For a brief time in the 1850s the telegraph companies of England and the United States thought that they could (and should) preserve every message that passed through their wires. Millions of telegrams—in fireproof safes. Imagine the possibilities for history!
And for the police.
“Fancy some future Macaulay rummaging among such a store, and painting therefrom the salient features of the social and commercial life of England in the nineteenth century,” wrote Andrew Wynter in 1854. (Wynter was what we would now call a popular-science writer; in his day job he practiced medicine, specializing in “lunatics.”) “What might not be gathered some day in the twenty-first century from a record of the correspondence of an entire people?”
It may not have happened with the telegram, but Andrew Wynter’s general point has turned out to be true: technological advances mean we now record all sorts of passing conversation and communications which is providing future historians with an enormous treasure chest of data (though the practical problems of using it are still formidable).