WHAT MAKES THE TROLLEY CAR GO. 411 



the bottom of the car, where it enters the wire d d &i the point c. 

 This wire d d, as will be seen, runs in both directions, and ends in 

 the stands C C. These latter are the controlling switches, and are 

 provided with a handle h, by means of which the current is turned 

 on or off from the motors, and is directed through them in such a 

 way as to make the car run in whichever direction may be desired. 

 From the controllers C C several wires are run under the car, as 

 shown at e e e. These wires are generally bunched into one or 

 two cables, but they are kept separate from each other by means 

 of strong insulating coverings. Four wires lead into each motor, 

 and three or four into each of the boxes marked G G. If the 

 motors were required to run in one direction only, then two wires 

 would be sufficient to convey the current to them ; but as they have 

 to run in either direction, at least three wires are necessary, but in 

 almost every case four are used, as the results obtained thereby are 

 more satisfactory. The boxes G G are called rheostats, and are 

 simply devices through which the current is run so as to reduce 

 the speed of the car, and also for the purpose of graduating the 

 strength of the current that passes through the motors in the act 

 of starting. These rheostats are very seldom in use when the car 

 is in motion, because it is a waste of power to pass the current 

 through them. After the current has passed through the motors 

 it enters the ironwork, and thus gets into the car wheels and 

 finally to the track. 



The lines drawn in Fig. 18 to indicate the position of the wires 

 in the car do not show their actual position, but only the general 

 direction they follow. From the trolley base to the first hood 

 switch the wire, as a rule, is run along the car roof on one side of 

 the ventilator, and the wire leading from the first to the second 

 hood switch occupies a corresponding position on the opposite side 

 of the roof. From the last hood switch, h, the wire is run down 

 one corner of the car body, being either within the car body, or, if 

 not, so covered by moldings as to not be reached by the hands of 

 passengers. The wires d and e are generally run under the car, 

 and are firmly secured to it by means of suitable fastenings. 



The controlling switches C C are provided with one and some- 

 times two handles, one of which is used to regulate the speed of 

 the car and stop and start it, while the other is for the purpose of 

 reversing the direction in which it runs. The handle h is for the 

 purpose of regulating the speed, and by means of Ic the direction 

 of motion is changed. Before h is moved from the inactive posi- 

 tion Ic is turned so that the car may run either forward or backAvard, 

 as may be desired ; then, when h is moved, the car will start, and by 

 varying the position of Tithe speed can be changed. If it is de- 



