THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[SIXTH SERIES.] 



FEBRUAR Y 1909. 



XVIII. Temperature-Radiation and the Partition of Energy 

 in Continuous Media. By J. H. Jeans, M.A., F.R.S., 

 Professor of Applied Mathematics in Princeton University* . 



Contents. Page 



§§ 1-7. Introduction , . 229 



§§ 8-15. The " Normal State " and Equipartition of 



Energy 233 



§§ 16-21. Examples and Discussion of the u Normal 



State " in Continuous Media 238 



I. A stretched string. 

 II. A tube of air. 



III. A mechanical model of the .Ether. 

 §$ 22-25. The Rate of Approach to the Normal State. 248 

 §§ 26-30. Conclusion 250 



Introduction. 

 1. TT1HE present paper attempts a critical examination o£ 

 JL some of the difficulties which surround the appli- 

 cation of the law of equipartition of energy to the energy of 

 wave motion in the aether or other continuous media. These 

 difficulties manifest themselves most clearly in connexion 

 with the problem of determining the law of partition of 

 radiant energy inside a uniform-temperature enclosure. 

 Accordingly it is with this particular problem that we shall 

 be mainly concerned. 



2. Let two or more bodies, originally at different tempe- 

 ratures, be supposed placed inside a closed chamber whose 



* Communicated by the Author. 

 Phil. Mag. S. 6. Vol. 17. No. 98. Feb. 1909. R 



