Gerardus Mercator (; 5 March 1512 – 2 December 1594) was a Flemish geographer, cosmographer and cartographer. He is most renowned for creating the 1569 world map based on a new projection which represented sailing courses of constant bearing (rhumb lines) as straight lines—an innovation that is still employed in nautical charts.
Mercator was a notable maker of globes and scientific instruments. In addition, he had interests in theology, philosophy, history, mathematics, and geomagnetism. He was also an accomplished engraver and calligrapher. Unlike other great scholars of the age, he travelled little and his knowledge of geography came from his library of over a thousand books and maps, from his visitors and from his vast correspondence (in six languages) with other scholars, statesmen, travellers, merchants and seamen. Mercator's early maps were in large formats suitable for wall mounting but in the second half of his life, he produced over 100 new regional maps in a smaller format suitable for binding into his Atlas of 1595. This was the first appearance of the word "atlas" in connection with maps, but Mercator did not intend the word to mean a collection of maps; it was a neologism for a treatise (Cosmologia) on the creation, history and description of the universe. He chose the word as a reference to a legendary king of Mauretania who was traditionally considered the first great geographer.
A large part of Mercator's income came from sales of terrestrial and celestial globes. For sixty years they were considered the finest in the world, and were sold in such numbers that there are many surviving examples. This was a substantial enterprise involving the manufacture of the spheres, printing the gores, building substantial stands, packing and distributing them all over Europe. He was also renowned for his scientific instruments, particularly his astrolabes and astronomical rings used to study the geometry of astronomy and astrology.
Mercator wrote on geography, philosophy, chronology and theology. All of the wall maps were engraved with copious text on the region concerned. As an example, the famous world map of 1569 is inscribed with over five thousand words in fifteen legends. The 1595 Atlas has about 120 pages of maps and illustrated title pages, but a greater number of pages are devoted to his account of the creation of the universe and descriptions of all the countries portrayed. His table of chronology ran to some 400 pages fixing the dates (from the time of creation) of earthly dynasties, major political and military events, volcanic eruptions, earthquakes and eclipses. He also wrote on the gospels and the Old Testament.
Mercator was a devout Christian born into a Catholic family at a time when Martin Luther's Protestantism was gaining ground. He never declared himself as a Lutheran but was clearly sympathetic, and he was accused of heresy by Catholic authorities; after six months in prison he was released unscathed. This period of persecution is probably the major factor in his move from Catholic Leuven (Louvain) to a more tolerant Duisburg, in the Holy Roman Empire, where he lived for the last thirty years of his life. Walter Ghim, Mercator's friend and first biographer, describes him as sober in his behaviour, yet cheerful and witty in company, and never more happy than in debate with other scholars.
Life Early years
Gerardus Mercator was born Geert or Gerard (De) Kremer (or Cremer) in Rupelmonde, Flanders, a small village to the southwest of Antwerp, which was in the fiefdom of Habsburg Netherlands. The seventh child of Hubert (De) Kremer and his wife Emerance, his parents came from Gangelt in the Duchy of Jülich (present-day Germany). At the time of the birth they were visiting Hubert's brother (or uncle) Gisbert De Kremer. Hubert was a poor artisan, a shoemaker by trade, but Gisbert, a priest, was a man of some importance in the community. Their stay in Rupelmonde was brief and within six months they returned to Gangelt, and there Mercator spent his earliest childhood until the age of six. In 1518, the Kremer family moved back to Rupelmonde, possibly motivated by the deteriorating conditions in Gangelt—famine, plague and lawlessness. Mercator would have attended the local school in Rupelmonde from the age of seven, when he arrived from Gangelt, and there he would have been taught the basics of reading, writing, arithmetic and Latin.
School at 's-Hertogenbosch, 1526–1530
After Hubert's death in 1526, Gisbert became the 15-year-old Geert's guardian. Hoping that Geert might follow him into the priesthood, he sent him to the famous school of the Brethren of the Common Life at 's-Hertogenbosch in the Duchy of Brabant. The Brotherhood and the school were founded by the charismatic Geert Groote, who placed great emphasis on study of the Bible and, at the same time, expressed disapproval of the dogmas of the church; both of these points of view were facets of the "heresies" of Martin Luther propounded a few years earlier in 1517. Mercator followed similar precepts later in life, with problematic outcomes.
During his time at the school the headmaster was Georgius Macropedius, and under his guidance Geert studied the Bible, the trivium (Latin, logic and rhetoric) and classics such as the philosophy of Aristotle, the natural history of Pliny and the geography of Ptolemy. All teaching at the school was in Latin; he read, wrote and conversed in Latin, and gave himself a Latin name, Gerardus Mercator Rupelmundanus, Mercator being the Latin translation of Kremer, which means "merchant". The Brethren were renowned for their scriptorium, and here Mercator might have encountered the italic script which he employed in his later work. The brethren were also renowned for their thoroughness and discipline, well attested by Erasmus, who had attended the school forty years before Mercator.
University of Leuven, 1530–1532 From the famous school at 's-Hertogenbosch, Mercator moved to the famous University of Leuven, where his full Latin name appears in the matriculation records for 1530. He lived in one of the teaching colleges, the Castle College, and, although he was classified as a pauper, he rubbed shoulders with richer students, amongst whom were the anatomist Andreas Vesalius, the statesman Antoine Perrenot, and the theologian George Cassander, all destined to fame and all lifelong friends of Mercator.
The general first degree (for Magister) centred on the teaching of philosophy, theology and Greek under the conservative Scholasticism which gave prime place to the authority of Aristotle. Although the trivium was now augmented by the quadrivium (arithmetic, geometry, astronomy, music), coverage of the quadrivium was neglected in favour of theology and philosophy; Mercator undertook further study of the first three subjects of the quadrivium in later years. He graduated as Magister in 1532.
Antwerp, 1532–1534 The normal progress for an able magister was to go on to further study in one of the four faculties at Leuven: theology, medicine, canon law and Roman law. Gisbert might have hoped that Mercator would go further in theology and train for the priesthood, but Mercator did not: like many twenty-year-old young men, he was having his first serious doubts. The problem was the contradiction between the authority of Aristotle and his own biblical study and scientific observations, particularly in relation to the creation and description of the world. Such doubt was treated as heresy at the university, and it is quite possible that he had already said enough in classroom disputations to come to the notice of the authorities; fortunately, he did not put his sentiments into print. He left Leuven for Antwerp, there to devote his time to contemplation of philosophy. The events of this period of his life are uncertain. He certainly read widely but succeeded only in uncovering more contradictions between the world of the Bible and the world of geography, a discrepancy which occupied him for the rest of his life. He certainly could not effect a reconciliation between his studies and the world of Aristotle.
During this period Mercator was in contact with the Franciscan friar Franciscus Monachus who lived in the monastery of Mechelen. He was a controversial figure who, from time to time, was in conflict with the church authorities because of his humanist outlook and his break from Aristotelian views of the world: his own views of geography were based on investigation and observation. Mercator must have been impressed by Monachus, including his map collection and the famous globe that he had prepared for Jean Carondelet, the principal advisor of Charles V. The globe was constructed by the Leuven goldsmith Gaspar van der Heyden (Gaspar a Myrica –) to whom Mercator became an apprentice. These encounters may well have provided the stimulus to set aside his struggle with theology and commit himself to geography. Later he said, "Since my youth, geography has been for me the primary subject of study. I liked not only the description of the Earth but the structure of the whole machinery of the world."
Leuven, 1534–1543
Towards the end of 1534, the twenty-two-year-old Mercator arrived back in Leuven and threw himself into the study of geography, mathematics and astronomy under the guidance of Gemma Frisius. At first Mercator was completely out of his depth but, with the help and friendship of Gemma (who was four years his elder) he succeeded in mastering the elements of mathematics within two years and the university granted him permission to tutor private students. Gemma had designed some of the mathematical instruments used in these studies and Mercator soon became adept in the skills of their manufacture: practical skills of working in brass, mathematical skills for calculation of scales, and engraving skills to produce the markings required.
Gemma and Gaspar Van der Heyden had completed a terrestrial globe in 1529, but by 1535 they were planning a new globe embodying the latest geographical discoveries. The gores were to be engraved on copper instead of wood, and the text was to be in an elegant italic script instead of the heavy Roman lettering of the early globes. The globe was a combined effort: Gemma researched the content, Van der Heyden engraved the geographical features and Mercator engraved the text, including the cartouche which exhibited his own name in public for the first time. The text in the cartouche attributes the production copyright to Mercator. The globe was finished in 1536 and its celestial counterpart appeared one year later. These widely admired globes were costly and their wide sales provided Mercator an income which, together with that from mathematical instruments and from teaching, allowed him to marry and establish a home. He married Barbara Schellekens in September 1536, and Arnold, the first of their six children, was born a year later.
The arrival of Mercator on the cartographic scene would have been noted by the cognoscenti who purchased Gemma's globe – the professors, rich merchants, prelates, aristocrats and courtiers of the emperor Charles V at nearby Brussels. The commissions and patronage of such wealthy individuals provided an important source of income throughout his life. His connection with this world of privilege was facilitated by his fellow student Antoine Perrenot, soon to be appointed Bishop of Arras, and Antoine's father, Nicholas Perrenot, the chancellor of Charles V.