We know Mercator's name today because of the projection he devised for his world map of 1569, showing Europe at the centre and the land masses at both poles grossly enlarged to accommodate the curvature of the longitudinal lines on a flat plane. Yet after his revolutionary map appeared, he was preoccupied with more pressing matters, such as preparing a chronology of world history, a revised edition of the maps based on the coordinates of the 2nd century Egyptian Claudius Ptolemy, and a new geography of the world based on his own maps.
Nowhere did he leave a mathematical theory of his discovery and how he had reached it. His projection had been devised to enable sailors to draw a direct line on the map to plot their course, which was impossible with earlier maps. This important discovery appears to have been ignored by them until Edward Wright in England some 30 years later published a set of tables in which he explained Mercator's achievement for both layman and sailor in a masterpiece of clarity and simplicity. By 1630, almost all the charts from the leading school of chart-makers at Dieppe were drawn on the new projection.
Mercator's early life, his studies in mathematics, his thirst for knowledge, his struggles for financial and political security are well discussed here. Throughout his life Mercator struggled to conform yet to adhere to the truth as he saw it. The bare facts of his life are known largely from a hagiographical account written by a friend soon after his death. In Andrew Taylor's book we get a clear picture of the world around him, his escape from the Inquisition after a spell in prison, financial worries and good friendships.
In the modern world, where fewer people practise religion, it is hard to understand what an important role it played in the 16th century. After Mercator's daughter died young from the plague, he wrote an anguished letter to his son-in-law begging for hope that her soul would have been saved. Not only was an outward show of piety essential; people also worried privately about salvation and the afterlife. As Taylor writes: "Science and scholarship were powerless before the awesome and incomprehensible power of God."
There is much new material in his book, the result of wide research, yet it reads easily and provides a good sketch of life in The Netherlands and Germany at the time. Political patronage was needed if a teacher such as Mercator was to succeed and have adequate time and funds to pursue his intellectual interests. He was often away at fairs, selling his globes and maps, gathering information to correct previous errors, corresponding with scholars in other countries, engraving many of the maps himself until his children were able to take on some of the tasks.
"Atlas" is a familiar word now, but not then. In a preface Mercator told the story of Atlas, a philosopher-king of Phoenicia, reputed to have been the first man to design a globe, and how he hoped to follow in the steps of a man "so excelling in erudition, humanity and wisdom, as from a lofty watchtower to contemplate Cosmography..." After Mercator's death the word was used to describe his collection of maps, and, like his projection, has lived on.
Susan Gole is international chairman, International Map Collectors'
The World of Gerard Mercator: The Mapmaker who Revolutionised Geography
Author - Andrew Taylor
Publisher - HarperCollins
Pages - 291
Price - £16.99
ISBN - 0 00 710080 9