THE RETURN CIRCUIT. 33 
sistance of the bonding wire is, of course, determinate, but 
that of the contact is most irregular, varying with every 
  
  
  
  
   
  
  
FIG. 22.-——WEST END BOND. 
  
  
  
  
  
& %, 
T E,> 
  
  
FIG. 23.—CHICAGO BOND. 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
FIG. 25.—PLASTIC BOND. 
kind and size of bond and with the thoroughness with 
which the mechanical work is done. No part of electric 
railway construction deserves more careful attention. Cull-