li )s > Prof. P. E. Chase on Radiation and Rotation. 



of air from the lips, it would appear probable that mouth- 

 piecea of different forms so modify this initial pressure as to 

 cause a variety in the number and intensity of the upper partial 

 tones. 



XVII. On the Nebular Hypothesis. — IX. Radiation and Ro- 

 tation. By Pliny Eaele Chase. LL.D., S.P.A.S., Pro- 

 fessor of Philosophy in Haver ford College*. 



[Continued from vol. x. p. 367.] 



AMONG the most interesting of the unsolved astronomical 

 problems are the questions as to the origin of solar ra- 

 diation and of cosmical rotation. These two problems, as I 

 have already shown, are intimately connected, at the centre of 

 our system, by the ultimate equality which exists between the 

 velocity of light, the limiting centrifugal velocity of solar ro- 

 tation, and the velocity of complete solar dissociation. 



It has been commonly assumed that physical forces tend to 

 ultimate equilibrium and consequent complete stagnation. The 

 imperfections of any plan which looks to such a final result 

 have led some writers to suppose that there may be some com- 

 pensating provisions, hitherto undiscovered, for a renewal of 

 activity. In the search for such provisions, the equality of 

 action and reaction, and the possibility that the compensation 

 is continually furnished by Him who is ever " upholding all 

 things by the word of his power/' seem to have been wholly 

 overlooked. 



If we assume the existence of a luminiferous aether, whether 

 as a reality, or as a convenient representative of coordinated 

 central forces, its undulations, when obstructed by inert centres, 

 would necessarily lead to such phenomena as those of gravi- 

 tation, light, heat, electricity, magnetism, &c. Confining our- 

 selves for the present to the action of gravitation, it is well 

 known that the limiting velocity of possible gravitating action 

 and consequent centrifugal reaction at any given point is \/2gr, 



the velocity varying as \ / — If, according to the hypothesis 

 V r 



of Mossotti, each particle is provided with a definite asthereal 



atmosphere, the density of that atmosphere in a condensing 



nucleus should vary as -j. But, according to Graham's law, 



* Communicated by the Author, having been read before the American 

 Philosophical Society," June 21, 1878. 



