266 Our Surroundings 



Electric Lines. The first public service lines for carrying 

 passengers within cities and towns used horse-drawn stages. 

 These stages were succeeded by rail lines on which street cars 

 were drawn by horses. After the development of electrical 

 power, electric cars took their place. These cars draw their cur- 

 rent either from an overhead wire running to a distant power 

 house or from a charged rail. In the latter case a plow, or 

 metal bar, reaches from the car down through a continuous slot 

 between the tracks and connects with the rail underneath, which 

 carries the current. In subways, and on elevated lines and some 

 interurban lines the electric cars draw their current from a third 

 rail located beside the tracks. 



The motor of an electric street car is much like an ordinary 

 electric motor. The armature is set on a revolving axis and 

 connected with the drive wheels of the car. When current from 

 the feed wire is passed through the machine, the poles of magnet 

 and armature are oppositely charged and the attraction between 

 them starts the revolution of the armature. The motor commuta- 

 tor maintains this opposite charging and revolutions continue. 

 By means of a control box the motorman is able to regulate the 

 power and the speed of the motor. The circuit of the current is 

 completed through the track, each rail being welded to the next. 



Certain of the steam railway lines also are being partly elec- 

 trified. Electric locomotives take the place of steam locomotives 

 around terminals in certain cities and in hauling trains through 

 tunnels, and one transcontinental line is electrified for a stretch 

 over the high western mountains. 



Electric locomotives are exceedingly powerful. The advan- 

 tages of electric over steam power on through rail lines are 

 freedom from coal dust, ease of motion, ease in starting heavy 

 loads, easily regulated power, and the use of natural water power 

 along the lines to supply electricity. 



Modern Motor Transportation. The gasoline motor is 

 making great changes in modern transportation. Today millions 

 of automobiles are used for pleasure and for business. Thou- 

 sands of trucks deliver goods and haul supplies. In addition, 

 motor freight and passenger lines form a network across the 



