292 



-46- 



The successive reflections are described in the 

 following table: 



etc« 



Set 



(5) 



^.- 



^ 



and 



(6) 



^n = V2 ^n 



By the inversion, d is also equal to — j- • The general 

 expressions for the strengths of the sources are: 



A point sovirce of strength AD^^ at Q^ and Qj^+^J 

 (7) .^ a uniform line sink of strength ^ per unit length 

 along Q^Q^^^ and Qn+iQn+2' 



