314 Mr. S. I. Vavilov on Dependence of the Intensity of 



the integral radiation calculated by means of the law of 

 Planck : 



T _2f\ 1 



e kat — 1 



with constants changed on the basis of formula (9). The 

 measured value of the integral radiation is 



2-15.10- 5 ^V 



sec. cm/' 



the calculated value 



2-74 . 10- 5 gr ^ cal V 



sec. cm/ 



The deviations lie, according to the above, in the red and 

 infra-red part of the spectrum. 



For the determination of distribution of energy of our 

 source, the prism of total reflexion was put instead of the vessel 

 F, the aperture d } was closed by a ground glass, and a 

 comparison was made between the intensity of the light 

 illuminating the ground glass with that o£ the light entering 

 the right slit of the spectrophotometer. Afterwards the 

 prism was removed, and by means of an achromatic lens the 

 image o£ the flame of a Hefner's candle was projected upon 

 the ground glass in such a way that the part of the flame 

 1*5 cm. above the wick was projected on the aperture d x *. 

 The curve of relations of measured intensities of source and 

 candle, multiplied by (9), gives the distribution of energy of 

 our source of light. The curve determined in such a way 

 satisfies sufficiently the formula of grey radiation : 



■ 2-67 



I K =Q.X~ s .e * (10; 



In Table I. are given the values of 1^ measured with those 

 calculated by (10), wherein Q is taken as 4*710 . 10 3 . 





Table I. 





X 



T\ tueas. 



T\ calc. 



0-410 



0-125 



0-133 



0-435 



0-258 



0-235 



0-455 



0-380 



0-345 



0-473 



0-480 



0-489 



0-490 



0-660 



0-645 



0-515 



0-880 



0-905 



0-548 



1-325 



1-350 



0-565 



1-588 



1-560 



0-580 



1-870 



1-910 



0-590 



2-080 



2-050 



* A. Becker, Ann. d. Phijs. xxviii. p. 1029 (1909). 



