and compressibility for the aether, and so brought the theory of the aether into perfect harmony with all observation and experiments relative to ordinary matter. It will be shown that Clerk Maxwell also definitely affirms the atomicity of the aether, while Tyndall and Huyghens also use the term "_particles of aether_" over and over again.

Moreover, in view of the most recent researches in electricity made by Sir William Crookes and Professor J. J. Thomson, we are compelled to accept an atomic basis for electricity, and as Dr. Lodge, in his _Modern Views of Electricity_, states that "Aether is made up of positive and negative electricity," then, unless we postulate atomicity for the aether, we have to suppose that it is possible for a non-atomic body (aether) to be made up of atoms or corpuscles, which conclusion is absurd, and therefore must be rejected as illogical and unphilosophical.

After postulating atomicity for the aether, we are then able to apply the Newtonian Law of Gravitation to it, which distinctly affirms that "every particle of matter attracts every other particle," and so we arrive at Thomas Young's fourth hypothesis given in the Philosophical Transactions of 1802, where he asserts that "All material bodies have an attraction for the aetherial medium, by means of which it is accumulated within their substance, and for a small distance around them in a state of greater density." He adds the significant remark that this hypothesis is opposed to that of Newton's. With an atomic and gravitative aether it is shown in Chapter IV. how the elasticity, density, and inertia of the medium are brought into harmony with all observation and experiments.

In the succeeding chapters the new theory is applied to the phenomena of heat, light, electricity, and magnetism, and the principles enunciated therein are then applied to solar and stellar phenomena.

One of the greatest stumbling-blocks to the discovery of the physical cause of gravitation, apart from the unphilosophical theory of the aether medium, lies in the fact that apparently the Law of Gravitation only recognizes a force of one kind. Dr. Lodge refers to this phase of the subject on page 39 of his _Modern Views of Matter_ just published. It is here where scientists have failed to solve the problem of universal gravitation, as there are _two_ forces at work in the solar system and not one; that is, if we are to accept the results of up-to-date experiments in relation to radiant light and heat as performed by Professor Lebedew, and Nichols and Hull of America. Their experiments conclusively prove that light waves exert a pressure upon all bodies on which they fall, and by no reasoning can this pressure be resolved into an attractive force.

Herschel in his _Lectures on Scientific Subjects_ definitely refers to the existence of a repulsive force in the solar system, and asserts that it offers the most interesting prospect of any future discovery.

The author has therefore attacked the problem of the cause of gravitation, by trying to solve the problem of the cause of the _repulsive_ force which has been experimentally demonstrated to exist by Professor Lebedew and others.

In his efforts to ascertain the physical cause of the Centrifugal Force, he has been assisted by an unknown and original essay written by an unknown writer over twenty years ago. That unknown writer was the author's father, who wrote an essay on the _Complementary Law of Gravitation_, and if it had not been for that essay, the present work would never have been attempted.

The main object of the author in Chapters VI., VII., and VIII., is to prove beyond the possibility of contradiction, from the phenomena of heat, light, and electricity, the existence of _two_ forces in the solar system; and by so doing, to bring our philosophy of the aether medium, and all gravitational phenomena, into harmony with all observation and experiments, which at present is not the case. In seeking to do this he found that the new theory of the aether harmonized with views given, by Faraday and Clerk Maxwell in relation to electric and magnetic phenomena, and by the new theory Maxwell's hypothesis of "Physical Lines of Force" receives a definite and physical basis. In Chapter X. the author endeavours to show what the Electro-Kinetic energy is, which term is used by Clerk Maxwell, the term being brought for the first time into harmony with our experience. The Electro-Magnetic Theory of Light also receives fresh light from the new theory of an atomic and gravitating aether.

In the succeeding chapters the theory is applied to Newton's Laws of Motion and Kepler's Laws, and is found to harmonize with all the results given by these laws. Such a result is a distinct advance on the application of a frictionless aether to solar and stellar phenomena, as it is impossible for Kepler's Laws to be reconciled in any way with our present theory of the aether.

In the concluding chapter on the unity of the universe, certain views are suggested as to the ultimate constitution of all matter, upon an aetherial basis, which hypothesis practically resolves itself into an electric basis for all matter. It is suggested that aether and electricity are one and the same medium, both being a form of matter, and both possessing exactly the same properties, viz. atomicity, weight, density, elasticity, inertia, and compressibility. This view of matter harmonizes with the most "Modern Views of Matter" as suggested by Sir Oliver Lodge in his Romanes Lecture 1903.

The author has accepted Newton's way of spelling "_aether_" as given in his work on _Optics_, and has given "_aetherial_" the same suffix as "material," in order to differentiate the word from "ethereal," which is too metaphysical a term for a material medium.

_Nottingham_, _Sept._ 1903.

Contents

Chapter I

Philosophy Of Gravitation

PAGE ART. 1. GRAVITATION 1 " 2. CAUSE OF GRAVITATION 1 " 3. NEWTON'S RULES OF PHILOSOPHY 3 " 4. FIRST RULE OF PHILOSOPHY 3 " 5. SECOND RULE OF PHILOSOPHY 4 " 6. THIRD RULE OF PHILOSOPHY 7 " 7. APPLICATION OF RULES TO GRAVITATION 9 " 8. ANALYSIS OF LAW OF GRAVITATION 9 " 9. PRIMITIVE IMPULSE 10 " 10. CENTRIPETAL FORCE 12 " 11. CENTRIFUGAL FORCE 13 " 12. NEWTON'S LAWS OF MOTION 15 " 13. FORCE 16 " 14. FIRST LAW OF MOTION 16 " 15. SECOND LAW OF MOTION 19 " 16. THIRD LAW OF MOTION 20 " 17. SUMMARY OF CHAPTER 22

Chapter II

PHILOSOPHY OF GRAVITATION--(_continued_)

ART. 18. GRAVITATION ATTRACTION 24 " 19. UNIVERSALITY OF GRAVITATION 24 " 20. DIRECTION OF THE FORCES 26 " 21. PROPORTION OF THE FORCES 26 " 22. LAW OF INVERSE SQUARES 27 " 23. TERRESTRIAL GRAVITY 29 " 24. CENTRIFUGAL FORCE 30 " 25. KEPLER'S LAWS 32 " 26. FIRST LAW OF KEPLER 33 " 27. SECOND LAW OF KEPLER 36 " 28. THIRD LAW OF KEPLER 37

Chapter III

Matter

ART. 29. WHAT IS MATTER? 40 " 30. CONSERVATION OF MATTER 42 " 31. MATTER IS ATOMIC 42 " 32. WHAT IS AN ATOM? 43 " 33. THE ATOMIC THEORY 44 " 34. KINDS OF ATOMS 44 " 35. ELEMENTS OF MATTER 47 " 36. THREE KINDS OF MATTER 47 " 37. MATTER IS GRAVITATIVE 50 " 38. MATTER POSSESSES DENSITY 51 " 39. MATTER POSSESSES ELASTICITY 51 " 40. MATTER POSSESSES INERTIA 52

Chapter IV

Aether

ART. 42. AETHER IS MATTER 54 " 43. AETHER IS UNIVERSAL 58 " 44. AETHER IS ATOMIC 59 " 45. AETHER IS GRAVITATIVE 64 " 46. AETHER POSSESSES DENSITY 71 " 47. AETHER POSSESSES ELASTICITY 74 " 48. AETHER POSSESSES INERTIA 76 " 49. AETHER IS IMPRESSIBLE 78 " 50. AETHER AND ITS MOTIONS 80

Chapter V

Energy

ART. 51. ENERGY 83 " 52. CONSERVATION OF ENERGY 84 " 53. TRANSFORMATION OF ENERGY 86 " 54. POTENTIAL ENERGY 87 " 55. KINETIC ENERGY 89 " 56. ENERGY AND MOTION 91 " 57. CONSERVATION OF MOTION 92 " 58. TRANSFORMATION OF MOTION 93 " 59. MOTION AND WORK 95

Chapter VI

Heat, A Mode Of Motion

ART. 60. HEAT, A MODE OF MOTION 98 " 61. HEAT AND MATTER 100 " 62. RADIATION AND ABSORPTION 104 " 63. HEAT IS A REPULSIVE MOTION 107 " 64. RADIANT HEAT 109 " 65. DIRECTION OF A RAY OF HEAT 111 " 66. LAW OF INVERSE SQUARES 112 " 67. FIRST LAW OF THERMODYNAMICS 114 " 68. SECOND LAW OF THERMODYNAMICS 116 " 69. IDENTITY OF HEAT AND LIGHT 119

Chapter VII

Light, A Mode Of Motion

ART. 70. LIGHT, A MODE OF MOTION 122 " 71. TRANSVERSE VIBRATION OF LIGHT 130 " 72. REFLECTION AND REFRACTION 135 " 73. THE SOLAR SPECTRUM 139 " 74. DIRECTION OF A RAY OF LIGHT 144 " 75. INTENSITY OF LIGHT 145 " 76. VELOCITY OF LIGHT 148 " 77. DYNAMICAL VALUE OF LIGHT 150 " 78. ELECTRO-MAGNETIC THEORY OF LIGHT 155

Chapter VIII

Aether And Electricity

ART. 79. ELECTRICITY, A MODE OF MOTION 162 " 80. ELECTRIC FIELD 166 " 81. ELECTRIC INDUCTION 174 " 82. ELECTRIC ENERGY 179 " 83. ELECTRIC RADIATION 182 " 84. LAW OF INVERSE SQUARES 184 " 85. SECOND LAW OF ELECTRICITY 186

Chapter IX

Aether And Magnetism

ART. 86. ELECTRO-MAGNETISM 192 " 87. THE EARTH A MAGNET 195 " 88. THE SUN AN ELECTRO-MAGNET 199 " 89. FARADAY'S LINES OF FORCE 203 " 90. TERRESTRIAL MAGNETISM 206 " 91. SOLAR MAGNETS 211 " 92. CAUSE OF ROTATION OF THE EARTH ON ITS AXIS 219 " 93. VORTEX MOTION 221 " 94. RELATIVE MOTION OF AETHER AND MATTER 224 " 95. VIBRATIONS IN THE ELECTRO-MAGNETIC THEORY OF LIGHT 228

Chapter X

Aether And Newton'S Laws Of Motion

ART. 96. AETHER AND CENTRIFUGAL FORCE 232 " 97. AETHER AND CENTRIPETAL FORCE 236 " 98. AETHER AND NEWTON'S FIRST LAW OF MOTION 239 " 99. AETHER AND NEWTON'S SECOND LAW OF MOTION 244 " 100. AETHER AND NEWTON'S THIRD LAW OF MOTION 251 " 101. WHY PLANETS REVOLVE FROM WEST TO EAST 253

Chapter XI

Aether And Kepler'S Laws

ART. 102. AETHER AND KEPLER'S FIRST LAW 256 " 103. AETHER AND KEPLER'S SECOND LAW 260 " 104. AETHER AND KEPLER'S THIRD LAW 263 " 105. ORBITAL MOTION OF PLANETS 266 " 106. ECCENTRICITY OF THE MOON'S ORBIT 268 " 107. THE SUN AND KEPLER'S FIRST LAW 270 " 108. THE SUN AND KEPLER'S SECOND LAW 274 " 109. AETHER AND THE PLANE OF THE ECLIPTIC 277 " 110. AETHER AND THE CENTRIPETAL FORCE 282

Chapter XII

Aether And Comets

ART. 111. WHAT IS A COMET? 291 " 112. ORBITS OF COMETS 293 " 113. KINDS OF COMETS 296 " 114. PARTS OF A COMET 298 " 115. CENTRIFUGAL FORCE AND COMETS 300 " 116. FORMATION OF TAILS 303

Chapter XIII

Aether And Starry World

ART. 117. STARRY WORLD 306 " 118. STARS AND KEPLER'S LAWS 309 " 119. AETHER AND NEBULAE 313 " 120. WHAT IS A NEBULA? 314 " 121. AETHER AND NEBULAR HYPOTHESIS 317 " 122. KINDS OF NEBULAE 319

Chapter XIV

Aether And The Universe

ART. 123. THE UNIVERSE 323 " 124. UNITY OF THE UNIVERSE 326 " 125. CONSTITUTION OF MATTER 334 " 126. QUOD ERAT FACIENDUM 337 " 127. GOD AND THE UNIVERS 342

Appendix 349 Index 351

Aether And Gravitation

Chapter I

Philosophy Of Gravitation

ART. 1. _Gravitation._--In the realm of Science, there exists a Force or Law that pervades and influences all Nature, and from the power of which, nothing, not even an atom, is free.

It holds together the component parts of each and every individual world, and in the world's revolving prevents both its inhabitants and its vegetation from being whirled off its surface into space. It exists in each and every central sun, and circles round each sun its associated system of planets. It rolls each satellite around its primary planet, and regulates the comet's mysterious flight into the depths of space, while the pendulation of even the remotest star is accomplished by this same force. Our own rocking world obeys the same mysterious power, that seems to grasp the entire material creation as with the grasp of the Infinite.

It exists in, and influences every atom, whose combinations compose and constitute the entire material creation, or each and every orb that bespangle the blue infinity.

As is readily seen, it weaves as it were around each and all, a mysterious network or chain, that binds star to star, and world to world, blending all into one entire, vast and complete unity. It decides all their orbits and distances, regulates and controls all their motions, from the most simple even to the more complex and intricate, ultimately producing that wondrous and beauteous order, unity and harmony that everywhere pervade and blend all the universe into one grand and harmonious whole.

That Law I need hardly say is the Law of Gravitation.

ART. 2. _Cause of Gravitation._--Now the question arises, and indeed has arisen a thousand times since the discovery of this law by Sir Isaac Newton over two hundred years ago, as to what is the physical cause, the true explanation of this universal attraction.

MacLaurin in his work on the philosophical discoveries of Sir Isaac Newton says: "In all cases when bodies seem to act upon each other at a distance, and tend towards one another without any apparent cause impelling them, this force has been commonly called Attraction, and this term is frequently used by Sir Isaac Newton. But he gives repeated caution that he pretends not by the use of this term to define the nature of the power, or the manner in which it acts. Nor does he ever affirm or insinuate that a body can act upon another body at a distance, but by the intervention of other bodies."

The results of modern discovery show that action at a distance, without the intervention of any medium, as for example the sun attracting the earth, is not the universal condition which governs all so-called forces.

It is now recognized that light and heat are both forms of energy, and therefore forces, using the term in the same sense that it is applied to Gravitation.

Both light and heat are transmitted through space with finite velocity through the intervention of a medium, the universal Aether. It is therefore only reasonable to suppose, that if one or more particular kinds of energy, or forces, require a medium for their transmission, why not another force, as for example Gravitation?

Gravitation is an universal force which operates throughout the length and breadth of the entire universe, and if there be a medium which is to Gravitation, what the Aether is to light and heat, the question at once confronts us, as to what are the characteristics, properties, and qualities of that universal medium, which is to form the physical basis of this universal attraction?

Newton himself suggested that Gravitation was due to an aetherial subtle medium, which filled all space.

In his well-known letter to Bentley, Newton writes as follows: "That Gravity should be innate, inherent, and essential to matter, so that one body can act upon another body at a distance through a vacuum, without the mediation of anything else, by and through which their action and force may be conveyed from one to another, is to me so great an absurdity, that I believe no man who has any philosophical nature or competent faculty of thinking can ever fall into it."

We also know from his Queries in his book on _Optics_, that he sought for the explanation of Gravitation in the properties of a subtle, aetherial medium diffused over the universe.

MacLaurin on this point says: "It appears from his letters to Boyle, that this was his opinion early, and if he did not publish his opinion sooner, it proceeded from hence only, that he found he was not able from experiment and observation to give a satisfactory account of this medium, and the manner of its operations in producing the chief phenomena of Nature."

Therefore, if we accept Newton's suggestion, and endeavour to trace the physical cause of Gravitation in the qualities, properties, and motions of this subtle aetherial medium to which he refers, we shall be simply working on the lines laid down by Sir Isaac Newton himself.

I wish therefore to premise, that the future pages of this work will deal with the hypothesis of this aetherial medium, by which will be accounted for, and that on a satisfactory and physical basis, the universal Law of Gravitation.

ART. 3. _Rules of Philosophy._--In order that we may rightly understand the making of any hypothesis, I purpose giving some rules laid down by such philosophers as Newton and Herschel, so that we may be guided by right principles in the development of this new hypothesis as to the cause of Gravitation.

The rules that govern the making of any hypotheses, so far as I can discern, may be summed up under the three following heads--

(1) Simplicity of conception.

(2) Agreement with experience, observation, and experiment.

(3) Satisfactorily accounting for, and explaining all phenomena sought to be explained.

ART. 4. _1st Rule. Simplicity of Conception._--From this rule we learn that the hypothesis must be simple in conception, and simple in its fundamental principles, and further, that the same characteristic of simplicity must mark each step of its development.

This rule of simplicity is distinctly laid down by Sir Isaac Newton in his _Principia_, Book 3, under the heading "Regulae Philosophandi."

In that work he writes: "Natura simplex est, et rerum causis superfluis non luxuriat."--"Nature is simple, and does not abound in superfluous causes of things."

He further states that: "Not more of the natural causes of things ought to be admitted, than those which are true and suffice to explain phenomena. In the nature of Philosophy nothing is done in vain, and by means of many things, it is done in vain when it can be done by fewer. For Nature is simple, and does not abound in superfluous causes."

While again in Rule 3, he adds: "Natura simplex est et sibi semper consona."--"Nature is simple, and always agrees with itself."

Whewell also considers simplicity as a fundamental principle of all true hypotheses. On this point he writes: "All the hypotheses should tend to simplicity and harmony. The new suppositions resolve themselves into the old ones, or at least only require some easy modification of the hypothesis first assumed. In false theories the contrary is the case."

Thus, it is the very essence of philosophy to build upon a foundation of simplicity, combined with the results of experience, observation, and experiment. For example, if we desired to form a hypothesis as to the cause of day and night, two hypotheses might be assigned as to the cause.

First, that the earth revolves on its axis once a day, and so presents each part successively to the light and heat of the sun; and second, that the sun revolves round the earth once every 24 hours. But such an assumption as the latter would involve the revolution of the sun through an immense orbit at an enormous velocity, in order for the journey to be accomplished in the time. So that it is much simpler to conceive of the earth revolving on its axis once every 24 hours, than it is for the sun to perform this journey in the same period. Hence the rule of simplicity is in favour of day and night being caused by the revolving of the earth on its axis. The same rule might be illustrated in many ways; but, however illustrated, the principle, according to Newton, always holds good that all effects are produced by the simplest causes, and if there are apparently two causes to the same phenomenon, then the simpler cause is the true and correct one. So that in the making and development of any hypotheses of the physical cause of Gravitation, this rule of simplicity must always be recognized; and, in conjunction with the other rules, we must seek to make our hypotheses, so as to be able to account and explain all phenomena sought to be explained.

ART. 5. _2nd Rule. Experience._--Newton fully recognized the necessity of experience in Philosophy. He saw the absolute necessity of appealing to experience, observation, and experiment, both as a basis for philosophical reasoning, and further, for the data which were necessary to verify particular applications of the hypotheses suggested.

In his Rules of Philosophy, referring to experience as a guide, he says: "Hoc est fundamentum philosophiae."--"This is the basis of philosophy."

Herschel, writing on the same subject in his _Natural Philosophy_, writes thus with regard to experience: "We have pointed out that the great, and indeed the only ultimate source of our knowledge of nature, and its laws, is experience. By which I mean, not the experience of one man only, or of one generation, but the accumulated experience of all mankind in all ages registered in books or recorded in tradition. But experience may be acquired in two ways, either first by noticing facts as they occur without any attempt to influence the frequency of their occurrence, or to vary the circumstances under which they occur. This is observation. Second, by putting in action causes and agents over which we have no control, and purposely varying their combination, and then noticing what effects take place. This is experiment. To these two sources we must look as the fountains of all natural science."

Herschel further writes: "Experience once recognized as the fountain of all our knowledge of nature, it follows, that in our study of nature and its laws, we ought at once to make up our minds to dismiss, as idle prejudices, or at least suspend as premature, all preconceived notion of what might, or ought to be the order of nature in any proposed case, and content ourselves as a plain matter of fact with what is. _To experience we refer as the only ground for all physical enquiry._ But before experience itself can be used to advantage, there is one preliminary step to make which depends wholly upon ourselves."

"It is the _absolute dismissal_ and clearing the mind _of all prejudices_ from whatever source arising, and the determination to stand or fall by the result of direct appeal to facts in the first instance, and to strict logical deduction from them afterwards."

From extracts like these, from such men as Newton and Herschel, it can at once be seen that experience, and experience alone, should be the chief fountain from whence we draw all our data to form the bases of any hypothesis or theory. If the hypothesis formed is contradicted by the result of any present or future observation or experiment, then such hypothesis will either become untenable, or must be so modified as to take in the new fact furnished by that observation and experiment.

It is a _sine qua non_ of all true philosophy, that philosophy should always agree with experience. To the extent that our Philosophy of Nature fails to agree with our experience, or with the results of observation and experiment, then to that extent it ceases to be philosophy. It may be a hypothesis or even a theory, but certainly it is not true Philosophy.

Now, in the elaboration and development of the theory as to the physical cause of Gravitation, I can premise that nothing will be postulated or supposed, unless such supposition can be directly verified by our own observation and experiments.

Any theory or hypotheses that are contradicted by our own experience in its widest form, will find no place in the development of this work. Further, any present accepted theory in relation to any natural phenomena, which is controverted by experiment, or observation, will be rejected as untenable in the scheme of Natural Philosophy to be submitted to the reader.

Whatever else the theory suggested may, or may not be, one thing it certainly shall be, and that is, that it shall be strictly based upon the Philosophical Rules as given by some of the greatest philosophers the world has ever seen. I do not premise that the hypotheses advanced will be strictly correct in every detail.

That would be to assume that my experience of all natural phenomena was perfect. To the extent that our experience is limited, to that extent our hypotheses will be limited and faulty. It would need an Infinite mind to form a perfect theory of the philosophy of the universe, because only an Infinite mind possesses infinite experience. A finite mind can, however, form true philosophical conceptions of natural phenomena, if that mind will only follow the guidance of his own experience, and be willing to accept the teaching that always arises from the results of that experience. In order to do this, however, it must be observed, as Herschel points out, that all old prejudices must be put away, and the question or problem to be considered must be viewed with an open mind. Let me illustrate what I mean. Suppose, for example, that for two hundred years, chalk had always been thought to be a mineral, and then, owing to the development of the microscope, and to the increased magnifying powers of the lenses, it was conclusively demonstrated that chalk is made up of the shells and remains of certain organisms that lived in the sea ages ago. Would it be philosophical to throw over the results of the microscopical research, and, simply because for two hundred years chalk had been thought to be a mineral, to argue, and still retain the idea that chalk was a mineral?

Such a result would be entirely opposed to all the teaching and principles of philosophy. In a similar way, suppose in the development of the physical cause of Gravitation, a certain conception of the universal Aether has to be put forth in order to account for Gravitation, and that that conception is opposed to some of the theories which have been held relative to the Aether medium for the past two hundred years; but that the conception so advanced is supported by the experiments and observation of some of the ablest scientists of the present century, would it be philosophical to reject the newer conception which harmonized with all experiment and observation, and still retain the old conception of the aetherial medium; or, to accept the newer conception of that medium, and to reject some of the ideas included in the old conception? From a purely philosophic standpoint, there can only be one reply, which would be in favour of the newer conception, by which our philosophy would be brought into harmony with our experience.

This I premise will be done in this work, and the result will be, that for the first time, our philosophy of the aetherial medium will agree with our experience; and, as the natural result, several outstanding problems will be explained on a physical basis, which at the present time cannot be satisfactorily explained except from the mathematical standpoint.

ART. 6. _3rd Rule. Satisfactory explanation of the Phenomena sought to be Explained._--The third rule which governs the making of any hypothesis is, that the hypothesis formed in accordance with the first and second rules shall satisfactorily account for all the phenomena sought to be explained.

Newton writes on this point as follows: "No more causes of natural things are to be admitted, than such as are true, and sufficient to explain the phenomena." While again in his fourth rule he states: "In experimental philosophy, propositions collected by induction from phenomena are to be regarded as accurately true, or very nearly true, notwithstanding any contrary hypothesis, till other phenomena occur by which they are made more accurate, or are rendered subject to exceptions." _Principia_, Book 3. Herschel in his _Natural Philosophy_ points out, that one of the chief requirements of any assumed hypothesis is, that it shall be sufficient to account for the phenomena to be explained, and that it shall be suggested by analogy.

Now the object of this work is to give a physical explanation of the cause and working of Gravitation, and to show how, by the properties, qualities and motions of the universal Aether, Universal Gravitation may be accounted for on a physical basis. So that every phenomenon, associated with, or included in the Law of Gravitation, should receive a satisfactory physical explanation by the proposed theory.

Thus the physical cause of the centripetal and centrifugal forces should receive for the first time a physical explanation.

Newton's Laws of Motion, in so far as they conform to his own Rules of Philosophy, should also receive a physical explanation.

Kepler's Laws, which govern the motion of planets in their orbits, should also receive a similar physical explanation. Indeed, all phenomena which the Law of Gravitation explains from a mathematical standpoint, ought to receive a physical explanation by the proposed new conception of the Aether medium.

In addition to the outstanding physical cause of Gravitation, there are other physical problems that yet remain to be solved; as, for example, there is the question as to what is the relative motion of Aether to moving matter. Does the Aether move with matter through space as suggested by Michelson's and Morley's experiment of America, or does it flow freely through all matter, as it is usually thought to do? I premise I will give a satisfactory solution of this problem in due course.

Again, in relation to the Phenomena of Light, there is still outstanding the problem of the physical explanation as to the transverse vibration of light. This problem will also be dealt with from the standpoint of our new conception of the Aether. Whether it will be as satisfactorily solved, as the physical cause of Gravitation, remains to be seen.

Further, there is also the important question yet unsolved, as to what Matter is. Lord Kelvin and Dr. Larmor have recently given to the world certain conceptions as to the origin of Matter, and I shall endeavour to show that such conceptions receive confirmation and support by the proposed new conception of the Aether.

Another problem that will be attacked and solved, will be the cause of the Permanent Magnetism of the earth, with an answer to some of the questions propounded by Professor Schuster at the British Association of 1892 relative to the magnetism of solar bodies.

There is certainly some physical explanation as to the cause of the earth being a magnet, yet up to the present no satisfactory physical theory has been given. I premise that the new conception of the Aether, to be submitted in the after pages, will satisfactorily account, and that on a philosophical basis, for this phenomenon.

Lastly, one of the most interesting discoveries of the present day will receive an added confirmation and explanation in the conception of the Aether medium to be advanced. I refer to the system of Wireless Telegraphy that has been so successfully developed by Signor Marconi, and I premise that new light will be thrown on that discovery by the suggested theory of the Aether.

Now, if all these problems can be partially or wholly solved by the same theory that is advanced to explain the physical cause of Gravitation, it needs no further comment to show that that theory is considerably strengthened and more firmly established.

For it is a rule in Philosophy, that the more problems any suggested theory can solve, the greater are the claims of that theory for acceptance by scientists generally. For, if two rival theories can solve three and ten physical problems respectively, then, in giving a decision as to which is the better theory, the balance of opinion would be overwhelming in favour of that theory which could solve the ten problems. So that, if in addition to the satisfactory explanation of the physical cause of Gravitation, some, if not all of the other problems can be solved, as I premise they can, by the same conception of the Universal Aether, then it follows our third rule of Philosophy will be more than fulfilled, and the theory so advanced will be placed upon such a strong foundation, that it can only be overthrown by proving that it contradicts the results of some undiscovered phenomena.

ART. 7. _Application of Rules to Gravitation._--Let us therefore apply Newton's own Rules of Philosophy to the Law of Gravitation, and endeavour to find out if the law, as at present understood, fully satisfies his own Rules of Philosophy. No one can reasonably object to subjecting the Law of Gravitation to the test of those principles which he lays down as the fundamental Rules of Philosophy.

If it comes through the ordeal with complete success, that is, if it is essentially simple in its conception and development, and if all its details are fully in accord with experience, as revealed by observation and experiment, then there will be no need to alter any of its hypotheses or axioms. If, on the other hand, it violates any of the rules as laid down by Newton, then, to that extent, an alteration will be necessary, in order that the Law of Gravitation may be brought into conformity with his own rules, and our Philosophy made to agree with our experience and observation.

ART. 8. _Analysis of Law of Gravitation._--In order to accomplish this, let us ask ourselves, "What are the component parts of this Law of Gravitation?" The Law is not a simple law, but a compound one. It is compounded primarily of three parts.

1st. A Primitive Impulse.

2nd. A Centripetal Force.

3rd. A Centrifugal Force.

To these must be added the three Laws of Motion; although they are not directly part of the Law of Gravitation, yet they are essential to its effectiveness and completion. Without any one of these, the Law of Gravitation would fail to account for all the phenomena that it does account for.

If there were no Primitive Impulse, then the planets and meteors, sun and stars would for ever remain at rest, and the Laws of Motion would remain inoperative. If there were no Centripetal Force, then the Centrifugal Force would hurl the planets and comets, asteroids or minor planets away into the depths of space, never to return to their central sun.

If there were no Centrifugal Force, then the Centripetal Force would draw all bodies, _i. e._ all planets, etc., to their central sun, and, instead of the planets continually revolving round the sun, there would be but one immense solitary mass in the centre of the solar system.

If there were no Laws of Motion, with their necessary corollary the Parallelogram of Forces, the Primitive Impulse would cease to act, and the Law of Gravitation would again fail in its attempt to account for those phenomena it does account for.

Thus, as it may easily be seen, Gravitation is a compound Law, depending upon at least four hypotheses, and therefore is not essentially a simple Force, or Law.

If, therefore, in giving a physical explanation of the cause of Gravitation, we can reduce all these four elements of the Law into one single physical cause, _i. e._ the Universal Aether, and show how they may all be explained and accounted for by the properties, qualities and motions of that physical medium, then such a result will be strictly in harmony with the first Rule of Philosophy, as laid down by Newton and others.

We will, therefore, proceed to consider some of these parts of the Law of Gravitation in detail.

ART. 9. _Primitive Impulse._--This may be explained as follows. At the creating and launching of each world, Newton supposed that there was given to each world an impulse or tendency to fly off from the controlling centre into space. On this matter MacLaurin writes as follows: "If we had engines of sufficient force, bodies might be projected from them, so as not only to be carried a vast distance away without falling to the earth, but so as to move round the whole earth without touching it; and, after returning to the first place, commence a new revolution with the same force they first received from the engine; and after the second revolution, a third, and thus revolve as a moon or satellite round the earth for ever. If this can be effected near the earth's surface, it may be done higher in the air, or even as high as the moon. By increasing the force or power, a body proportionately larger may be thus projected, and by a power sufficiently great, a heavy body, not inferior to the moon, might be put in motion, which might revolve for ever round the earth. Thus Sir Isaac Newton saw that the curvilineal motion of the moon in her orbit, and of a projectile at the surface of the earth, were phenomena of the same kind, and might be explained from the same principle extended from the earth so as to reach the moon, and that the moon was only a greater projectile that received its motion in the beginning of things from the Almighty Author of the Universe."

Now what I desire to know is, "What is the nature, the mode of operation, and, above all, the physical cause of this Primitive Impulse?" Is it in its nature and mode of operation a simple Force, or Cause? Does it fulfil the condition of Newton's First Rule of Philosophy? Permit me to suggest several lines of thought which may be made the basis of its analysis.

Astronomers tell us that there are in existence millions of stars, and suns, flooding immensity and space with their light and heat.

Now the question I wish to ask regarding Primitive Impulse in relation to all these stars is this: "Was the Primitive Impulse imparted to each sun, and star, and planet, separately and distinctly?" If so, then there must have been just as many Primitive Impulses as there are stars and suns and planets, and there would be according to a certain astronomer's estimate at least 800,000,000 Primitive Impulses, which assumption is altogether opposed to, and violates the First Rule of Philosophy.

If, on the other hand, it is affirmed that they all received their motion at one and the same time, then I ask: "What was the physical cause and method adopted to communicate the impulse to each one at the same time?" If the reply is given, that it was by Universal Gravitation, I have two objections to make to such a reply: first, that Gravitation is altogether inoperative without the Primitive Impulse, otherwise why was it conceived? and secondly, what is the physical cause of Gravitation?

Again, scientists inform us that there is every reason for believing, that stars and suns are still being formed in the universe, and that there are certain distinctive phenomena which go to prove that statement. Now, if that be true, and I believe it to be true, I wish to ask if the Primitive Impulse as suggested by Newton, is applicable to the stars and suns already in process of formation in the various nebulae? and, if so, at what point in the star's history or development is that Impulse applied?

Personally, I cannot conceive of the Great Creator of all things being so lacking in inventive genius, if I may reverently use that term, as to necessitate a separate Impulse being given to every separate star, or sun, as each one is created or formed during the progress and development of the universe of worlds.

I would much rather believe that which I hold to be the correct explanation, viz. that He has given to a certain fundamental and primordial medium, certain qualities and properties, by, and through which are originated and perpetuated, all the motions of the heavenly bodies already existent in the universe, or that are ever likely to be existent throughout all time.

The question of separate Primitive Impulses for separate bodies becomes more and more incongruous and inadmissible, as we consider it in its application to such small bodies as meteors and planetoids. Is it not contrary to our fundamental principles of Philosophy, that a separate Impulse should be necessary for all small bodies that exist in their myriads throughout the solar system, not to speak of the universe of which that system forms a part? Such a conception as Primitive Impulse, to each separate world, is altogether opposed to one's idea of that simplicity and beauty which govern the universe at large, and violates the first rule of our philosophical reasoning, and for this reason must be rejected from the System of Philosophy to be propounded in this work.

ART. 10. _Centripetal Force._--Let us now look at the Centripetal Force, and ask ourselves what is meant by such a force, and what is its mode of action and working. Centripetal Force, strictly, may be defined as that force which is always exerted towards the centre of the attracting body.

Taking the earth as an example, Newton points out, that though the gravity of bodies arises from their gravitation towards several parts of the earth; yet, because this power acts always towards the centre of gravity of the earth, it is therefore called the Centripetal Force.

This force, then, is that part of the Law of Gravitation which corresponds to the Attraction of Gravitation, and is always exerted in that straight line from the body attracted, to the centre of the attracting body, which joins the centres of gravity of the two bodies concerned.

The combination and effect of the various forces included in the Law of Gravitation are illustrated by the familiar illustration of the ball whirled round the hand by a piece of string, or the bucket filled with water, whirled round in the same way. Let us take the former. A piece of string with a ball attached to one of the ends is held firmly by the hand. An impulse or motion is imparted to the ball by the hand, that motion being continued by the movement from the hand. The first impulse given to the ball by the hand represents the Primitive Impulse. The tension on the string which holds the ball to its controlling centre represents the Centripetal Force, while the opposite force on the string, which takes up the Primitive Impulse and continues it, is represented by the Centrifugal Force.

The conception of the Centripetal Force is therefore simple, and entirely in accordance with our experience as gathered from observation and experiments. Both in the spheres of electricity, and magnetism, we find a similar force acting, which tends towards the centre of the attracting body, and therefore the Centripetal Force satisfies the first two Rules of our Philosophy.

Further, it adequately accounts for certain distinctive phenomena which occur through the Law of Gravitation, as, for example, the falling of bodies to the earth, and therefore is entirely in harmony with all the requirements of those principles enunciated by Newton for the successful explanation of any phenomena. I need hardly point out, therefore, this being so, any physical cause suggested as the explanation of Gravitation must deal with the Centripetal Force, and be able to give a physical explanation of the mode and manner in which the Centripetal Force operates.

The Attraction of Gravitation or the Centripetal Force, however, being, as its name implies, simply a drawing or pulling power to a centre, that is, a force that is ever and ever only drawing matter to matter, or body to body, it could not of, and by itself, accomplish those necessary stellar and planetary motions by which are produced that universal order, unity and harmony which characterize the universe. It is essentially in its operations and influences, a one-sided force, ever tending and influencing towards self, and therefore by itself would only be a detriment and an evil; and, unless it were accompanied by some companion or complementary and counter force, with which it acts in union and concert, and which exactly counteracts its pulling power and influence, it would soon draw star to star, and world to world, crashing and heaping them together in ruinous and dire confusion. So that, instead of the infinitude of worlds which now exist, which flash and sparkle in the heavens, and in their intricate, elaborate, and mazy motions move through the vast infinity like stately armies on the march, there would only be one agglomeration of matter, a silent and solitary mass existing in the vast abyss of space.

Therefore, as soon as Sir Isaac Newton had discovered and demonstrated the existence of the power of Attraction, as represented by the Centripetal Force, and its association with the universe at large, there was seen at once the necessity of another Force, of an opposite character, which would form the companion and complementary force to Attraction; a repulsive, repellent force, one tending or repelling from a centre, so as to counterbalance the influence of the Centripetal Force which ever tends towards the centre.

To fill up the blank, there was conceived to exist what is called a Centrifugal Force, that is, literally, a Force acting, and ever acting from a centre, and with that Force we will now deal.

ART. 11. _Centrifugal Force._--In applying our Rules of Philosophy to this Force, if by Centrifugal Force is simply meant that Force which is the exact opposite of the Centripetal Force, that is, a Force which acts from a centre, instead of to a centre, then such a Force is strictly in harmony with, and satisfies all the conditions of the two first Rules of Philosophy.

Not only is such a conception simple, but it is also in accordance with experience and observation. Professor Hicks in his address to the British Association in 1895 said: "What is called Centrifugal Force is an apparent bodily Force directed outwards from the centre of curvature of the body's path, and having an intensity equal to the distance from the centre multiplied by the square of the absolute angular velocity."

In the sphere of magnetism and electricity, the operation of two equal and opposite forces prevails. The attractive force of electricity, which is exerted to the centre, is always accompanied by the generation and development of a repulsive force, it being one of the fundamental rules of electricity that equal and opposite quantities of electricity are always generated at one and the same time. So that if the Centrifugal Force is viewed as being simply the exact opposite of the Centripetal Force, it fully satisfies the test when the first two rules laid down by Newton are applied to it.

If, on the other hand, Centrifugal Force implies and embodies the idea of continuance of the Primitive Impulse, as I believe it is supposed to do, then to that extent it is not conformable to the principles of our Philosophy, as embodied in the rules given by Newton.

Simply because, while it supposes a source or origin of its activity at the first, it goes on to suppose a continuance of that activity, without recognizing a continuing source or cause. It only recognizes and supposes the one original impulse given at the beginning, to account for the cause of the continually existing, and exerted power of the Centrifugal Force. I do not for a moment suggest, that the Divine Creator of all things, and the Ordainer and Upholder of all powers, forces and laws could not, had He chosen to give such a force, have given it and for ever operating. With that aspect of the question I have nothing to do, and of it nothing to say. I am dealing, and only wish to deal, with scientific facts, and scientific teaching from the purely philosophical standpoint.

Such an idea of a continuing effect, without a continuing cause, is altogether opposed to experience and observation, and is a violation of the second Rule of Philosophy.

Look where we will, or at what we will, and not only effects and causes are seen on every side, and in every thing, linked together inseparably, but wherever, and in whatever phenomena there is found a continuance of effect or effects, there is always and without exception found also a continuing source or cause.

Wherever Nature, therefore, gives us a continuous effect of any kind or sort, she always gives us a continuing cause, that can be both proved and demonstrated to exist. Nowhere in Nature, amid all her powers, principles and laws, is there to be found an effect without a cause, and in all continuing effects, a continuing and perpetuating cause also, and that effect exists just as long as the cause exists.

If the effect is perpetual, then the source and cause is perpetual also, both in its existence and energy. Hence if the Centrifugal Force embodies the idea of continuance of the Primitive Impulse, without showing how that Primitive Impulse is continued, then such an idea is an anomaly in the universe, is altogether opposed to the teaching of Nature and science, and violates the most fundamental principles of our Philosophy.

The philosophic explanation, therefore, of the Centrifugal Force, is that Force which flows from a centre, and _which is the exact opposite and counterpart of the Centripetal Force_. Further, as the Centripetal Force is an attractive Force ever attracting to a centre, so the Centrifugal Force, being its exact opposite, is a repulsive Force, which fulfils all the laws and conditions which govern the Centripetal Force, as it is in every phase and aspect the exact opposite, being indeed its complement and counterpart.

Any physical explanation of the Law of Gravitation, therefore, must also give a satisfactory physical explanation of this Force, and show its mode of operation and working. This I premise I will do without the faintest shadow of doubt or failure; that is, if we are to accept the evidence of some of the most delicate experiments of modern times relative to aetherial physics.

ART. 12. _Laws of Motion._--One of the most important factors in the successful application of the Attraction of Gravitation to the universe at large, are the Laws of Motion enunciated by Sir Isaac Newton. These are three in number, and are as follows--

1st. Every body continues in its state of rest, or of uniform motion in a straight line, except in so far as it may be compelled by impressed Forces to change that state.

2nd. Change of motion is proportionate to the impressed Force, and takes place in the direction of the straight line in which the Force acts.

3rd. To every action there is always an equal and contrary reaction.

_Corollary._--To these must be added the first Corollary of the three laws which is commonly known as the Parallelogram of Forces, which is as follows: "That when a body is acted upon by two Forces at the same time, it will describe a diagonal, by the motion resulting from their composition, in the same time that it would describe the sides of the parallelogram."

Now let us apply Newton's Rules of Philosophy to these laws, and see if they fulfil the conditions laid down therein.

In the first place, there being three laws necessary to cover all the motions involved, there is not that simplicity of conception which is a primary factor in the making of any hypothesis. Then it will be observed that even after postulating the three laws, Newton was unable to account for the elliptic orbits of the planets, until he had added a Corollary known as the Parallelogram of Forces.

ART. 13. _Force._--The question has arisen also, as to the meaning of the term Force which Newton uses. What is a Force, its cause and mode of operation? The idea of Force is conveyed to us by our "muscular sense," which gives us the idea of pressure, as for example when we push or pull a body along the ground.

We must not, however, limit our idea of Force to that narrow circle. It has now been fully established that Sound and Heat, Light, Magnetism, and Electricity are Forces, and therefore capable of doing work, as will be shown later on. Newton's use of the term Force is therefore somewhat vague; he does not definitely say what the Force is which causes the change of position, of the body, or of the rate of motion of that body. That it is something to do with Gravitation is obvious, but its exact nature or character is not revealed.

Since Newton's time we have made an advance in the definition of Force, and have come to consider Force as a kind of energy; the application of Force being the application of energy. Such terms as Mechanical Force, Chemical Force, Vital Force, are therefore out of date, and in their place the more definite ideas of energy are substituted. Instead, therefore, of getting such terms as Transformation of Forces, we now get Transformations of Energy. In the chapter on Energy, I hope to show that even that is not a satisfactory solution of the definition of a Force. If we are to make our Philosophy agree with our experience, then Force is due to motion, and motion alone.

So that Centrifugal Force will imply a motion from the centre; Centripetal Force a motion whose effect is ever towards the centre of gravity of any body.

ART. 14. _First Law of Motion._--This may naturally be divided into two parts for the purpose of applying the Rules of Philosophy.

(I) Every body continues in a state of rest, except in so far as it is compelled by impressed Forces to change that state. To what extent is this statement conformable to our experience and observation? If I place a body, as for example a weight, on a table, will it remain in that state until it is moved by some other Force? I think that it will so remain, and to that extent the law conforms to experiment.

Wider observation, and all experience, also prove the conformity of this part of the First Law of Motion to the second Rule of Philosophy, as all experience testifies to the fact that a body remains at rest, until some other power or force moves it from the position of rest. The application of this position of rest to any of the planets is, however, very difficult to conceive. MacLaurin, in relation to this fact, states: "This perseverance of a body in a state of rest can only take place in absolute space, and can then only be intelligible by admitting it." In dealing with the physical cause of Gravitation, I hope to be able to show that it can not only be admitted as a mathematical proposition, but that it can be made intelligible from the physical standpoint.

The second part of the First Law of Motion may be stated as follows: "Every body continues in a state of uniform motion in a straight line, except in so far as it is compelled by impressed forces to change that state."

Now what is the testimony of observation and experiment in regard to this part of the First Law of Motion? Let us test the question by the results of our experience. If a ball is sent rolling along the ground, its motion is gradually reduced until it comes to rest. If the ground is very rough indeed, as for example a ploughed field, then its speed will be very soon reduced, and the ball quickly comes to a standstill. If, however, the ground is smooth and level, like a well-kept cricket-field, then the motion of the ball will be reduced more slowly, and it will travel further before being brought to rest; while, if the ball is thrown along a very smooth surface of ice, it will travel a much longer distance before it is finally brought to rest.

Thus we learn, that the more we can get rid of all resistances to the motion of any body, the greater distance will the body travel, and the less diminution there is in the uniform motion of the body. So that, if it were possible to obtain a medium which offered no resistance at all to a moving body, then it would be a legitimate inference to infer that a body in such a medium, when once set in motion, would move with uniform motion for ever. Under such conditions, therefore, this part of Newton's First Law of Motion is physically conceivable. The crux of the whole matter, therefore, lies in the problem as to whether there is, or there is not, in existence, such a thing as a frictionless medium. We will therefore consider the problem of the existence of a frictionless medium from the philosophical standpoint.

Professor Lodge, in _Modern Views of Electricity_, p. 331, writes: "Now, if there is one thing with which the human race has been more conversant than another, and concerning which more experience has been unconsciously accumulated than about almost anything else that can be mentioned, it is the action of one body upon another; the exertion of Force by one body on another, the transfer of motion and energy from one body to another, any kind of effect, no matter what, which can be produced in one body by means of another, whether the bodies be animate or inanimate."

"Now I wish to appeal to this mass of experience, and to ask, Is not the direct action of one body on another across empty space, and with no means of communication whatever, is not this absolutely unthinkable? We must not answer the question offhand, but must give it due consideration, and we shall find, I think, that wherever one body acts on another body by obvious contact, we are satisfied and have a feeling that the phenomena is simple and intelligible, and that, whenever one body apparently acts on another body at a distance, we are irresistibly impelled to look for the connecting medium."

Again, on p. 333 of the same work, he adds: "Remember then, that whenever we see a thing being moved, we must look for the rope. It may be visible, or it may be invisible, but unless there is either a push or a pull, there can be no action."

Now, in relation to celestial phenomena, we are confronted with the fact of bodies acting on one another, and yet apparently they do not act upon one another by or through a medium, and to that extent according to the above extracts, such phenomena are opposed to universal experience. Again, we find planets and satellites moving through space with more or less uniform speed, and yet apparently there is no physical medium that acts upon them with either a push or a pull, as the present conception of the Aether is that of a frictionless medium, so that experience in its widest form seems altogether opposed to the existence of a frictionless medium.

Again, Tait in his _Natural Philosophy_ says: "The greater masses, planets and comets moving in a less resisting medium, show less indications of resistance. Indeed it cannot be said that observations upon any one of these bodies, with the exception of Encke's Comet, has demonstrated resistance. The greater masses, planets and comets moving in a less resisting medium, show less indications. No motion in Nature can take place without meeting resistance due to some if not all of these influences. _The analogies of Nature and the ascertained facts of physical science forbid us to doubt that every one of them, every star, and every body of every kind has its relative motion impeded by the air, gas, vapour, medium, or whatever we choose to call the substance occupying the space around it_, just as the motion of a rifle-bullet is impeded by the resistance of the air."

What is the testimony of our own personal observation and experiments to such an impossible entity as a frictionless medium? Can any of the readers tell me of any medium, be it solid, liquid, or gaseous, that they have ever heard of, or read of, or experimented with, that possesses the quality of being frictionless? The answer is unanimously in the negative. But a frictionless medium was absolutely imperative to the success of the Newtonian aspect of the Law of Gravitation. If the Aether had not been frictionless, then the First Law of Motion would have been violated, and a body, as for example a planet set in motion, would not then have moved with uniform motion, but would have been brought to a standstill by the resistance of the Aether. Accepting therefore experience as a guide, as we are bound to do if we wish to be strictly philosophical, as Newton pointed out, then we are compelled to come to the conclusion that there is no such thing in the entire universe as a frictionless medium. Such a hypothesis is contrary to all laws and rules of Philosophy, and to continue to advocate its claims is to remain where we are in relation to the cause of Gravitation, and in complete ignorance of the beauty and harmony of the wonderful physical mechanism that underlies the whole of the universe. Of course, if experience and observation are no guide to Philosophy, then we will let imagination run riot, and postulate the most extravagant explanations for the varied phenomena of the heavens. With experience of no account, we will affirm that the moon is made of green cheese, that the earth is flat, that the sun revolves round the moon, and a host of other absurd hypotheses that require no correction by experience and observation. But there, a truce to such absurd imaginations. Experience is a guide to Philosophy, its claims are recognized by the greatest Philosopher the world has ever known, and therefore as either experience or a frictionless medium has to go, we will part with the frictionless medium, and endeavour to make a hypothesis of the Aether that is in greater harmony with our Rules of Philosophy.

ART. 15. _Second Law of Motion._--The application of Newton's Rules of Philosophy to the Second Law of Motion is attended with greater success than was the case with his First Law. "Change of motion," he states, "is proportionate to the impressed Force, and takes place in the direction of the straight line in which the Force acts."

Newton adds this explanation to his Second Law: "If a Force generates any motion, a double Force will generate double motion, and a triple Force triple motion, whether they are applied simultaneously or gradually and successively. And this motion, if the body were already moving, is either added to the previous motion, if it is in the same direction, or subtracted from it if directly opposed to it, or is compounded with the previous motion if the two are inclined at an angle."

According to that, a force which presses or pushes with a four-pound pressure per square inch, if doubled, would press with a force of eight pounds per square inch, which fact agrees with experience. If the force is applied gradually, then the change of motion would be gradual; if applied suddenly, then the resultant motion would be sudden and violent.

The impressed force, therefore, always produces a definite and corresponding effect on any moving body, however that force may be originated, and however it may be applied. The effect so produced is always a change of motion, or, in present scientific terms, a change of momentum in the moving body. If the impressed force is halved, by an alteration in the mass of the body which exerts the impressed force, then the resultant momentum produced is halved also. If the impressed force is doubled, through any alteration in the velocity of the body which exerts the force, then the momentum produced in the moving body will be doubled also. So that the impressed force is equal to the change of momentum in the moving body upon which it is impressed.

When similar forces are impressed upon exactly similar bodies, the velocities produced are exactly the same; but, if similar forces act on dissimilar bodies, then the velocities produced in the different bodies are not the same; yet the total motion produced on all bodies, according to the Second Law of Motion, must always be proportionate to the impressed force. So that when we compare the effect of similar forces on different bodies, we find that there are two factors involved, viz., the mass and velocity of the moving body. The product of these two quantities is termed the momentum of the body.

When we apply the Second Law of Motion to the theory of aetherial dynamics, as suggested in this work, we shall seek to show that Newton's Second Law of Motion holds good in its application to the new theory. With the present conception of a frictionless Aether, however, it is philosophically impossible for the Aether to exert force on any body that may exist in it. Because, to the extent that it is frictionless, to that extent it ceases to possess mass. If it does possess mass, then it cannot be frictionless. Such an assumption violates all the Rules of Philosophy.

Yet the Aether is supposed, in some unknown manner, to possess inertia, which property is also dependent on mass. If the Aether really possesses inertia, then it must possess mass, and possessing mass it ceases to be a frictionless medium. So that if it possesses mass, then it can exert force the same as any other body, and Newton's Second Law of Motion is applicable to it.

ART. 16. _Third Law of Motion._--Newton's Third Law of Motion reads as follows--

"Action and re-action are equal and opposite, or, to every action there is always an equal and contrary re-action." This law is also conformable to experience; for, by experiment, it has been proved to hold good for electric and magnetic action. As MacLaurin points out, the Third Law of Motion may be extended to all sorts of powers that take place in Nature, and belongs to attraction and repulsion of all kinds, and must not be considered as being arbitrarily introduced by Newton.

The mutual action between any two bodies has, therefore, a double action. Thus a piece of stretched string must be conceived as pulling at both ends; the pull at the one end being exactly equal and opposite to the pull on the other end.

A magnet will attract a piece of iron with a certain force, but it is equally true that the iron attracts the magnet with an exactly equal and opposite force. We might even extend the application of this Third Law to a falling stone in its relation to the earth. Thus, if a stone is dropped from a high altitude to the surface of the earth, although the motion seems to be all in one direction, yet if the Third Law holds good, then the earth is attracted by the stone in exactly an equal, but opposite direction, to that in which the earth attracts the stone.

As, however, the mass of the earth is very great compared with that of the stone, it follows that the velocity of the stone compared with the velocity of the earth, must be very much greater, in order that the forces shall be equal.

The application of this Third Rule of Motion to planetary and celestial phenomena is therefore philosophical, in that its conception agrees with experience and observation.

Thus, while it is true that the sun attracts each of the planets in his system, it is equally true that the planets, in their turn, attract the sun with an exactly equal and opposite force. But the velocity of motion induced by the earth's attractive power upon the sun, would be less than the velocity of motion induced by the sun's attractive power upon the earth, although the two forces would be equal and opposite, simply because force, being a compound quantity, is dependent upon the mass of a body as well as upon its velocity.

Not only, however, is it true that the sun and all the planets jointly attract each other, but it is equally true that the planets attract each other also, with an exactly equal and opposite effect. Indeed, as Gravitation is universal, it has to be conceived that there are no two bodies existing, but what the Third Law of Motion equally applies to those two bodies; so that equality of action and re-action is as universal as the Law of Gravitation itself.

In coming to a conclusion with reference to Philosophy and the Laws of Motion, I wish to say that I am strongly of the opinion that the day has come, or will soon come, when they will pass away and give place to a more direct and simple method of working of the great Law of Gravitation. I look upon the Laws of Motion as part of the scaffolding which has been used to build up the Law of Gravitation. That Law has now been erected, and stands firm and secure in its position in the universe. Whatever changes may take place in its scaffolding, the Law itself will stand out with greater beauty and clearness, if we could but see the perfected structure, apart from the props and helps which have assisted in its successful erection and completion. As Dr. Larmor said, in his address to the British Association, 1900: "There has even appeared a disposition to consider that the Newtonian principles, which have formed the basis of physical phenomena for nearly two centuries, must be replaced in these deeper subjects by a method of more direct description of the cause of the phenomena. The question has arisen, as to how far the new methods of aetherial physics are to be considered as an independent departure; or how far they form the natural development of existing dynamical science."

I hope, therefore, to be able in this work to do something towards clearing the completed Law from some of the outside props, which have long hidden the simplicity, beauty and harmony of the physical working of Gravitation from the eyes of those who feign would see its wonderful mechanism.

In the elaboration and development, therefore, of the physical cause of Gravitation, it will be necessary to conceive a medium, whose properties and motions shall be able to account for all the movements of the planets, comets, suns and stars that the Laws of Motion now account for. Instead, however, of there being several Laws purely and simply mathematical in their application, there will be one physical medium, which will by its properties and motions account for--and that in a satisfactory manner--all the motions of the heavenly bodies. That such a medium is required in the scientific world is proved by the statement made by Professor Glazebrook, in his work on J. C. Maxwell, page 221, where he says: "We are still waiting for some one to give us a theory of the Aether, which shall include the facts of electricity and magnetism, luminous radiation, and it may be Gravitation."

ART. 17. _Summary of the Chapter._--In summing up the contents of this chapter, we find therefrom, that there is a Universal Law in existence that is known as the Law of Gravitation. The physical cause of this Law, however, is unknown; Newton suggesting that it was due to the properties of an aetherial medium that pervaded the universe.

To form a right conception of this medium, and to develop the hypotheses of the same on strictly philosophical lines, it is essential for us to know the rules which govern the making of any hypothesis.

Those rules, according to Newton, and other philosophers, are chiefly three in number, and form the very essence of any philosophical reasoning. Any departure from those rules will entail partial or entire failure in the success of the undertaking.

The application of Newton's rules to parts of the great Law of Gravitation show that some of those parts are not fully in harmony with the rules which Newton laid down in his _Principia_.

Any physical theory that may be hereafter suggested as the physical basis for the Law of Gravitation, must itself not only account for the various forces already referred to, but must itself fulfil the Rules of Philosophy laid down by Newton. That is to say, the conception of the physical medium must be simple in character, its properties and motions must agree with all our experience, as given by observation, and experiments; and the properties and motions postulated for it must satisfactorily account for, and explain all the phenomena that are presented to us by the Universal Law of Gravitation.

If all this be done, then from the standpoint of strict philosophical reasoning, the physical medium so suggested, and the theory so made, will be incapable of being overthrown or disproved.

Chapter II

Philosophy Of Gravitation

ART. 18. _Gravitation Attraction._--The Law of Gravitation being a compound law, and not a simple law (Art. 8), it is necessary that the principles which govern universal attraction should now be considered.

The law which governs Gravitation Attraction may be defined as follows: Every particle of matter in the universe attracts every other particle with a force whose direction is that of a line joining the centre of their masses, whose magnitude is directly as the product of their masses, and inversely as the square of the distance between them.

This may be divided into four parts.

(1) The Universality of Gravitation. (2) The Direction of the Forces involved. (3) The Proportion of these Forces. (4) The Law of Inverse Squares.

The theory of the Aether, therefore, which will be perfected in this work, must not only satisfactorily account for the Attraction of Gravitation on a strictly philosophical basis, but the laws, governing the pressures or tensions of that physical medium, must harmonize with each of the parts of the complex Law of Gravitation into which it has been resolved.

ART. 19. _Universality of the Attractive Force._--The principle upon which Universal Attraction rests is found in the words: "Every particle of matter in the universe attracts every other particle." It must, however, be admitted that this statement has never actually been proved. The smallest body that Newton used to prove his Law of Attraction was our satellite the moon.

Cavendish, however, in 1798, by a series of experiments, conclusively demonstrated that the force of Gravitation existed in small bodies. He took two small leaden balls of a certain weight, and fixed them at the ends of a rod about six feet long, the rod being suspended by a piece of wire in the air. Large leaden balls were then brought near the small ones, and great care was taken to see if there were any twist in the wire by which they were suspended. It was found that the wire had become twisted on the approach of the large leaden balls, and thus he was able to prove that every particle of the attracted and attracting body are mutually concerned in the Attraction of Gravitation. There is abundant evidence of the application of this force in relation to our earth, as we shall see later on.

The universality of the Attraction of Gravitation is a fact that has been proved in a thousand ways, and a thousand times. All stars and suns, and all planets, satellites and comets and nebulae are subject to this universal law. Astronomy teaches us that its power extends across the vast abysses of space, and that stars situated at distances that cannot possibly be measured, are subject to this world-wide law. Some of the greatest discoveries in astronomical science were due to the operations of this wonderful law, the gravitating influences of certain planets indicating their existence, although their discovery had not yet been made.

The discovery of Neptune through the mathematical calculations of Le Verrier and Mr. Adams in 1846 was the crowning proof of the Law of Gravitation. Mr. Adams in England had noticed that the planet Uranus was being pulled out of the course by some unknown power, and so set to work to calculate the position of the body which thus influenced the motion of Uranus in its orbit. He located the position of the supposed influencing body strictly by mathematical calculations, and then took his results to the Astronomer Royal. Delay, however, occurred in the search for the supposed new planet, and nothing was done further in the matter for many months. Meanwhile Le Verrier in France, unknown to Mr. Adams, had been making similar calculations with reference to the perturbations of Uranus, and had arrived at similar results.

These results were sent to the Berlin astronomers, and the heavens were searched for the supposed new planet. After a time, the planet was discovered in that part of the heavens indicated by Le Verrier, and for a time his name stood out as the sole discoverer. Gradually, however, the claims of Adams were admitted and recognized, and to-day his claims to participate in the honour of the wonderful achievement are generally admitted. Thus the discovery of Neptune gave to the Law of Gravitation a stability and proof that perhaps it had never received before.

Further evidence of the existence of the universality of the attractive force, is to be found in a certain system of stars known as binary stars, which revolve around each other, while they gravitate around a common centre. Recent researches in astronomy only seek more and more to confirm the universality and effectiveness of this grand law, that seems to hold the entire universe in its sway.

Any medium, therefore, which is postulated as the physical cause of Gravitation, must itself be as universal as Gravitation, in order for it to be able to fulfil this condition of universality. We shall find, as we proceed, that the only possible medium which can fulfil this condition, is the universal Aether, whose qualities and properties are already partly known and partly understood.

ART. 20. _Direction of the Forces._--The attraction of Gravitation is always directed along the straight line which joins the centres of masses of the attracting and attracted bodies. Thus, if the earth and moon are taken as examples, an imaginary straight line drawn from the centre of the earth's mass to the centre of the mass of the moon would be the direction in which the gravitative force would be exerted. Now a line which joins the central body to its satellite we shall see when we come to deal with Kepler's Laws is known as the Radius Vector. Thus the path of the attraction between the two bodies is along the Radius Vector. It is a singular coincidence that the path of a ray of light from the sun also coincides with the Radius Vector, as it is one of the laws of light that the path of a ray always follows a straight line.

It must not, however, be assumed, that while the attractive power is being exerted along any one straight line joining the centres of two bodies, therefore the attractive power is not operative in relation to any other part of the space, around the body. If our earth, for example, had four moons instead of one, and they were each in different positions in relation to the earth, then the law as to the direction of the forces would still hold good. We have examples of this in the case of Jupiter with his five moons, and Saturn with his eight moons. So that the attractive force of Gravitation is again like light, it operates on all sides equally at one and the same time. A lamp in the middle of a room sends its light waves on every side at one and the same time, so that while each ray has for its path a straight line, yet those rays are emitted equally on every side. In like manner, though the direction of the forces between two attracting bodies is that of a straight line, yet the law of universal attraction is equally exerted on every side of the planet at one and the same time.

In the theory of the Aether, therefore, to be developed in this work, it will have to be demonstrated that the direction of the forces, which are originated and transmitted by that physical medium, must philosophically fulfil the conditions which govern the direction of the forces, as observed in gravitational phenomena.

ART. 21. _Proportion of the Forces._--Newton proved that the attraction is proportional to the product of the masses of the bodies concerned.

Hence it is that the sun, which is the centre of the solar system, is capable of attracting the most remote planets, because the mass of the sun is greater than the mass of all the planets put together. Or take another illustration. Suppose that the sun and the earth are at equal distances from Saturn. Now the sun's mass is about 300,000 times that of our earth. Therefore if the earth draws Saturn through a certain distance in one second, the sun would draw Saturn through a distance which is 300,000 greater than the earth in the same period.

The governing principle, therefore, which decides the proportion of the attractive forces between two bodies is mass, and not simply density or volume. The mass of a body is a property which remains the same, as long as the inertia of the body remains constant. Mass is really a measure of the inertia of a body, or that property of a body by which it continues in its state of motion or of rest.

Mass is therefore a compound quantity, being equal to volume multiplied by density, so that if the volume of any body is halved, the density is doubled. Thus, the proportion of the attractive force between any two bodies ever remains the same, so long as the masses of the two bodies remain the same. Through all the changes of volume and density of any body, its attractive force remains constant, as long as the mass remains constant; for the simple reason, that as the volume of a body is increased, the density is proportionately decreased; or, as the volume is decreased, the density is increased.

For example, the volume of the sun as compared with the volume of the earth, is about 1,300,000 times greater, but the proportion of the attractive forces between the two bodies, is about 324,000 to 1. This difference is accounted for by the fact, that the density of the sun is about one quarter the mean density of the earth, hence their masses are in the proportion of 324,000 to 1. Thus the proportion of the attractive forces between any two bodies is dependent upon their masses, and not simply upon their volume or density.

ART. 22. _Law of Inverse Squares._--The Law of Inverse Squares which is applicable to Gravitation is equally true of Sound, Light, Heat and Electricity, the Law being that Gravitation acts inversely as the square of distance. That is to say, if the distance of any body from the sun, for example, be doubled, then the force of Gravitation is diminished to one quarter of the intensity which would be exerted on the body in the first position.

Thus the further a body is from its controlling centre, the weaker the Attraction of Gravitation upon it becomes. Taking therefore Mercury and the earth as examples, we find that their mean distances are respectively 35,000,000 miles and 92,000,000, which is a proportion of about 1 to 2-1/2. So that the intensity of the sun's attraction on the earth is about four-twenty-fifths of what it is on Mercury, that being the inverse square of the relative distances of the two bodies.

Now the intensity of Light and Heat received by the earth is regulated by the same law of inverse squares, so that the earth would receive about four-twenty-fifths the intensity of light and heat which Mercury receives when they are both at their mean distances.

This law of inverse squares is applicable to every body which acts as a gravitating source throughout the whole of the universe, whether that body be small or large, and whether it be in the form of meteor, satellite, planet, sun or star.

Each satellite, planet or sun exerts an attractive influence upon every body that exists, that attractive influence being regulated by the masses of the respective bodies, and decreasing inversely as the square of the distance from the body viewed as the centre of attraction. So that, the further the attracted body is from the attracting body, the less is the intensity of the mutual attracting forces, though that intensity does not vary simply as the distance, but rather as the square of the distance, and that in its inverse ratio. Thus if we take two masses of any kind or sort, and place them at various distances as represented by the numbers 1, 2, 3, 4, 5, 6, the intensity of the attracting forces between the same masses at the relative distances will be represented by the numbers 1, 1/4, 1/9, 1/16, 1/25, 1/36, which are the inverse squares of the respective numbers representing their distances. As we shall see, the same law holds good in relation to heat, light and electricity, and indeed to all forms of energy which radiate out from a centre equally in all directions.

There is no need to apply Newton's Rules of Philosophy to this Attraction of Gravitation, as it has been demonstrated to exist, times without number. Moreover its laws are exactly the same as those governing the phenomena of sound, light, heat, and electricity, so that apart from being proved by actual experiments in relation to the gravity of the earth, we have a wider experience of the application of the same ruling principles of the law in other departments of science.

The Law of Universal Attraction, which is strictly the Centripetal Force of the compound Law of Gravitation, fully satisfies the three governing rules of Newton's Philosophy. Not only is it simple in its conception, but it is borne out by experience, and adequately accounts for the distinctive phenomena which it seeks to explain. By it, astronomical observations can be taken with a precision and certainty that defy error or failure. The motion of a planet in its orbit can be so perfectly calculated, that its position in space in relation to other planets can be foretold years in advance. The theory of the Aether, therefore, which is to be perfected in this work, must philosophically show that the pressures or tensions of that medium, which are postulated as the cause of Gravitation Attraction, must themselves fulfil the laws of inverse squares, which govern light, heat, electricity and the Attraction of Gravitation. I premise that this will be done in the theory of the Aether to be submitted to the reader in the after pages of this work.

ART. 23. _Terrestrial Gravity._--Before passing from this phase of the subject, I should like briefly to look at the question of the Attraction of Gravitation from the standpoint of our own earth, as by so doing we shall notice some facts regarding the same, hitherto unnoticed, in the preceding articles.

Terrestrial Gravity is but a phase of Universal Gravitation. One of the most familiar facts and phenomena of everyday life is, that when a body, such as a stone or stick or bullet, is thrown or projected into the air, it always falls to the earth again. This is due to the attraction of the earth and the stone for each other. It has been proved experimentally that if a stone and a weight are let fall from a height of 16 feet, they would reach the earth in one second of time. Again, a feather, or cork, or even a piece of iron would take exactly the same time falling through the same space, provided that the feather or cork could be screened from the resistance of the air.

The distance, however, through which a body falls in one second varies at different parts of the earth's surface, being least at the equator, and greatest at the North and South Poles. This is accounted for by the fact that the polar diameter is only 7899 miles, while the equatorial diameter is 7925 miles, thus the distance from the centre of the earth to either pole is about 3950 miles, or 13 miles less than the equatorial radius of the earth. Now the force of gravity decreases upwards from the earth's surface inversely as the square of the distance from the earth's centre of gravity, but decreases downwards simply as the distance from the centre decreases. Thus if a ball were taken down 2000 miles, that is half the distance to the centre, it would only weigh half-a-pound, while if it were taken to the centre of the earth, it would have no weight at all; while a pound weight at the equator would not weigh one pound at the poles, because it would be nearer the centre of the earth by 13 miles.

Thus a pound weight is not always a pound weight. It varies as we carry it to different parts of the earth's surface, depending upon its relation to the centre of the earth for its exact weight. The point which I wish to make perfectly clear, as it will be necessary for future reference, is, that there is no such thing as weight apart from the gravity of the earth; or, if we apply the principle to the solar system, there is no gravitating force in that system apart from the gravitating force of the central body, the sun, or the planets and other bodies which form the solar system.

Let us look at this matter from another standpoint, in order to prove this truth and make the same perfectly clear. If a pound weight were put in a spring-balance, then at the surface of the earth it would weigh one pound. Now, we will suppose that we have taken the weight to a height of 4000 miles above the surface of the earth, that is exactly double the distance from the centre of the earth, the radius of the earth being approximately 4000 miles. According to the law of inverse squares, the force of Gravitation decreases inversely as the square of the distance. The distance having been doubled, the proportion of the forces at the two places, _i. e._ the earth's surface and 4000 miles above it, are as 1 to 1/4.

Thus at a distance of 4000 miles the weight which weighed one pound at the earth's surface, now only weighs a quarter of a pound. At a distance of 8000 miles, the distance would be trebled, therefore the force of Gravitation is one-ninth, and the weight would weigh one-ninth of a pound. If we could take the pound weight to the moon, the attractive force of the earth would be reduced to 1-3600, as the moon is 240,000 miles distant, that is sixty times the earth's radius. The square of 60 is 3600, and if we invert that we get 1-3600, so that the weight which weighs a pound at the earth's surface, would only weigh 1-3600 part of a pound at the distance of the moon. This again proves, that apart from the Attraction of Gravitation, there is no such thing as weight, and that the weight so called of any body, such as a planet or satellite, increases or decreases as its distance increases or decreases from its central attracting body.

ART. 24. _Centrifugal Force._--I have already shown in Art. 10 that the Centripetal Force and Universal Attraction are one and the same; as the Centripetal Force always acts towards the centre, and must therefore be in its operation and influence a gravitating or attractive power.

I have also pointed out in the same article, the necessity of another force, which is to be the complement, and the counter part of Gravitation Attraction. That complement and counter force was conceived by Newton, and called by him the Centrifugal Force. The very nature of the Centripetal Force demands and necessitates a force which in its mode of operation is exactly the opposite of the Centripetal Force. Unless there were such a force, a repellent and repulsive force, then instead of there being that harmonious working of the universe that now exists, there must inevitably be a gradual drawing together of all planets and satellites, of all stars and suns, into one vast, solitary, and ruinous body.

There are also other phenomena which demand a Centrifugal Force in the universe. It is a well-known fact, that there exist between the orbits of Jupiter and Mars, what are called planetoids, about 500 in number, which are supposed to be the remnants of a broken or shattered world. As may be expected from such an accumulation, they present the most extraordinary diversities and eccentricities in the orbits that can possibly be conceived. They are of all shapes and sizes, and besides their orbits round the sun, have orbits among themselves. They are so clustered together that their orbits intersect each other at numerous points, and when in conjunction are said to suffer great perturbations, being pulled great distances this way and that by each other's attractive influence. It is further stated that their orbits so intersect each other, that if they were imagined to be material rings, they would be inseparable, and the whole could be suspended by taking any one of them up at random. Here, then, is presented to us a kind or order of celestial phenomena for whose well-being and effectual working the Centripetal Force or the Attraction of Gravitation cannot possibly account. In their case another force is demanded which shall be the exact complement and counterpart of the Centripetal Force. There needs therefore a force, not an imagined one, simply conceived to fill a want, but a real Force, as real and as plainly to be understood as the Centripetal Force. A force existing in each world just like the Attraction of Gravitation, only the reverse of Gravitation, a repellent, repulsive Force, acting in the reverse mode, and way, to universal attraction. This Force must be governed by the same rules and laws that govern the Centripetal Force, if it is to work in harmony with the same. It must be universal in its character, having a proportion of forces equal to the product of the masses of the two bodies which are concerned, and its path must coincide with the path of gravitational attraction, that is, in the straight line which joins the centres of gravity of the two bodies. Further, and what is perhaps the most important of all, it must act as a repelling or repulsive force which shall be in the same proportion in regard to distance, as the law governing Centripetal Force, that is, inversely as the square of the distance.

Again, and briefly, there are also in existence small bodies called meteors, which are said to exist by myriads, which float in space, and circle round the sun. They are of all shapes and sizes, from one ounce to a ton or even tons, thousands of them coming into contact with our earth's atmosphere every year, especially in August and November. All of these small bodies have orbits among themselves, and gravitate round one another, as they revolve round the sun. Now if the orbits of the planetoids be such an entangled mass, what must be the orbits of these meteors? What an indescribable, unimaginable mass of labyrinthian motions must exist among these myriads of little bodies! How they must intersect, cross and intermingle each other's orbits! What attraction and counter-attraction they must exert upon each other! Let me ask any man to sit down and try to imagine how the present recognized Centripetal and Centrifugal Forces can account for the effectual working of these meteors. As illustrating the necessity of a real and physical Centrifugal Force which is to be the exact counterpart of the Centripetal Force, I would call the attention of the reader to Herschel's view of this matter. In dealing with the phenomena of comets' tails he writes:[1] "Beyond a doubt, the widest and most interesting prospect of future discovery, which this study holds out to us, is, that distinction between gravitating and levitating matter, that positive and irrefutable demonstration in nature of a repulsive force, co-extensive with, but enormously more powerful than the attractive force we call gravity which the phenomena of their tails afford." I premise that this prophecy of Herschel's will be fully demonstrated and proved in the succeeding pages of this work. For, in the theory of the Aether that is to be afterwards perfected, it will be philosophically proved that the physical medium so conceived will satisfactorily account for a force or motion from the centre of all bodies; which motions fulfil all the conditions required by that Centrifugal Force, which is the complement and counterpart of the Attraction of Gravitation. At the present time, with the conception of a frictionless Aether, it is impossible to harmonize the existence of such a force or motion with our theory of the Aether. Yet Professor Lebedew of Moscow, and Nichols and Hull of America, have incontrovertibly demonstrated by actual experiments the existence of such a force. Therefore it follows, that if our present theory of the Aether fails to agree with experimental evidence, such a theory must be reconstructed in order that our philosophy may be made to agree with our experiments and our experience.

[Footnote 1: _Lectures on Scientific Subjects._]

ART. 25. _Kepler's Laws._--A long time before Newton had discovered the Law of Gravitation, Kepler had found out that the motions of the planets were governed by certain laws, and these came to be known as Kepler's Laws.

These laws which were given to the world by Kepler, simply represented facts or phenomena which had been discovered by observation, as Kepler was unable to account for them, or to give any mathematical basis for the same.

On the discovery, however, of Universal Gravitation, Newton saw at once that these laws were simply the outcome of the application of the Law of Gravitation to the planets, and that they could be accounted for on a mathematical basis by the Law of Gravitation, as they seemed to flow naturally from that law.

Kepler's Laws are three in number and may be thus stated--

_1st Law._ Each planet revolves round the sun in an elliptic orbit, with the sun occupying one of the Foci.

_2nd Law._ In the revolution of a planet round the sun, the Radius Vector describes equal areas in equal times.

_3rd Law._ The squares of the periodic times of planets are proportional to the cubes of their mean distances.

Now the question arises, whether it is possible to form a theory of the Aether which shall satisfactorily and philosophically account for all the phenomena associated with Kepler's Laws in their relation to the motions of planets, satellites, or other solar bodies? On the present conception of the Aether such a result is an absolute impossibility. With the theory of the Aether, however, to be submitted to the reader in this work, the result is possible and attainable. If, therefore, such a result is philosophically proved, as I submit will be done, then we shall have greater evidence still that the theory so propounded is a more perfect theory than the one at present recognized by scientists generally.

ART. 26. _Kepler's First Law._--Each planet revolves round the sun in an elliptic orbit, the sun occupying one of the Foci.

The ancients thought that the paths of the planets around the sun were circular in form, because they held that circular motion was perfect. A system of circular orbits for the paths of the planets round the sun would be very simple in its conception, and would be full of beauty and harmony. But exact calculations reveal to us that the path of a planet is not exactly that of a circle, as the distance of a planet from the sun in various parts of its orbit is sometimes greater, and sometimes less, than its mean distance.

The planet Venus has the nearest approach to a circular orbit, as there are only 500,000 miles between the mean, and greatest and least distances, but both Mercury and Mars show great differences between their greatest and least distances from the sun.

If, therefore, the orbits of a planet are not exactly circular, what is their exact shape? Kepler solved this problem, and proved that the exact path of a planet round its central body the sun was that of an ellipse, or an elongated circle. Thus he gave to the world the first of his famous laws which stated that each planet revolves round the sun in an orbit which has an elliptic form, the sun occupying one of the Foci.

Not only is the orbit of a planet round the sun elliptic in form, but the path of the moon round the earth, or the path of any satellite, as for example a satellite of Mars or Jupiter or Saturn, is also that of an ellipse, the planet round which it revolves occupying one of the Foci.

It has also been found that certain comets have orbits which cannot be distinguished from that of an elongated ellipse, the sun occupying one of the Foci.

Now let us apply the Law of Gravitation to Kepler's First Law, and note carefully its application.

[Illustration: Fig: 1.]

Let _A_, _B_, _C_, _D_ be an ellipse representing the orbit of the earth, and let _S_ represent the sun situated at one of the Foci.

We will suppose that the earth is projected into space at the point _A_, then according to the First Law of Motion, it would proceed in a straight line in the direction of _A_ _E_, if there were no other force acting upon the earth. But it is acted upon by the attraction of the sun, that is the Centripetal Force which is exerted along the straight line _S_ _A_ (Art. 20), which continues to act upon it according to the principle already explained in Arts. 21 and 22.

Now, according to the Second Law of Motion and the Parallelogram of Forces, instead of the earth going off at a tangent in the direction of _A_ _E_, it will take a mean path in the direction of _A_ _B_, its path being curved instead of being a straight line.

If the sun were stationary in space, then the mean distance, that is, the length of the imaginary straight line joining the sun _S_ _A_ to the earth, would remain unaltered. The Radius Vector _S_ _A_, or the straight line referred to, would then be perpendicular to the tangent, and the velocity of the earth round the sun would be uniform, its path being that of a circle.

The Radius Vector _S_ _A_, however, is not always perpendicular to the tangent _F_ _E_, and therefore the velocity of the earth is not always uniform in its motion in its orbit, as sometimes it travels at a lesser or greater speed than its average speed, which is about 18 miles per second.

It has to be remembered that the sun itself is in motion, having a velocity through space of about 4-1/2 miles per second, so that, while the earth is travelling from _A_ to _B_ the sun is also travelling in the direction of _S_ _B_. Thus the orbital velocity of the earth, and the orbital velocity of the sun, together with the Centripetal Force or universal Gravitation Attraction, are all acting in the same direction when the earth is travelling from _A_ to _B_, that is, in the direction of the orbit situated at _B_. This point of the orbit is known as the perihelion, and at that point the velocity of the earth is at its greatest, because the earth is then nearest the sun.

According to Newton, the planet when at _B_ would still have a tendency to fly off into space owing to its Centrifugal Force, but it is held in check by the Centripetal Force, so that instead of it flying off into space, it is whirled round and starts off on its journey away from the sun in the direction of _B_, _C_. The sun, however, is still continuing its journey in the direction of _S_, _H_, so that not only is the increased orbital velocity of the earth, which it obtained at its perihelion, urging the earth away from the sun, but the sun itself in its advance through space is leaving the earth behind it. The combined effect of the two motions, the advancing motion of the sun, and the receding motion of the earth, due to its increased orbital velocity, drives the earth towards the aphelion, where its distance from the sun is greatest, and its orbital velocity is the least.

By the time the planet has arrived at point _C_, its motion through space has gradually decreased, and the Centripetal Force begins to re-assert itself, with the result that the earth is slowly made to proceed towards the point _D_ of the ellipse, at which point its motion is the slowest in orbital velocity, only travelling about 16 miles per second, while the distance of the earth from the sun is the greatest and has increased from 91,000,000 miles at the perihelion to 94,500,000. This point of the orbit is known as its aphelion.

After rounding this point, the orbital velocity of the earth begins to increase again, owing to the diminishing distance of the earth from the sun, which according to the law of inverse squares (Art. 22) gives an added intensity to the Centripetal Force.

Thus by the combination of the Laws of Motion and the Law of Gravitation discovered by Newton, he was able to satisfactorily account for and explain on a mathematical basis, the reason why the earth and all the other planets move round the sun in elliptic orbits, according to Kepler's First Law.

In the development of the physical cause of gravitation, therefore, the same physical medium, which accounts for that law, must also give a satisfactory explanation of the first of Kepler's Laws.

ART. 27. _Kepler's Second Law._--This law states that the Radius Vector describes equal areas in equal times. The Radius Vector is the imaginary straight line joining the centres of the sun and the earth or planet. While the First Law shows us the kind of path which a planet takes in revolving round the sun, the Second Law describes how the velocity of the planet varies in different parts of its orbit.

If the earth's orbit were a circle, it can be readily seen that equal areas would be traversed in equal times, as the distance from the sun would always be the same, so that the Radius Vector being of uniform length, the rate of motion would be uniform, and consequently equal areas would be traversed in equal times. Take as an illustration the earth, which describes its revolution round the sun in 365-1/4 days. Now if the orbit of the earth were circular, then equal parts of the earth's orbit would be traversed by the Radius Vector in equal times. So that with a perfectly circular orbit, one half of the orbit would be traversed by the Radius Vector in half a year, one quarter in one quarter of a year, one-eighth in one-eighth of a year, and so on; the area covered by the Radius Vector being always exactly proportionate to the time.

From Kepler's First Law, however, we know that the planet's distance does vary from the sun, and therefore the Radius Vector is sometimes longer and sometimes shorter than when the earth is at its mean distance; the Radius Vector being shortest at the perihelion of the orbit, and longest at the aphelion. We learn from Kepler's Second Law that when the Radius Vector is shortest, that is, when the planet is nearest the sun, it acquires its greatest orbital velocity; and when the Radius Vector is longest, that is, when the planet is farthest from the sun, the orbital velocity of a planet is the slowest.

Let _A_, _B_, _D_, _C_ represent the elliptic orbit of a planet, with _S_ sun at one of the Foci, and let the triangles _A_, _S_, _B_ and _D_, _S_, _C_ be triangles of equal area. Then, according to Kepler's Second Law, the time taken for the Radius Vector to traverse the area _A_, _S_, _B_ is equal to the time that the Radius Vector takes to traverse the area _D_, _S_, _C_. So that the planet would take an equal time in going from _A_ to _B_ of its orbit, as it would take in going from _D_ to _C_. Thus the nearer the planet is to the sun, the greater is its orbital velocity, and the farther it is away from the sun the slower is its velocity, the velocity being regulated by the distance. The manner in which the difference of velocity is accounted for by the Law of Gravitation has already been explained in the preceding article. Thus Newton proved that Kepler's Second Law was capable of being mathematically explained, and accounted for, by the universal Law of Gravitation.

[Illustration: Fig: 2.]

If, therefore, a physical cause can be given for Newton's Law of Gravitation, then such physical cause must also be able to account for, and that on a strictly philosophical basis, the second of Kepler's Laws as well as the first.

ART. 28. _Kepler's Third Law._--The Third Law of Kepler gives the relation between the periodic time of a planet, and its distance from the sun. The periodic time of any planet is the time which it takes to go once round the sun. Thus the periodic time of the earth is 365-1/4 days. The periodic time of Venus is 224.7 days, while that of Mars is 686.9 days.

Kepler had found out that different planets had different periodic times; he also found out that the greater the mean distance of the planet, the greater was the time which the planet took to perform its journey round the sun, and so he set to work to find out the relationship of the periodic time to the planet's mean distance.

After many trials and many failures he arrived at the right conclusion, and at last discovered the true law which is known as Kepler's Third Law, which states that for each and every planet, the squares of their periodic times are proportional to the cubes of their mean distances.

For purposes of illustration let us take the earth and the planet Venus and compare these two. The periodic time of the earth is 365 days, omitting the quarter day. The periodic time of Venus is 224 days approximately. Now, according to Kepler's Third Law, the square of 365 is to the square of 224, as the cube of the earth's mean distance is to the cube of Venus's mean distance, which are 92.7 millions of miles and 67 millions of miles respectively. The problem may be thus stated--

As 365^2: 224^2:: 92.7^3: 67^3:

This worked out gives--

133,225: 50,176: 796,597.982: cube of Venus's mean distance.

So that by Kepler's Third Law, if we have the periodic time of any two planets, and the mean distance of either, we can find out the mean distance of the other by simple proportion.

In making astronomical calculations, the distances of the planets are generally obtained by means of Kepler's Third Law, as the periodic time of the planet is a calculation that may be made by astronomers with great certainty, and when once the periodic times are found, and the mean distance of a planet, as our earth for example, is known, the mean distances of all the other planets in the solar system may soon be obtained.

In like manner this Third Law of Kepler's is equally applicable to the satellites of any planet. For example, when the periodic time of both of Mars' satellites, Phobos and Deimos, are known, being about 8 hours and 30 hours respectively, and the distance of either is known, as Phobos with a mean distance of 5800 miles, then the mean distance of Deimos can easily be calculated by this law, and is found to be 14,500 miles.

As discovered by Kepler, the Third Law was simply the result of observation. He was unable to give any mathematical basis for its existence. The Laws as they were given to the world by Kepler were simply three great truths which had been discovered by observation. It rested with Newton to show how these laws could be accounted for on a mathematical basis, and to show how they all sprang from one and the same source, namely the universal Law of Gravitation. In his _Principia_, he proved that all Kepler's Laws were fully expounded and explained by his great discovery of Universal Gravitation.

Now what Newton has done for Kepler's Laws from the mathematical standpoint, we propose to do from the physical standpoint. In the development of the physical agency or cause of Gravitation, therefore, among the phenomena and laws, which have to be satisfactorily accounted for on a physical basis, are these three Laws of Kepler's just referred to.

So that in addition to the satisfactory explanation of a physical cause for the Laws of Motion, and the Centripetal and Centrifugal Forces, the hypothesis of a physical cause of Gravitation must fully and satisfactorily account for the Laws of Kepler, whose mathematical explanation was given by Newton.

Further, and what is as equally important, the explanation so given must be strictly in harmony with the Rules of Philosophy as laid down in Art. 3. That is, the explanation must be simple in character, must not be contrary to experience or observation, and must satisfactorily account for the laws which the hypothesis of the physical cause of Gravitation seeks to explain. This I premise we will do as we pass from stage to stage in the development of the theory.

I can safely premise that it will be simple in character and conception, that it will be entirely in harmony with all experience and observation, and that the physical cause so advanced will give as physical a basis to Kepler's Laws as Newton's mathematical calculations gave them a mathematical basis.

In summing up, I need hardly point out, that if all that I have premised in this and the preceding chapter is accomplished in the after chapters of this book, then for the first time since the discovery of Universal Gravitation by Sir Isaac Newton, his great discovery will have received the long-expected and long-desired physical explanation, that explanation and cause being founded on his own Rules of Philosophy given in his immortal _Principia_, and for the first time our Philosophy will be brought strictly into harmony with our universal experience.

Chapter III

Matter

ART. 29. _What is Matter?_--The law of Universal Attraction states that "Every particle of matter attracts every other particle," etc., and the question at once arises as to what is meant by the term Matter, what are its properties and its constitution? Tait, in his _Natural Philosophy_, gives the following as the definition: "Matter is that which can be perceived by the senses, or is that which can be acted upon by, or can exert force."

It has already been pointed out in Art. 13 that force is due to motion, and that wherever we get motion of any kind or sort, there we get energy, or what used to be termed force. The consideration of this phase of the question will be more fully dealt with in the chapter on Energy and Motion. Suffice to say, that all experience teaches us that force is the outcome of motion.

Accepting this definition therefore of force, Tait's definition of matter will read thus, if brought up to date: "Matter is that which can be perceived by the senses, or is that which can be acted upon by motion, or which can exert motion."

The common idea that matter can only be that which can be seen or actually felt, is not large enough for a definition of Matter. There are numbers of things in Nature which cannot either be seen or felt, yet which are included in the term Matter. Let us take one or two examples. Every one admits that nitrogen and oxygen are matter, yet I venture to say that no one has actually seen or felt either of these gases. Both of these gases are colourless and invisible, and are both tasteless. You may open your mouth and inspire both gases, and yet if they are pure, you cannot taste either of them. They are only matter, in the sense that they appeal to our sense of force through the motion which they may acquire.

Or again, take air, which is a mechanical mixture of several gases. Can you see air? If it be free from vapour and smoke, air is invisible, and on a clear day you may look for miles across the sea, or from the top of a mountain, and yet not have your sight impeded in any way by the atmosphere. Neither can it be felt by the sense of touch. Open and shut your hand, and see if you can feel the air while you do so. In similar ways it may be demonstrated that the air is tasteless. So that it is not necessary for us to see, or feel, or taste, or even smell that which we term Matter, in order for it to be included in that term. So long as that which we term Matter is able to accept motion in any manner from any body that is either moving, or in a state of vibration, and not only accepts, but also transmits the vibratory, or the kinetic motion so called of the moving body, then that which accepts the motion is legitimately termed Matter.

It becomes perfectly clear, therefore, why air, aether, oxygen, and hydrogen are termed Matter. Because they can be all acted upon by motion, and after being so acted upon, they can exert motion upon some other body. Heat is a form of motion, and when heat acts upon the air, the latter is set in motion, and we have what are commonly known as winds. It is unnecessary for me to prove that the motion of winds can be transmitted to other matter, as we have numerous examples from our observation and experience, in the case of windmills driven by the motive power of the winds, and also balloons urged along by the same cause; apart from the devastating effect produced in towns and country by a hurricane or storm.

The point which I wish to emphasize is, that Matter, strictly defined, is that which can be acted upon by motion, such as heat or electricity, both being forms of motion, and which can exert the motion so derived upon some other body.

Wherever, therefore, in the universe we find any body, whether it be solid, liquid or gaseous, or any medium which can be acted upon by motion, and after being so acted upon, can exert motion, that body or medium may legitimately be included in the term Matter, although it may be absolutely invisible to the eyes, or insensible to the sense of touch, or taste, or smell. In the same work,[2] Tait states that in the physical universe there are but two classes of things, "Matter and Energy," and then goes on to give examples of both. He adds that a stone, piece of brass, water, air, _aether_, are particles of matter, while springs, water-power, wind, waves, heat and electric currents are examples of energy associated with Matter.

Now I may add here, that within these two statements is to be found the germ of the physical cause of Gravitation, together with the satisfactory explanation of all phenomena that the universe reveals to us, either by observation or by experiments. I purpose therefore, before giving any detailed accounts of that medium which is to form the physical basis for the cause of Gravitation, to look at the term Matter in all its aspects, in order that we may get a right conception of the universe, and of the part that Matter plays in the same.

[Footnote 2: Tait, _Natural Philosophy_.]

ART. 30. _Conservation of Matter._--The Theory of the Indestructibility of Matter was first introduced by Lavoisier in 1789. This theory may be thus summed up; that Matter which fills the universe is unchangeable in quantity, so that the total quantity ever remains the same. Changes may take place in regard to the state of the Matter, but the sum-total of Matter throughout all the changes remains unaltered. Thus when we burn coal, it is changed into carbonic acid by combination with the oxygen of the atmosphere; when sugar is put into water, it simply passes from the solid to the liquid condition. If a piece of iron or steel is allowed to rust, the surface of the iron has entered into combination with the oxygen and water of the atmosphere, and formed a new substance. So that a body may change from solid to liquid, as for example from ice to water, or from liquid to a gaseous condition, as from water to steam, and probably from a gaseous condition to an aetherial condition as we shall see later on, but the sum-total of Matter throughout all these changes ever remains the same. Thus, throughout all the physical and chemical changes that Matter may undergo in the universe, there is no actual loss in weight or quantity. Throughout the whole realm of Nature we do not find a single instance of the production of absolutely new Matter. We may, and can produce new combinations of the forms of Matter. The substance so formed by chemical combination may be different from anything that has ever been seen or produced before, but the elements of which it is formed must have existed in some other form before its production.

This principle is the great underlying principle of all chemical investigation and research, and may be proved at any time by means of the scales or balance in the laboratory. Lavoisier first made the experiment with the scales and proved this truth by actual demonstration.

ART. 31. _Matter is Atomic._--The hypothesis that Matter is made up of infinitely small particles which are termed atoms, was first proposed by the Grecian philosophers. This hypothesis has gradually taken definite shape, but it remained for Dalton to first put the hypothesis into a connected form, and that form is now known as Dalton's Atomic Theory.

According to this theory, an atom of hydrogen was the lightest atom known, but comparatively recent researches by Sir W. Crookes have shown that there are possibly in existence minute particles which are even lighter than an atom of hydrogen. Thus Sir W. Crookes has suggested that there are certain particles associated with an atom of hydrogen which are 700 times less in weight than the atom itself.

Professor J. J. Thompson has further suggested that if we could divide an atom into a thousand parts, and could take one of those parts, we should find that this corpuscle, as he has termed it, would be the carrier of the charges in an electric current, so that it will be seen that we are moving into the direction of the continuity of Matter. Let us now look at the question as to what is meant by an atom more fully.

ART. 32. _What is an Atom?_--Clerk Maxwell's definition of an atom is, "a body that cannot be cut in two." An atom is the smallest part of a simple substance which can enter into combination with another element, and is incapable of being further subdivided.

An atom of hydrogen is the smallest part of that particular gas which can enter into combination with any other element, as oxygen, to form a chemical compound as water, which is composed of two atoms of hydrogen and one of oxygen.

Further, an atom of any kind or sort, retains its identity and remains the same throughout all chemical combinations or physical changes which it may undergo. By spectroscopic analysis, it has been ascertained, for example, that hydrogen exists in the sun and stars, and the conclusion is arrived at in connection therewith, that an atom of hydrogen in any sun or star is the same as an atom of hydrogen in our atmosphere, or in any of the compounds, as water, in which it is found. Thus it has come to be received as an accepted fact, that every atom of any substance, as oxygen, nitrogen, and hydrogen, whether they exist in the earth or sun, in meteorites or the farthest stars or nebulae, wherever they are found, possesses the same identity and the same physical properties.

Atoms attract one another, and this atomic attraction is known as affinity. There is not the least possible doubt that affinity is a form of universal attraction, except that the affinity of atoms is selective. This affinity of atoms for each other gives rise to the combination of atoms known as molecules and chemical compounds.

_Size of Atoms._--It has been computed by Lord Kelvin and others, that an atom may be as small as 1/50,000,000 of an inch in diameter, so that if 50,000,000 of them were put side by side, they would just measure one inch in length. Atoms are not all of the same size or weight. An atom of oxygen weighs 16 times as much as an atom of hydrogen. It has been proved by Kirchhoff and Bunsen, that the 3/1,000,000 part of a milligramme of sodium chloride is sufficient to give a yellow colour to a gas-jet. Faraday prepared some sheets of gold, so thin that he estimated they only measured the 1/100 part of the length of a light-wave. We have to remember that each sheet of gold must have contained molecules of gold composed of atoms. What must have been the size of the atoms therefore of which the sheet was composed?

ART. 33. _The Atomic Theory._--The Atomic Theory was revived by Dalton in 1804, in order to account for the fact that elements unite in certain definite proportions. From that time to the present, the theory has grown and developed until at the present time it is looked upon as a well-established theory. It is, however, simply a theory, and from the very nature of the hypothesis is incapable of proof. No one has ever seen an atom of hydrogen or oxygen, or an atom of any solid, liquid, or gaseous matter. The Atomic Theory suggests, therefore, that there is a limit to the divisibility of matter. All chemical experiments lend support to the theory, and by it we are able to give an intelligible and easy method of expression to what would otherwise be difficult phenomena to explain.

Ancient philosophers were divided on the question of the infinite divisibility of matter. The Epicureans were of the opinion that matter was incapable of infinite division, and that even if we were able to make the smallest possible division, it would be impossible for us to reach the smallest particle termed "Atom."

ART. 34. _Kinds of Atoms._--Various forms of atoms have been conceived by philosophers from time to time, ranging from the Hard Atom, and the simple point-centres of Boscovitch, until we come to the more modern Vortex Atom of Lord Kelvin, or the Strain Atom of Dr. Larmor, which will be looked at separately. Democritus conceived a hard atom as long ago as 500 B.C., while the notion of a hard atom is not absent from the works of Newton himself. We find that Newton suggested that the particles of air might be hard spherical bodies, at a distance from one another of about nine times their diameter.

The hard atom, however, seems to be refuted by spectroscopic analysis, which reveals to us in a manner that has never been revealed before, something of the sizes and vibrations of atoms.

From the phenomenon of heat, which is simply matter in motion, we feel compelled to accept the fact that an atom is not a hard particle, but that it is something which is more closely allied to the Vortex Atom, or the Strain Atom of Dr. Larmor.

_Boscovitch Atom._--According to Boscovitch's theory, each atom is simply an indivisible point in space capable of motion, and possessing a certain mass whereby a certain amount of energy is required to produce a certain change of motion. In addition to this, any two atoms could attract or repel each other with a force depending upon their distance apart. The Law which regulates these forces for all distances greater than 1/1000 of an inch is an attraction varying inversely as the square of the distance, and a repulsion for less distances.

We have, therefore, to suppose that in place of the hard atom, there is merely a geometrical point which can exert attractive or repulsive forces to, or from, the central point. So far as external particles are concerned, they would behave just the same as a hard atom would do. This conception was largely entertained in recent times by Faraday. It is more a mathematical explanation than a physical one, but has been found convenient in explaining what takes place in the interior of bodies in their three states, namely: solid, liquid, and gaseous.

_Lord Kelvin's Vortex Atom._--Another hypothesis which has been suggested for the constitution of an atom, is that known as the Vortex Atom, which received its birth at the hands of Lord Kelvin. The underlying principle of this Vortex Atom is, that matter may be entirely due to the rotating parts of a fundamental medium, the Aether, which fills all space.

The properties of vortex motion were first mathematically calculated by Helmholtz, but it was left to Sir Wm. Thompson, now Lord Kelvin, to give a physical idea of the Vortex Atom.

Before entering further into the question of the Vortex Atom, it may be as well to explain how vortex smoke rings may be made.

[Illustration: Fig: 3.]

All that is required is a wooden box, about one cubic foot in size, with a round hole perforated in one of the sides, and the opposite side covered with a piece of linen in place of the wooden side. The bottom of the box should then be covered with some strong solution of ammonia, and some hydrochloric acid poured into a saucer and put into the box. The combination of these two will cause thick clouds to form in the box, and if the linen is sharply tapped by the hand, a ring of this cloud will be forced through the hole on the opposite side of the box. The ring so formed will be circular in shape, and will go sailing through the room in which it is made.

When the hole is circular, the rings will be found circular also, but if the hole is square, then the rings will be irregular in shape. One remarkable characteristic about these rings is, that when two of the rings are travelling in the same straight line, the one behind will overtake the front one, and while so doing, the diameter of the front one is enlarged, while that of the one behind contracts. The front one will also travel slower, while the one behind travels faster until it has caught up the former, and then the latter, having contracted sufficiently, will pass through the diameter of the former as illustrated in the figure. This alternation of contraction and expansion is continued as long as the two rings move in the same plane and until they are destroyed. When, however, the two rings are moving in opposite directions, and meeting each other in the same straight line, they will repel one another, instead of attracting each other.

Their rate of progress is gradually reduced as they approach together, and they begin to expand and enlarge, but they never touch each other. Another peculiar feature about the rings consists in the fact, that the central core of air in the ring remains the same all the time the ring is in motion through the room, so that it has the same core of air at the end of its journey as it had when it left the box.

As Lord Kelvin pointed out, if there were no friction of the air, the ring once created would rotate for ever. If, therefore, there were such a thing as a perfect fluid, and there were vortex rings in it, nothing could destroy these rings when once they were created, and this is one of the most striking suggestions with reference to the Vortex Atom theory of matter. It remains to be seen whether in the universe we have such a medium as a perfect fluid.

Sir Wm. Thompson has applied the Vortex Atom theory of matter to the Aether, but from mathematical calculation he was unable to arrive at a satisfactory conclusion as to the Aether being composed of vortex atoms.

Another remarkable property belonging to these rings, lies in the fact that they cannot be cut in two. It will be found that when the knife is brought near to them, they seem to recoil from the knife. In that sense, it is literally an atom, a thing which cannot be cut in two.

The Vortex Atom has many recommendations in its favour. Many of the most important properties of matter are possessed by it, as for example indestructibility, elasticity, inertia, compressibility, and its incapability to be cut in two. Further, it may be linked with another ring, and so give the basis to the combining properties of atomic weights.

The Vortex Atom theory is simple in character, as it does not postulate any extravagant hypothesis, but makes use of the Aether as the common basis for all matter, simply stating that this property of rotation may be the basis of all that we call matter. We shall further consider the relation of the Vortex Atom to matter, when we deal with the constitution of matter and the unity of the universe.

ART. 35. _Elements of Matter._--As is well known, modern chemistry has succeeded in reducing all the complex forms of matter in Nature into a number of simple substances, which are called elements. Of these elements about seventy are at present known, some of which, however, are very rare. An element therefore is a simple substance which cannot be decomposed by any known force or process, as heat or electricity, into other elements.

There are, however, only about fourteen of these elements that enter largely into the constitution of the earth, the most common being oxygen and silicon. By the use of the spectroscope, it has been proved that many of these elements, as for example oxygen, hydrogen, sodium and calcium, exist in the sun and stars, as well as in the most distant nebulae. Most of the elementary bodies are to be found in a gaseous form as hydrogen, oxygen, fluorine and chlorine, though it has been found possible to liquefy even these gases. Thus we see that matter may be roughly divided into three states, viz. solid, liquid, or gaseous.

The condition in which the substance is found depends upon its temperature and pressure. An example of matter in its three stages is best shown in the case of water, where in the solid condition we have it as ice, in the liquid condition as water, and in the gaseous condition as steam.

By recent researches it has been found possible to liquefy gases at a very low temperature and increased pressure, with the result that now nearly all known gases as hydrogen, oxygen, and carbonic acid are to be obtained in liquid form. By still more recent experiments made by Professor Dewar, it has even become possible to liquefy the air we breathe, with the result that at a temperature of about 270 degrees below freezing-point and at an increased pressure, the otherwise invisible and gaseous air may be changed into a liquid, and poured out from one vessel into another in the same way that water can be poured out. A vessel, however, at the ordinary temperature into which such liquid air is poured, would be so hot compared with the coldness of the liquid air, that as soon as the exceedingly cold liquid air came into contact with the vessel, the comparatively hot vessel would make the liquid air to boil.

ART. 36. _Three Divisions of Matter._--Matter has been divided into three divisions, viz. solid, liquid, and gaseous. These divisions are each known by characteristic qualities, which separate the one division from another. At the same time, it is possible for matter to pass from one division into another, as for example in the case of water, which may exist in solid, liquid, and gaseous form. In view of the recent researches of Sir. Wm. Crookes and Professor J. J. Thompson, it is very probable that before long we shall have to add a fourth division to matter, which we should have to call ultra-gaseous form, or it may possibly be the aetherial form. If it should prove to be true that Aether is matter, and possesses the essential qualities of matter as suggested by Lord Kelvin, then certainly we shall have reached the boundary of another great division of matter, and our conception of the divisions of matter will have to be enlarged to take in that form, so that matter would then be divided into four great divisions, viz. solid, liquid, gaseous, and aetherial.

We will now consider the three groups as at present recognized.

_Solid._--Examples of solid bodies are common and familiar, and are typified by such things as iron, silver, copper, and lead. The chief characteristic of this condition of matter is that its condition or state is fixed, and cannot be altered without the expenditure of heat or electricity or some other form of energy.

All solid elementary substances, with the exception of carbon, can be melted or reduced to a molten condition, although some of them require a very high temperature to effect this reduction, as, for example, platinum. When a still higher temperature is applied, the metals may be vaporized, or reduced from a molten state to that of a vaporous condition. In the case of solids, the atoms have not a free path in which to move. It must not be thought, however, that the atoms of a solid are motionless, as there is nothing absolutely motionless in the universe. In the case of the solid, the molecules which compose it, preserve their relative position and are linked together in relation to each other by the force of Cohesion.

_Liquid._--When matter is in a liquid condition, as, for example, water and oil, the condition of its molecules are not so fixed and stable as they are in the solid state. The molecules can move freely about one another, and their freedom is increased compared with their condition when in the solid state.

As already indicated, the reduction of a solid body to a liquid or molten state may be effected by heat. When heat is applied to a solid body, several results follow, each of which is the outcome of the other.

1. There is an increase of temperature which is due to the increased energy of the molecules, through the added heat.

2. There is an enlargement of the volume or size of the body, and if the addition of heat be continued, the molecular forces which hold the molecules together are broken down, and then the molecules, loosened from those forces which in the solid state have bound them together, begin to move about with greater freedom, and thus give rise to the molten condition of metals, or liquid condition of water. Thus, it is the heat which has set the atoms which compose the molecules in motion. The atoms of the solid have absorbed the heat, and the heat which has thus been absorbed has imparted vibratory energy to the atoms, which they did not possess before. Now when a substance is in the liquid state, the atoms of that substance have not only a vibratory motion, but have also a translatory motion, so that they can move in and out among one another. This is proved by the phenomenon of diffusion, where we have the case of two different-coloured liquids, for example, intermingling with each other, which is conclusive evidence of the translatory motion of the atoms in liquids.

_Gaseous._--The third state in which matter is found is the gaseous state. In this condition, the particles of matter which form the gas have the greatest possible freedom of movement, and are able to move about with inconceivable velocity. There is abundant evidence to prove that gases consist of particles of matter which are perfectly free, and are able to fly about in all directions. The simplest proof is obtained by mixing two gases together, as, for example, when any gaseous substance is allowed to mix with the air of a room, when we find that the particular gas soon mixes itself thoroughly with all the air in the room. This process of mixing is known as Diffusion, and the lighter a gas is, the more quickly does it diffuse itself. The rate of movement of the various particles is varied, by reason of the encounters which each particle undergoes from time to time. Through experiments made by Joule, he arrived at the conclusion that particles of hydrogen attained a velocity of 6055 feet per second at 0 deg. C., which is a velocity much greater than that of a cannon-ball. In spite of the enormous velocity with which a particle of hydrogen would move, there are such a large number of particles in a single cubic inch of space, that no one particle has an absolutely free path from the one side of the enclosed space to the other. To this constant movement of the individual particles is due the elasticity or pressure of gases. The outward pressure which they exert on any body which encloses the gas is caused by the total effect of the impact of the particles, and is proportional to the sum of their masses multiplied into the square of their velocities. If we halve the enclosed space, then we should double the number of impacts in a given time, so that the number of impacts is inversely as the volume of the gas. This is equivalent to the statement, that the pressure of a gas varies inversely as its volume, which is Boyle and Marriotte's Law.

ART. 37. _Matter is Gravitative._--If there is one property which is essentially characteristic to all matter, it is that all matter is gravitative. To this rule there is no exception, as the universal Law of Attraction states that "every particle of matter attracts every other particle." Thus, wherever in the whole universe there is a particle of matter of any kind or sort, whether such matter be solid, liquid, or gaseous, there the force of attraction will be exerted with a force proportionate to the mass of the particle, and inversely as the square of the distance between the attracted particles.

Gravitation, then, is a property which is essentially inherent in matter, and any substance which is termed matter, or fulfils the conditions that govern matter, must be gravitative, whatever other property it may, or may not, possess. Unless this be so, we should have a violation of the universal Law of Gravitation, which would cease at once to be a universal law, for instead of reading "every particle of matter attracts every other particle," we should have to say that "some particles of matter attract some other particles," which would be a violation of that universal law which, through the genius of Newton, has given to the universe an unity from the philosophical standpoint that it did not possess before.

Some matter may, or may not be elastic; it may, or may not be solid, or liquid, or gaseous; but there is this fact regarding matter which is absolutely undeniable, and that is, "All matter is gravitative."

That this is true of each and all kinds of matter has been proved by direct experiment times without number, and the constant application of the law to all forms of matter is a fact observable from the phenomena incidental to every-day life. Astronomical observation teaches us also, that all stars, suns, planets, satellites, and comets are subject to this great Law of Gravitation, as indeed they must be if they are composed of matter. That they are all composed of exactly similar elements of which the earth is composed, has b