Reinerus Gemma Frisius, aka Fries

Gemma Frisius was a cartographer, astronomer, mathematician, and creator of scientific instruments.

In 1529, Frisius published an edition of Petrus Apianus’s ‘Cosmographia’, which was bound with his own cartographic text called ‘Libellus de locorum describendorum ratione’. In 1533, Frisius created the triangulation method, proposing that portable clocks could be used to establish longitude. One of his greatest works was the book: ‘Arithmeticae practicae methodus facilis’ (1540), which was reprinted more than fifty times during the sixteenth century. Frisius also published a treatise on astrolabes in 1556.

He taught many notable students such as Gerard Mercator, John Dee, and Andreas Vesalius, who went on to leave their marks on 16th century cosmography, geometry, and anatomical medicine.