The Theatrum was not a work of original scholarship, and in that word saleable, there is a very human mixture of admiration and something a little less generous—a recognition by the scholar painstakingly creating his own maps that Ortelius's project was both less and more than his own. It had called for no judicious weighing of contrasting claims of accuracy, no balancing of probabilities, and certainly no mathematical wrestling with the multiple dilemmas of projection. Mercator was well aware of the need to produce what people wanted to buy, but his own maps had always gone beyond what was merely "saleable." He praised the shrewdness of Ortelius's business sense as much as his book. The Theatrum was a compendium of other men's maps that had added very little to the sum of knowledge about the world, though it made its publisher a very rich and well-respected man.
As ORTELIUS LUXURIATED in the plaudits he was receiving and counted the profits of successive editions of the Theatrum in English, Latin, Dutch, German, French, and Spanish, Mercator struggled solemnly on in Duisburg with his scholarly edition of Ptolemy's maps.
He had been unstinting in his encouragement of Ortelius's efforts at gathering the best maps of his generation, but he intended to produce a collection of his own work, feeling that only original cartography would be worthy of a place in the Cosmographia. Walter Ghim, loyal to a fault, insisted, "Since this Ortelius was an intimate friend of his, he purposely held up the enterprise he had begun until Ortelius had sold a large quantity of his Theatrum Orbis Terrarum and had substantially increased his fortune with the profits from it."14Truthfully, Mercator's own projected book was simply not ready: Another eight years elapsed before his edition of Ptolemy's maps was printed, and seven years after that before the initial collection of his own, original maps, bound together as the first volume of his atlas, was completed. He was constantly struggling to meet the orders for his terrestrial and celestial globes, the mainstay of his business, and all the time he could spare from his workbench was taken up with his work on Ptolemy. From one year to the next, he struggled through the Geographia, painstakingly constructing maps based on Ptolemy's own instructions. Details of the sources he consulted took up five pages in the book when it was eventually published.
He labored at it with urgency, resenting anything that called him from his desk: "I am so distracted by business that I am slow in finishing Ptolemy, but I do what I can," he told Ortelius in 1575,15 five years after he started. Age and interruptions appeared to conspire against him: In another letter that same year, he wrote wearily: "As I toil alone, I get on very slowly. Other occupations keep cropping up to interrupt this work, but I hope to be able to finish it by the end of the year.""16His timetable was slow, but still overambitious: The book would not be finished for another two and a half years from the date of his letter.
The work took its toll on his health. Some years after the appearance of the Theatrum, Mercator's portrait was engraved by his friend Frans Hogenberg.* Ortelius had asked for the picture, to be included in his Album amicorum, or book of friends. Mercator had been reluctant to supply it—not through any lack of friendship, but because, he explained, "I feel ashamed to parade myself among famous men, as if I were of any importance."17The picture has become the image by which he is remembered, and his diffidence is reflected in its worn and weary features. One hand is laid across a globe, half covering America, the continent that was still, more than eighty years after Columbus's arrival, largely hidden and unexplored, while the other holds a pair of dividers, symbols of the meticulous measurement and calculation that he had brought to the art of mapmaking. Yet his eyes are the most memorable feature of the portrait. Heavy lidded, surrounded by deeply etched wrinkles, they gaze into the middle distance, ignoring the globe in front of him, the eyes of a tired and aging man.
In a letter of 1578 to the emperor's physician, Johannes Crato von Krafftheim,18Mercator referred to a "serious illness" he had suffered some six years earlier. Worse than that, it was already becoming clear that he had set himself an impossible task. Before he could even start work on the next phase of his Cosmographia, he still had to finish his edition of Ptolemy.
The actual research remained his own, as he sifted patiently through the hundreds of different versions, revisions, and improvements of Ptolemy's maps that had been produced over the preceding hundred years; but Mercator was in his sixties and could no longer trust his own hand to carve the delicate lines across the wax-coated copper plates. Not only his surviving sons but also his grandsons, Arnold's children Gerard and Jean—the latter would become official geographer himself at the court of the duke of Cleves—helped him with the engraving. His was truly a family business, almost a dynasty, with Mercator himself at the head of three generations of scholars, but there were never enough workmen at the benches to produce copies of the globes ordered from his workshop, which had to be carefully packed in straw and shipped off. Mercator worked with some of the best craftsmen in Europe, but there were too few skilled engravers to be found in Duisburg, and the growing backlog of work preyed on his mind.
Even the tragic news from Wesel, thirty miles farther down the river, that his daughter Dorothee had died could not distract him. His friends were alarmed at how hard he was driving himself—"You are so deep in your studies that you can't enjoy life, never mind your friends," Vermeulen wrote to him reproachfully.19He ignored their pleas, just as he had ignored the warning breakdown that followed his efforts in Lorraine six years before. "I am continually overburdened with a crowd of different occupations.. . . For three years, I had hoped each term to be able to finish, but as I pressed on, I found more difficulties and problems which I hadn't seen at first," he wrote to a friend, in a letter marking the completion of the edition of Ptolemy in the autumn of 1578, a full nine years after the publication of the map of the world.20 Mercator was sixty-six years old when the new book was published, presenting readers with the most accurate representation of Ptolemy's work that had ever been produced. The maps were precisely drawn according to Ptolemy's coordinates—indeed, if the Geographia had included maps, they would have looked like the ones in Mercator's edition. Camels, elephants, and strange beasts that Herodotus might have described prowled through the interior of Africa, while a winged dragon roared in the Libyan desert. The creator of a new, objective, and mathematical system of geography was demonstrating his skill as a medieval cartographer.
The great atlas that Mercator planned needed these maps to put the modern view of the world into a universal context. He acknowledged that the maps showed the way the world had been imagined, not the way it was—the huge island of Taprobane dominated an Indian Ocean with no India; Africa disappeared off the bottom of the map; there was no America, and no Pacific Ocean—but just as he had traced the story of the Earth from its very beginning in the Chronologia, so in his Ptolemy's Geographia he showed the origin of geographic thought. The maps of Ptolemy were the maps of Mercator's own intellectual history. For the rest of his life, he would concentrate on mapping the world as he knew it to be."
*Charles handed over his possessions in the Netherlands to Philip one year before his formal abdication as king of Spain.
*The wordplay, "Moorderatie, niet moderatie," works better in Flemish than it does in English.
*Van Durme, in his edition of Mercator's letters, suggests that the gift may have been an account of a journey through France and the Low Countries made by Ortelius and his friend, an Antwerp merchant named Jean Vivianus.
*Antonio Lafreri in Rome and Paolo Forlani in Venice are two of several Italian map sellers and publishers known to have produced collections of their wares in the 1560s. Such books were generally designed for individual customers rather than compiled for publication. Portuguese discoveries of the fourteenth and fifteenth centuries had also been recorded in collections of manuscript charts bound together as books.
*The engraving, dated 1574, was later used as the frontispiece for Mercator's atlas.
Chpater Twenty
A "Thick Myste
> of Ignorance" Dispelled
BECAUSE OF HIS INTENSE FOCUS on Ptolemy, Mercator had published no new contemporary maps for almost a decade. Ortelius's Theatrum reflected the scholarly regard in which his world map was held—Mercator was by far the most prolific contributor to the collection— but he had made no significant progress on his Cosmographia or on the atlas of modern maps that was to be its crowning glory.
The maps that Ortelius had borrowed were drawn in the Theatrum, as on the original wall map from which they were taken, according to Mercator's projection, but there was no sign that any cartographers appreciated or even understood what he had achieved. Among sailors— who were specifically mentioned in the title—there was even less comprehension.
In 1576, seven years after publication, the financial accounts for Martin Frobisher's first expedition to the Far Northwest included a provision for the purchase of a printed copy of Mercator's world map—"a great mappe universal of Mercator in prente." It was one of a very few copies to be sold for such use, rather than hung on the wall of a library. Frobisher's accounts were precise about its price—one pound, six shillings, and eight pence'—but the journals are infuriatingly silent about its value at sea. Even though John Dee gave rudimentary instructions in the latest techniques of navigation before the voyage, it is unlikely that any of Frobisher's seamen understood properly how to use Mercator's map.
They were not alone. Four years later, the expert chart maker William Burrough was called in by the backers of yet another English expedition to the North. His role, like John Dee's before him, was to train the shipmasters in modern navigational techniques, but he advised them to stick meticulously to the methods that had been employed by Columbus nearly a century before. They should keep a careful note of their latitude, he said, and do their best to establish their longitude by dead reckoning, with the conscientious use of the hourglass to measure the time—"one, two, three or four glasses at most" between readings. He provided the sailors with simple charts, or plats, and instructions on how they could mark down and map the observations they made, but he warned them of the difficulties they would meet in the polar regions, where traditional charts were so distorted by the failure of mapmakers to allow for the problems of projection.
Burrough, younger brother of Stephen Burrough, who had looked in vain for the people of Cathay along those same frozen coastlines years before, knew Mercator's world map well; he liked to claim that part of it had been based on a map of Russia he had drawn himself. The problem of projection, he said later, had been solved. "These defects of the latitudes have been very well reformed by . . . Gerard Mercator (whom I honour and esteem as the Chief Cosmographer of the World) in his uni-versall mappe."2
Burrough had finally hit upon the way in which the map was truly revolutionary. The new projection of "the famous and learned Gerardus Mercator," he said later, and "the streight lines in sea cardes" which it provided, had given navigators a new way to plot a course. "Such as condemne them for false, and speak most against their use, cannot give other that should serve for navigation to better purpose and effect. Experience (one of the keyes of knowledge) hath taught mee to say it."3
Significantly, Mercator's map had made use of the sailors' portolan charts, dismissed contemptuously by many other scholarly cartographers, as important source material, but his second and greatest innovation tackled the problem that had defeated not just Ptolemy but every cartographer who had followed him. Thanks to his new projection, a navigator could plot a straight course on the map and follow that same compass bearing across the sea.
The problem was that sailors would not use it. Intellectuals like Burrough might appreciate its creator's ingenuity, but there is no evidence that Mercator's map was actually consulted by the navigators Burrough advised in 1580 or by anyone else at sea. As a tool of navigation, which is what Mercator thought he was designing, the map of 1569 was an initial failure. For several reasons, only after another sixty years did maps based on the new projection become standard equipment on oceangoing expeditions.
For all Mercator's stated intention to produce a map fit for sailors to use, the 1569 world map has the look of an academic document, rather than a practical aid to navigation at sea. Its cartouches, notes, and explanations are all in Latin, rather than the vernacular, while the accounts of famous explorers and the allegorical representations of Peace, Justice, and Piety all seem more suitable for a library, not a ship's chart room. In short, the projection worked, but the map didn't.
The lack of interest among professional seamen may have been due partly to their own instinctive resistance to change, and partly to a crucial weakness of the map: Despite the fact that direction could be calculated easily, the distortion of distance that resulted from the projection made it difficult to work out the exact position of a ship. Chart makers, too, were reluctant to incur the trouble and expense of reengraving their plates unless a clear and immediate profit was to be made.
In a triple irony, the map was largely ignored by ships that were pushing deep into the very latitudes where it would have been most useful; designed to be easy to use, it was rejected because it was too complicated; and although aimed at seamen, it was purchased overwhelmingly by intellectuals. Even so, Mercator, remembering his days in the studio of Gemma Frisius, realized he needed to protect his work. He wrote to the emperor Maximilian, who had succeeded to the imperial crown five years earlier, asking for a fourteen-year ban on any copies being made— effectively, the granting of an exclusive copyright—and showed no false modesty about the extent of his achievement. "I omitted nothing by which I could emend geographical knowledge, but I restored everything to its true state . . . not only in regard to the arrangement of meridians, parallels, and compass points (in which our nautical tables have so far been erroneous) but also in the descriptions of shorelines and seas, which have been erroneous in existing maps," he declared.4
Apart from this businesslike concern, he did nothing actively to promote his invention; on the contrary, he never made any detailed attempt even to explain the theory behind it. According to a comment made by Walter Ghim, after Mercator's death, the great geographer could offer no mathematical formula to prove that his projection worked. He simply knew that it did. The projection, said Ghim, was "a new and convenient device, which corresponded so closely to the squaring of the circle that nothing, as I have often heard from his own mouth, seemed to be lacking except formal proof."5
The words were precise—Mercator had indeed transformed a circular world into a rectangle—but from the moment he took the map from his printing press, it appears as though he simply forgot about what would prove to be one of the greatest technical advances in mapmaking, never writing about it further, never even numbering it among his achievements. Only Ghim's comment survives to suggest that he even talked about it with his friends. He had other priorities; as he aged, his great medieval synthesis of knowledge, not his "squaring of the circle,"was what inspired him.
Nearly thirty years after the map appeared, the English geographer William Barlowe, one of the tutors of the young son of James VI of Scotland,6Prince Henry, described Mercator's projection in his book The Navigator's Supply. The imperfections of other charts, he said, were well-known, but there existed a forgotten alternative, "set forth by the excellent cosmographer Gerardus Mercator," that solved all those problems— one which had been kept from widespread appreciation only by the jealousy of other cartographers. "A cloude (as it were) and thick myste of ignorance doth keep (this chart) hitherto concealed; and so much the more, because some who were reckoned for men of good knowledge, have by glauncing speeches (but never by any one reason of moment) gone about what they coulde to disgrace it," he said. Navigators on long voyages, he went on, would find that traditional charts, or cards, could not show places in their correct position, "being yet the very principal point that the navigator desireth." Mercator's map had solved the problem. "No card hitherto invented was ever comparable unto it, neither (as I
think) any that shall be hereafter, will in all respects surpass it."7
In the same year that Barlowe invoked Mercator's projection, an English mathematician, Edward Wright, finally dispelled the "thick myste of ignorance," explained the new system, and produced a series of tables to enable navigators to correct the distortions of distance that it produced.* Wright's book of 1599, confidently titled Certaine Errors in Navigation Detected and Corrected, explained Mercator's achievement for both layman and sailor in a masterpiece of clarity and simplicity. The Earth, he suggested, might be imagined as a partially inflated round balloon, with latitudes and meridians equally spaced around it. If the balloon were placed inside a cylinder so that its equator just touched the cylinder's walls, and then more air were pumped in, its curved meridians would be flattened against the walls of the cylinder. If each line then left an imprint, simply unrolling the cylinder would reveal the impression of a Mercator-projection map on the inside.
More important for navigators, he went farther and worked out how much distortion of distance there would be at each individual line of latitude on the map. All a navigator had to do was measure the latitude of his ship and find the equivalent figure in Wright's tables. With the map alone, a vessel might be almost anywhere on the compass bearing it was following; using Wright's mathematical tables, its position could be calculated with remarkable accuracy. Where Mercator seemed to have lost interest in his own masterpiece, Wright had seen its potential.
Wright admitted he was inspired by Mercator's map; only after viewing it had he spotted the "gross errors and absurdities" of common, non-Mercator, sea charts. Certaine Errors had a map of the world drawn according to Mercator's projection for its title page. At the same time, Wright was jealous of his own achievement in showing how it could be made easier to use. "The way how this should be done, I learned neither from Mercator nor any man els," he added defiantly in the preface to the book, staking out his own claim to mathematical excellence. He had made his own calculations, the mathematician following in the direction that the cartographer had indicated.
The World of Gerard Mercator Page 23