52 S. Nakainnra and K. Honda : 



we obtain 



T =14.97'". 



(7) Let l be the distance between any two consecutive 

 sections and let W and li" be the mean depths at these two sections. 

 The mean value of V^/T between these sections is 



I 



, ^ 1 



(V h )m=—j-l'\/ h • dx. 



Let us now assume that the depth /t at any place x between 

 these two sections is given by 



then we have 







Calculating T by the formula 



0( fh-'I'O , '1-2— Ih , ] 



where 1= q^ and /'o ^h ^i are the mean depths at several 



sections, we have 



T=15.75™. 



(8) LTnder the same supposition that h—h' + — j — • x, we see 



that 



/ dx 21 



