Fifty-two discoveries from the BiblioPhilly project, No. 39/52

Regiomontanus, Tabulae directionum et profectionum; University of Pennsylvania, Lawrence J. Schoenberg Collection, LJS 172, pp. 146–47
Johannes Müller von Königsberg (1436–76), better known as Regiomontanus, was a Central European astronomer whose peripatetic career brought him into dialogue with some of the key humanist thinkers and patrons in the period following the fall of Constantinople in 1453. He was one of the founders of modern observational astronomy; his works exerted a profound influence on Nicolaus Copernicus and were used by Christopher Columbus and Vasco da Gama as navigational aids. As we’ll see, this particular manuscript turns out to be quite closely linked to Regiomonatnus’ activity. But first, some background.