One of the great and generally unsung wonders of the modern world is the array of submarine cables that knit together continents, carrying everything from news and fiscal transactions to this very text. Up until 170 years ago, messages between America and Europe moved at the speed of ships. For centuries this hadn't been different from anywhere else. Messages had always moved only at the speed of people carrying them, with only very limited exceptions. Signal fires and flags could be used to convey a message if the recipient could see the sender, but these messages tended to be simple and with extremely rare exceptions couldn't go over the horizon.1 It wasn't until 1792 that the first large-scale system for moving messages faster than a horse was created, when the Revolutionary French government built a system of towers with arms on top that could pass complex messages across France in hours rather than days. Similar systems were built in other countries, but building and maintaining a tower every 5-10 miles was expensive, it only worked in daylight and the need to repeat the message so frequently made it somewhat prone to error.

A French optical telegraph
The discovery of electricity, and the realization that it moved through wires far faster than anyone could measure, quickly sparked interest in using it to send signals. A number of different efforts were made, although most were hindered by attempts to send each letter separately and unambiguously, which in turn meant lots of wires and complex machinery. The first commercial electric telegraph was of this type, but it was an American painter, Samuel Morse, who finally devised a truly practical system. Morse's great innovation was less in what he did than what he didn't do. Instead of multiple wires and complicated equipment, he used a single wire2 and a manually-operated "key" to start and stop the flow of current, relying on a trained operator and a code he had devised to send and receive messages.3 Read more...





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