Again, all forms of water-power, whether it be in the form of the flowing river or the tidal motion of the sea, possess a large amount of potential energy which may be used up to do mechanical work. They also possess kinetic energy, or energy of motion. We find illustrations of the possession of potential energy by rivers and tides, in the fact that by their fall from a higher to a lower level they may be made to do mechanical work, as in the case of the turning of the water-wheel by the fall of the water, which motion is communicated to machinery, and various forms of work are the result. In Switzerland and America advantage is being taken of the energy of falling water to generate electricity, by means of which villages and towns are being supplied with electric light at a very small cost.
Art. 55.Kinetic Energy.--Kinetic energy may be defined as energy of motion, and is the energy which a body possesses in consequence of its motion. A body in motion thus possesses kinetic energy, which it must impart to some other body before it can be brought to a state of rest. The body may be simply an atom, as a vortex atom, but if it be in motion, as all atoms are, then it must possess kinetic energy, which may be transferred to another atom by collision, or by some other method. As has already been pointed out in previous articles, kinetic and potential energy are complementary to one another, the sum-total of the two combined always remaining the same in any cycle of work, according to the principle of the conservation of energy. We get a good example of this oscillation from kinetic to potential, andvice versâ, in the planetary system. When the earth is farthest from the sun, its velocity, and consequently its kinetic energy, is at its lowest point; but there the potential energy is at its greatest. As the earth turns round in its orbit, however, and begins to approach the sun again, its potential energy decreases, while its kinetic energy increases with its increased velocity. So that by the time it has reached the nearest part of its orbit to the sun, its velocity, and consequently its kinetic energy, is at a maximum, while the potential energy is at a minimum. Then as the earth passes round its perihelion, the kinetic energy is used up in assisting the earth to overcome the attraction of the sun. Thus there is this oscillation from kinetic to potential, and from potential to kinetic, year in and year out, as the earth performs its cycle round its central body the sun.
Professor Tait, in the work referred to in the previous Article, gives examples of kinetic forms of energy under the following heads--
1st. Winds.
2nd. Currents of Water.
3rd. Hot Springs and Volcanoes.
It can be readily seen that winds are a form of energy, as we have innumerable instances of the power and energy which they exert. Advantage is taken of that kinetic energy by means of windmills, in which the energy of the wind is imparted to the revolving sails, and thence to the machinery, various forms of mechanical work being the result, as, for example, the grinding of corn, or the pumping of water. The pressure or energy of winds has even been calculated, the following figures being examples--
In the case of currents of water, whether they are in the form of river currents or ocean currents, as has already been pointed out in the previous article, the question of potential energy, or energy of position, is associated with their kinetic energy. Water is taken at a certain elevation, and then allowed to fall to a lower level, and in its fall from the high level to the lower level, its kinetic energy is used to drive mill-wheels, and thus work is done, the kinetic energy of the water being transformed into the motion of the machinery. This machinery may be used to work a dynamo, and thus electric light may be generated, or it may drive an electric motor which may perform all sorts of mechanical work. The great underlying principle of either kinetic or potential energy rests in the fact, that wherever we have energy of any kind or sort, whether it be associated with water, wind, or Aether, there we have the capacity to do work, the amount of work depending upon the amount of energy that exists in the matter which is the vehicle of energy.
InArt. 50it has been indicated that the Aether possesses several kinds of motions. From the sphere of light and heat, we learn that the Aether possesses certain motions which are always exerted in a direction from the central body, which gives rise to the light- and heat-waves. Thatbeing so, it conclusively follows that the Aether possesses kinetic energy, and therefore, possessing this energy, it also possesses the power to do work. It must be remembered we are no longer dealing with a frictionless medium, but with a gravitating medium, possessing mass and inertia, and, that being so, wherever we have the Aether in motion, there we have kinetic energy or the power to do work; and that work will correspond to the particular kind of motion which is exerted on any body by the aetherial motions, and will be equally subject to Newton's Laws of Motion.
Art. 56.Energy and Motion.--An advance, however, as to the meaning of the term Energy has been made within recent years, which brings it more into harmony with that simplicity of conception, and accordance with experience which are the very foundation of all philosophy. Instead of the term Energy, there is now being used another term to denote the forces which form the life of the universe, and that term is the word “Motion.”
Professor Poynting says: “All energy is energy of motion” (British Association Report, 1899).
Thus motion is the fundamental principle of all phenomena. If we analyze all forms of energy with which we are familiar, we shall soon find that they are only changes of one form of motion into another. Thus we shall see that heat is a mode of motion, as has been proved by Tyndall, that light is another mode of motion, and that electricity is also a mode of motion. I need hardly point out that this advance in our conception of energy is strictly in accord with the Rules of Philosophy. First, it is simple in conception. When we say that a body possesses energy, whether that energy be potential energy or kinetic energy, it does not convey to the mind some definite concrete fact, as does the statement that a body possesses motion. Every one, whether familiar with scientific teaching or not, understands and is familiar with the word Motion, as it is a common phenomenon of everyday life and experience. As Energy was simpler in conception than Newton's term Force, so Motion is simpler in conception than the rather vague and indefinite term Energy; therefore when we say that all energy is energy of motion of some kind or sort, we state that which is philosophically correct.
It is also in accord with the second Rule of Philosophy, in that it is strictly in harmony with experience and observation. Look where we will, or at what we will, there we find motion of some kind or other, whether it be among the innumerable stars, or in our own solar system, or any phenomena on the earth, or even among the world of atoms in their minute and atomic systems. Such a thing as absolute rest, or stagnation, isunknown in the universe. Wherever there is matter, there we find motion of some kind or other. It may be vibratory motion as heat, or wave motion as light, or rotatory motion as electricity, but motion of some sort is inseparably connected with all matter. So that when we say that all energy of the universe is the energy of motion, and motion only, we state that which according to the second Rule of Philosophy is absolutely correct.
Further, I wish to premise that by the use of the term modes of motion, in lieu of energy, the third Rule of Philosophy will be fulfilled. For if all phenomena of the universe, whether it be heat, light, electricity, be due to different modes of motion, then Gravitation should be explained from the physical standpoint by some kind of aetherial motion also. This I can safely premise will be done, and in the later chapters of this work, Gravitation will be shown to be due to the motions of the aetherial medium which floods all space. By so doing, all the Rules of Philosophy will be fully satisfied, and Gravitation will then be brought into line with all the other forms of motion, as heat, light, electricity, and magnetism, which are in themselves modes of motion, as will be shown in subsequent articles.
Art. 57.Conservation of Motion.--If it be true that all energy is the energy of motion, then the principle of the conservation of energy ought also to apply to all the modes of motion, and in its place we should then have the principle of the conservation of the various forms of motion. This defined would be, that the total amount of all motion in the universe, as heat and light, electricity, magnetism, and Gravitation also, if that be due to the motion of the Aether, is unalterable and unchangeable.
There may be changes from one form of motion to another, from heat to light, and light back to heat; heat into electricity, and electricity into light or heat; from Gravitation into heat or into light, or even into electricity; but the sum-total of the whole remains the same.
Again, as the principle of the conservation of energy is inseparably connected with the conservation of matter, so the principle of the conservation of all the modes of motion is also inseparably connected with the conservation of matter. They cannot be divided, so that wherever we get matter of any kind or sort, there we get motion of some kind, either in the form of heat, light, or electricity, or those aetherial motions which produce those phenomena associated with Gravitation.
As matter cannot be destroyed by any known process to man, so motion cannot be destroyed either. On the vortex atom theory of matter, this principle of the conservation of any mode of motion is perfectly intelligible, especially if added to that theory we have Dr. Larmor'selectron theory as the basis of the vortex atom. An atom in its ultimate state is nothing more or less than Aether in rotation, and as Aether is matter, we see that on the assumption of this atomic basis, we have even in the atomic world an illustration of this conservation of matter and motion, as in such an atom we have nothing but matter (i. e.Aether) and motion. Carrying the idea upwards in the atomic scale, if atoms of hydrogen or oxygen are multiples of these vortex atoms, then again we have nothing in all the elements, or combination of the elements, but matter and motion. Again, as all planets and satellites, suns and stars, are but agglomerations of elements, we have still the same two classes of things, matter and motion, and so from the most infinitesimal atom in existence, up to the most ponderous star that exists in the universe, we have running through them all the principle of the conservation of motion, which is to matter the source of all its activities, energies, and powers. Motion, therefore, might almost be said to be eternal. We have heard from time to time of the term perpetual motion. Philosophers have from time to time endeavoured to discover some application of this perpetual motion, but all efforts in this direction up to the present have proved futile. In one sense there is no such thing as perpetual motion. In another sense, that is from the standpoint of the conservation of all modes of motion, as motion cannot be destroyed, it must therefore be perpetual.
It is an absolute impossibility to obtain motion except from some antecedent energy, which is itself a form of motion. It would require the distinctive fiat of an Almighty Creator to produce motion from nothing, and I question whether such a result is obtainable, as I hold that if the Creator, at any time in the history of the universe, set any substance in motion, the source from which that motion was derived, was His own Divine Energy, and in that sense the physical motion was not produced from nothing. Such an assumption is altogether opposed to all philosophical reasoning and experience. I hope to deal with the question either in the last chapter of this book, or in another work.
Art. 58.Transformation of Motion.--Again, if energy be the energy of motion, and the principle of the transformations of energy holds good, then it is equally true that all modes of motion are also transformable. Thus heat is a mode of motion, being due to the vibration of the atoms which go to make up any body. Light is also a mode of motion, being due, as far as solar light is concerned, to the periodic wave motion of the Aether. While electricity, as we shall see later on, is also due to some form of rotatory motion. It has already been shown (Art. 54) that lightcan be converted into heat, so that the periodic wave motion of light can be transformed into the vibratory motion of heat.
Heat can also be converted into electricity, and if electricity be rotatory motion, then the vibratory motion of heat can be transformed into the rotatory motion of electricity. Again, as electricity can be converted into light, the rotatory motion of electricity can thus be transformed into the periodic wave motion of light. Thus through all the forms of motion with which we are familiar, we find this principle of transformation holds good, so that each form of motion may be directly or indirectly transformed into any one of the other kinds. Whenever, therefore, one kind of motion disappears, it is absolutely necessary, according to the principle of the conservation of motion, that some other kind shall be produced. There cannot be any real loss or destruction of the motion. It may be transformed, but not lost. By the use of proper apparatus, therefore, any form of motion with which we are familiar may be converted into another form, and in the process not the least quantity of any form of motion is lost. Heat may be changed into light, and light into heat; electricity into light, and light into electricity; heat into electricity, and electricity into heat. Indeed, starting from any one form, any of the other modes of motion may be produced, either directly or indirectly, and mechanical effects or work may be produced by each and all. Then, again, the order can be reversed, as by doing work which is simply applied motion, any of the other modes of motion can be produced. Thus heat can be produced by friction, and if the friction which is the outcome of muscular energy be continued long enough, a light will be the result, in the form of fire. When certain forms of work are done, as the turning of the handle of an electrical machine, frictional electricity will be produced. So that not only are all the modes of motion convertible into work, but work itself can be transformed into the modes of motion known as heat, light, electricity, and magnetism.
Now, if Gravitation be due to motion of the Aether, and if it is true that all modes of motion are convertible, then the application of this principle should also hold good in relation to Gravitation. It has been demonstrated by Joule and others that Gravitation can be converted into heat, light, and electricity. It can be converted first into heat. Joule made a number of experiments to ascertain what quantity of heat is produced by falling bodies, that is bodies under the influence of Gravitation. From experiments he has calculated that if one lb. of water falls through a space of 772 feet, it would raise the temperature ofthe water one degree Fahrenheit--that is, the water after its fall will be one degree hotter than when it started to fall. Here, then, we have the exact equivalence of a certain amount of gravitational motion expressed in terms of heat. So that, whenever motion of a falling body produced by gravity is arrested, heat is generated, and as heat is a mode of motion, it follows that the motion of Gravitation has been converted into the motion of heat. Again, the motion of gravity may be converted into that of light. This may be demonstrated as follows: Lord Kelvin has suggested that the light and heat of the sun are maintained by the falling into the sun of meteorites. Now the cause of the falling of these meteorites into the sun is the Attraction of Gravitation, and therefore if the falling of these meteorites produces light and heat, it necessarily follows that the motion of Gravitation, whatever that may be due to, is converted into the motion known as light and heat. Thus it can be seen that Gravitation, looked at from the standpoint of a mode of motion, is itself conformable to the principle of the transformation of motion, and this is an indirect argument in favour of the fact that Gravitation is itself due to certain motions of the universal Aether.
Art. 59.Motion and Work.--InArt. 52we have seen that energy is the power which a body possesses to do work, the amount of work which a body can perform being regulated by the amount of energy which such a body possesses. InArt. 57we have further seen that all energy is the energy of motion, and that wherever we have energy of any kind or sort, whether it be in the form of light, heat, or electricity, there we have motion of some kind or other. That being so, we arrive at the conclusion, that wherever in the universe we have motion of any kind or sort, whether it be the motion of Aether, or wind, or water, there we have the power of doing work, and the work so done will be proportionate to the motion which the medium possesses. The amount of work that air in motion can do has been measured, as we have already seen (Art. 55) that air which moves at the rate of 30 miles per hour exerts a force of 4-1/2 lb. per square foot.
The amount of work that water in motion can do has also been measured. The carrying and erosive powers of a river depend on the rapidity of its currents. It has been calculated that a velocity of three inches per second will transport fine clay; eight inches per second coarse sand; while three feet per second will transport stones as large as eggs.
If, therefore, air moving at the rate of 30 miles an hour can exert a force of 4-1/2 lb. per square foot, what must be the force or pressure of aetherial motion, as light-waves for example, which move with avelocity of 186,000 miles per second? The amount of work which such an aetherial motion can perform has actually been measured by Professor Lebedew of Moscow, and will be dealt with in the chapter on “Light, a Mode of Motion,” when the application of the work done on a body, as a planet for example, will also be considered. Work, therefore, can always be done by motion against resistance. This is a fundamental principle in the sphere of dynamics, which is incontrovertible, as all experience, observation, and experiment teach us, that wherever we get motion of any kind or sort, there we have the capacity or power to do work. The work done may be either in the form of pushing a body along, or pulling a body towards a centre. All experience and observation teach us that no body moves (whether it be an atom, or moon, or planet, or sun, or star), unless some other body or medium, which is in direct contact with the moving body, exercises some pressure or pull upon the moving body. The action is purely and simply a mechanical one. So that if this be true, then the earth and the planets, the sun and stars, comets and meteors, are moved through space solely because they are being pushed by some medium, or pulled to the centre by the motions of the same medium. If this can be proved to be true, then, as can be readily seen, our philosophy will then be made to agree with our experience, and the second Rule of Philosophy fully satisfied. As has already been pointed out, there is no such thing as action at a distance, therefore the Law of Gravitation demands a medium for its operation, production, and continuity. Newton distinctly points this out in his Letters to Bentley, where he says: “That one body should act upon another through empty space without the mediation of anything else, by and through which their action and pressure may be conveyed from one to another, is to me so great an absurdity that I believe no man who has in philosophical matters a faculty for thinking can ever fall into it.” It has already been pointed out (Art. 42), that the only medium which is universal is the Aether medium, and we have therefore to look to the motions and properties of that medium for the solution of the problem as to the physical cause of Gravitation. That such a medium has motions which are as regular as the tides of the sea, or the trade winds of the atmosphere, will be proved later on, when it will be found that Gravitation, with all that that law implies, is due, as Newton and Challis suggested, to the pressure, properties, and motions of the aetherial medium, which is as universal as Gravitation itself. This being so, it is essential that we should set ourselves to find out from the analogies of Nature, what are those properties and motions of the Aether which give rise to the universal Law of Gravitation. This Ipropose doing by a consideration of three different modes of motion--viz. Heat, a mode of motion; Light, a mode of motion; and Electricity, a mode of motion. I venture to premise, from a careful consideration of these three truths, that we shall be able logically and philosophically to arrive at the simple, yet grand truth which reveals the physical source of all motion of the universe.
Art. 60.Heat is Motion.--On the phenomena of Heat, Newton in his eighteenth query inOpticsasks the questions: “Is not the heat of a warm room conveyed through the vacuum by the vibrations of a much subtler medium than air, and is not the medium the same as that medium by which light is reflected and refracted, or by whose vibrations light communicates heat to bodies? And do not the vibrations of this medium in hot bodies, contribute to the intenseness and duration of their heat? And do not hot bodies communicate their heat to contiguous cold ones by the vibrations of this medium propagated from them into the cold ones? And is not this medium exceedingly more rare and subtle than air, and exceedingly more elastic and active?” Thus it can be seen that Newton was of the opinion that heat consists in a minute vibratory motion of the particles of bodies, and that such motion was communicated through what he calls a vacuum by the vibrations of an elastic medium, the Aether, which was also concerned in the phenomena of light.
One of the first experimental investigations into the real nature of Heat was made in 1798 by Count Rumford.
While he was engaged in boring brass cannon in the arsenal at Munich, he was struck with the degree of heat which the brass gun acquired, and with the still more intense heat which the metallic chips, which were thrown off, possessed. Of the phenomena he says: “The more I meditated on these phenomena, the more they appeared to me to be curious and interesting. A thorough investigation seemed even to bid fair to give us a farther insight into the hidden nature of Heat.” Rumford therefore set himself to find out by actual experiments what the nature of Heat was. For this purpose he constructed a cylinder, and mounted it so that it could be made to rotate by horse-power. At the beginning of the experiment the thermometer stood at 60° Fahrenheit, and after half-an-hour, when the cylinder had made 900 revolutions, the temperature was found to be 130° Fahrenheit, so that there had been an increase in the temperature of the cylinder of 70° Fahrenheit. The experiment was again repeated in another form with similar results.Rumford in dealing with the results of his experiments said: “It appears to me to be extremely difficult, if not quite impossible, to form any distinct idea of anything capable of being excited and communicated, in the manner the Heat was excited and communicated, in these experiments, except it be Motion.”
Only a year later, Davy gave to the world some results of experiments which he had performed, by which he had arrived at a similar conclusion to that of Rumford, viz. that “Heat is motion of some kind.” His experiment consisted of rubbing two pieces of ice together, and by so doing showed the ice could be melted. He then caused two pieces of metal to be rubbed together, keeping them surrounded by ice, and still he found that the two pieces of metal when rubbed together, produced heat, and melted the ice. He therefore rightly concluded that heat was produced by friction, and of the experiment adds: “A motion or vibration of the corpuscles of bodies must necessarily be generated by friction. Therefore we may reasonably conclude that this motion or vibration is Heat. Heat then may be defined as a peculiar motion, probably a vibration of the corpuscles of bodies tending to separate them. It may with propriety be called a repulsive motion. Now bodies exist in different states, and those states depend upon the action of the attractive and of the repulsive powers on their corpuscles, or in other words, on their different quantities of repulsion and attraction.” It was not, however, till 1812 that Davy confidently stated that “The immediate cause of the phenomena of Heat is motion, and the laws of its communication are precisely the same as the laws of the communication of motion.”
The question therefore confronts us, if heat be motion, what is the particular character of that motion? Is it a vibratory motion as Davy suggested, or is it similar to the undulatory wave motion of light? I need hardly point out, that we have evidence in favour of the hypothesis that light is due to some form of periodic wave motion in the Aether, the hypothesis being that known as the undulatory theory. We have also similar evidence in favour of the hypothesis, that heat is also due to some form of motion of the same aetherial medium. Indeed, it can be shown that heat possesses all the properties of light, and is subject to the same laws, with the exception that it cannot affect the sense of sight.
Heat, then, is due to some motion in the universal aetherial medium, that not only fills all space, but also forms an atmosphere around every atom or particle of matter that exists in the universe, and that motion is generally known as a vibratory or backward and forward motion.
Heat, then, may be said to be due to the vibrations of the Aether thatsurrounds all atoms and molecules, and of which those very atoms are composed, that is if we accept the aetherial constitution of all matter. So that, whenever a body, whether it be an atom or a molecule, or a planet or sun or star, is heated in any way whatever, such bodies excite waves in the surrounding Aether, and these waves travel through the Aether towards us from the heated body with the velocity of light. When these waves fall upon any other body, they become more or less absorbed by the body on which they fall, and cause corresponding vibratory motions in the same, which give rise to the phenomenon of heat in that particular body.
It has to be remembered that nothing definite is actually known as to the character of this vibratory motion. It is called a vibratory motion because it possesses a periodic vibratory movement, but as to its exact character, that has not yet been discovered. I hope, however, to indicate what the motion is that produces heat before the completion of this work.
Art. 61.Heat and Matter.--If it be true that heat is due to the vibrations of the aetherial medium, the question now arises, as to how a body may become heated, and by so doing be transformed into the three stages in which matter is found. We have already seen (Art. 36), that matter may be found in three forms, viz. solid, liquid, and gaseous, and that all these different forms of matter are composed of minute parts called atoms. In the case of the solid, the atoms are held closely together by some strong attractive power, termed cohesion; in the case of the liquid, the atoms have a greater freedom; while in the gaseous form they have a greater freedom of movement than when in either the liquid or the solid state. According to Young's Fourth Hypothesis (Art. 45), we find that all matter, and therefore all atoms have an attraction for the Aether, by means of which it is accumulated within their substance, and for a small distance around them in a state of greater density, and therefore of greater elasticity. In other words, as Aether is gravitative, every atom possesses an atmosphere of Aether in the same way that the earth has its atmosphere of air; and further, the aetherial atmosphere of each atom is densest nearest to the atom, gradually getting rarer and rarer the further the atmosphere recedes from the nucleus or centre, the elasticity or pressure being always proportionate to the density. Professor Challis, in his Dynamical Theory of Light and Heat, states that all the forces in Nature are different modes of pressure under different circumstances of the universal Aether, and as heat is a Force, and therefore a mode of motion, that also must be due to some form of pressure due to the vibrations of the Aether.
Professor Challis[8]on this point says: “According to this theory, the atoms of any substance are kept in position of equilibrium by attractions and repulsions resulting from the dynamical action of the vibrations of the Aether which have their origin at the atoms. Each atom is the centre of vibration propagated equally from it in all directions, and that part of the velocity of the vibration which is accompanied by change of density (of the Aether) gives rise to a repulsive action on the surrounding atoms. This action is the repulsion of heat, which keeps the individual atoms asunder.”
With all these facts before us, we are now in a position to account for the changes of matter which take place when heat is applied to either a solid or a liquid body. We have already seen (Art. 36) that it is by the application of heat that matter in its solid form is changed into a liquid, and from a liquid into a vaporous or gaseous form. It is now for us to endeavour to form a mental picture as to how this is done.
For example, let us take an iron ball, and apply heat to it, either by putting it in a furnace or suspending it in some way over an intense heat. As the heat, which is vibratory motion of the Aether, begins to be absorbed by the iron ball, it sets the atoms which compose the ball in motion, urging them to separate, and thus cause the iron ball to expand and increase in volume. As greater heat is absorbed, so greater motion among the atoms is the result. So that the motion of heat is tending all the time to expand the body, while they are held together by the attraction of cohesion, whatever that may be. As the heat is further increased, the iron ball begins to assume a liquid or molten form, its atoms beginning to move about with greater freedom, though held together by a decreased attractive power. In this condition we now say that it is in the molten state. Now during all this time, what has the Aether been doing, or what part has it played in the expansion and changing of the solid to a liquid? We have to remember, fromArt. 60, that wherever there is motion of any kind or sort, there we have a capacity to do work, and that the aetherial motion which we term heat is no exception to this rule. We are now no longer dealing with a frictionless medium, but with a medium which possesses weight, because it is gravitative, and consequently possesses inertia also. So that whenever the Aether is set in motion by flame or heat, its motion would be transmitted by waves of some kind to the iron ball. These periodic waves, acting upon the mass of the ball, attack the molecules of the ball and begin to set them in motion. It is supposed that they are already in motion, as nothing isabsolutely cold, and the motion of the aetherial waves imparts a greater motion still to the molecules, with the result that the agitation becomes greater and greater, until at length the agitation becomes so great, that the molecules break away from the power of attraction that holds them together, and so begin to move about with greater freedom and with greater rapidity. It is this state which we call molten. Now if Aether be frictionless, as has hitherto been supposed, and if heat be due to the vibratory motions of Aether, the problem confronts us, as to how the motion of a frictionless medium can do work in expanding a body, and urging the molecules of a body further and further apart. If the Aether be frictionless, then the waves of Aether known as aetherial heat waves ought to pass between the atoms as water passes through a sieve, or wind passes through a forest. Yet it is assumed that the vibratory motions of a hot body are caused by vibrations of the periodic waves of the Aether, which act upon the molecules of the body; and, in order for such an assumption to be consistent with the results, the only possible conception that can be accepted of the Aether, is that it is gravitative, and consequently possesses mass and inertia, and therefore has a capacity not only to accept motion, but also to transmit motion to another body, and impart the motion which it has accepted to a colder body.
By imparting such motion, it increases the motion of the cold body, and gradually changes its state from a solid to a liquid condition. Here, then, from the realm of heat we have another argument in favour of the fact that Aether is gravitative, and therefore possesses mass and inertia.
In the experiment of reducing the iron ball from a liquid state, so to speak, to a vaporous condition, we have practically a continuation of the same process, only that greater heat or greater aetherial motion is required, and whereas in the previous experiment the molecules of the ball were acted upon, in this case the atoms are more directly acted upon by the Aether waves. In all these processes it suggests itself to me that the aetherial atmosphere must take its share in the expansion and transformation of the liquid form into a gaseous form, or the solid into a liquid form. Taking the analogy of our atmosphere in its relation to the earth, we know that when heat is absorbed by it, it expands, the result being that a greater pressure is exerted by the expanding atmosphere, than would be exerted if it remained at the same temperature all the time. If, therefore, each atom has an aetherial atmosphere, which is capable of expansion, then the effect of the absorbed aetherial motion of the heat waves on each atomic atmosphere must be to expand it, and thus there will be a pressureaway fromthe atom, because of the increased elasticity acquired by the heated aetherial atmosphere. Sothat the expansion of the liquid is due to the increased elasticity of the aetherial atomic atmosphere, which has been expanded by heat, and which exerts an increased pressure on neighbouring atoms, thus seeking to push them farther away from each other. There are other motions of the atoms themselves in addition to this to be considered, but I am now seeking to show only the effect of the aetherial atmosphere of each atom upon the neighbouring atoms. This would give each atom a larger sphere of freedom in which to move, and that state would then be called a gaseous and not a liquid one. This assumption of the part which the aetherial atmosphere plays in the expansion of a body is therefore in agreement with Professor Challis' theory of heat already referred to, in which he states that heat gives rise to aetherial vibrations which act repulsively on the neighbouring atoms. In further confirmation of the existence of these aetherial atmospheres that exist around atoms, I would like to draw the attention of the reader to a theory of heat given to the world by Rankine,Phil. Mag., 1851. His theory is known as the “Hypothesis of Molecular Vortices.”
He assumed that “each atom of matter consists of a nucleus or central point, enveloped by an elastic atmosphere, which is retained in its position by attractive forces, and that the elasticity due to heat arises from the centrifugal force of those atmospheres revolving or oscillating about their nuclei or centres.”
Now in this assumption we find that he admits that each atom has an atmosphere, such atmosphere evidently being an aetherial one, and in that case the hypothesis would agree with the statement inArt. 46, that every atom possesses an aetherial atmosphere. He further points out that the atmosphere is retained in its position by attractive forces. This is also in harmony with the hypothesis given inArt. 45, which proves that Aether is gravitative, and therefore the atmosphere of the atom would be held in its position by the attractive force of Gravitation, as suggested by Young in his Fourth Hypothesis.
Further, he goes on to show that the elasticity of the atomic atmosphere is proportionate to its density, which is also in conformity with the statement made inArt. 47, and is also in accordance with Boyle's Law. Then he goes on to prove that the quantity of heat in a body is measured by the molecular revolutions of the vortices.
He does not clearly define the exact character of those molecular vortices, but I take it to mean that each atmosphere is in a state of revolution around its atomic centre, in the same way that the atmosphere of a planet is in a state of revolution around its central body.
Such an assumption is entirely in harmony with experience, as there isan analogy for its assumption from the planetary system; and if an atom is a world in miniature, as I believe it to be, then the atmosphere of the atom ought to revolve around its central nucleus in the same way that the atmosphere of a planet revolves around its nucleus or central body.
He then deals with temperature, and with the pressure of gases caused by heat, showing the relation of elasticity and pressure to temperature in a table of results given in thePhil. Mag. for 1851. I must refer the reader to the paper itself for fuller details. Thus from one of the greatest thinkers of modern times we have further testimony to the hypothesis that Aether is matter and is therefore gravitative, and because of its gravitating tendency, it forms around every atom and molecule elastic envelopes or atmospheres, whose pressure is always proportionate to their density.
[8]Phil Mag., 1859.
[8]Phil Mag., 1859.
Art. 62.Radiation and Absorption.--We have already seen (Art. 31) that all matter is made up of atoms and molecules, each of which is surrounded by its atmosphere of Aether. By means of the Aether, motion in the form of light and heat may be transmitted from one atom and molecule to another. The transmission of heat from one body to another is termed Radiation, while the acceptance of heat is termed Absorption. Tyndall defines Radiation as “the communication of molecular motion from the heated body to the Aether in which it is immersed,”[9]and Absorption, therefore, would be the acceptance of motion by the body from the Aether. So that in Radiation, the atom, molecule, or body parts with motion to the Aether, while in Absorption it gains motion from the Aether.
Now in order for us to understand this theory of Radiation and Absorption, it will be well for us if we look at a similar effect in the sphere of music and sound. Let us suppose that we have two tuning-forks of the same pitch, placed on a table at a distance of a foot from each other. If we set one of the forks vibrating, the waves which it radiates through the air will fall upon the other one, and will also set it in vibration, because they are of the same period or size as those waves which it would itself give off when sounded. Thus while one is losing its motion, the other is gaining it, or while one is radiating motion, the other is absorbing motion. This can readily be proved by stopping the vibration of the first fork, when it will be found that the second fork is now giving out a similar note to the first, although it was silent at the commencement. Thus we have here an example of radiation and absorption of sound, the success of the experiment depending upon the fact that both forks shall have the same pitch. Again, it must be noted, that if we have two tuning-forks both of which are of the samepitch, and both vibrating at the same time, then, while one is radiating sound and consequently losing motion to the other, yet at the same time it is absorbing motion from the other. Because, if fork A can transfer motion to fork B, the latter can equally transfer its motion to fork A, and when both are vibrating together, each is the recipient of part of the other's motion, while at the same time giving off motion in the form of sound waves itself. So that the power of a fork to radiate sound waves equals its power to absorb sound waves. If now we apply this simile to the atomic and molecular world, we shall be able to form a mental picture as to what takes place in radiation and absorption.
All atoms and molecules are ever in a state of ceaseless motion, ever moving, never still. All are creating Aether waves which move away with the velocity of light. If, in the transmission of the waves by the Aether, they fall upon another atom which can emit a wave of similar length, in the same way that two tuning-forks emitted sound waves of the same length, then the atom upon which the waves strike will be set in vibration, as the second tuning-fork was set in vibration by the first. We shall look again at the principle of wave motion in the next chapter. Further, from the simile of the two forks, which absorb sound at the same time that they radiate sound, we learn that an atom or body radiates heat waves at the same time that it is absorbing heat waves. Suppose that we have two bodies at equal temperatures, it must not be thought that the radiation or absorption has ceased, for, according to the simile used, they both still continue to vibrate and emit the aetherial heat waves; but where we get equality of temperatures, there we get equality of radiation and absorption. Before this equality of temperatures, however, is reached, the hotter body will radiate more heat waves than it absorbs, while the colder body will absorb more heat waves than it emits. All bodies, whatever their temperature, are incessantly radiating heat waves. This may be proved experimentally with proper apparatus, as for example with an instrument known as the thermopile. When, however, the total heat waves radiated out by a body are less than it absorbs, the body gets gradually colder, and the temperature decreases. So long as this is continued, so long will the body continue to get colder and colder, until it arrives at the same temperature as the surrounding bodies, at which point the total heat waves radiated out will equal the total heat waves absorbed, and at that point the temperature of the body will remain constant.
This aspect of temperature was first introduced by Prevost of Geneva in 1792, in an article in which he tried to explain the radiation from a cold body. According to his reasoning, a body is not simply regarded asradiating heat when its temperature is falling, or absorbing heat when it is rising.
What he tried to make clear was, that both radiation and absorption were going on at one and the same time; the radiation depending upon the body itself, but the absorption depending upon the nature of the body. While radiation and absorption are thus reciprocal, which implies that a good radiator is a good absorber, and a bad radiator is a bad absorber, it does not follow that all bodies radiate and absorb alike.
The capacity of bodies to radiate and to absorb differ considerably. Dr. Franklin made several simple experiments to prove the relative powers of radiation and absorption with several pieces of cloth. These were put out on the snow, and exposed to the heat of the sun. He found that the pieces which were dark in colour sank deepest into the snow, while those which were lightest in colour sank the least. From this he inferred that the darkest pieces were the best absorbers, and therefore the best radiators, while the light-coloured cloths were the worst absorbers, and therefore the worst radiators.
Radiation, therefore, may be said to be the propagation of a wave motion through the Aether; and, as all motion is a source of power or energy, we have in the radiation of heat from one body to another by the aetherial waves, the transmission of a motive power capable of doing work, either internal work as increasing the temperature of the molecule or body, or external work as separating the atoms, or driving them further apart. It can readily be seen that if the Aether were frictionless, as has generally been supposed, the Aether could not have any motive power at all, and therefore could not transmit heat from one body to another. Professor Tyndall[2] on this point says, referring to the cooling of a red-hot ball: “The atoms of the ball oscillate in a resisting medium, which accepts their motion and transmits it on all sides with inconceivable velocity.” Now in the previous quotation given in this article from the same authority, he states that the atoms are immersed in the Aether. So that evidently in his opinion the Aether and the resisting medium are one and the same. So that our assumption of the gravitative property of the Aether is perfectly in accord with Professor Tyndall's conception of the Aether, in so far as it concerns the propagation of heat waves; and, as will be shown later on, heat and light waves are due to the same physical agent--that is, the Aether; therefore, wherever we get heat and light, there, according to Professor Tyndall's statement, we must have a resisting medium, and as Aether fills all space, the resisting medium must fill allspace. This is perfectly in accord with our assumption that the Aether is gravitative and possesses inertia--that is, the capacity to receive and to impart motion, and being gravitative it possesses mass or weight, which is the very quality necessary for the existence of a resisting medium.