8 Ss, YOKOTA: A METHOD OF DETERMINING THE CROSS-SECTION 
OA 
Values of r= ds :— 
d 
(nk=0°85) (nk =1'67) Mean 
d= Ofte 0'250 0-250 0-250 
= mite 0'224 0'235 0-230 
lite 0:218 0:230 ()-224 
„alte 0.210 0'225 0217 
lies 0-203 0-218 0-210 
„= Sit: 0197. 0.211 0.204 
Looe 0-190 0-203 127 
Hence, for practical purposes, we may assume that the values of r 
for a given d remain constant throughout and are equal to the mean value 
cited above. The error affeeting the result due to this assumption is 
small, as we will see later. 
Now, let dj==md be the depth of the required section, Then, in 
Kio ial. 
EG x DG __ 
Ne ae le 
i ate ome 
But, EG=b+( ha cot @. dd] 27 + (1+m) (2k’- aa) 
=— 0k Si +2 (14m) k’} 
DG= (1—m) d 
& MN= md. 
Therefore, 
(Eh 
Also, 
un m 
==) aR +2(1+m)k’k 
MIDI ont 
But DL= (1-m) eosee 0. d = (1 - m) (gr + 2k") A. 
Therefore, 
(10) = f(t +2k la. 
m t 8k’ 
Now, 
Te Ml PN eMedia 
malic are and substituting the value of MJ 
from (10), 
