14 POWER DISTRIBUTION FOR ELECTRIC RAILROADS. 
with a branch, B C, which is straightened and made paral- 
lel to the main in order to more clearly show their rela- 
tions. Unless the branch is of such magnitude and posi- 
tion as to require special feeders, it is supplied with 
current from the main linear system. In a few cases the 
service on a branch is from B to Cand back. More gen- 
erally it is from C to A and back, a part of the cars being 
devoted to a through branch route. On the section A B, 
the load is the sum of those due to each line of cars. Be- 
yond B there are two independent linear systems. 
HIG, 'S; 
If there are 2 cars on the route A D, and 7 cars on 
the route A C, then the load on A B, due to both lines, 
will be 
  
AB AB 
i /ne 
and the loads on B C and B D respectively will be 
7 BC BD 
P land om0 
A0 AD 
Consequently, if the section A B is computed for this load 
according to {10) we shall get the proper conductor for the 
assumed loss E. The lines B C and B D can then be com- 
puted for losses E, and E,. The values of E, E,, E, are 
usually taken with the condition imposed that E -+ E,, 
E -+ E, shall be less than a certain specified maximum. 
A more general method is that of Fig. 8. Here thereisa 
line, A B, with branches running to C, D, E, F. The 
loads are /, m, n, o, p, amperes respectively. A B, A C, 
A D, AE, AF, are now considered as separate, each subject 
m