go Art. 3.— K. Hirayama: 



a;2 — 5^ = Qp^e cos d + 6^ië e^ _ ^2 _ (a; — a;) 



and 



s'ex=—pi 



Accordingly 





p^sind s'\/l2p^ê—{x + xf 



in which the negative sign will be taken if e^—e' and sin^ have 

 the same sign, and the positive sign if otherwise. Hence 



where eo and e'o are the limiting values of e determined by the 

 equations 



Putting fie) = 12pé -(x + xf 



and e=e±B e>0 



we have 





3s' '^è 



Now 



