Samuel Morse's original telegraph transmitter and receiver, 1837
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The original Morse telegraph did not use a key and sounder. Instead it was a device designed to print patterns at a distance. The transmitter, in front, had code slugs shaped in hills and valleys. These represented the more familiar dots and dashes of Morse code. These patterns were printed at a distance by the receiver (shown in the rear). It recreated the hills and valleys as the arm was pulled back and forth by an electro-magnet, which was responding to the signals sent by the transmitter. Morse developed a key and sounder for his first commercial telegraph in 1844