We have therefore arrived at exactly the same result that Newton arrived at, except that he had to introduce a third factor, viz. the Parallelogram of Forces, while we have produced the result by a simpler method, which, according to his own rules, is more philosophical, as all effects are produced by the simplest causes, as Newton himself stated in Rule 1. Thus it is the rotatory electro-magnetic Aether currents that urge the planets round the sun; and, as will be shown later, it is the same Aether currents in combination with the other motions that give rise to the physical cause of Kepler's Laws. It is the electro-magnetic Aether currents that produce the regular decrease in the velocity of the planets in their orbits, because of the regular decrease of the mass and velocity of the Aether currents themselves.
We have now a physical cause as well as a mathematical explanation of the decrease of the velocity of a planet in its orbit, which physical cause is in perfect harmony with all philosophical rules. The following table shows the gradual decrease in the velocity of each planet as the various planets recede from the sun--
| mean distance. | period of revolution. | velocity in orbit per hour. | |
|---|---|---|---|
| Mercury | 35,900,000 | 87.9 days | |
| Venus | 67,000,000 | 224.7 | 77.000 |
| Earth | 92,700,000 | 365.2 | 66.500 |
| Mars | 141,000,000 | 686.9 | 53.000 |
| Jupiter | 482,000,000 | 4,332.6 | 28.744 |
| Saturn | 884,000,000 | 10,759. | 21.221 |
| Uranus | 1,780,000,000 | 30,687. | 14.963 |
| Neptune | 2,780,000,000 | 60,127. | 11.958 |
Art. 100. Aether and Third Law of Motion.--We have seen ([Art. 16]) that action and reaction are equal and opposite, and that it is true of the centripetal force in its application to all matter throughout the universe. If, therefore, the centrifugal force is the exact opposite of the centripetal force, then the Third Law of Motion should equally hold good in relation to that force also.
We have, therefore, to form a physical conception of the application of the third law of motion, as it relates to the centrifugal force. As we have already learned, this force is due to the universal electro-magnetic Aether, which being gravitative, surrounds all atoms and molecules that may exist throughout the whole universe. It can readily be seen, therefore, that if the Aether surrounds every atom and molecule, then each atom repels another atom or molecule when the two forces are in equilibrium with exactly the same intensity with which the atom and molecule attract each other.
But the centrifugal force in each case is due to the pressure of the Aether, which presses always proportionately to the density of the Aether surrounding the atom or molecules, as suggested by Professor Challis.
The mean density, however, of each atomic or molecular atmosphere is regulated solely by the mass of the atom or planet, therefore the pressure exerted by one atom on another is proportionate to the mass of each atom, and to that extent is strictly in accordance with the law which governs the proportion of the forces between the two atoms or molecules. If, therefore, we have two atoms, A and B, of different masses, then it is true that while A exerts a pressure on B, which pressure takes the form of a repulsion, at the same time B exerts a pressure on A which is equal and opposite in its character and intensity, and in each case the pressure is due to the aetherial medium which surrounds each atom or molecule.
When the atoms are equal in mass, then the resultant motion produced on each atom would be exactly equal, but when the masses vary, the resultant motion produced on each atom would vary also, though the momentum in each case would be exactly equal and opposite, as momentum is a compound term dependent partly upon the mass of the body concerned.
In [Art. 16] we saw that when this third law was applied to planetary phenomena, not only did the sun attract all the planets, but all the planets attracted the sun with equal and opposite forces, and the planets also attracted each other with equal and opposite forces. In the same way it can be proved, that as the sun repels all the planets by the pressure exerted by the aetherial centrifugal force on those planets, the planets repel the sun with an exactly equal and opposite force at their mean distances. In Newton's conception, however, of the third law of motion, there was simply mathematical data to deal with, by which the law was shown to apply to the planetary and stellar world. In the case, however, of the centrifugal motion, we have a definite physical medium, which by its motions produces the pressure on the planets or suns that exist in space, which pressure forms the physical centrifugal force that forms the counterpart of Gravitation Attraction.
Let us look at this phase of the case in detail, and by so doing help to establish and confirm the physical existence of the force or motion referred to. We have learned from Chapter [IV]. that as Aether is gravitative, it surrounds all satellites and planets, suns and stars that exist in the universe.