In the old days, a designer working on an airplane wing handed a bunch of punch cards to the computer operator and waited a week to get back thousands of numbers on fanfold paper.
Before email was popular and mechanical typewriters weren't just for hipsters, the quickest way to make copies of a document was to use a special sheet of paper called carbon paper.
For a month he had worked on these papers, scribbling them during working hours, typing and making carbons on the typewriter at the New York Cafe, distributing them by hand.
The door of Scrooge's counting-house was open that he might keep his eye upon his clerk, who in a dismal little cell beyond, a sort of tank, was copying letters.
Uh, the palimpsest then went through some more tough times, but eventually it ended up at an art auction, where it was bought and then donated to an art museum in Baltimore for conservation and study.
" Very well, then, " said Fudge, now radiant with glee, " duplicate your notes, Weasley, and send a copy to the Daily Prophet at once. If we send a fast owl we should make the morning edition! "