76 Mr. S. B. McLaren on the Emission and 



E may be supposed given by a series of terms o£ the 

 simple harmonic type. Taking one of these, 



E = l 1 ^(« + i i S)^+(a-tiS)r*' I [. • • (25) 



t 1 = t-lx/c, (26) 



where a + i/3 and u — i/3 are conjugates, and 



l=(l,m,n), li=(Z l9 m 2 , ^) 3 11 1 = 0, . . (27) 



(25) represents a wave travelling parallel to the lines whose 

 direction cosines are Imn, the components of 1, and polarized 

 in the perpendicular direction 1 1# 

 From (25) and (23) 



H = [11J { (* + i/3) e iph + (a - i/3)e~ iph } ; 

 E ' = { ll+ \}lt [lli]]}(« + ^)6^ + Conjugate; 



^{(^V (li^)l}t- + ^^ + Cooi.; 

 and 



n 



or 



-pv^r _a + ift d 



{^r)-^i^%^^-- ^ 



dic n ip dt\ 1 dfc n J ip dfc n 



Using (28) in (17) and (18) 



AW n=i - L d/e n J to 

 + e (j^mtM* { f !, p r , dt \ +COHJ. (29) 



AW n=l n dK n LJf, dt J 



P=/ a + ' 



V w =l n L d* n J * c 



The first terms in (29) and (30) result from an integration 

 between the limits t and t, and the values at the lower limit 

 must be subtracted from those at the upper. The complete 



