STALLO'S <' CONCEPTS OF MODERN PHYSICS.'' 237 



B's rhythms in size and B's waves with A's rhythms. When A is in the crest of B's 

 wave it rapidly expands into the sinus and when in the sinus it contracts into the 

 crest. B does the same by A's wave. What happens? Let a body rapidly ex- 

 pand from a dense toward a rare medium and it will necessarily leap forward to- 

 ward the rare one. As it contracts in going into the dense one again it does 

 not lose the ground gained. The ether contractions and expansions for waves 

 must of course be of different atoms from the little ones forming the molecule 

 by their rush. We need in other words two ethers, one for undulations and a 

 finer one for the cohesive force of our molecules. 



Many known facts in science constrain us to believe in two ethers aside Irom 

 this theory. When a swimmer turns the narrow part of his hand to the water 

 in his cut stroke and the palm in his back push he does virtually what we imagine 

 our gravific molecules do. When fish with fins and tails and birds with wings 

 propel themselves by presenting a narrow surface forward and a broad one in 

 the back push, they do the same. Our molecules by their movements can go in. 

 but one direction and that in an exactly straight line to the source oi radiation. 

 Could the first condition of a good theory of gravity be better filled ? "Its direc- 

 tion is radical toward the acting mass " As the source of power is in the mole- 

 cule itself, exactly as you increase the number of such molecules so you will in- 

 crease the power. It exactly fills the second condition and its corollary. "Its 

 quantity is exactly proportional to the acting mass." " No multiplication of duty 

 in the slightest degree impairs its previous tensions." All radiation obeys the 

 law of inverse squares. The crests and sinuses on which the reaction of our 

 molecules depend vary in their power of reaction inversely as the square of the 

 distance from their source. The third condition of the problem here meets a re- 

 markable agreement. " Its intensity is diminished by recession, in proportion to 

 the square of the distance through which it acts." The source of action being in 

 the molecule itself no time whatever is necessary for its manifestation. It is im- 

 mediate — instantaneous in its power, for all places. On this fourth condition 

 every other kinetic theory hitherto advanced has broken down. 



In seeking for the action outside the molecule time was necessary to carry 

 the effects across space. By seeking it within the molecule and giving to all mat- 

 ter a common time of rhythm " its time of action is instantaneous." As the wave 

 determines the acceleration of a falling body "its 7-aie of action is precisely the 

 same on bodies at all velocities 



Such molecules as we have depicted are kept saturated with energy in rela- 

 tion to each other. No sooner have they by the outward rush upon the ether 

 sent forth waves at the expense of their energy than it is re-supplied. They re- 

 ceive from the minutest of our ether atoms by clash and give to the larger ones 

 by rebound. They absorb no radiant energy that reaches them, but add more to 

 it. A world of such molecules put between a sun and moon of them would be 

 absolutely transparent. It would not abstract a particle from the radiant force 

 but would add to it in exact proportion to its size. Thus is the fifth condition 

 satisfied. ''Its quality is invariable under all circumstances." The fact that the 



