A cartographer, astronomer, mathematician, physician, and maker of scientific instruments. Fries studied at the University of Louvain, and was appointed professor of medicine there in 1541. His first work on the principles of astronomy and cartography attempted to establish longitude by proposing the use of portable clocks, which would only be vindicated 200 years later. Fries published his first 

’s ‘Cosmographia’ bound with his own ‘Libellus de locorum describendorum ratione’ in 1533. Other works include a 

of Ptolemy's 'Geographia' (1541), and his blockbuster ‘Arithmeticae practicae methodus facilis’ (1540), which was reprinted more than 50 times during the 16th Century.

Colourful upper body painted portrait of Reinerus Gemma Frisius.