The Morse sending instrument was simply a convenient way to open and close the electric circuit.
Quickly pressing down and releasing the lever represents the dot in the Morse Code. Holding the lever for a slight interval represents the dash.
At the other end of the circuit in the Morse telegraph was the receiving instrument or sounder.When the current reached the sounder it flowed trough coils of wire wrapped around a bar of soft iron.
This bar became a magnet and attracted a metal lever and the pencil marked the paper.