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An electrical telegraph was independently developed and patented in the United States in 1837 by Samuel Morse. Morse's first telegraph receiver made from a modified canvas stretcher. The original receiver was an electromagnet which actuated a pencil pressing down on a moving strip of tape. Each pulse from the sender made the pendulum swing. The paper tape then showed a series of sawtooth marks that corresponded with the ridges of the original slug and the message could be deciphered from the paper strip. Morse's original plan did not include a key. Instead, he copied the early printer's use of a composing stick. Slugs of metal wire were ridge along one face and each slug represented a letter. The entire message was mounted in a line of slugs and pushed along beneath a wooden finger that made and broke the circuit. His original code was too complicated to be memorized.