One of the more delicate areas of engineering must be paper engineering – from pop-up books to origami it brings solid physical process and design into the realm of the ephemeral. But beyond delighting children and calming adults, paper engineering has a long history of guiding scientific progress, not least through a small paper device called a volvelle.
The volvelle derives its name from the Latin volvere – to turn. It is a paper device of one or more moveable circles, surrounded by other graduated circles used to calculate various mathematical processes, from the rising of the sun and the state of the tide, to cryptographic code generation and standards conversions. In short, they were paper machines, which could turn the illuminated manuscripts of the Middle Ages into computers.
Mediaeval volvelles usually consisted of parchment circles set into a book, the centre being held in place with a silk thread so the circles could revolve. Who originally...