Chemical and Physical Papers. 57 



gravity will be the center of the sphere, but if unsymmetrically, the 

 gravity center will be eccentric with reference to the spherical cen- 

 ter. The latter relation exists in the moon. But this incoinci- 

 dence has no dynamic effect in a non-rotating sphere. In a rotating 

 sphere this incoincidence becomes a very important source of dy- 

 namic action. The internal mass is constantly impelled to adjust 

 itself symmetrically concentric to the middle point of the axis of 

 rotation. The movements of adjustment engender heat, intense in 

 dense matter, and are continuously and eternally operating while 

 equilibrium is unsatisfied. This a law of gravity, everlasting, in- 

 variable, and instantaneous in action. The earth's center of grav- 

 ity is, therefore, the central point of its axis of rotation. 



The ratio of the moon's mass to that of the earth has not been 

 certainly determined, but is assumed to be about as one to eighty, 

 a convenient one to use in this connection. The geolunar gravity 

 center is near the center of the earth. It would be if the two 

 planets were in contact, but by reason of the distance of the 

 eighty-first part from the main mass it is nearer. It is a constantly 

 changing point, and the earth's center revolves about it monthly, 

 at a varying distance regulated by the moon's perigee and apogee 

 positions. 



In an old edition of Burritt's Astronomy, a popular work forty 

 to fifty years ago, the geolunar gravity center was placed at about 

 3000 miles from the earth's center. But this assumed distance 

 seems to have been suggested on the principle of the steelyard. 

 In modern works of astronomy and physics which I have consulted, 

 but little reference to this important focus is to be found. That 

 it must be near the earth's center is evident or the mensal revolu- 

 tion about it would be a very obvious and remarkable phenomenon 

 in astronomical observations. But it is certain that it cannot be co- 

 incident or identical with the terrestrial center ; if this were the 

 case there would be no tides. Now, this eccentric destroyer of 

 equilibrium cannot be eliminated by any rearrangement of the 

 earth's materials, because it is a continually shifting point west- 

 ward, northward, southward, centripetally and centrifugally. Yet 

 it is the point towards which all the earth's substances are con- 

 stantly pressing, keeping up an incessant churning of the fluid in- 

 terior already under pressures of 2,000,000 to 3,000,000 atmospheres. 

 The heat engendered must be beyond calculation, and it is not ex- 

 travagant to suppose that gases as dense as metals on the surface 

 mingle according to the law of gaseous diffusion. And yet this 

 heat is not equivalent to what escapes from the surface, as shown 



