( 149 ) 



So we find finally: 



- = — Tr~T — 1 '^ ' (^«) 



which is the required expression, by means of which the limiting 



T 



value of - at ,t = may be calculated for every given value of 

 (f and n. 



4. Now it remains only to express the relations found in the 

 ordinary variables. 



These are viz. (see § 1) : 



Now the quantity ^// introduced by us in § 2 and 3 is represented 

 by: 



^ l^ Va, \/h^T, _ 1__ 



while n is given by : 



Formula (2a) passes therefore into 



{} ~ '1^ Vö^J 



^ ^ - '^ ■ -|-2(i/<9i|'-l)-(n'-l), 



or 



^ = 74 [(/^^-l) - V3(tp-1)] + 2i/d^ - (1 + tfO, 



or finally, as t = — - — ; 



T 



-T 1 /dT \ I 1- 



(3) 



The original expression, derived on the assumption that fRT^ 

 ay be approximate! 

 completed hy a term 



may be approximately represented by —, must therefore (see § 1) be 



A (i/6'rp-i)-v,(tp-i) . 



This is the correction which must be applied, and it is easy to 

 see, that it can consideraJ>h/ modify the original approximated 

 expression. 



