Chta-Shun Yth 
1 
al = - —> (109) 
2 ee 
We shall endeavor to determine y for a given channel 
cross-section anda given £6 in (61). 
Substituting (107) and (108) into (63) and taking terms 
of order k? ; we obtain 
Zabe,te ssestsethde ads tOsnibak sheng saat (110) 
Let the channel boundary be given by (62). Then the condi- 
tion there is, from (34), (43), (45), and the definition of »2 given 
by (64), 
md, -, p = 0 Cre} 
Z 
The terms containing k in (111) are 
-2 
2m y+ ar et) = OC (112) 
2y $ ly) me ay Gyr -S) 0, (113) 
after substitution of y for mx (it being sufficient to consider one 
half of the symmetric boundary). 
Combination of (110) and (113) gives 
1 2 
M tal Ge. i aeat 
iT} 
Oo 
(114) 
1426 
