60 POWER DISTRIBUTION FOR ELECTRIC RAILROADS. 
from & to cand the feeder ¢. With the arrangement of Fig. 
40 it is quite possible to hold the voltage fairly uniform by 
giving sufficient area to the longer feeders. Asa matter of 
convenience, to avoid the undue multiplication of wires, the 
distances A a, a b, etc., between feeders are made consider- 
ably longer than in the ladder system: hence the trolley 
wire is generally larger. Of course, it must be large enough 
to avoid excessive drop in the sections &4 and ¢d when 
load 1s applied at d. As a rule the distances A a, 2 b, etc., 
are several thousand feet except where the traffic is very 
heavy. With No. o or No. oo trolley wire the distance 
named 1S not generally excessive. As compared with the 
ladder distribution this one has the great advantage of giv- 
ing a fairly uniform voltage, and can be more readily ar- 
ranged to handle abnormal loads at distant parts of the 
L_—T 1 
A 
a b : ¢ i 
d Street Ry. Journal 
HiIe. 10: 
  
  
line. It has also the same convenient property of giving 
current to each car from two directions so as to minimize 
the effect of breaks in the trolley wire. It is however ex- 
posed to trouble in case of serious short circuits, and is in- 
convenient in the matter of cutting out portions to execute 
considerable changes in wiring or to avert accident. 
4. An obvious modification of the arrangement just 
mentioned is that shown in Fig. 41. ‘This bears the same 
relation to (3) that (2) does to (1).. It shares with (3) 
the advantage of maintaining fairly constant voltage under 
normal conditions, though it is somewhat at a disadvantage- 
in case of a heavy load on a distant section, since that sec- 
tion must depend on its own feeder alone without assist- 
ance from adjacent sections. ‘The feeders a, 4, ¢, etc., are 
provided with individual switches and cut-outs at the station 
so that if a short circuit occurs nothing worse can happen