from an Electric Source. 169 



of a large number of crowded and mutually interfering 

 atoms or molecules, and in the latter case (a being atomic), 

 a single atom or molecule in its undisturbed individual 

 action. But at the same time I must warn the reader that 

 even the mere thought of entering into the structural details 

 of the atomic " source " is entirely foreign to the circle of 

 ideas here developed. 



Unit Permittivity. Specific-lieat Curves. 

 For K = 1 we have u = w and, by (12), 

 A 2 = a% 2 {l + ic 2 )/Aw\ 

 Thus, the mean energy of the source becomes, by (8), 



U =|^I±^G(uO, .... (13) 



where w = 27ra/\, as above, and G(w) is given by (9) or (10). 

 The mean energy emission J, per unit volume of the source, 

 and per unit time, is, in the present case, 



J=^V«. (14) 



g being defined by (7). It is precisely the curve (11), 

 whose first "branch," from w = Q down to the first root of 

 g(w) = 0, turned out to fit closely with the black-body 

 radiation curve, as was mentioned in the first Note. 

 Formula (14) is the particular case, K = l, of the formula 

 numbered (1), but not written out in that Note; it will be 

 given in the next section. If the absolute temperature T 

 is introduced as a parameter determining the reduction of 

 scale of the radiation curve (14)*, in accordance with 

 Wien's law, then a?e 2 is proportional to T, and a to T _1 , say 



■* o Tl a "lircc . _ . 



7ra°e " = yi, a = r ^; w = ^ , . . . (15) 



where u and 7 are " universal " constants. 



* It will be understood that, from the atomistic point of view, this is 

 legitimate only as long as the sphere a is large enough to contain quite 

 a crowd of molecules, but not when it shrinks down to molecular 

 dimensions. No inferences therefore will be drawn about the role of 

 " temperature " in the case of large K and molecular a, corresponding to 

 line spectra. 



