1883.1 5 ^ "^ [Chase. 



stellar rotations may accord with solar rotation in alternately consuming 

 and resuming, at alternate half-rotations, the photodynamic energy of all 

 the superficial particles. At the outer limits of our ajthereal system, the 

 aether, if material, should rotate with the stars, so as to radiate and absorb 

 heat like an ordinary atmosphere. A full discussion of conservation of 

 energy in the several stellar systems, requires the consideration of time in- 

 tegrals of various kinds, gravitating, thermal, photic, rotating and re- 

 volving. Continual shiftings of position may, perhaps, continually restore 

 to cosmical centres a reactionary vis viva which is exactly equivalent to 

 their active radiations. 



332. Hirn's Hypothesis. 



G. A. Hirn {Comptes Rendits, Nov. 6, 1882), agrees with Faye in be- 

 lieving that astronomers need an absolute vacuum of matter in order to 

 assure the stability ot cosmical movements. He thinks that the doctrine 

 must be discarded which excludes from the physical universe everything 

 but matter and motion, and refers approvingly to Newton's letter to 

 Bentley, implying the necessity of a constant spiritual activity, which can- 

 not be subjected to anj'- materialistic formulation. Seven years ago {Proa. 

 Am. Phil. Soc, xiv, 611, xvi, 302) I published a number of postulates, 

 among which were the following : 



"11. Any aethereal medium through which impulses are progressively 

 transmitted, must be material. 



"12. Any medium through which impulses are transmitted instantane- 

 ously, must be devoid of inertia and, therefore, spiritual." 



333. Laplace's Principle of Periodicity. 



I have elsewhere {Proc. Am. Phil. Soc, xviii, 41-3). given some illustra- 

 trations of the general principle, which was established by Laplace, that 

 the state of a system of bodies becomes periodic when the eifort of prim- 

 itive conditions of movement has disappeared by the action of resistances. 

 The periodicity of solar rotation shows the action of gravitating resistance 

 against the efforts of luminous undulation. The resistance is just as con- 

 stant as the radiation, and it would be far to seek any good reason why 

 any provision for perpetuity which may be needful should not accompany 

 every effort and every antagonizing resistance. If spiritual intervention is 

 taken into consideration, its action may be merely directive, because there 

 is a theoretical instant of absolute rest when one oscillation ends and its 

 successor begins, so that there is no material vis m'va to be overcome. 



334. Two-Fold Nucleation in the Dense-Belt. 



Jupiter's nodal influence (Note 331), co-operating with central condensa- 

 tion in the dense-belt, is shown in the following additional harmonies : 



I. Jupiter's semi-axis major represents Laplace's limit for its own con- 

 densing nebula, of which the nucleal limit is the locus of incipient subsi- 

 dence of Mars. 



PKOC. AMER. PHILOS. SOC. XX. 113. 3u. PRINTED MARCH 12, 1883. 



