Chemical and Physical Papers. 61 



The action of the sun in gravity work is all direct, for the geo- 

 solar gravity center is in the body of that governing fire-ball, and so 

 of. all the intra-Jovian planets, and, probably, of all the others. It 

 may be that the planets themselves are responsible for much of the 

 heat they receive from the sun, for the numerous eccentric gravity 

 centers in that revolving and rotating star must cause an agitation 

 and disruption of its entire constitution, with evolution of heat. 

 This is no fanciful conjecture of what may be, but a certain result 

 of admitted gravitational law. 



Turning to the question of the moon's influence to affect the 

 length of the siderial day, we have seen that the tides are mainly 

 caused by the eccentricity of the geolunar gravity center to the 

 purely terrestial center and the axis of rotation, and to rotation 

 itself, and that the moon's direct influence is simply a slight abate- 

 ment or augmentation, as the case may be, of the normal weight of 

 terrestrial matter ; in either case producing no result not oftset by 

 a counter result. Unless it can be shown that purely secular re- 

 distributions of matter, such as come from trade-winds and ocean 

 currents, have an effect to check rotational velocity, we may dismiss 

 the idea that the moon does. 



The premises and chief corollaries of the theorem may be 

 summed up in the following propositions : 



The geolunar gravity center is the point which all the matter of 

 the earth presses to attain. 



It is eccentric to the axis of rotation and to the earth's center of 

 gravity. 



It is a constantly shifting point, thereby causing a perpetual 

 churning of the earth's fluid or plastic matter in its efforts to dis- 

 tribute its masses in equilibrium concentric to it, evolving heat. 



It affects the fluids of the exterior less than those of the in- 

 terior, conformable to the second Newtonian law of gravitation. 



The oceanic tides result from the same influences that cause the 

 interior clash, and are essentially waterfalls of vast extent, inter- 

 cepted by sections of solid crust above or slightly below the nor- 

 mal sea surface. 



The direct influence of the moon only feebly effects the normal 

 ponderal relations of terrestrial matter, and does not retard terres- 

 trial rotation. 



The solid, brittle upper strata of the earth's crust, lined below 

 by the semiplastic and plastic cushions of mixed material, are af- 

 fected to continuous vibrations of very mild degrees. 



A concluding thought is this: We are indebted to the moon for 



