FUNDAMENTAIL PRINCIPLES. 3 
A,B,, but whether it be a small tramway line along a single 
street, or a long interurban road, it retains as its main 
characteristic a single working line, not generally re-curved 
on itself, and subject throughout its length to fairly uni- 
form conditions of traffic. 
The second class is illustrated by the branched type, 
represented in Fig. 2. As shown, it consists of a main 
line, A B, into which run two branches, C D and Bk 
The branched distribution is the one most commonly met 
with in electric street railways of moderate size, and may 
assume an infinite variety of forms. Itisthe legitimate re- 
  
  
  
  
  
  
  
  
e 
sult of growth from the linear type, and, through all its 
modifications, is noteworthy in consisting of several lines 
which are neither interlinked, although often overlapping, 
nor stbject to the same traffic conditions. Its conducting 
system is therefore essentially complex. 
Finally, we have the meshed system, Fig. 3. Ideally, 
it is, as shown, a simple network composed of parallel lines 
crossing each other at right angles and at nearly equal in- 
tervals, and under fairly uniform conditions. Practically, 
the various lines composing the network cross at all sorts of 
angles and intervals, and are subject to all sorts of condi- 
tions of traffic. All networks however have this property, 
that they are composed of interconnected lines, so that the 
conducting system of any line can reinforce, and can be re- 
ir.zorced by, other systems. Fig. 4 shows that portion of