In 1872, Western Union {by then the dominant telegraph company in the United States} decided to implement a new, secure scheme to enable sums of up to $100 to be transferred between several hundred towns by telegraph. The system worked by dividing the company's network into twenty districts, each of which had its own superintendent. A telegram from the sender's office to the district superintendent confirmed that the money had been deposited; the superintendent would then send another telegram to the recipient's office authorizing the payment. Both of these messages used a code based on numbered codebooks. Each telegraph office had one of these books, with pages containing hundreds of words. But the numbers next to these words varied from office to office; only the district superintendent had copies of each office's uniquely numbered book.
( Tom Standage )
[ The Victorian Internet ]
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