352 M. F. Zollner on the Temperature and 



in the wires, but the light-emission increases at a much quicker 

 rate than the heat producing it. I therefore put 



and assumed, in a preliminary experiment, that for both groups 

 of rays a= 1 ; so that, on this hypothesis, 



— ^— = const. 

 w 



The following Table contains the values of this quotient for 

 each wire and for each of the two classes of rays. 



No. 



Red light. 



Green light. 



logJp 



logJp 



logJ x 



Wi 



logJ* 



1. 

 2. 

 3. 



4. 

 5. 

 6. 



7. 

 8. 



0-5717 

 0-5653 

 0-5669 

 0-5678 

 0-5562 

 0-5709 

 0-5725 

 0-5714 



0-5054 

 0-5249 

 0-5158 

 05356 

 0-5205 

 0-5135 

 0-5188 

 0-5192 



0-4210 

 0-4470 

 0-4815 

 0-4880 

 0-4933 

 0-5136 

 0-5197 

 (T5265 



0-3784 

 0-4158 

 0-4391 

 0-4603 

 0-4616 

 0-4619 

 0-4709 

 0-5784 



From this we gather that, for the more homogeneous red rays, 

 the constancy of the required ratio indeed takes place with suffi- 

 cient exactness. That the value of the constant a agrees closely 

 with the arbitrarily chosen fundamental unit of light, is ob- 

 viously a purely accidental circumstance. But, without approach- 

 ing here to a more precise determination of the constant of the 

 hypothetic function, the following brief remarks may be made 

 respecting the less homogeneous green rays. 



Supposing that, for rays of the same wave-length, the ratio 

 between the quantity of heat developed in a body and its emis- 

 sive power is universally the one assumed, 



Z—a.e cw } 



it is clear that, for a mass of rays which is not homogeneous, 

 but, like that transmitted through the green glass, is continually 

 taking up into itself new rays of less wave-length as the tempe- 

 rature rises, c cannot be a constant quantity, but must much 

 more increase with rising values of w, in correspondence with 

 a greater increase of the total quantity of light emitted. Now 

 such a continual increase is in fact exhibited in the above values 



of the ratio ■ - x for green light. 



