Gerard Mercator's scientific library reconstituted

Complementing the virtual sessions of the ICA Commission on the History of Cartography on September 30, 2021

In 2012, we celebrated the 500^th anniversary of Gerard de Cremer (1512-1594), better known by latinized name of Mercator. He is best known for his projection system which he invented and described in 1569 in his map AD USUM NAVIGANTIUM. This projection still today shapes our mental perception of the world, constantly reinforced by its ubiquitous presence from school maps to the media. I was impressed that nobody described how he invented his system. Map historians agree that the system works and described the mathematics behind the system, but nobody described how he invented his system with increasing latitudes. Reading Mercator’s scientific books should help to find out. Thus, I identified some 235 relevant books known to have been in his vast library, which was sold at the first public book auction in Leyden in 1604. I spent the last ten years mainly looking and obtaining these mathematical books, wherever possible the original copies Mercator possessed – some with his annotations – or copies of the same edition. This journey and the showing some of the books originally in Mercator’s library are the content of the presentation.

Jan de Graeve was born in Bruges (Belgium) in 1945 and became a land surveyor and valuer of fixed assets. Within the International Federation of Surveyors (FIG), in 1994, he created a group to study history of his profession. He proposed to put the Struve Meridian Arc on the UNESCO World Heritage list and was instrumental that this succeeded in 2005. With his colleague Jim Smith he wrote an extensive history of the shape and figure of the earth in all civilizations from about 3,000 BC to 1960, published by FIG Foundation in seven volumes. Currently Jan prepares a book on Mercator’s scientific library.