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Age of Discovery and Exploration




After this assignment, you should be able to define and discuss the following terms:

  • Prince Henry "The Navigator", Christopher Columbus, Eratosthenes, Marco Polo, Queen Isabel of Castile, Vasco da Gama, Amerigo Vespucci, Ferdinand Magellan

You should also have been considering the following matters:

  • Why did the Portuguese undertake sea-exploration?
  • How could the medieval Europeans have been so sure that the Earth was a sphere?
  • How did Eratosthenes determine the distance around the Earth?
  • Why did Columbus believe the traditional ideas about the distance around the Earth were wrong?

You might also think about some matters that we have not addressed directly:

  • If so many people already knew of the existence of land to the west, what made Columbus' voyage of discovery significant?
  • What caused this burst of activity that we call The Age of Discovery and Exploration?
  • Were there other "voyages of discovery and exploration" going on within Europe?


The diet of the Europeans in the middle ages was pretty bland. At least they thought so, and they were willing to pay a high price for aromatic spices brought in from the East. Cloves, tamarind, mace, cinnamon, allspice, nutmeg, saffron, white and black pepper, anise, and even sugar coming from India and Indonesia provided the trading goods that led to a great network of trading routes that spread throughout the Eurasian and African continent. Europe was at the Western end of this network, and, after passing through so many hands, the spices that arrived there were quite costly. The merchant-states of Italy -- Genoa, Pisa, Venice, Naples, Palermo -- had established trading posts in the eastern Mediterranean and along the coast of the Black Sea, and it was they who carried the spices on the last leg of their journey to Europe and it was they who sold those spices at a high price and for a great profit.

Many of the other European states envied the Italian city-states, especially because purchasing spices drained their economies of gold and silver. In the mid- fifteenth century, the Portuguese government decided to try to bypass the Italians and other middle men, and to find an all-water route to the source of those spices. Under the direction of Prince Henry "The Navigator" (1394-1460), well-planned expeditions were sent southward annually from 1418 to explore the African coast and to establish forts and trading posts along its extent. By 1444, they had reached Cape Verde and had built up a thriving trade in gold, ivory, and other goods. In 1487, Bartolomeo Dias rounded the Cape of Good Hope, and it became clear that the sea-lanes to India were clear.

Spain was not happy at the prospect of its small neighbor gaining control of a trade that would make it the richest kingdom in Europe, but there was little the Spanish rulers could do about it. They were getting ready to mount a campaign to drive the Muslims from the last bit of territory they had taken from the Christians almost eight hundred years before, and they had very little money to invest in anything else. This is where Christopher Columbus comes in. There are a lot of misconceptions about Columbus that it would be well to clear up. The most common misconception is that Columbus believed that the world was round and that everyone else thought it was flat.

As a matter of fact, everyone knew that the Earth was a sphere. Kings were normally portrayed, on coins and elsewhere, holding stick and a ball. The stick is the scepter, and the ball is the orbis terrarum, the symbol of "sphere of the earth." The little cross at the top marks the location of Jerusalem and the T- shaped bands represent the division of the continents of Africa, Asia, and Europe.

What's more, most educated Europeans had a pretty good idea of how large the earth was. That had been rather ingeniously determined in about 240 BC by Eratosthenes, a scholar at the Library and Museum in Alexandria.

Some distance south of Alexandria, there was a very deep and very straight well, so deep, in fact, that sunlight reached its bottom only at noon on one day of the year. Eratosthenes saw that the well must be pointing directly toward the center of the Earth and so the sun was exactly above that well only at that one time during the year. He figured that the sun was so far away that its rays were just about parallel when they reached the Earth, and that noon would come at the same time as at the well at any spot directly north or south. So he set up a tall and straight pole some distance north of the well, balanced so that it, too, pointed toward the center of the Earth. He then waited until noon and then measured the length of the shadow cast by the pole.

Things were pretty straightforward after that. He knew the height of the pole and the length of the shadow, so he had two sides of a triangle, and the pole was perpendicular to the Earth's surface, so he had a ninety degree interior angle. That made it easy to calculate angle A, formed by the pole and the sun's rays. Knowing that, when a straight line crosses two parallel lines, the opposite angles formed are equal, he then knew what the angle was between his pole, the center of the earth, and the deep well. Since he knew the distance between his pole and the deep well, he knew that distance had the same relationship to the distance around the Earth as angle A had to the circumference of a circle. Quod erat demonstrandum.

A century before, A Venetian merchant by the name of Marco Polo had travelled to China and back, and had left a detailed account of his journeys, so people had a pretty good idea of how far it was from Europe to China and India. It was not hard to subtract that distance from the circumference of the Earth and realize that you would have to sail West a long way to get to India.

So where does Columbus come in? Columbus was an experienced navigator from the Italian city of Genoa who had been studying geography and old travel accounts, including that of Marco Polo, for some time. He had come up with the strange idea that the Earth was not round, but shaped like an egg, that the ancient geographers had measured it the long way around (from north to south), and that its circumference was much less when measured from east to west. His figures showed that it was a relatively easy sail from the Canary Islands (where there was always a favorable wind blowing west) to India.

There were a number of very good reasons for considering his theories about the shape of the Earth to be more than a bit crackpot, but most people who were interested in such things knew that there was some big land mass not all that far to the west. The Vikings had explored some of the coast of North America in 1000, and had established colonies in Greenland, Newfoundland, and islands in the estuary of the St. Lawrence River, colonies that endured for a long time. What is more, the Vikings had composed accounts of these explorations and settlements, accounts that were relatively well-known, at least in northern Europe and Iceland. Besides, the sea around the St. Lawrence estuary (the Grand Banks was teeming with marine life, and Portuguese cod-fishers and Basque whalers had been hunting those waters (and setting up processing stations on shore) for many years. The Europeans knew of this land-mass, but most were certain that it was neither China nor India.

Nevertheless, Queen Isabel of Castile was willing to take a gamble, even if it was a long-shot, to try to beat the Portuguese to the riches of the Orient. She gave Columbus three old and leaky ships -- the smallest no bigger than a modern life-boat -- and emptied a small-town jail to provide him with a crew. He proceeded south to the Canary islands, refitted his little ships, took on supplies, and then caught the westerly winds on 6 September 1492. He landed on one of the islands of the Bahamas on 12 October, a voyage of a little over five weeks. After some exploration and leaving a small fort and garrison behind, he returned to Spain. He landed on 15 March 1493 and announced that he had reached India. Not too many people believed him, but it was enough for Spain to ask the pope for an injunction against the Portuguese continuing to sail east into what the Spanish claimed was now their territory.

This diplomatic wrangling did not last long, however, and, in 1497, a small Portuguese fleet under the command of Vasco da Gama made a round trip from Lisbon to Calcutta and return. In the same year, John Cabot, of England, explored the coast of North America. In 1501, a Portuguese expedition commanded by Amerigo Vespucci, from the Italian city of Florence, explored the South American coast. Vespucci later published his conclusion that this western land-mass was a great continent, and geographers soon began calling this continent America. Finally, in 1519-1522, a Spanish fleet under the command Ferdinand Magellan managed to sail completely around the world.

In the years that followed, European fleets -- first those of the Spanish and Portuguese, and then those of the French, English, and Dutch -- gained control of the world's sea-lanes. Where the local population was dense, they established fortified settlements on islands of the coast, but where the local residents could not effectively defend themselves, they moved inland along the rivers to establish colonies to exploit the rich resources of what was essential virgin land.



There is a text outline of the age of discovery and exploration that will provide you with an overview of the period and movement. The Discoverers Web Homepage offers a number of links to full discussions of several things upon which we have only touched. Finally, the Library of Congress has mounted a major exhibit, called 1492, that will be well worth your while to see.


If you have the time, you might want to get an early start in visiting Expo98, this year's world's trade fair, being held in Lisbon, Portugal, and dedicated to The World's Oceans. The site is still under construction, but is fun to explore. Be sure to see The Portuguese Pavilion, which will feature the Portuguese contribution to opening the world's seaways. You can find out a great deal about the knowledge of geography in the time of Columbus by visiting the exhibit Expanding Horizons.

This text was produced by Lynn H. Nelson,
Department of History,
University of Kansas.
12 January 1998
Lawrence KS