Telegraph Key

Wessmann, Martin F. · 1873

Telegraph keys are electrical on-off switches used to send messages in Morse code. The message travels as a series of electrical pulses through a wire. The sequence and duration of pulses represent letters and numbers. This patent model shows Martin Wessmann's design for an automatic key. His idea involved a key for each letter, number and character, somewhat like a piano keyboard. Each key included a circuit breaker controlled by gearing so that the pulses were generated at a regular speed. That prevented operators from blurring the message.