Diagram showing the electric circuit through each car, and illustrating the method of sending more than one car along the same wire.
Some time after this was discovered, it became known that if the two wires from a dynamo were joined to a second dynamo instead of to an electric lamp, this second dynamo would revolve, and could be used to drive a machine, such as a sewing-machine or a printing-press.
At first this electric motor, as it was called, was used only for turning wheels that were stationary, but it was soon seen that there was good work for it to do in turning wheels that should travel along over the ground. Then began the electric railway.
Having got your electric motor it would seem a comparatively easy job to mount it on a car, to fix up a moving connection with an electric wire, and to make the motor turn the car-wheels. It looks easy enough to-day in places where hundreds of horseless cars are running about in all directions as if by magic. In the beginning it was not such an easy job, and those who led the way in the building and running of electric cars had many difficulties to contend with and many obstacles to overcome before they made the electric street-car the practical everyday affair that it is now.
Just look first at your electric motor. It is, like all electrical instruments and machines, a pretty delicate affair, very likely to suffer serious injury from hard usage or exposure to bad weather.
To place such a machine underneath a jolting car close to the surface of the street, and make it work properly at all times and in all weathers, is no small feat. One great difficulty was to keep the wire coils of the motor properly insulated. If two neighboring coils get connected with each other the motor goes wrong, and as water is a powerful conductor of electricity such accidents often happened at first through parts of the motor getting wet from splashings from the street. Now motors are made water-proof, and the cars go along merrily, even though there may be an inch or two of water in the streets, or several inches of snow or slush.
The motor is attached to the frame of the car-truck, and the power is transmitted to the axle of the car by means of gearing. In some electric locomotives that have been made the armature of the motor is wound on the axle itself, but for ordinary street cars it is found best to keep the motor separate from the axle, and to transmit the power by geared wheels.
THE TROLLEY-CAR.