by Val Ross
It’s not quite what we think of as an atlas — a collection of maps — because it also includes astrological charts. But much of it is recognizable. The Asian panels name such places as “Delly” (Delhi in India) and “Mecho” (Mecca in Arabia) from information gathered from Arab and Italian travelers. One panel shows the camels of Marco Polo’s caravan as it made its way to “Catayo” or Cathay (China).
The mapmakers incorporated scientific elements from the “portulan” (port-finding) charts of Mediterranean sailors. Their map is one of the earliest maps to show a “wind rose” — the circle of points that show where the winds blow from: North, South, East, and West.
By this time, Duarte had died too, leaving the throne to his son Afonso, who was still a child. With no strong ruler, it looked like Portugal would slide back into civil war. The nobles voted to make Pedro the acting king. Like Henry, Pedro was greedy for riches. He started to buy his own maps and send his own caravel boats down the coast of Africa, in direct competition with Henry. Then Pedro was murdered in 1449 by some nobles at Alfarrobeira. Some people whispered that Henry knew about the murder and could have prevented it. Henry certainly failed to protect his brother’s wife and children, who fled for their lives. It’s also suspicious that it took Henry five years to finally organize an elaborate funeral for Pedro.
Meanwhile, young Afonso became king. Around 1457, he commissioned a great Venetian mapmaker, a priest named Fra Mauro, to work on a mappamundi, a map of the world. Afonso’s mappamundi has been lost, but another Fra Mauro map survives — one showing Africa as a continent you could sail around. This was just the encouragement Henry needed.
By now Henry was an old man, with memories of a broken promise to his mother and his failure to prevent the deaths of his brothers Pedro and Fernando. If these memories bothered Henry, it didn’t show in the single-mindedness with which he kept pushing his sailors to explore more African coastline. By 1457, Henry’s sailors had crossed the Tropic of Cancer. Soon after, they reached Cape Verde and that part of Africa where it no longer bulges to the west but starts to curve eastward again.
Showing Henry holding a model of a caravel and looking out to sea, this statue captures the Prince’s obsession with exploration and discovery.
When news came back to Sagres that his sailors were now following the African coast eastward, Henry may have hoped that his expeditions would soon reach the fabulous wealth of India. But he never found out that there was much more land to be discovered before India; he fell ill and died on November 13, 1460.
Henry left no children, yet in a sense fathered many lives. He was the first to organize an expert team of discoverers — shipbuilders, navigators, and mapmakers. And he was one of the first to understand that the urge to perfect existing maps would encourage generations of Portuguese explorers who came after him. One was Bartolomeu Dias, who in 1487 sailed a Portuguese ship around the Cape of Good Hope at the tip of Africa. Ten years later, Vasco da Gama reached India. In 1500, Alvares Cabral was blown off course as he tried to follow da Gama’s route around Africa; he crossed the south Atlantic to discover Brazil. Then there was the greatest navigator of his age, Ferdinand Magellan, a Portuguese navigator sailing under the flag of the Spanish kingdom of Seville. Magellan died in the Philippines, but his expedition was the first to sail round the world in 1522. All these heroic explorers owed some of their achievements to Henry.
But Henry was also father of Europe’s slave trade — tens of millions of human lives wrecked in cruelty and exile. If the ghosts of his brothers haunt Henry’s story, so do theirs.
THE MAPMAKER’S BELIEFS
Gerard Mercator
IT IS THE cold spring of 1544, and Gerardus Mercator, father of six children and one of the most famous names in mapmaking, expects that at any moment his dungeon door will be thrown open. Then he will be dragged out and executed — perhaps burned at the stake — because Queen Maria, sister of the Holy Roman Emperor Charles V, has ordered that her holdings in the Low Countries (modern-day Belgium and parts of Holland) be cleansed of people with suspicious religious beliefs.
As the mapmaker stares at the stone walls of his cell in Rupelmonde Castle, he wonders whether his maps will be used as evidence against him. How can the map of a serious, internationally respected scientist reveal his private beliefs? Easily, in the troubled times of Gerard Mercator. It is a time of terrible religious wars and upheavals, a world where the agents of the Emperor try to enforce loyalty to the Catholic Church by scrutinizing any clue — even the shape of a map — for signs of secret loyalty to the new Protestant forms of Christianity, which are seen as treason against the Emperor.
Mercator knows a secret: maps are never purely scientific. Mapmaker’s select what seems important and leave other things out. Maps always reflect their maker’s beliefs.
The very first map Mercator published, in 1537, was of the Holy Land at the time of the Exodus, showing the Israelites’ route as they fled slavery in Egypt. Where other mapmakers of the time drew tiny figures of slaves passing through the Sea of Reeds pursued by Pharoah’s armies, Mercator had drawn only the Sea’s parted waves — as if inviting the readers of his maps to imagine themselves as the Israelites. Inviting ordinary people into the pages of the Holy Bible to interpret it for themselves — that was what Protestantism was about.
And this isn’t the only map that casts suspicion on the man in Rupelmonde Castle’s freezing dungeon. In his first map of the world, published in 1538, Mercator showed the Earth as if he had split its skin down one side and spread two hemispheres apart like sides of a heart. The heart-shaped projection (map format) is no help to anyone trying to understand the shapes of continents, but it suggests that the world is like the human heart. The Protestant reformer Martin Luther taught that Christians should look into their own hearts to seek God. For a mapmaker to use the world-as-heart design is to play with fire.
Mercator knows all that. But he also knows that his is the great age of geographical discovery, and that never before have the design and making of maps been so exciting.
Gerard Kremer was born in 1512 near the Belgian city of Antwerp. (Kremer is Flemish for “merchant”; he later changed it to its Latin version, Mercator.) With his parents, traveling shoemakers, he lived in a region of market and university towns. The people they met were buzzing with news of the latest discoveries — Portuguese voyages around Africa, and the voyages of Christopher Columbus and John Cabot across the North Atlantic. Just five years before Mercator’s birth, a German monk named Martin Waldseemüller had produced a map of the world labeling the new-found lands “America” and showing them to be a continent. Young Gerard must have figured that mapmaking looked like a more exciting way of making a living than mending shoes.
THE GENIUS OF GEMMA
Finding a way to figure out longitude — that is, how far east or west you were — was a big problem for sailors. Failure to calculate longitude could mean a ship missing a port and a chance to get fresh water; or it might lead the ship to run aground on a rocky coast. In 1533, Gemma Frisius proposed a solution. He pointed out that the world took twenty-four hours to spin around in a circle. If you divided the 360 degrees of that circle into twenty-four parts, you got one hour’s difference for each 15 degrees you moved west or east. So if travelers could compare the time at a fixed point (home port or some internationally agreed-upon starting point) with the time at their present position, they would know how far east or west they were.
Gemma had other ideas about mapmaking too. The flat landscape of the Low Countries where he and Gerard Mercator lived was ideal for the development of new surveying techniques. If you climbed a church tower, you could see roads and canals running in straight lines off into the distance. Gemma described how to survey an area of great size using a method called triangulation. A surveyor would walk the distance between two church towers, A and B, very carefully. Next, he would climb tower A and measure the angle between the sightlines to tower B and a third tower C, or angle BAC
. He’d do the same at tower B, measuring angle ABC. With this information — the length of a base line and two angles — he could calculate the length of the other two sides of the triangle — the distances AC and BC.
A rich uncle paid the boy’s school fees, and Gerard studied calligraphy. He became very skilled at a newly-invented script that sloped gently to the right, was easy to read, and was called “italic.” Gerard also studied engraving and tool-making. And he took mathematics under the brilliant mathematician Gemma Frisius at the University of Louvain.
Gemma was famous, not only for writing books on surveying, but also for designing scientific instruments and globes. Charles V, the Holy Roman Emperor, wanted a Gemma globe so much, he issued royal charters to protect Gemma’s copyright so that the scientist could make him a state-of-the-art version. Gemma couldn’t do this on his own, so he brought in collaborators, including his promising student. Gerard Mercator was hired to write the globe’s place names in his special, elegant italics.
The globe’s face was to be printed on twelve flat pieces of paper and then glued in place. As you know if you have ever tried to wrap a round present with a flat piece of wrapping paper, the result is bunching and mess — unless you trim the paper first. Mercator lettered his map onto twelve separate gores, pieces shaped like elongated footballs, to avoid bunching. Working on this project probably made him think harder than ever about how to represent a round world on a flat map.
The Gemma-Mercator globe of 1535 drew on the latest information from explorers. Decorated with sailing ships and tiny drawings of exotic people, it showed Africa’s shape and length more precisely than any previous map had done. It also depicted more than fifty-five individual place names in the Americas. But it wasn’t that accurate: The Mediterranean looked longer and skinnier (the way the ancient Greek geographer Ptolemy had calculated) than we now know it to be. And the globe featured a huge southern continent, which scientists convinced themselves should exist to keep the planet in balance.
One of Mercator’s sources of information for this polar map of the Arctic was a monk who claimed to have gone there and who said that the top of the Earth was like a giant bathtub drain. “The water rushes round and empties into the earth just as if one were pouring it through a filter funnel,” Mercator wrote. In the drain’s center was a rock, which the map-maker figured was a giant magnet.
Working on the Gemma globe must have made young Mercator feel that his future was fairly secure. Around this time, he married a girl named Barbara Schelleken. Like her husband, she was interested in new religious beliefs. The two of them would end up paying for this interest.
In nearby Antwerp, around the time that Mercator was finishing his first globe, Catholic Church officials arrested the English theologian and printer John Tyndale. One of Tyndale’s crimes was to translate the Bible into English so it could be read by ordinary people, and not just priests. Just a few weeks after Mercator’s marriage, Tyndale was executed for heresy. Because printers were the people who published new editions of the Bible, the whole printing profession — engravers, calligraphers, and cartographers as well — came under suspicion.
Barbara and her husband tried to keep their beliefs quiet and concentrate on work and raising their children. By 1540 they had two sons, two daughters, and so much new information about the latest geographical discoveries that the Gemma globe of 1536 needed to be updated. To drum up sales, Mercator wrote that his new, improved model would have the latest information for “Zipangri” (Japan), “the lowest parts of Africa,” and details about the American interior.
Emperor Charles V was so pleased with Mercator’s globe of 1541 that he commissioned the mapmaker to design a set of surveying and drafting instruments. But the Emperor’s patronage did not stop the agents of his sister, Queen Maria, from investigating Mercator. In February 1544, Barbara heard rumors that her husband was to be arrested for suspicious religious beliefs. She told him to slip out of town. She was alone when she answered the door to the men sent by the same church officials who had executed John Tyndale.
Barbara told them that her husband had gone away on innocent family business, to visit his rich uncle. But the officials tracked Mercator to Rupelmonde and arrested him in the street. Now they had two offences to charge him with: heresy and — because he left Louvain — resisting arrest. He was thrown inside the high, grim walls of Rupelmonde Castle.
All through the spring and summer, Barbara pestered powerful friends in the church and at the university to write the Queen and beg for her husband’s life. Many sent letters, at great risk to themselves. Meanwhile, Barbara was frightened to learn that more than forty suspected heretics were arrested, tortured, and executed in Louvain and Rupelmonde. But after seven months, Mercator was released from Rupelmonde Castle, and back into his family’s arms.
On the Mercator projection shown above, scale and therefore area are distorted more and more towards the extreme north and south. Greenland, for example, is shown to be almost as big as South America. Compare this to the more recent Robinson projection below, which does not exaggerate Greenland and other northern countries so much.
Once you are under suspicion, however, its shadow does not go away. In 1552 the Mercators piled their belongings onto a cart and left Louvain, heading eastward away from Queen Maria’s domains. In Duisburg, under the protection of the Dukes of Julich and Cleves, Mercator and his family settled into a new life. The Emperor sent a welcome commission, asking Mercator to make two new small globes. But Mercator’s interests now lay in finding ways of drawing the round Earth onto a flat surface.
In 1554, Mercator produced a great map of Europe that used a grid of best estimates of latitude and longitude. This map portrayed the Mediterranean more correctly than before, trimmed down in size (the trouble with maps is that they often force you to correct your notions of what you thought was big and important in the world).
Since his imprisonment, Mercator took care that his maps would not endanger his family. His maps from the 1550s acknowledged the Catholic Church’s power, prominently marking the Catholic Church headquarters at the Vatican in Rome. And wherever a small city had a bishop, he made it more prominent than a larger city that had no Catholic leader. The map’s subtle message was that the power of the Church trumps political power.
THE MERCATOR PROJECTION
Mercator knew that sailors who depended on their compasses for long ocean crossings had a problem. If you placed a compass on the surface of a globe and then tried to steer a straight line along the compass bearing, you would spiral slowly but inexorably towards one of the poles. On long journeys, sailors had to constantly correct their compass bearings. How could these curving lines be made straight on a map?
Mercator’s breakthrough was to make the lines of longitude — which converge toward the poles on a globe — parallel on a flat map by distorting the distances between them. His strategy makes scale, and therefore area, inaccurate, but it preserves shape and direction.
Shown here on the right with Mercator on the left, Hondius honored Mercator among the classical giants of mapmaking.
Yet Mercator could no more abandon science than he could face jail again. In 1569 he brought out the world map for which he is famous, with the projection that bears his name. The Mercator Projection stretches wide the top and bottom of the Earth’s round surface in order to make lines of longitude run parallel and to have them meet lines of latitude at right angles in a neat grid.
The Mercator Projection was enough to assure Mercator a reputation as one of the giants of cartography. But there was more. In his seventies and early eighties Mercator worked with his sons on a book of maps. The title was the old mans idea, borrowed from the Greek myth about Atlas, the giant who holds up the sky on his broad shoulders. When the first Atlas was published two years after Mercator’s death at age eighty-two, it carried affectionate and respectful tributes by many friends — merchants, map collectors, even his competitors. Here’s another tribute — until
the middle of the 20th century, sailors were still doing most of their calculations using Mercator’s projection. Some still do.
THE MAPMAKER’S FAMILY HONOR
The Cassini Family
IN THE YEAR 1682, a group of scientists led by Abbé Jean Picard and Jean-Dominique Cassini assemble at the Royal Observatory in Paris to meet France’s King, Louis XIV The mapmakers look very grand — it is the age of plumed hats and shoulder-length wigs — but they are as nervous as students before a test. They are about to reveal the map they have worked on for more than twelve years — the first complete map of France drawn by triangulation from an accurately placed meridian (line) of longitude measurements, cross-checked on sightings of the stars — to the most powerful monarch France has ever known.
Louis XIV known as the Sum King, is such a stickler for formality, he makes his courtiers bow to the royal dinner when it passes them on a tray. He takes his own glory and power very seriously. And the mapmakers know their map is about to challenge both.
The Observatory doors are flung open. The courtiers swan in, followed by His Majesty. The scientists sweep off their hats and bow very low, trailing their plumes across the floor. The Sun King walks slowly over to the table on which the new map is laid out beside the old.
His long-nosed face creases into a frown of displeasure, for the new map shows that, compared to the old image of France, His Majesty’s domains do not extend nearly so far into the Atlantic or the Mediterranean. In fact, France appears to have shrunk.
Does the Sun King feel the urge to cry, “Off with their heads”? If so, his need for accurate maps — to build roads and canals to increase trade, and to enrich (and tax) his people — suppresses it. Looking up, His Majesty complains, “Your survey has cost me more territory than a war.” Then he orders his royal mapmakers to carry on.