The Use of Visual Media in Renaissance Cosmography: the Cosmography of Peter Apian and Gemma Frisius

Peter Apian's Cosmography (1524) first reached a large audience through the re‐editions of the Leuven mathematician Gemma Frisius. The book seems to have been intended as a didactic tool for use in a largely auto‐didactic and non‐institutionalised context. This disciplinary situation entailed the necessity of legitimation, which was partially attained by visual reference to instruments, available from the cosmographer‐instrumentmaker. Realistic depiction as well as explicit references to linear perspective painting were important means of reinforcing the rhetorical strength of these references. A second consequence of cosmography's educational context was the necessity of efficient didacticism. Because most of the (astronomical) subject‐matter of the Cosmography draws on visual thinking, powerful visual information was equally essential from this perspective. This was implemented in paper derivatives of common astronomical instruments included in the book itself. These at once enabled readers to train themselves in the use of various instruments and—because of the visualizing nature of these instruments as such—to become acquainted with specific aspects of astronomical visual thinking.