Peter Apian (1496-1552) was a sixteenth century German mathematician, astronomer, and instrument maker. His book seen here, Cosmographia, is a treatise on the field of cosmography. Cosmographers tried to mathematically map out the universe and describe the Earth relative to the heavens. It combines the modern disciplines of cartography, navigation, and instrument making.

Apian’s Cosmographia was first published in 1524 and remained popular throughout the sixteenth century, with dozens of different editions published. In 1529, another German mathematician, Gemma Frisius (1508-1555), published an expanded edition of the Cosmographia. Frisius’ expanded edition became more popular and was published more widely than the original work by Peter Apian. This 1584 edition is the expanded version by Frisius.

The practical appeal of the Cosmographia is clear when looking at the four volvelles which were included. Volvelles are paper instruments made of movable parts, typically rotating discs made from paper or vellum, attached at the center with a string or pin. Rotating the discs allows users to align different sets of information, revealing calculated results or other data based on the alignment. With the volvelles in the Cosmographia, readers could solve problems, such as finding the time at different places or calculating one’s latitude, given the height of the Sun above the horizon.