If a book had been sent to a printer over 30 times and published in 14 different languages during the early 16th century, it must mean that a lot of people wanted to get their hands on it. Peter Aspian’s Cosmographia, published in 1524, had this level of success. His book gave readers instructions in astronomy, geography, cartography, navigation, and instrument-making. It also included moveable paper volvelles such as this one. A volvelle, or wheel chart, is an early example of a paper-based computer which used rotating paper discs to help readers calculate information. A volvelle in an astronomy book may have enabled the user to determine the position of the sun at a given time during the year. Other volvelles provided information about the phases of the Moon and the movements of the planets.