( 675 ) 

 TABLE IV. 



TABLE V. 



length SlOfiju. At first sight the evidence is in favour of tlie results 

 obtained by Frost, because the ma.vimum of the curve representing 

 the energy in the solar spectrum (or perhaps rather the "center of 

 gi-avity" of the enclosed surface) lies closer to 650}ift than to SlOfijx. 

 But this argument fails ; for the measurements of Vogel and those 

 of Frost are all disturbed alike by atmospheric diffusion. Had the 

 spectro-photometric observations been free from this influence, then 

 Ihe rate of decrease of the radiation from the center toward the 



