Maps to Accompany the essay
"What Columbus Knew" by Helen Wallis

 

I. Professor Wallis argues that there are two primary issues to consider when discussing Columbus' conception of the world.

A. First one must look at Columbus' conception of the circumference of the globe.

B. Second one must consider Columbus' conception of the size of the oecumene, the continental landmass of Europe, Africa and Asia, in relation to the whole circumference.

C. If one puts Columbus' views on these two issues together, then one can see that he underestimated the circumference of the earth and overestimated the size of the oecumene.

D. Thus, Columbus believed that it would be a short sail from Spain around the world to China.

 

II. In her essay, Professor Wallis explains how Columbus developed his ideas about the size and nature of the world.

 

III. Professor Wallis begins by looking at Claudius Ptolemy and Marinus of Tyre, geographers of the ancient world, who were major authorities in Columbus' calculations. [link on Ptolemy and Marinus of Tyre]

A. Ptolemy and Marinus were particularly important for Columbus in his determination of the circumference of the globe, our first issue of consideration.

B. Though Ptolemy's book Geography (written c. 150 C.E.) had been lost to the west during most of the Medieval period, it was rediscovered during the fifteenth century.

C. When the Geography began to be printed with maps (from 1477 onwards), the world map attributed to Agathodaemon (sometimes Agathodaimon), a contemporary of Ptolemy, became widely known. [link on Agathodaemon]

1. Constructed on a framework of latitude and longitude, the map reveals the extent of the known world in relation to the whole.

2. It shows Eurasia extending through 180 degrees of longitude from Cape St Vincent in Portugal in the west, to Catigara in the Far East.

3. This was a great overestimation, as the true distance is only 100 degrees.

4. The error arose from the fact that Ptolemy had taken the circumference of the earth to be a quarter too small.

5. In correcting Ptolemy, however, Columbus made an even greater error.

a. He preferred the estimate of Marinus, who calculated the oecumene to cover 225 degrees in east-west extent. An even greater error.

b. Columbus then made a further adjustment, arguing that Marinus and Ptolemy had underestimated the size of Eurasia.


IV. The theory of Paolo dal Pozzo Toscanelli, a Florentine doctor and cosmographer, reinforced Columbus's suspicions that the Ocean was narrow.

A. In 1474, Toscanelli had first expressed his views in a letter sent through Canon Fernao Martins of Lisbon to Afonso V, the king of Portugal, who had asked the scholar for information on the shortest route to Asia.

B. In 1481, upon Columbus's request for the same information, Toscanelli sent him a copy of the letter he had sent to Martins, which Columbus transcribed in his copy of Piccolomini's Historia.

C. In this important letter (accompanied by a world chart, which has been lost but reconstructed), Toscanelli argued that the distance from the Canary Islands to Cathay (China) was 5,000 nautical miles.

D. Although this distance was a too far for ships of the era, Toscanelli said the journey would probably be broken by the mythic Portuguese island of "Antillia" and by the "very noble island of Cipango [Japan]," which was a land thought to be "rich in gold, pearls, and precious stones."

E. Of note: There is a much more famous Ptolemaic map of 1482 called the Ulm world map. See it [here].

 

V. When discussing the size of Eurasia, Columbus also relied on Toscanelli, who in turn relied on the narative of Marco Polo and the account by the Venetian trader Nicolo de' Conti of travels to the Far East over twenty-five years in the early fifteenth century.

A. The Genoese world map of 1457, which records the results of Nicolo's travels to Asia has been identified by Sebastiano Crino as probably the work of Toscanelli, but it depicts the sea route from Europe south-eastward to Asia, not the western route which was the subject of the letter and the purpose of the map. It thus could not have been the map sent to Lisbon, with a copy sent later to Columbus.

B. There is no evidence that Columbus saw the Genoese world map, but the achievements of the Portuguese in their search for the route to India, which the map illustrated, were an important influence on his plans.

 

VI. Of course, Columbus' experiences as a mariner and his years in Portugal from December 1476 were the initial impetus for his "Enterprise to the Indies."

A. In an early biography of Columbus, his son Fernando provides what he says is Columbus' first hand account of a voyage beyond Tile (Thule), namely Iceland, in 1477.

1. Although the evidence for this voyage has been contested, the Paris map, c. 1490, with its detailed depiction of Iceland, appears to support Fernando's statement.
[Paris map] [Paris map detail]

2. The Paris map, an anonymous manuscript chart on vellum in the Bibliotheque Nationale, shows the coasts of the Atlantic from Norway to the mouth of the Congo.

3. In the neck of the vellum is drawn a small circular mappa mundi surrounded by nine spheres on the moon and planets. On this mappa mundi Africa is depicted to the Cape of Good Hope and eastern Asia follows Ptolemy.

4. Inscriptions on the map derive mainly from D'Ailly's Imago Mundi and duplicate Columbus' annotations in his own copy. Charles de la Ronciere in 1924 identified the map as by Columbus. Of the various theories put forward today, David Quinn's suggestion that the map was made by Bartolome Colon in association with his visit to England in 1488-89, is the most convincing.

B. Columbus probably sailed to Mina in Guinea in 1481 under Diogo d'Azambuja, or made a trading voyage in 1482-83 or 1483-84.

C. In about 1484, after his return from Guinea he put his proposal for a western voyage to Don Joao II of Portugal. The king referred the matter to his Maritime Committee, the Junta dos Mathematicas. The historian Joao de Barros (1552) reports that the experts 'considered the words of Christavao Colon as vain, simply founded on imagination, or things like that Isle Cypango of Marco Polo...' The proposal was rejected.

D. Columbus moved to Spain in 1485 to seek support from the Catholic sovereigns, Ferdinand and Isabella. The Junta in its meetings at Salamanca in 1486-87 and again at Santa Fe near Grenada in 1491, debated the question of the proportions of land and sea on the terrestrial sphere.

E. Two divergent theories were current concerning the size of the oecumene, both derived from writings of Aristotle.

1. Roger Bacon (c. 1219-92), citing the De Caelo, argued that the oecumene was large in relation to the terrestrial sphere and that 'those who imagine that the region around the Pillars of Hercules joins the regions of India ... are not suggesting anything incredible'. Between Spain and India there was a 'Mare parvum' (small sea). Bacon was accepted by Pierre d'Ailly in his Imago Mundi (Louvain, 1480-83), Columbus' favoured authority.

2. In contrast, Paul de Burgos (1350-1435), a converted Jew, interpreted Aristotle's four elements - earth, water, air and fire - as lying in concentric circles, with water preponderant over earth. He argued that the oecumene could not be greater than half the circumference of the sphere of the water. Spanish cosmographers accepted his ideas.

F. An Italian observer at the meetings, Alexandro Geraldini, pointed out that the Portuguese voyages into the southern hemisphere had disproved Paul de Burgos' theory. The extension of the African continent far to the south indicated a large-sized oecumene, since the land mass was regarded as circular in shape.

G. The discouraging experience of the long navigations down the African coast probably explains why Joao II asked Columbus back to Portugal in 1488.

H. Columbus was present in Lisbon in December when Bartolemu Dias arrived home with his report of discovering, naming and rounding the Cape of Good Hope. [Exploration map]

I. In a postil (note) in Imago Mundi Columbus refers to Dias taking an observation of latitude by astrolabe at the Cape.

J. Dias' success in entering the Indian Ocean explains why Joao abandoned further consideration of Columbus' project.

 

VII. Columbus returned to Spain and had his proposals examined by the Junta of Santa Fe in 1491.

A. There followed a surprising about face on the part of Spanish officials, who had previously dismissed Columbus' ideas.

B. Luis de Santagel, keeper of King Ferdinand's privy purse, presented himself to Queen Isabella and pleaded Columbus' cause.

C. Columbus was recalled and his project accepted. With the Portuguese well on the way to India, Spain had nothing to lose by backing an alternative western route.

 

VIII. As Columbus finally prepared his mission, he may have had (in addition to the Paris map mentioned above) the large world map (c. 1490) done by Henricus Martellus, a German cartographer working in Italy in association with the Florentine map engraver and publisher Francesco Rosselli.

A. The map is marked with degrees of latitude and longitude.

B. Although Martellus follows Ptolemy in many features, he corrects him in depicting Portuguese discoveries round Africa and in opening up the closed Indian Ocean.

C. He extends Asia to include China and marks Cipango 20 degrees to the east of China.

D. The discovery in 1961 of the Martellus map, now in Yale University Library, has solved a puzzle which confounded experts.

E. There is the striking resemblance between the conceptions of Toscanelli and Columbus and the depictions on the globe made by Martin Behaim at Nuremberg in 1492, the earliest extant terrestrial globe.

F. Yet we have no evidence that Columbus and Behaim were collaborators or acquainted.

G. To explain the similarity, authorities such as George E. Nunn conjectured that Columbus and Behaim drew on a common map source.

H. Roberto Almagia speculated that the prototype map was one by Henricus Martellus. The Yale map fits Almagia's concept of the missing map. It appears that Columbus had seen this map, or one very like it, and that Behaim used a copy as one of his main sources.

IX. When Columbus finally prepared to sail, then, we know that his vision of the world was very much like that of Martin Behaim, the map-maker of Nuremberg who made the first known global representation of the world. [the globe] [the globe flat] [the globe/world today]

 

X. What this tells us then, in conclusion, is that:

A. Columbus believed that the world was much smaller than it is. He thought it was around 18,000 miles in circumference, when it is in actuality around 25,000 miles in circumference.

B. Columbus believed that the oecumene, the continental landmass of Europe, Africa and Asia, made up most of the worlds area. That is, he believed that Eurasia covered 200 of 360 degrees in the circumference of the globe.

C. So, Columbus' conception of the world was much like that of Behaim's. He thought the world map looked like Behaims'.

D. Here is a map of Columbus' first voyage as we understand it today.