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XI. Radiation from an Electric Source. {Second Paper.) 

 By L. Silberstein, Ph.D., Lecturer in Natural Philosophy 

 at the University of Rome *. 



Contents. 



Remarks on the Method adopted. 



Mean Energy of the Source. 



Unit Permittivity. Specific-heat Curves. 



Large K, and molecular dimensions of source. 



IN the first Note on this subject t I have applied my 

 general formula for the radiation from an electric 

 source to the case of line spectra (which corresponds to 

 high values of the permittivity K of the source), and more 

 especially to the case of the hydrogen series. Having 

 attributed there to the source only the simplest kind of 

 dispersion, i. e. 



fc = 4A*K=a+-|^-3 . . • • (3 a) 

 A* — 7 



(taken as valid only down to X = 7, of course), I at- 

 tempted to show that the formula in question represents 

 fairly well at least twenty-five lines of the hydrogen 

 series. (Cf. Tables I— III.) Since that time I have found 

 that the few rebellious lines, and especially H a , can be 

 reconciled with the remaining ones by taking 7 = A,b> 

 i. e. Balmer's theoretical limit, and by introducing a second 

 44 free period " or convergence point in the far infra-red. I 

 hope to be able to report on the corresponding numerical 

 results at a later opportunity. Meanwhile I desire to 

 develop somewhat further the general properties of the 

 source, and especially such as may be interesting in con- 

 nexion with subsequent physical applications and are likely 

 to bring into prominence the essential features of the 

 investigation. 



■&■ 



Remarks on the Method adopted. 



Maxwell's equations for an isotropic, non - magnetic 

 insulator are 



KdE/'dt = c. curlM, "dM:'c^=— c.curlE, . (a) 



K being the permittivity of the medium and c the velocity 



* Communicated by the Author. 



t Phil. Mag. May 1915, p. 709. The symbols of the first ("Pre- 

 liminary ") Note will be retained here, and the numeration of formulae 

 will be continued. 



M2 



