Morse transmitter. Handset of a telegraph transmitter machine used to send Morse code. The operator taps out the code on the button at centre left, to send an electrical signal through the wire (top left). Short and long electrical signals are used to represent the dots and dashes of the Morse code. The code is seen printed on the handset. In this way, messages can be sent to a receiver that converts the signals into a printout of dots and dashes, which can be translated back into a message.