288 



G. H. BRYAN. 



Wlience b}' determiuauts tlie coiulition tliattlie accélérations of[^r] -] 

 [2 ^'2^] '-^^^ [^'1 ^^2] shoulcl vanisli gives 



[m, Vi 2]: 



^[m^v^^}. 



= ['t^i «'2] : 



Z[{X,+R){X,-B)l W 



= 1 



[p] , [p] . 



[p] 



^'^l [p] 



m, [p] 



[?,+p]— ^>'.[s^2+P] 



(^'). 



If we Write tliese équations in tlie abbreviated form 



[wV^j2j ^ [m.^''-] ^ [^', t^o] ^ i 



^ ^ y/ c 



tlien for auy value of ;. we obtain 



A w«, -\-'-ZKm^ m.^ H-\- K" B iii.^ 



[(w/, t\ +;.;//, ''2)'] = 



C 



and since tlie left liand side is essentially positive tlie condition for 

 energy-equilibrium to be possible is tliat tlie riglit liand side must be 

 essentially positive. Hence 



(I) A and B must be of tlie same sigu as C, 

 (II) AB~:> on, w,H-. 



