Electricity travels along a wire a long way very quickly. It is used to make heat or light and work machines. And it is important in modern message- sending. The electric telegraph was invented in 1835, just after the first railway was built. It is possible for us to send a message quickly a long way without a messenger. The message is taken with the help of electricity along a wire. By one method, the electricity is allowed to go for a shorter or longer time and is then stopped. The electricity is broken up into short and long signals. These are known as dots and dashes. Dots and dashes are written on paper The signals are sent by a key. One is shown in the like this picture on this page. The key is pressed down so that the points A and B in the picture touch each other. When this happens, electricity passes from one point to the other and then along the wire. When the key is open (as in the picture), A and B do not touch, and no electricity can pass. At the other end of the wire the electric signals are turned into signals that we can see or hear. So each short or long signal is changed into the movement of a needle backwards and forwards. By watching this, or listening to the sounds, a person can read the dots and dashes, when someone sends them to him. How can dots and dashes mean anything? Each letter of the alphabet is a different group of dots and dashes. This alphabet of dots and dashes is known as the morse code. It is written like this: