Telegraph Key Patent Model
From the collection of National Museum of American History. Free to download, adapt and use — no permission needed.
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 Lucien Crandall's design for an automatic key. His idea involved a key for each letter, number and character, set on a frame like a typewriter. Each key included a ratcheted wheel with conducting and insulated segments around the edge. When the operator pressed a key, the wheel rotated and generated morse code pulses at a regular speed. His goal was to permit operators to send messages, "with greater rapidity, uniformity, and certainty than with the common telegraphic key."
National Museum of American History’s own description
