DIRECT FEEDING SYSTEMS. 61 
than the temporary disabling of that particular section, 
while if necessity demands any section can be promptly cut 
out of circuit in case of fire along the line or any other 
sufficient cause. (4) is very well adapted for use on long 
lines with fairly regular traffic. Like (3) it requires a 
rather heavy trolley wire for the best results. A load at 
any point is supplied by the feeder for that section in 
series with the trolley wire between the load and the feeder 
junction, so that the drop under any given conditions is 
very readily computed. 
In both (3) and (4) it is sometimes convenient to tie 
two or more feeders together, as shown by the dotted line 
at 4 (Fig. 41). 'This procedure reinforces the conduc- 
tivity with reference to the section thus connected, as 4, 
and while it may lower the voltage of sections beyond the 
  
  
  
  
A A L B 
. Street Ry. Journal 
BIG. AT. 
link, is very useful when a particular section is exposed to 
severe loads from grades or massing of cars, particularly 
since such linking can be applied at any time that the 
service may require it. 
In very many cases it is advantageous to install a com- 
posite feeding system which can be made in a considerable 
measure to unite the advantages of those already described. 
A very useful combination is that shown in Fig. 42. 
Here the trolley wire, A B, is cut into sections of vary- 
ing length, short where considerable danger of interruption 
of service exists, long where longer sections can be more con- 
veniently utilized. C is a principal feeder as in the ladder 
system connected at @ and & to a continuous trolley line, 
and at ¢, 4 and ¢ to trolley sections. ‘This principal feeder 
is reinforced by feeders E and F to equalize the voltage 
more perfectly in the region of dense traffic, while the inde-