212 POWER DISTRIBUTION FOR ELECTRIC RAILROADS. 
elsewhere on the section at the same time, calling perhaps 
for one hundred amperes. 
The joint load can be best taken care of by a pair of 
feeders, one to B of, say, 500,000 ¢. m., the other out, say, 
four miles from F, of about 250,000 c. m. The function of 
the latter is to handle cars within that distance of ¥ and 
also to improve the conditions at B. These are shown 
with the rest in Fig. 112. ‘The weight of the main feeder 
here would be 60,000 1lbs., that of the small feeder, say, 
15,000 1bs. 
We can now take account of stock and find the total 
cost of copper for the feeding system. We may tabulate 
as follows: 
  
Section. Wt. 
AE 48,000 
E G (main) 80,000 
(adjunct) 20,000 
G’ F (long main) 80,000 
adjunct 18,000 
F B (main) 60,000 
adjunct 15,000 
321,000 
This would cost at fifteen cents per pound about $48,000, 
a very different figure from that previously found by the 
assumption that the maximum load may be taken at the 
middle point of the proposed line to be fed. 
The existence of this excess and the causes that pro- 
duce it must be carefully examined. In the first place 
20,000 1bs. of copper, the section of feeder G’G belonging 
to station F, is directly chargeable to safety precautions, 
and is for the purpose of enabling the two stations to be of 
some material assistance to each other in case of accident 
to one of them. 
The large refnaining discrepancy is almost wholly due 
to the fact that the load on an electric railway is a shifting 
one. Instead of being able to assume a uniform distribu- 
tion of the maximum load, it must be treated as a concen- 
trated load, perhaps even at the most unfavorable point of 
the line. In fact, it often happens that the maximum load