In the nineteenth century, a number of people tried to develop a method of sending messages by using electric signals. The signals were produced by interrupting the flow of electricity with a simple on-off switch. They reached the receiver in the form of dots and dashes, which were changed into words. This new system of communication, called telegraphy, developed swiftly, along with the spread of railway networks. Telegraph lines were laid alongside the railway tracks so that they could be repaired easily. This was the beginning of the era of rapid communication.