The telegraph is an electromagnet connected to a battery via a switch. When the switch is down, the current flows from the battery through the key, down the wire, and into the sounder at the other end of the line. By itself, the telegraph could express only two states, on or off. This limitation was eliminated by the fact that it was the duration of the connection that determined the dot and dash from each other being short and long, respectively. From these combinations of dots and dashes the Morse code was formed. …
