From the trolley wire, through the trolley pole _t_, to the fixture on top of the car which holds the latter. From this fixture, as shown by the heavy full line, the current passes to _a_, which is a switch located under the car hood overhanging the platform. From this switch the current passes to a similar one, marked _b_, located in a like position at the other end of the car. These two switches are called emergency switches; they are provided simply as a safety device, and are used only when the main switches get out of order and the motorman can not turn the current off in the regular way. From the last hood switch _b_ the current passes to the bottom of the car, where it enters the wire _d d_ at 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, _b_, 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.