Telegraphs

Any of numerous types of devices or systems that allow the transmission of information by coded signal over a distance. Many telegraphic systems have been used over the centuries, but the term most often refers to the electric telegraph, which was developed in the mid-19th century and was the principal means of transmitting printed information by wire or radio wave for over a century. It consisted of a transmitting or sending instrument and a distant receiving instrument connected by a conducting wire or other communications channel.