﻿of Radiation in any Material Si/stem. 525 



time t due to the radiation. Then by the method of variation 

 of elements, 



r=l\ dc s l dCsJ J r ciflC| t tfgy (it (ill r ) 



(49) 



In (49) the lower limit is left indeterminate so that the 

 particular values of CiC 2 . . .c n , that is the particular undisturbed 

 motion from which the deviation is measured, is not fixed 

 nor is it necessary to do so. 



On the right hand of (49) the values of p r and q r may be 

 either these in the actual disturbed motion or in the 

 undisturbed motion, for the terms in question are already 

 small of the first order in <E> representing the force of 

 radiation. Our justification for neglecting squares of the 

 deviation is not only to be found in the actual calculation 

 given in another paper (see Phil. Mag. July 1911), but in 

 the undisputed fact that absorption is always proportional to 

 the intensity of radiation. 



There are 2n equations such as (49) in which s takes all 

 values from 1 to 2n. 



r =" (hjr f d® _ d_ (d®\~\ __ r | n rd®<lqr d® da, 1 

 r -i dcs Ldqr dt\du r ) J r =i \dq r dc s du r dc s J 



_ r |" rd®d rdqA d /V<|>\ 9 dgr\ 

 r -i\du r dt\dc s J ' dt\durJ dcsj 



__d<§ _ r = n d /d® dq r \ 

 dc 8 r -i dt \du r dc s / 



since $ is a function of the w's and ^'s and v r ~ - , . 

 (49) then becomes dt 



'•-% d,/ r . dp r d f< r * n d®dOr 



,._! ■* acs dc s acgj r -i avi-acs 



Solving these 



8/.,+ ■ = 2 jy„f <bdt. . . . (50) 



fyr=- £ M rs A &dt .... (51) 



s = l CtCsJ 



M is the minor of -. p and J/',-,, the minor o^ V in the 



